TO Category:
Locksmith work - general
Basic plumbing operations and their purpose
Locksmith operations are related to the processes of cold metal cutting. They are carried out both manually and with the help of a mechanized tool. The purpose of locksmith work is to give the workpiece the shape, size and surface finish specified by the drawing. The quality of the locksmith work performed depends on the skills of the locksmith, the tool used and the material being processed.
The metalworking technology contains a number of operations, which include: marking, cutting, straightening and bending of metals, cutting metals with a hacksaw and scissors, filing, drilling, countersinking and reaming holes, threading, riveting, scraping, lapping and finishing, soldering and tinning , bearing casting, bonding, etc.
In the manufacture (processing) of metal parts by the locksmith method, the main operations are performed in a certain order, in which one operation precedes the other.
First, locksmith operations are performed to manufacture or correct the workpiece: cutting, straightening, bending, which can be called preparatory. Next, the main processing of the workpiece is performed. In most cases, these are cutting and sawing operations, as a result of which excess
layers of metal and it receives the shape, dimensions and condition of the surfaces, close or coinciding with those indicated in the drawing.
There are also such parts of machines, for the processing of which the operations of scraping, grinding, finishing, etc., are also required, in which thin layers of metal are removed from the manufactured part. In addition, during the manufacture of a part, it can, if necessary, be connected to another part, together with which it is subjected to further processing. For this, drilling, countersinking, threading, riveting, soldering, etc.
All of these types of work relate to the main operations of locksmith processing.
Depending on the requirements for finished parts, additional operations can also be performed.
Their purpose is to impart new properties to metal parts: increased hardness or ductility, resistance to destruction in the environment of gases, acids or alkalis. Such operations include: tinning, enamel coating, hardening, annealing, electrohardening, etc.
When determining the sequence of processing, it is taken into account in what form the parts (blanks) arrive; coarser processing always precedes the final (finishing).
Fitting and assembly work at a machine-building enterprise is a set of operations for connecting parts in a strictly defined sequence to obtain a mechanism or machine that meets the requirements for them. technical requirements. When assembling, all the main types of locksmith work are used, including fitting the assembled parts into assemblies, followed by adjustment and checking the correct operation of mechanisms and machines. The assembly quality of the machine affects its durability and reliability in operation, since the fewer errors are allowed during assembly, the greater the performance and the better specifications machines and mechanisms.
Maintenance and repair work is aimed at maintaining the efficiency of the equipment. Repair of equipment is carried out at enterprises primarily in order to eliminate defects in machines that impede their normal operation. Worn parts are replaced during repair with new ones or restored to their original dimensions in various ways.
Technological progress and related equipment of enterprises the latest technology, as well as the introduction of advanced technology into production processes, impose new requirements on existing equipment, therefore, along with the repair of machines at plants and factories, a lot of work is being done to modernize (update) it. Modernization of equipment is aimed at increasing the speed and productivity of machines, the power of their engines, reducing the time of idling and auxiliary operations, creating a narrow specialization, as well as expanding technological capabilities. certain types equipment and improve the wear resistance of machine parts. Work on the modernization of equipment is carried out at the plant according to a specific plan.
The volume of locksmith processing to a large extent characterizes the technical level of the technology used and depends on the nature of production. At machine-building plants that produce heterogeneous products in small quantities (single production), the proportion of locksmith work is especially large. Here, the locksmith is obliged to perform a wide variety of locksmith work, that is, to be a universal locksmith. If necessary, he repairs and installs machine tools, manufactures fixtures, etc.
IN serial production, where homogeneous parts are manufactured in large batches, the accuracy of machining increases and, accordingly, the volume of locksmith work decreases somewhat. The work of locksmiths continues to be necessary even in mass production factories, where homogeneous products are produced in large quantities and for a long time (a year, two, etc.).
In all factories and factories, regardless of the type of production, locksmiths are needed for the manufacture of dies, fixtures and tools, for repairs and installation industrial equipment, sanitary works, industrial ventilation, etc. You can’t do without locksmiths in a modern agriculture; here they repair tractors, combines and other equipment.
Many defects of machines entering repair enterprises are well studied and systematized in a typical repair technology. This technology has been developed for most tractors, combines and agricultural machines. It indicates the methods of restoring parts, the tool used for this, the specifications for the repaired parts. However, it is simply impossible to foresee all the cases that may occur in the practice of repair. Sometimes the necessary tool or material may not be available, sometimes it becomes possible to apply a simpler and more reliable repair method.
The repairman must be a generalist. In addition to the ability to perform all general plumbing operations, he must know the rules for the production of dismantling and assembly work, be well versed in the drawings of machine parts and assemblies, designations of tolerances and landings, know the basic mechanical properties of metals and other repair materials, have an idea about the repair process.
1.Technological repair process
The technological process of repairing a machine consists of a series of sequential operations that differ from one another in the nature of the work performed and the equipment used. However, many repair operations are similar to each other. For the production of the same type of technological operations at repair enterprises, special jobs are organized. They are equipped with machine tools, stands, fixtures, instruments and other equipment for disassembling, restoring parts and assembling machines and their components.
The main element of the technological process is an operation performed at one workplace and covering all the actions of the working (or working) and used equipment on one or more jointly processed, disassembled or assembled products. In addition to technological, in the repair industry there are also auxiliary operations: transport, washing, quality control, marking, etc. Technological operations are divided into transitions, passages and receptions.
The transition is a part of the operation, characterized by the invariance of the machined surface (or mating surfaces during assembly), the tool used and the operating modes of the equipment.
Pass - part of the transition, in which one layer of material is removed.
Reception is a complete set of individual movements of a person working in the process of performing an operation (for example, when drilling a hole in a product, the methods will be: fixing the product on the machine table, turning on cr.li ;, approaching the drill to the product, turning on the feed, turning off the feed, retracting the spindle, turning off machine, product release). different nature, complexity and precision. The quality of repair operations is directly related to the qualifications of workers and the equipment of repair enterprises with equipment, fixtures and tools.
1.1. Basic plumbing operations
The main general plumbing operations include: marking, cutting and cutting, straightening and bending, filing, drilling and reaming holes. Some of them, for example, marking products and drilling holes, the locksmith performs at specially equipped general workplaces for this purpose, and the rest at his individual workplace, where he also cuts threads, scrapes, and solders.
The rational organization of the locksmith's workplace allows for the highest productivity, good quality and safe working conditions with the least expenditure of effort, time and money. It is important to properly equip the workplace and observe the established order on it once and for all.
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Basic plumbing operations - Other
Basic plumbing operations
EAT. Muravyov, Plumbing, Moscow, "Prosveshchenie" 1990, pp. 43-94
Basic plumbing operations
marking, cutting, straightening and bending of metals, cutting of metals, filing, drilling, countersinking, countersinking and reaming of holes, threading, riveting, lapping and finishing, soldering
Workplace- locksmith's workbench
It is customary to call a workplace a certain section of the workshop, designed to perform certain work.
Rybins - removable wooden gratings installed on top of the deck.
A clamp is also called a screw clamp.
Chair vise.
Advantages - simplicity of a design and high durability. The disadvantage is that the working surfaces of the jaws are not parallel in all positions.
Rotary parallel vise.
The advantage is the possibility of a tighter clamping of the workpiece. In addition, you can fix at a certain angle.
A hand vise is used to secure small parts or workpieces that are inconvenient or dangerous to hold with your hands.
Marking tool
The operation of drawing small dots-depressions on the surface of a part is called. The point, axis of symmetry or plane from which all dimensions on the part are measured is called the marking base.
markup
The operation of drawing lines and dots on a workpiece intended for processing is called marking. The marking consists in drawing lines (rises) on the surface of the workpiece, which, according to the drawing, determine the contours of the part or the places to be processed.
Scribers are used to draw lines (marks) on the marked surface of the workpiece.
A center punch is used to apply recesses (cores) on pre-marked lines.
Marking (locksmith's) compasses are used for marking circles and arcs, dividing circles and segments into parts, and other geometric constructions when marking a workpiece.
Calipers
Caliper - a measuring (measuring) tool used in plumbing to remove and transfer the dimensions of a part to a scale
Goniometers
Used to measure angular values
Measuring tool
The measuring ruler is used for rough measurements
Straightening and bending
Editing - the operation of returning curved or bent metal products to their original straight or other shape. Giving the metal a certain configuration without changing its cross section and metal cutting is called flexible bending thin sheet metal produced with a mallet. For parts that are bent at right angles without rounding on the inside, the bending allowance of the workpiece should be 0.6 ... 0.8 of the metal thickness.
metal cutting
A percussion instrument consisting of a metal head, a handle and a wedge is called a hammer.
metal cutting
With the help of cutting, metal irregularities are removed (cut down) from the workpiece, hard crust, scale, sharp edges of the part are removed, grooves and grooves are cut, and sheet metal is cut into pieces.
For cutting profile (cutting) grooves (semicircular, dihedral, etc.), special crosscuts are used - groovers, which differ from each other in the shape of the cutting edge.
metal cutting
Hand shears - the simplest tool for cutting metal
Punches (notches)
Locksmith's tool, which is used for punching holes in sheet or strip metal or non-metal materials with a thickness of not more than 4 mm
Pipe cutters
Cutting steel pipes relatively large diameters - the operation is laborious, therefore, special pipe cutters are used to perform it.
filing metal
Sawing - the process of removing the allowance with files, needle files and rasps
sharpening machine
Drilling, countersinking, countersinking and reaming
Drilling consists in obtaining and processing holes by cutting with the help of a special tool - a drill.
3e, the upper surfaces of the hole are machined in order to obtain chamfers or cylindrical recesses, for example, under a countersunk head of a screw or rivet.
Countersinking processes holes obtained by casting, stamping or drilling to give them a strict cylindrical shape, improve accuracy and surface quality.
scraping
scraping
The process of obtaining the accuracy of shapes, sizes and relative position of surfaces required by the working conditions to ensure their tight fit or tightness of the connection
Lapping
The removal of the thinnest layers of metal by means of fine-grained abrasive powders in a lubricating medium or diamond pastes applied to the surface of the tool is called.
To make accurate measurements, calipers are used. The caliper tools include a caliper, a caliper gauge, a caliper depth gauge, a caliper gauge.
There are three types of calipers: SC-I, SC-II, SC-III. The divisions marked on the bottom of the caliper slider are called vernier.
Linear measurements
Micrometers
Micrometer
A universal tool (device) designed for measuring linear dimensions by the absolute or relative contact method in the area of small sizes with a low error (from 2 microns to 50 microns, depending on the measured ranges and accuracy class), the converting mechanism of which is a screw-nut micropair.
Micrometer scale
Micrometer instruments allow measurements with an error of up to
0.01 mm (6.035)
Diametric expansion of the ends of the pipes to the outside in order to obtain a tight and strong press connection of the ends of the pipes with holes.
Soldering - the process of creating a permanent connection of metals using a filler binder
Tinning - coating the surface of metal products with a thin layer of tin or a tin-based alloy
Threading
Thread types
Metric thread - with a pitch and basic thread parameters in millimeters and a profile angle at the top of 60 °.
Inch thread - with basic thread parameters in inches, pitch in the number of threads per inch and a profile angle at the top of 55 °.
Pipe thread - with the main thread parameters in inches, a pitch in the number of threads per inch and a profile angle at the top of 55 °, designed to connect pipes, fittings and structural elements with pipe threads.
Dial indicator
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Basic plumbing operations.
Locksmith profession.
Locksmith work is usually understood as work performed by hand and mechanized tools and completing the manufacture of most products through fitting and finishing work, connecting various parts into assembly units, kits and complexes and adjusting them.
Assembly fitters assemble various machines and mechanisms. Maintenance and their repair during operation is carried out by repairmen. Locksmiths - toolmakers provide production with the necessary tools, facilitate and improve machining. Locksmiths for the installation of equipment, instruments, communications securely install them and the proper place, let down different kinds energy and necessary for the production of basic and auxiliary materials. All these workers are united by the ability to perform various plumbing operations. This is what they learn in the general locksmith course.
The degree and type of professional training, the availability of knowledge, skills and abilities and the suitability to perform work of a certain content and complexity determine the qualifications of the worker. It is estimated by the tariff category, which is assigned to the worker by the qualification commission. The basis for this is the qualification characteristic given in special, tariff-qualification reference books. It states that the worker ʼʼshould be ableʼʼ and what ʼʼshould knowʼʼ to obtain the appropriate tariff category in their specialty.
Basic plumbing operations.
Consider the basic plumbing operations using the example of processing simple parts - a guide key (Fig. 1). Like wine from the drawing, all surfaces of the key are machined, it has three holes: two stepped fixing screws and one with a thread.
The key is made of keyed steel - a bar of rectangular section. To obtain a workpiece of the desired length, markings are made - lines are applied to the surface of the circle with a scriber, which determine the shape and dimensions of the part. Next, a chisel (the operation is commonly called cutting) or a hacksaw (cutting) separates the workpiece. During the cutting process, the workpiece must be bent. She needs to be corrected. Often it is required to perform the opposite work: to bend a workpiece that has a complex shape. Then perform bending.
It is impossible to obtain the correct shape of the surfaces of the part and the specified dimensions with the listed operations. Οʜᴎ are preliminary, procurement. Their goal is to prepare the workpiece for further processing, to ensure and accelerate it by removing large layers of metal. To give the key the desired shape and size, the workpiece is cast. A hole ø 11 mm and for M10 thread is obtained by drilling, and a local expansion of the hole size up to ø 17 mm is drilled. The thread in the drilled hole is cut with a tap. When the hole must have exact dimensions, it is deployed. Except
considered, there are other operations: sawing and fitting - obtaining holes of complex shape and very precise processing of two parts to be joined; scraping and lapping - precise final operations that ensure high accuracy, tightness of joints; riveting, soldering and gluing are operations that allow parts to be joined together to form permanent joints.
As can be seen from the foregoing, all operations for the manufacture of any product must be performed in a certain
sequences. Together they make technological process detail processing.
referatwork.ru
Basic plumbing operations.
Locksmith department.
| date | watch | The content of the classes. | Material support. |
| Theoretical part: General information: the importance of metalwork and metalwork and assembly work in the national economy. The concept of surface roughness and surface treatment. Sketches of products and blanks. Organization of the locksmith's workplace - typical equipment, working and measuring tools. Locksmith operations: marking, bending, cutting, cutting material. Practical part: Safety briefing. Preparation and equipment of the locksmith's workplace for this cycle of operations. Requirements for the working tool. The study of the elements of working drawings of products and blanks. Preparation of blanks for marking, straightening, straightening, bending, cutting, cutting blanks. Making hooks for hangers. | Locksmith's workplace. Journal of safety briefing. Files, calipers. | ||
| Making a chisel. | Files, calipers. |
Report in practice.
Locksmith's workplace equipment.
In metalwork workshops and on sites the equipment of individual and general use is located. Equipment for individual use are workbenches with vise. General use equipment includes: drilling and grinding machines, marking and checking plates, dressing plate, screw press, lever shears.
A vice is used to install and secure workpieces in a position convenient for processing.
The locksmith's working tool is divided into:
· Manual.
· Mechanized.
A typical set of hand tools for metalwork is divided into four groups:
1) cutting tool - files, hacksaws, chisels, drills, taps, dies, scrapers, reamers, abrasive tools;
2) auxiliary tool - hammers, cores, barbs, scribers, compasses, knobs, die holders;
3) fitting and assembly tools - wrenches, screwdrivers, pliers, hand vise, clamps, pullers;
4) measuring and control tools - rulers, calipers, calipers, calipers, micrometers, squares, goniometers.
Basic plumbing operations.
There are the following main plumbing operations:
Marking - drawing on the workpiece to be processed or the surface of the material, intended for the day the workpiece was received, marking lines.
Editing - irregularities, curvature, curvature, defects in the shape of blanks are eliminated.
Straightening - elimination of irregularities in the sheet or warping of the workpiece that has undergone hardening.
Bending - a workpiece or part of it is given a curved shape.
Cutting - removing an excess layer of metal or cutting a workpiece into pieces using a cutting tool.
Cutting.
Sawing - processing holes, grooves and grooves.
Fitting is the processing of one part according to the existing one in order to connect them.
Fitting - the exact mutual fit of parts.
Lapping - finishing of parts working in pairs to ensure the best contact of working surfaces,
Riveting - a type of assembly for the formation of an integral connection of two or more parts using rivets.
Soldering - a type of metalwork for the formation of a permanent connection using a molten intermediate material or alloy, called solder.
Tinning - coating the surface of metal parts with a thin layer of molten tin.
Thread cutting.
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Topic 1.1. The main operations of locksmith processing and their characteristics.
⇐ PreviousPage 3 of 6Next ⇒Correlate the image with the type of processing and tool
Write your answer in the following form: 1-3-5
Topic 1.5. Tolerances and fit and technical measurements
Task 1 Name the main parts of the caliper
Fill the table
Task 2 Name the main parts of a micrometer
Fill the table
Task 3 Read the readings of the micrometer.
Task 4 Consider the schemes of tolerance fields. Determine the shaft tolerance, holes, type of fit.
| Tolerance field scheme | Hole tolerance | Shaft tolerance | fit type | ||||
| 1 |  | 1 | 0,052 | 1 | 0,040 | 1 | with gap |
| 2 |
 | 2 | 0,046 | 2 | 0,019 | 2 | |
| 3 |  | 3 | 0,030 | 3 | 0,032 | 3 | Transitional |
| 4 |
| 4 | 0,040 | 4 | 0,025 | 4 | with interference |
Topic 1.2. The main operations of locksmith processing and their characteristics.
Plumbing Test
Choose the correct answer
What is markup:
1. The operation of drawing lines and dots on the workpiece intended for processing
2. Operation to remove a layer of metal from the workpiece
3. The operation of applying a protective layer to the part. The operation of removing burrs from the part.
Choose the correct answer
Name the types of markup:
1. There are two types: straight and angled
2. There are two types: planar and spatial
3. There is one type: basic
4. There are three types: circular, square and parallel
Choose the correct answer
Name the tool used for marking:
1.File, needle file, rasp
2.Drill, countersink, countersink, countersink
3.Pipe cutter, hacksaw, scissors
4. Scriber, hammer, rectangle, center punch, marking compasses
Choose the correct answer
Name the measuring instruments used for marking:
1.Scale ruler, caliper, square, height gauge
2. Micrometer, indicator, thread template, probe
3. Scriber, hammer, rectangle, center punch, marking compasses
4. Mallet, trowel, sledgehammer, hammer with a round head
Choose the correct answer
On the basis of which the markup of the part is made:
1. Produced based on personal experience
2. Produce based on drawing
3. Produced based on the advice of a colleague
4. Produced on the basis of a defective part
Choose the correct answer
What is pinching:
1. This is an operation for applying points-recesses on the surface of the part
2.This is an operation to remove burrs from the surface of the part
3.This is a square hole sawing operation
4. This is an operation to straighten warped metal
Choose the correct answer
Tool used for cutting metal:
1.Applicable: tap, die, klupp
2.Applicable: center punch, scraper, countersink, mallet, trowel
3.Applicable: hacksaw, pipe cutter, metal shears
4.Applicable: metalwork chisel, chisel, groover, hammer
Choose the correct answer
What is metal straightening:
1. Operation to straighten bent or warped metal, only ductile materials are exposed
2. Operation to form a cylindrical hole in a solid material
3. Operation to form a threaded surface on the rod
4. Operation to remove a layer of metal from the workpiece in order to give the desired shape and size
Choose the correct answer
Name the methods of metal straightening:
1. Editing by twisting, breaking and extruding
2. Straightening by pressing, bending and crimping
3. Straightening by tightening, twisting and flaring
4.Editing by bending, pulling and smoothing
Choose the correct answer
Name the tools and fixtures used in editing:
1.Applicable: Parallel Vice, Chair Vice, Clamps
2.Applicable: stretching, crimping, support, chasing
3.Applicable: straightening plate, headstock, mallet, hammer, trowel.
4. Applicable: center punch, scraper, countersink, mallet, trowel
Choose the correct answer
What is metal cutting:
1. This is an operation related to the separation of materials into parts using a cutting tool
2. This is an operation, drawing marking lines on the surface of the workpiece
3. This is an operation to form a threaded surface inside the hole
4. This is an operation to form a thread on the surface of a metal rod
Choose the correct answer
Name a hand tool for metal cutting:
1. Chisel, cutter, groover
2.Hacksaw, hand shears, pipe cutter
3. Smoother, mallet, sledgehammer,
4. Reamer, countersink, countersink
Choose the correct answer
What is filing:
1. Operation to remove the broken saw from the cut on the surface of the workpiece
2. The operation of sawing the workpiece or part into pieces
3. Operation to remove a layer of metal from the surface of the workpiece using a cutting tool - a file
4. Operation to remove metal filings from the surface of the workpiece or part
Choose the correct answer
What tools are used for sawing?
1.Applicable: pliers, round nose pliers, wire cutters
2.Applicable to: round-faced hammer, square-headed hammer
3.Applicable: flat scraper, chisel, mallet
4.Applicable: files, needle files, rasps
Choose the correct answer
What are the types of file notches:
1. Triangular, pitted, square, oval
2.Linear, parallel, perpendicular, angular
3.Broach, shock, planed, persistent
4. Single, double cross, arc, rasp
Choose the correct answer
How many classes are files divided into depending on the number of notches per 10 mm of length:
1. Divided into 7 classes
2. Divided into 6 classes
3. Divided into 5 classes
4. Divided into 8 classes
Choose the correct answer
Name the cross-sectional shapes of the file:
1. Flat, square, trihedral, round, semicircular, rhombic, hacksaw
2. Oval, triangular, square, fork, straight, hexagon
3. Double-sided, three-sided, universal, specialized
4. Ordinary, professional, semi-professional
Choose the correct answer
What is drilling:
1. This is an operation for the formation of through or blind square holes in a solid material, using a cutting tool - a drill
2. This is an operation to form through or blind oval holes in a solid material, using a cutting tool - a drill
3. This is an operation to form through or blind triangular holes in a solid material, using a cutting tool - a drill
4. This is an operation for the formation of through or blind cylindrical holes in a solid material, using a cutting tool - a drill
Choose the correct answer
Name the types of drills:
1. Triangular, square, straight, angled
2. Hacksaw, manual, machine, machine-hand
3. Spiral, feather, centering, ring, rifle
4. Self-sharpening, basic, trapezoidal, thrust
Choose the correct answer
Name the types of shanks for a twist drill:
1. Oval and parallel
2. Cylindrical and conical
3. Semi-circular and outer
4. Special and regular
Choose the correct answer
What is a drill:
1. A cutting tool that cuts the workpiece into pieces
2. Cutting tool that forms cylindrical holes
3. Cutting tool used in soldering
4. Cutting tool for threading
Choose the correct answer
Name a manual drilling tool:
1. Drill, reamer, countersink, countersink
2. Bench drill, vertical drill, radial drill
3. Hand drill, brace, ratchet, electric and pneumatic drills
4. Lapping, scraper, frame, holder
Choose the correct answer
What is called stationary drilling equipment:
1. Such equipment is called equipment that is transferred from one workpiece or part to another.
2. Such equipment is called - equipment operating on electric current
3. Such equipment is called - equipment located in one place, while the workpiece being processed is delivered to it
4. Such equipment is called - equipment operating on compressed air
Choose the correct answer
Name the types of drilling machines:
1. Suspended, floor and diagonal
2. Desktop, vertical and radial
3. Screw-cutting, boring and slotting
4. Manual, machine and machine
Choose the correct answer
What is reaming:
1. This is an operation related to the processing of a previously drilled, stamped, cast and other hole in order to give it a more regular square shape, higher accuracy
2. This is an operation related to the processing of a previously drilled, stamped, cast and other hole in order to give it a more regular triangular shape, higher accuracy and higher roughness.
3. This is an operation related to the processing of a previously drilled, stamped, cast and other hole in order to give it a more regular oval shape, lower accuracy and lower roughness
4. This is an operation associated with the processing of a previously drilled, stamped, cast and other hole in order to give it a more regular geometric shape, higher accuracy and lower roughness
Choose the correct answer
Name the types of countersinks:
1. Pointed and blunt-nosed
2. Machine and manual
3. Stone and concrete
4. Solid and mounted
Choose the correct answer
What is deployed:
1. This is a threaded hole processing operation
2. It is an early-drilled hole processing operation with a high degree of accuracy.
3. It is a square hole machining operation with a high degree of precision
4. It is a taper hole machining operation with a high degree of precision
Choose the correct answer
Name the types of sweeps according to the method of use:
1. Main and auxiliary
2. Manual and machine
3. Machine and locksmith
4. Straight and tapered
Choose the correct answer
Name the types of sweeps according to the shape of the working part:
2. Rhombic and semicircular
3. Tetrahedral and trihedral
4. Straight and tapered
Choose the correct answer
Name the types of reamers according to processing accuracy:
1. Cylindrical and conical
2. Rough and finish
3. High-quality and low-quality
4. Manual and machine
Choose the correct answer
Name the thread profiles:
1. Triangular, rectangular, trapezoidal, thrust, round
2. Oval, parabolic, three-dimensional, overlap, scalloped
3. Semi-circular, mortise, heavy duty, anti-friction
4. Modular, segmented, tubular, countersunk
Choose the correct answer
Name the thread systems:
1. Centimeter, foot, battery
2. Gas, decimeter, calibrated
3. Metric, inch, pipe
4. Millimeter, water, gas
Choose the correct answer
Name the thread elements:
1. Tooth profile, outside corner, middle corner, inside corner
2. Profile angle, thread pitch, outer diameter, diameter, inner diameter
3. Tooth, modulus, outer radius, middle radius, inner radius
4. Tooth pitch, module angle, outer profile, middle profile, inner profile
Choose the correct answer
Name the tool for cutting internal threads:
1. Kreuzmeysel
Choose the correct answer
Name the external threading tool:
1. Countersink
2. Counterbore
Choose the correct answer
Name the types of plates:
1. Round, square (sliding), thread rolling
2. Hexagonal, spherical, face
3. Resistant, alloyed, hardened
4. Modular segment, profile
Choose the correct answer
What is sawing:
1. Variety of filing
2. Variety of lapping
3. Variety of scraping
4. Variety of fitting
Choose the correct answer
What is an attachment:
1. This is a locksmith operation for mutual adjustment of cutting methods for two mating parts
2. This is a locksmith operation for mutual adjustment by scraping two mating parts
3. This is a locksmith operation for mutual adjustment by grinding in two mating parts
4. This is a locksmith operation for mutual fitting by means of filing two mating parts
Choose the correct answer
What is scraping:
1. This is the final locksmith operation, which consists in scraping very thin layers of metal from the surface of the workpiece using a cutting tool - a lap
2. This is the final locksmith operation, which consists in scraping very thin layers of metal from the surface of the workpiece using a cutting tool - a scraper
3. This is the final locksmith operation, which consists in scraping very thin layers of metal from the surface of the workpiece using a cutting tool - a needle file
4. This is the final locksmith operation, which consists in scraping very thin layers of metal from the surface of the workpiece using a cutting tool - a rasp
Choose the correct answer
Name the types of scrapers according to the shape of the cutting edge:
1. One-sided, double-sided, three-sided
2. Flat, trihedral, shaped
3. Modular, profile, segment
4. Steel, cast iron, brass
Choose the right carrier
Name the types of scrapers by design:
1. Riveted and welded
2. Pin and wedge
3. Whole and composite
4. Keyed and splinted
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| 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 |
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Practical work.
Practice #33
studopedia.net
Markup.
Locksmith's workplace.
studlib.info
The main types of plumbing operations
Markup.
Locksmith's workplace.
Topic 25. Basics of plumbing.
1. Locksmith work is the manual processing of materials, fitting parts, assembly and repair of various mechanisms and machines.
A workplace is a part of the production area with all the equipment, tools and materials located on it, which are used by a worker or a team of workers to complete a production task.
The workplace should occupy the area necessary for the rational placement of equipment on it and the free movement of the locksmith during work. The distance from the workbench and racks to the locksmith should be such that he can use mainly the movement of his hands and, if possible, avoid turning and bending the body. The workplace should have good individual lighting.
Locksmith workbench (Fig. 36) - the main equipment of the workplace. It is a stable metal or wooden table, the lid (tabletop) of which is made of boards 50 ... 60 mm thick of hardwood and covered with sheet iron. Single workbenches are the most convenient and common, since on multi-seat workbenches, when several people work at the same time, the quality of precision work is reduced.
Rice. 36 Single locksmith workbench:
1 - frame; 2 - countertop; 3 - vice; 4 - protective screen; 5 - tablet for drawings; 6 - lamp; 7 - shelf for tools; 8 - tablet for a working tool; 9 - boxes; 10 - shelves; 11 - seat
The workbench contains the tools necessary to complete the task. The drawings are placed on the tablet, and the measuring tools are placed on the shelves.
Under the tabletop of the workbench are drawers, divided into a number of cells for storing tools and documentation.
To fix the workpieces, a vise is installed on the workbench. Depending on the nature of the work, parallel, chair and hand vices are used. The most widespread are parallel swivel and non-swivel vices, in which the jaws remain parallel during divorce. The rotary part of the vise is connected to the base with a center bolt, around which it can be rotated at any angle and fixed in the required position with the help of a handle. To increase the service life of the vise, steel overhead sponges are attached to the working parts of the jaws. Chair vise is rarely used, only for work related to shock loading (when cutting, riveting, etc.). When processing small parts, use a hand vise.
The choice of the height of the vice according to the height of the worker and the rational placement of the tool on the workbench contribute to a better formation of skills, an increase in labor productivity and reduce fatigue.
When choosing the height of the vise installation, the left hand bent at the elbow is placed on the vise jaws so that the ends of the straightened fingers of the hand touch the chin. Tools and devices are arranged so that it is convenient to take them with the appropriate hand: what is taken with the right hand - hold on the right, what is taken with the left - on the left.
A protective screen made of metal mesh or durable plexiglass is installed on the workbench to retain pieces of metal that fly off during cutting.
Blanks, finished parts and fixtures are placed on racks installed in the area allotted for them.
2. Marking - the operation of drawing lines (rises) on the workpiece that determine (according to the drawing) the contours of the part and the places to be processed. Marking is used for individual and small-scale production.
Marking is carried out on marking plates cast from gray cast iron, aged and precisely machined.
Lines (risks) with a planar marking are applied with a scriber, with a spatial marking, with a scriber fixed in the thickness gauge collar. Scribers are made from steel grades U10 and U12, their working ends are hardened and sharpened sharply.
The center punch is intended for drawing indentations (cores) on pre-marked lines. It is made from steel grades U7, U7A, U8 and U8A.
The marking compass is used to draw circles, divide angles and apply linear dimensions to the workpiece.
3. The main types of plumbing operations.
Cutting is a locksmith operation, during which excess metal layers are removed from the workpiece with a cutting and impact tool, grooves and grooves are cut out, or the workpiece is divided into parts. The cutting tool is a chisel, a cross-cutting tool, and a hammer is a percussion tool.
Cutting is the operation of separating metals and other materials into pieces. Depending on the shape and size of the blanks, cutting is carried out with a hand saw, hand or lever scissors.
A hand saw consists of a steel solid or sliding frame and a hacksaw blade, which is inserted into the slots of the heads and secured with pins. A handle is fixed on the shank of the fixed head. A movable head with a screw and a wing nut is used to tension the hacksaw blade. The cutting part of the hacksaw is a hacksaw blade (a narrow and thin plate with teeth on one of the ribs) made of steel grades U10A, 9XC, P9, P18 and hardened. Hacksaw blades are used with a length (distance between holes) of 250-300 mm. The teeth of the blade are spread (bend) so that the width of the cut is slightly greater than the thickness of the blade.
Metal dressing is an operation in which irregularities, dents, curvature, warpage, waviness and other defects in materials, workpieces and parts are eliminated. Editing in most cases is a preparatory operation. Straightening has the same purpose as straightening, but defects are corrected in hardened parts.
Bending is widely used to give blanks a certain shape in the manufacture of parts. For manual straightening and bending, correct plates, straightening headstocks, anvils, vices, mandrels, sledgehammers, metal and wooden hammers (mallets) and special devices are used.
Riveting is a metalwork operation of joining two or more parts with rivets. Rivet connections are one-piece and are used in the manufacture of various metal structures.
The riveting is performed in a cold or hot (if the rivet diameter is more than 10 mm) state. The advantage of hot riveting is that the rod fills the holes in the parts to be joined better, and when cooled, the rivet pulls them together better. When riveting in a hot state, the diameter of the rivet should be 0.5 ... 1 mm smaller than the hole, and in a cold state, by 0.1 mm.
Manual riveting is performed with a hammer, its mass is chosen depending on the diameter of the rivet, for example, for rivets with a diameter of 3 ... 3.5 mm, a hammer weighing 200 g is required.
Sawing is a plumbing operation in which a layer of metal is cut off from the surface of a part with files to obtain the required shape, size and surface roughness, to fit parts during assembly and prepare edges for welding.
Files are steel (steel grades U13, U13A; ShKh13 and 13Kh) hardened bars of various profiles with teeth cut on the working surfaces. The teeth of the file, having the shape of a sharpened wedge in cross section, cut off layers of metal in the form of chips (sawdust) from the workpiece.
Scraping is the operation of scraping thin layers of metal from the surface of a part with a cutting tool - a scraper. This is the final processing of precision surfaces (machine guides, control plates, plain bearings, etc.) to ensure tight mating. Scrapers are made of U10 and U12A steels, their cutting ends are hardened without tempering to a hardness of HRC 64...66.
Lapping and finishing - operations of surface treatment with especially fine-grained abrasive materials using lapping.
These operations achieve not only the required shape, but also the highest accuracy (5 ... 6th grade), as well as the lowest surface roughness (up to 0.05 microns).
Fitting and assembly work is the installation and dismantling work performed during the assembly and repair of machines. Various connections of parts performed during the assembly of machines are divided into two main types: movable and fixed. When performing locksmith and assembly work, a variety of tools and devices are used: wrenches (simple, socket, sliding, etc.), screwdrivers, punches, pullers, devices for pressing and pressing out.
Markup. Drawing needles (scribers) are used to draw lines (marks) on the marked surface of workpieces. Straight lines should be drawn with a scriber with a little pressure along the lower edge of the steel ruler or square (Fig. 39). The part must be stable on a flat base.
Rice. 39. Drawing lines
:
a - wrong; b - right
Circles are marked with a measuring compass. Its legs with points are fixed with a locking screw. So that the compass does not move when marking, the center of the hole is marked with a core. In order for the core to be clearly visible, the core must first be held at an angle, set to the intended point, then transferred to a vertical position, without tearing off the end from this point, and with a hammer blow on the core, mark the workpiece (Fig. 40). It is also necessary to core before drilling a hole in order to center the drill.
Rice. 40. Punching
The punching of thin metal plates must be done on a solid base with a light blow of a hammer so as not to pierce the plate through. The markup can be made inaccurately, which leads to a marriage in the manufacture of products, since there is a discrepancy between the marked workpiece and the dimensions indicated on the drawings. The reasons may be different: human inattention, inaccurate installation of the workpiece during marking, inaccuracy of measuring tools. In general, accuracy - in any phase of locksmith work - is the key to success. The caliper is a tool for measuring external and internal linear dimensions (Fig. 41) with an accuracy of 0.05 mm.
Rice. 41. Caliper :
1 - sponges for internal measurements; 2 - movable frame; 3 - depth gauge; 4 - sponges for external measurements; 5 - nonius
It consists of a rod with two fixed jaws, on which a scale scale with a division step of 0.05 mm is applied. A frame also moves along the bar with two jaws and a rod rigidly fastened to it - a depth gauge. The vernier scale is marked on the edge of the frame. The zero stroke of the vernier indicates the number of whole millimeters (in Fig. 41 - 13 mm) on the main scale. Tenths of a millimeter are read on the vernier - where the strokes of both scales coincide (in Fig. 41 - 0.3 mm). Fixed in Fig. 41 size is 13.3 mm. When measuring, the scale must be viewed at a right angle.
Fixing details. The main device for this operation is a vice. They must be completed with various protective sponges (see above). The place of processing should be located as close as possible to the vise jaws. The height at which the vise is installed is very important - your energy consumption when processing parts depends on it. Locksmiths use the following method to determine the optimal height of the vise: bending your right hand, touch your chin with your fist, then try to touch the jaws of the vise with your elbow without extending your arm. If this can be done without bending or standing on your toes, then the vise is set at the required height.
Cutting and cutting of metal. Having finished the markup, they begin to remove the “excessive” fragments of the workpiece. The roughest such operation is cutting, in which the workpiece is cut into pieces with a chisel or crosshead and a hammer, or unnecessary parts are removed. In addition, with the help of cutting, irregularities, scale, sharp edges of parts are removed from the workpieces, grooves and grooves are cut down. Usually this procedure is carried out in a vice, and sheet metal is also cut on a plate. When chopping, it is important to take the correct posture: the body body is straight and half-turned to the axis of the vise; the left foot is half a step ahead of the right; the angle between the feet is about 70°. The chisel should be held in the left hand by the middle at a distance of 15-20 mm from the edge of the impact part. It is installed so that its cutting edge is located on the cut line, and the longitudinal axis of the chisel rod makes an angle of 30-35 ° to the workpiece surface being machined and an angle of 45 ° to the longitudinal axis of the vise jaws (Fig. 42). The hammer force must be significant. The heavier the hammer and the longer its handle, the stronger the blow.
Rice. 42. :
a - side view; b - top view
Sheet and strip metal is cut at the level of the sponges, the wide surfaces of the blanks are above this level (by risks); brittle metals such as cast iron and bronze are cut from the edge to the middle to avoid chipping the edges of the part. Finishing the felling, the impact force should be reduced. For cutting metal blanks and parts, a hacksaw is used more often than other tools. The choice of blade is determined by the thickness and hardness of the metal being processed. For cutting steel and other hard metals, as well as thin-walled pipes and profiles, blades with fine teeth are needed, and for copper, brass, aluminum and other soft metals - with large ones. High-quality blades are marked with the length, width and thickness of the cut, as well as the number of teeth per inch (25.4 mm). For saws with fine teeth, this figure is 28-32, with medium - 18-24, with large -16. Cloths are made from different grades of steel: high-speed (HSS), from bimetallic materials, the latter being more elastic than the former and, accordingly, breaking less. Conventional hacksaw blades are 300 mm long. They are installed in the hacksaw frame with the teeth forward and moderately tightened, since if the tension is too strong, the blade may burst during operation. Before starting processing, the workpiece is firmly fixed in a vice, so that the cut point is as close as possible to the vise jaws. Before starting sawing, it is recommended to make a notch on the workpiece with a triangular file - this will greatly facilitate filing. After that, take the correct posture for sawing. The position of the hands on the hacksaw is shown in fig. 43.
Rice. 43. How to hold a hacksaw
Cutting should start from a plane (with a slight inclination of the hacksaw), but not from the ribs, since in the latter case the teeth of the blade may crumble. Moving the hacksaw with a working stroke (away from you), they make pressure; during the reverse (idle) course, the blade is driven without pressure so that it does not become dull. The highest cutting speed is achieved at 40-50 double hacksaw strokes per minute. For long cuts, the blade must be rotated 90°. In all cases, for more uniform wear of the teeth along the length of the blade, it is necessary to use a larger part. Electric saws and pipe cutters are also used to cut metal blanks. When working with the first, you must wear gloves and goggles. The machine must be held firmly with both hands, otherwise the cutting disc may be distorted. It should, however, be known that with this cutting method coarse burrs are formed, which make it difficult to carry out subsequent processing operations.
When using a pipe cutter, the pipe is clamped in a vice, a pipe cutter is put on it and the cutting roller is brought to the surface of the pipe. By rotating the pipe cutter around the pipe, the movable roller is gradually pressed and thereby cut through the pipe wall. Metal sheets - galvanized tin, copper, aluminum up to 0.5 mm thick - are cut with manual metalwork scissors. Compared to other cutting tools, scissors do not allow material loss. Metal shears cut the same way as others. Their cutting ability is determined by the quality of sharpening and the length of the levers. It is convenient to use scissors with a lever length of at least 20, and best of all - 30 cm. For curved scissors, 20 cm is enough. When cutting a sheet, the scissors are held with the right hand, covering the handles with four fingers and pressing them to the palm (Fig. 44). The little finger or index finger is placed between the handles, retracting the lower handle to the required angle.
Rice. 44. How to hold metal shears
:
a - grip with unclenching the scissors with the little finger; b - grip with unclenching the scissors with the index finger
The scissors should be opened approximately 2/3 of their length, since with a larger opening they will not cut, but push the sheet. The sheet is held and fed with the left hand between the cutting edges, guiding the top blade along the marking line. Squeezing the handles with your fingers, cutting is carried out.
Sawing of metals. This one of the most widely used finishing operations consists in removing small layers of metal with a file. With its help, rust, scale are removed from workpieces, rough surfaces are leveled, and parts are given the necessary shape and size. It is clear that in order to carry out such an operation, the master must have a whole set of files. On the working surface of the file there is a notch that forms the cutting edges. Notches are single, double, arc and point. According to the shape of the cross-sectional profile, files are divided into flat, square, trihedral, round, semicircular, rhombic, hacksaw and some others (Fig. 45).
Rice. 45. :
1 - flat pointed (a - double notch; b - single notch; c - ring; d - shank; d - handle); 2 - flat, blunt; 3 - semicircular; 4 - round; 5 - trihedral
The use of a file of one form or another is determined by the profile of the workpiece. Files with a single cut (rectangular at an angle or arcuate) are usually used in the processing of soft metals, as they remove chips along the entire length of the cut. Files with a double (cross) notch remove small chips (due to the large number of small cutting wedges), and they are used for filing steel and other hard metals. The working properties of a file are characterized by two related indicators: the notch pitch and the number of notches. The notch pitch is the distance between two adjacent teeth of the file, and the number of notches is the number of them per 1 cm of length. According to the number of notches, bastard files (0-1), semi-personal (2), personal (3) and velvet (4-5) files are distinguished. The latter are used for fine filing, grinding and finishing of parts, while bastard ones are used for preliminary, rough filing. Files with a large notch and coarse, sharp teeth are called rasps, and small and finely notched files are called needle files. Before filing, the part is fixed in a vice, while the sawn surface should protrude 8-10 mm above the level of the jaws. To avoid dents in the workpiece, the soft protective sponges described above can be used. To perform this operation, the following working posture is recommended: half-turned to the vise, the left leg is set forward and half a step to the left, the angle between the feet is 40-60 ° (Fig. 46).
Rice. 46. Pose (a) and grip of the file (b) when filing
The optimal height of the vise should be such that when the file is applied with the right hand to the vise jaws, the shoulder and forearm of this hand form a right angle (Fig. 46a). The file is held by the handle with the right hand so that the rounded end of the handle rests on the palm; the palm of the left hand is applied almost across the axis of the file at a distance of 2-3 cm from the edge of its toe (Fig. 46b). Sawing should be done with a uniform movement of the file: forward - with pressure and when moving back - without pressure. The file must be pressed against the part with both hands, and in different phases of movement in different ways: when the file moves forward, the pressure on the handle is gradually increased with the right hand, while simultaneously weakening the pressure on the toe of the file with the left. The optimal filing speed is considered to be 40-60 double movements (i.e. forward and reverse) per minute. If the surface being machined is flat, then the main task during processing - to maintain its flatness, that is, to prevent "blockages". The quality of the sawn planes is evaluated using various control and measuring instruments: flatness - with a curved ruler in the light; the accuracy of adjacent planes processed at a right angle - with a square; parallel processed planes - with a caliper (Fig. 47).
Rice. 47. Ways to control surfaces when filing
:
a - with a curved ruler; b - square; c - caliper
There are specific features in the processing of curved surfaces. Convex surfaces are processed using the rocking movements of the file (Fig. 48a), in which it, as it were, goes around the convex surface. Concave surfaces are processed (with round or semicircular files), making intricate movements - forward and to the side with rotation around its axis (Fig. 48b). Control is carried out by marking or using templates.
Rice. 48. Sawing curved surfaces
:
a - convex; b - concave
When filing, metal chips clog the notches, so it is necessary to clean the file blade from time to time with a metal brush, which should be moved along the notches. Chalk can be applied to a file with a fine notch. Then the chips will clog less.
drilling. Through this operation, through and non-through holes of various depth diameters are obtained in metal and other materials using drills. The most common drilling tools are manual mechanical and electric drills. Such a tool, however, does not allow precise holes to be drilled, for example for threading. For these purposes, use a drilling stand or a drilling machine. The workpiece and the tools used (stand, drill, drills) must be rigidly fixed. This allows you to drill holes of the same depth perpendicular to the surface and adjust the drilling depth. Important right choice drill speed. Holes of large diameters and hard metals are drilled at low speeds. For drilling metals, spiral (screw) drills with a conical sharpening, made of high speed steel, are usually used. Their blades are made in the form of helical grooves running down to the guide point at a certain angle (Fig. 49). According to this angle (y) and the angle at the top (b), the following types of drills are distinguished (table 6).
Rice. 49. Drills :
H - for hard materials (stone); N - for normal materials (aluminum, copper)
Table 6
In addition to drills made of high-speed steel, drills with hard-alloy (pobedite) tips, which form a particularly wear-resistant cutting edge, are used for drilling especially hard materials. When drilling metal manually, first, the center of the future hole is marked on the workpiece with a center punch, and so that the tip of the drill does not pop out when entering the metal. Having fixed the drill in the chuck, its tip is brought to the intended center of the hole so that the axis of the drill exactly coincides with the axis of the future hole (it is clear that the part must be fixed in one way or another). Drilling should be started at low speed, without pressing hard, smoothly and without jerks, avoiding the swing of the drill. The pressure is gradually increased (if the drill goes in the right direction) and the hole is drilled to the end. An emulsion, lubricating oil, or soapy water should be used to cool the hot drill bit. If these fluids are not available, frequent and long pauses must be made so that the drill cools down. So, in particular, gray cast iron and zinc are drilled. Drilling of sheet metal should be done on a wooden stand located under the sheet.
If a through hole is drilled, when the drill exits the workpiece, the pressure is gradually weakened, and the number of revolutions is also reduced (if possible). If the drill sticks, it must be told to reverse rotation and pulled out of the hole, and then eliminate the cause of the jam. When drilling deep holes, the drill must be periodically removed and cleaned of chips. It is better to drill holes with a diameter of more than 6 mm in two steps: first, drill a pilot hole with a diameter of 4 mm at a shallow depth at the point of punching, and then “put into action” a drill of the desired diameter. During operation, the drills become dull and need to be sharpened. Twist drills are sharpened on an abrasive stone of a grinding machine (Fig. 50). Naturally, this requires some skill. The drill is slightly pressed with a cutting edge to a rotating grindstone, it is led slightly up (against the direction of rotation), while slowly turning it along its axis. The sharpening angle is checked with a special template.
Rice. 50. Drills :
1 - storage; 2 - sharpening; 3 - check
On fig. 50 also shows a way to store drills - in a wooden or plastic block with holes: they can also be stored in a box with holes.
Countersinking. When drilling holes, burrs form on their sharp edges, which can be removed either with a drill of a smaller diameter or with a special conical countersink (Fig. 51a). A countersink is a multi-blade cutting tool used to process previously obtained holes in order to improve their quality and accuracy. In particular, conical countersinking is also used to obtain conical recesses for countersinks of screws and rivets. With an end cylindrical countersink (Fig. 51b), cylindrical recesses are made for the corresponding heads of screws, bolts and nuts. The countersinking operation should be done at the lowest rotational speed of the electric drill with minimal effort.
Rice. 51. :
a - conical; b - cylindrical
Thread cutting. The drilling and countersinking operations described above precede the cutting of internal threads. A thread is a helical groove of constant cross section on an inner or outer cylindrical surface: in the first case, the thread is called internal, in the second - external. Before describing the process of threading, we briefly describe its main types. In the direction of the helix, the thread is divided into right and left. A thread profile is a section of its coil in a plane passing through the axis of the cylinder on which the thread is cut. The main thread parameters are shown in fig. 52. The shape of the profile is as follows: triangular (shown in Fig. 52), rectangular, trapezoidal, persistent (with a profile in the form of an unequal trapezoid) and round.
Rice. 52. Thread parameters
:
1 - outer diameter; 2 - inner diameter; 3 - thread length; 4 - thread pitch
In a metric thread, the angle of the triangular profile is 60°, and the thread parameters are expressed in millimeters. For example, the designation M20x1.5 is “translated” as follows: M - metric thread, 20 - outer diameter in mm, 1.5 - pitch in mm. There are other thread systems - inch and pipe. But back to threading. Let's start with the inside. It is cut with a tap, the tail of which is fixed in the collar. For through holes, a tap with a chamfer (lower) part is used on the first 4-5 threads of the thread, which direct the movement of the tap along the walls of the hole. For blind holes, taps with a shorter chamfer (by 2-3 threads) are needed so that the effective (cutting) thread zone reaches almost to the bottom of the hole. For manual threading, taps are usually produced in sets, which include 2-3 tools: roughing, semi-finishing and finishing. The first and second pre-cut threads, the third give it the final size and shape. This stepwise threading significantly reduces the cutting force. Taps are distinguished by the number of notches on the tail: a rough tap has one risk, a semi-finishing tap has two, and a finishing tap has three or none. The double set includes rough and finish taps.
Of no small importance is the correct choice of the diameter of the drill, which drills a hole for the internal thread, and the diameter of the rod - for the external one. The diameter of the drill (and shank) should be slightly smaller than the outside diameter of the thread. The table below gives drill and shank diameters for some common metric thread sizes.
Table 7
| Thread diameter, mm | Drill diameter, mm | Rod diameter, mm | ||
| hard metals | soft metals | hard metals | soft metals | |
| M4 | 3,3 | 3,3 | 3,9 | 3,9 |
| M5 | 4,1 | 4,2 | 4,9 | 4,8 |
| M6 | 4,9 | 5,0 | 5,9 | 5,8 |
| M8 | 6,6 | 6,7 | 7,9 | 7,8 |
| M10 | 8,3 | 8,4 | 9,9 | 9,8 |
| M12 | 10,0 | 10,1 | 11,9 | 11,8 |
Internal threading is performed as follows. The workpiece (part) with a drilled hole is fixed in a vise so that the axis of the hole is strictly vertical. The intake part of the rough tap is inserted into the hole and its installation is checked on the square. The surface of the hole and the cutting part of the tap should be lubricated with a cutting fluid (machine oil for steel, kerosene for cast iron). A collar is put on the tail of the tap. With the left hand, the collar is pressed against the tap, and with the right hand it is turned until it cuts several turns into the metal. After that, they take the knob with both hands and begin to slowly rotate it in this mode: 1-1.5 turns clockwise, 0.5 turns counterclockwise (Fig. 53).
Rice. 53. Internal thread cutting
Reverse rotation is needed to break the chips. At the end of threading with a rough tap, a semi-finishing tap is placed, and then a finishing tap, and the same manipulations are performed with each of them as with a rough tap. All the time, with the help of a square, you need to control the position of the axis of the tap relative to the surface of the workpiece. For cutting external threads, dies with a die holder are used. The same tool is used to update timed threads on bolts, screws and studs. The cutting thread of the die has an intaking (initial) part on one or both sides. In the first case, the die should be adjacent to the stop of the die holder with the opposite side (without the intake part). To avoid thread distortion, a chamfer is removed from the end of the rod (having previously fixed it vertically in a vice). Then the die is installed on the end of the rod perpendicular to its axis and, slightly pressing the die holder with the right hand, turn it with the left (Fig. 54) until the die is firmly cut into the metal.
Rice. 54. External thread cutting
This is achieved after inserting the first threads. After that, pressure is no longer needed, you just need to slowly rotate the die. The cutting process can be facilitated by simultaneously increasing the purity of the thread by dropping a few drops of machine oil or cutting fluid on the rod and die. External threading is continued until the die has passed the entire required length of the rod. After that, the die is rolled off the rod, they are cleaned of chips and grease, and the cut threads are checked with a reference nut. Chips should be cleaned with a brush, not by hand, to avoid cuts on the sharp cutting edges of the tap or die.
Metal bending. This is a method of processing metals by pressure, in which one part of the workpiece is bent relative to the other at a certain specified angle. Bending is used to give the workpiece the curved shape required by the drawing. Manual bending is carried out in a vice with a hammer and various devices. The force that must be applied in this case, and the sequence of operations during bending, depend on the material, shape and cross section of the workpiece. In this case, it is important to correctly determine the dimensions of the workpiece. They are determined according to the drawing, taking into account the radii of all bends. The easiest way is to bend thin (0.3-1 mm) sheet metal. To accurately bend the part, it is clamped on both sides, up to the bend line, with wooden blocks (mandrels) (Fig. 55).
Rice. 55. sheet metal bending
:
a - incorrect; b - correct
In this case, one mandrel is not enough, because the workpiece, clamped in a vise with only one mandrel, leads to the side when the edges are bent. If the workpiece is clamped on both sides, then a good bending quality is obtained. The mandrels must be made of solid wood. For bending, use a mallet (wooden hammer) or an iron hammer with a rubber cap. The workpiece, together with the mandrels, is clamped in a vise and gradually bent along the entire edge, applying light blows with a hammer. It is not recommended to immediately bend completely any section of the workpiece, otherwise the metal will be deformed and the edge will be wavy. The thickness of wooden mandrels should be at least 25-30 mm. A slightly different way is bending a metal sheet along the radius. This is done using a hardwood template (Fig. 56).
Rice. 56. Radius bending of sheet metal
When bending soft, tensile metals, the shape of the template must exactly match the shape of the part being made. When bending elastic metals its radius should be slightly less than the required one, since in this case the sheet springs. In order to use the lever more efficiently, when bending elastic metals, the sheet is clamped in a vice between two mandrels, one of which is a template, and the other, longer side is carefully struck with a hammer, obtaining the required shape. To achieve tightness, the connection of the blanks is made by the so-called longitudinal lock - a seam seam, or a fold. The seam is used when performing roofing work, connecting ventilation systems, making buckets, tanks and other products from tin. The simplest seam seam is called a single lying seam. To obtain it, mark the fold line on the edge of the workpiece, then bend along this line by 90 °. This operation is called flanging. The height of the bent edge, depending on the thickness of the sheet, can be 3-12 mm. After flanging, the workpiece is turned over and its edge is bent another 90°. The same operations are performed with the second workpiece or the second joined edge (Fig. 57).
Rice. 57. Seam blank
The folded edges (folds) of the two sheets are connected to each other. In order for the sheets to be located on the same level, the fold is upset (compacted, in Fig. 58 along the dotted line). To do this, the workpiece is placed on a solid base, clamped, and with the help of a hammer and a hardwood bar, the sheet is first upset, striking along the fold, and then the fold itself (Fig. 59).
Rice. 58. Rebate line
Rice. 59. Seam joint draft
There are cases when the edge of the sheet needs to be reinforced, i.e. give it extra rigidity. This operation is carried out as shown in Fig. 60.
Rice. 60. Making edges with reinforcement. The edge of the sheet acquires additional rigidity if you put a wire under the bend and roll it up:
1 - the edge of the sheet is marked: the width of the bent part is equal to two wire diameters plus double the thickness of the sheet; 2 - the edge is bent at an angle of 90 °; 3 - the edge is folded over a metal gasket; 4 - the edge of the sheet is finally bent on a wooden mandrel
It is also possible to bend in a “cold way” (i.e., without heating) strips of steel of sufficiently large thickness, for example, with a section of 40x45 mm. Such a strip is clamped in a vise and, if possible, first bent by hand to avoid injury from kickback of a long workpiece at the first blows of the hammer. After that, pulling the free end of the workpiece with one hand, strikes with a hammer at the bend. When bending metal strips and bars, templates are often used. In the manufacture of parts with a small bending radius, a thick wire (see Fig. 60) or a pipe of a suitable diameter is used as a template. One end of the workpiece is usually fixed.
Hot bending of metals. Most ferrous and non-ferrous metals used, such as structural mild steel, copper, aluminum and their alloys, etc., can be cold-formed. But some metals - high-quality steels, duralumin - are not always flexible in this way. This becomes possible if the metal being processed is heated. For example, in order to be able to bend steel (without shock loads), it is subjected to heating to red heat. If the steel billet is obtained by forging, then it is better to process it in a state of white heat, since at red and yellow heat the billet is destroyed under hammer blows. Non-ferrous metals and alloys are bent in several steps, in the intervals between which the metal is tempered. Tempering is a type of heat treatment of metals, consisting in the fact that the hardened part is heated to a relatively low temperature, after which it is gradually cooled in the open air or in water. The temperature of the heated hardened part during tempering is estimated from the tint colors that result from the formation of oxide films. various colors during heating: light yellow (straw) - 220 ° C, dark yellow - 240 ° C, brown-yellow - 255 ° C, brown-red - 265 ° C, purple-red - 275 ° C, violet - 285 °C, cornflower blue - 295 °C, light blue - 315 °C, gray - 330 °C. Table 8 lists recommended tempering temperatures for some steel tools and parts.
Table 8
| Tools (parts) | Recommended holiday temperature, °C |
| Gauges, templates and other measuring instruments | 150-180 |
| Cutting tools made of carbon steels: cutters, drills, taps | 180-200 |
| Hammers, dies, taps, dies, small drills | 200-225 |
| Punches, drills, dies, taps, drills for mild steel and cast iron, scribers, cutters | 225-250 |
| Drills, taps for copper and aluminum, chisels, punches, impact tools | 250-280 |
| Chisels, woodworking tool | 280-300 |
| Springs | 300-330 |
| Springs, forging dies | 400-500 |
| Parts and tools operating under heavy loads | 500-650 |
At home, small-sized workpieces are heated with a gas burner or blowtorch. During "hot" bending at an angle of 90°C with a minimum radius, the metal at the bend is deformed. This undesirable effect is especially noticeable when bending workpieces of greater thickness. In order for a workpiece of great thickness to retain its cross-section, flattening of the metal is carried out before the bending, as a result of which the bending point thickens, which compensates for its deformation during subsequent bending. When flattening, the metal at the bend is brought to a state of white heat and both ends of the workpiece are cooled so that only the bend itself remains red-hot. After that, the workpiece is upset from the ends, as a result of which the metal thickens in a hot place.
Rice. 61. Hot bending of sheet metal
:
a - thin workpiece; b - thick workpiece; c - bending along the radius along the horn of the anvil; g - the same, on a mandrel clamped in a vise
On fig. 61 shows some operations for bending metal in a hot state: a - bending of thin workpieces is performed on top or on the side of the vise jaws; b - workpieces of great thickness - along the vise jaws, if the width of the jaws is not enough, the workpiece is bent along an anvil or steel mandrel; c - bending of blanks along the round horn of the anvil or steel mandrel of the appropriate shape; d - bending along a mandrel clamped in a vise, while the free end of the workpiece contributes to bending due to the lever effect. To facilitate the machining of metals, they are often subjected to a special thermal operation - annealing; as a result, the hardness of the metal decreases. Annealing consists in heating a metal object (part, workpiece) to a certain temperature, keeping it at this temperature until it is heated throughout the volume and then, as a rule, slowly cooling to room temperature. Annealing is applied to both ferrous and non-ferrous metals. As a result, the material becomes less rigid and can be easily cold-bent. Table 9 lists the recommended temperatures and coolants for the heat treatment of some steels.
Table 9
| steel grade | Recommended temperature, °C | Cooling medium | |||
| during hardening | on vacation | during annealing | during hardening | on vacation | |
| Steel 30 | 880 | 180 | 845 | water | water, oil |
| Steel 45 | 860 | 80 | 820 | -//- | -//- |
| Steel 55 | 825 | 200 | 780 | -//- | -//- |
| U7, U7A | 800 | 170 | 780 | -//- | -//- |
| U8, U8A | 800 | 170 | 770 | -//- | -//- |
| U10, U10A | 790 | 180 | 770 | -//- | -//- |
| U11, U11A | 780 | 180 | 750 | -//- | -//- |
| U12, U12A | 780 | 180 | 750 | -//- | -//- |
| U13, U13A | 780 | 180 | 750 | -//- | -//- |
Greetings friends! Let's discuss what types of plumbing operations exist. Let's not forget to understand in detail what they are intended for and how to perform them correctly in order to prevent jambs and injuries.
Locksmith operations. Who performs and what is it.
locksmith operations- this is a set of actions of a toolmaker or repairman performed by a special tool in a certain sequence. During these operations, the metal is subjected to manual processing. Seven sweats can break while you complete these works. This includes various adjustments and adjustments of parts, repair of mechanisms and assemblies.
By the way, I was inspired to write this post by the unexpected (for me) popularity of the post, which I recently published on my blog. I wrote it from my own experience at the factory. Glad you liked it.
Types of plumbing operations. Appointment and application.
To get started, check out this one video lesson about the main types of plumbing operations:
There are actually plenty of such works and we will talk about each operation separately. For some points, we will watch video materials to consolidate information.
1. Metal cutting.
When cutting metal, it is enough to clamp it in a vise and pick up a tool called a chisel. Please note that before performing this locksmith operation, you must at least theoretically imagine what you are doing. From the outside it looks simple and easy, but in fact there are a number of tricks.
For example, the angle of the chisel should be approximately 35 degrees. If more or less work will go very reluctantly. No need to cling to the death grip on the chisel. Hold it with 3-4 fingers with a little effort. Well, how to hit it with a hammer - it already depends only on you. Hit rhythmically and don't beat your fingers.
2. Part marking.
The main types of plumbing operations include such - markup. The locksmith takes tools such as a square, a pattern, a hammer, a chisel and even a special marking compass. He chooses devices depending on the complexity of the operation performed. Perhaps the most popular is a metal scriber, we will shine a separate post on it. Stay tuned.
Putting a sheet of metal in front of him, the locksmith begins to create. To begin with, he uses a regular pencil to apply preliminary markings. When the design of the future part is drawn, we put the pencil aside. Then a rough tool comes into play, which literally tears out (scratches) the contour of the part blank. When all the lines are applied, it is very easy to cut, cut or extrude the necessary part or workpiece along them.
3. Metal cutting.
Then I remembered my school years, and my daughter probably took classes in kindergarten. When you have made the markup, take the scissors and feel free to start cutting. To tell the truth, the process is not very pleasant. From the side it seems even cool to cut metal figures. In life, when metal scissors begin to dig into your fingers and cause unbearable pain, then there is no time for jokes. Out of habit, this type of plumbing operation causes great discomfort to the hands.
The more often you perform these actions, the painless this process will be. If the metal is thick or strong enough, the scissors will not take it. Here you will have to resort to hydraulic shears or a guillotine. The guillotine is not the one that has been used since 1791 for cutting off the head (which was invented by Joseph Guillotin), but a machine for cutting off sheets of metal. Watch the video - how to use metal shears.
4. Editing of metal.
We see in the figure two main options for editing metal. The top two figures show the case when shock loading is needed to correct the curved meanders of the metal. To do this, you need special hammers. The striker of such a metalworking tool is made of wood, brass, duralumin, plastic with a metal core, etc. The main condition for such a tool is that it must be softer than the workpiece that you are going to edit.
The second view shows how a piece of metal is corrected using a special tool (to increase torque) and a conventional metalwork vise. For straightening bars, special machines and devices are used. If you are interested in this topic, read more on the Internet, but rather take a book on plumbing. And we continue study the main types of plumbing operations.
5. Riveting. Creation of permanent connections.
I'll tell you right away. The connection of two sheets of metal with rivets by experienced locksmiths is called a “rivet seam”. The figure on the left shows stretch And support.
On the right is shown swage. The whole riveting process looks something like this.
The riveting process. Step-by-step instruction.
Today, there are already a lot of devices and automated machines for making a riveted seam. But they all work on the same principle. Classic is immortal..
Take a file in your hands and let's go. That's what our locksmith teacher told me. But in the process of filing, it is important not only to remove chips from the part, but also to maintain the size according to the sketch or drawing. Perform this metalworking operation with extreme care - there is a high probability of injury. When the work is completed, it is necessary to check the compliance of the part with the drawing parameters.
Inspection of the part after filing.
Everything is much simpler here. Attach the control square (or template) to the part and look at the clearance. There should be no gaps, or it will be minimal if allowed. Patterns can be varied depending on the detail.
7. Scraping or fitting surfaces.
scraping- This is a locksmith operation for particularly precise fitting of surfaces. Even today this one seems to be deprecated method relevant and mechanization is not acceptable. The process is as follows. Minium type paint is applied to the surface and a mating part is applied. All the irregularities that remain as a result of such an overlay are eliminated using a tool called a scraper.
Shabreni, I tell you, is not for the faint of heart. In terms of accuracy, it can be compared with jewelry. Such operations are used in the manufacture of guides production equipment, sliding bearings of machine carriages, etc. When scraping, it is possible to achieve a roughness of up to 0.32 Ra.
Types of plumbing operations. Conclusion.
And I say goodbye to you! ALL THE GOOD TO YOU!
Andrey was with you!
The main types of locksmith work
markup
]
Rice. 30. Marking plate
Marking is the drawing of borders on the surface of the workpiece in the form of lines and points corresponding to the dimensions of the part according to the drawing, as well as axial lines and centers for drilling holes.
If the markup is made in only one plane, for example, on sheet material, then it is called planar. The marking of workpiece surfaces located at different angles to each other is called spatial. The blanks are marked on a special cast-iron plate (Fig. 30), called marking, mounted on a wooden table so that its upper plane is strictly horizontal.
Tools for marking-to and. When marking, use various marking tools.
Scriber (Fig. 31) is a steel rod with sharp hardened ends. With a scriber, thin lines are applied to the surface of the workpiece using a ruler, template or square.
Thickness gauges are used to apply horizontal lines on the workpiece parallel to the surface of the marking plate. Reismas (Fig. 32) consists of a base and a stand fixed in its center, on which there is a movable clamp with a scriber that rotates around its axis. The movable clamp can move along the rack and be fixed on it in any position with a clamping screw.
Rice. 31. Scribbler
The marking compass (Fig. 33) is used to draw circles and roundings on the marked workpiece.
Rice. 32. Reismas
Rice. 33. Marking compasses
For accurate marking, use a height gauge (Fig. 34). A bar with a millimeter scale is firmly fixed on a massive base. A frame with a vernier and a second micrometric feed frame move along the bar. Both frames are fixed on the rod with screws in any desired position. A replaceable scriber leg is attached to the frame with a clamp.
A marking caliper is used to draw circles of large diameters with direct sizing. A marking caliper (Fig. 35) consists of a rod with a millimeter scale printed on it and two legs, of which the leg is fixedly mounted on the rod, and the leg is movable and can move on the rod. The movable leg has a vernier. Hardened steel needles are inserted into both legs. The needle of the movable leg can move up and down and be clamped in the desired position with a screw.
Rice. 34. Height gauge
Rice. 35. Marking caliper
Rice. 36. Center Finder
The center finder is designed to determine the center of the end face of a cylindrical billet (Fig. 36). The center finder consists of a square with shelves located at an angle of 90° to each other, and a leg, the inner side of which divides the right angle of the square in half. To determine the center, the center finder is installed so that the square shelves touch the cylindrical surface of the workpiece. The scriber is drawn along the inner side of the leg, thus drawing a diameter line, then the center finder is rotated 90 ° and a second diametrical line is applied. The intersection point of these lines will be the center of the end face of the cylindrical blank.
A scale altimeter (Fig. 37) is used for marking in cases where it is necessary to set the tip of the scriber at a certain height. It consists of a fixed scale bar attached to a cast-iron square, a movable ruler moving along guide bases, and a fine-line targeting engine. When marking, the sighting engine is set so that its thin line coincides with the main axis of the workpiece, and is fixed in this position. After that, the zero division of the movable ruler is placed against the thin line of the sighting engine and the distance (height) from the main axis of the workpiece to other axes is read on the movable ruler.
The center punch is used to make small indentations on the marking lines of the workpiece, so that these lines are clearly visible and not erased during the processing of the workpiece. The punch (Fig. 38) is made of tool steel in the form of a rod, the middle part of which has a notch. The working part of the lower end of the center punch is sharpened at an angle of 45-60 ° and hardened, and the upper end is a striker, which is hit with a hammer when punching.
Marking devices. In order to protect the surface of the marking plate from scratches, nicks, as well as to create a stable position when marking parts that do not have a flat base, and to facilitate the marking process, cast iron linings are used (Fig. 39, a), jacks (Fig. 39 , b) and marking boxes (Fig. 39, c) of various shapes. Squares, clamps and adjustable wedges are also used.
The markup process is carried out as follows. The surfaces of the marked workpieces are cleaned of dirt, dust and grease. Then cover with a thin layer of chalk diluted in water with the addition of linseed oil and desiccant or wood glue. Well-treated surfaces are sometimes covered with a solution of copper sulphate or quick-drying paints and varnishes. When the applied layer of chalk or paint dries, you can start marking. The markup can be made according to a drawing or a template.
Rice. 37. Scale altimeter
Rice. 38. Punch
The process of marking the workpiece according to the drawing is performed in the following sequence:
- the prepared workpiece is installed on the marking plate;
- the main lines are applied to the surface of the workpiece, by which it is possible to determine the position of other lines or centers of holes;
- apply horizontal and vertical lines in accordance with the dimensions of the drawing, then find the centers and draw circles, arcs and oblique lines;
- along the lines drawn with a center punch, small recesses are knocked out, the distance between which, depending on the state of the surface and the size of the workpiece, can be from 5 to 150 mm.
Rice. 39. Devices for marking:
a - linings, b - doykratiki, c - marking boxes
For planar marking of identical parts, it is more advisable to use a template. This method of marking consists in the fact that a steel template is applied to the workpiece and its contours are circled on the workpiece with a scriber.
metal cutting
Bench cutting is used to remove excess metal in cases where high precision processing is not required, as well as for rough leveling of rough surfaces, for cutting metal, cutting down rivets, for cutting keyways, etc.
Cutting tools. The tools for cutting metal are chisels and crosscutters, and the percussion tool is a hammer.
The chisel (Fig. 40, a) is made of U7A tool steel and, as an exception, U7, U8 and U8A. Chisel blade width from 5 to 25 mm. The angle of sharpening the blade is selected depending on the hardness of the metal being processed. For example, for cutting cast iron and bronze, the sharpening angle should be 70°, for cutting steel 60°, for cutting brass and copper 45°, for cutting aluminum and zinc 35°. The chisel blade is sharpened on an emery wheel so that the chamfers have the same width and the same angle of inclination to the chisel axis. The sharpening angle is checked with a template or goniometer.
Rice. 40. Tools for cutting metal:
a - a chisel, b - a cross-cutting tool, c - a locksmith's hammer
Kreutzmeysel (Fig. 40, b) is used for cutting keyways, cutting rivets, pre-cutting grooves for subsequent cutting with a wide chisel.
To prevent jamming of the crosscut when cutting through narrow grooves, its blade must be wider than the retracted part. The sharpening angles of the crosscut blade are the same as those of the chisel. The length of the crosscut is from 150 to 200 mm.
Locksmith hammer (Fig. 40, b). When cutting, hammers weighing 0.5-0.6 kg are usually used. The hammer is made of tool steel U7 and U8, and its working part is subjected to heat treatment (hardening followed by tempering). Hammers come with round and square heads. Hammer handles are made of hard wood (oak, birch, maple, etc.). The length of the handles of medium weight hammers is from 300 to 350 mm.
To improve productivity in Lately began to carry out the mechanization of felling by using pneumatic hammers, working under the action of compressed air coming from the compressor unit.
The manual cutting process is as follows. The workpiece or part to be chopped off is clamped in a vice so that the marking line for cutting is at the level of the jaws. Cutting is carried out in a chair vice (Fig. 41, a) or, in extreme cases, in a heavy parallel vice (Fig. 41.6). When cutting, the chisel should be in an inclined position to the cut off surface of the workpiece at an angle of 30-35 °. The hammer is struck in such a way that the center of the hammer striker hits the center of the chisel head, and you need to carefully look only at the chisel blade, which should be moved exactly along the marking line for cutting the workpiece.
Rice. 41. Vise:
a - chair, 6 - parallel
When cutting, a thick layer of metal is cut down in several passes of a chisel. To remove metal with a chisel from a wide surface, grooves are first cut down with a crosscut, then the resulting protrusions are cut down with a chisel.
To facilitate work and obtain a smooth surface when cutting copper, aluminum and other viscous metals, periodically moisten the chisel blade with soapy water or oil. When cutting cast iron, bronze and other brittle metals, chipping often occurs on the edges of the workpiece. To prevent chipping, chamfers are made on the ribs before cutting.
Sheet material is cut on an anvil or on a plate with a chisel with a rounded blade, and do I do it first? notch with light blows along the marking line, and then cut the metal with strong blows.
The main equipment of the locksmith's workplace is a workbench (Fig. 42, a, b), which is a solid, stable table 0.75 high and 0.85 m wide. The workbench cover must be made of boards with a thickness of at least 50 mm. From above and from the sides, the workbench is upholstered with sheet steel. A chair or heavy parallel vice is installed on the workbench. The table has drawers for storing metalwork tools, drawings and workpieces and parts.
Before starting work, the locksmith must check the locksmith's tools. Defects found in the tools are eliminated or replaced by a serviceable tool that is unsuitable for work. It is strictly forbidden to work with a hammer with an oblique or knocked down surface of the striker, to work with a chisel with an oblique or knocked down head.
Rice. 42. Locksmith's workplace:
a - single workbench, b - two-man workbench
To protect the eyes from fragments, the locksmith must work with glasses. To protect others from flying fragments, a workbench is installed metal mesh. The workbench must be firmly planted on the floor, and the vise must be well secured to the workbench. It is impossible to work on poorly installed workbenches, as well as on a loose vice, as this can lead to injury to the hand, and it also quickly tires.
Metal straightening and bending
Locksmith editing is usually used to align the curved shape of workpieces and parts. Dressing is carried out manually or on straightening rolls, presses, straightening and angle straightening machines, etc.
Manual dressing is carried out on a straight cast-iron plate or on a blacksmith's anvil with metalworkers' wooden or metal hammers. Thin sheet material is corrected on the correct plates. When straightening sheet material with a thickness of less than 1 mm, wooden or steel bars are used to smooth the sheets on a straightening plate. When editing sheets with a thickness of more than 1 mm, wooden or metal hammers are used.
When manually editing the sheet material, all the bulges are first identified and marked with chalk, then the sheet is placed on the correct plate so that the bulges are on top. After that, they begin to strike with a hammer from one edge of the sheet in the direction of the bulge, and then from the other edge. Hammer blows should not be very strong, but frequent. The hammer should be held firmly and hit the sheet with the central part of the striker, avoiding any distortions, since dents or other defects may appear on the sheet if the blows are incorrect.
The strip material is corrected on the right plates by hammer blows; round bar material is straightened on a special straightening and sizing machine.
Dents on the wings, hood and body of the car are first straightened with curly levers, then a blank or mandrel is installed under the dent and the dent is straightened with blows of a metal or wooden hammer.
Metal bending is used to obtain the required shape of products from sheet, bar material, as well as from pipes. Bending is carried out manually or mechanically.
When bending by hand, a pre-marked metal sheet is installed in a fixture and clamped in a vice, after which the part protruding from the fixture is struck with a wooden hammer.
Pipes are bent manually or mechanically. Large pipes (such as silencer pipe) are usually bent with preheating at the bends. Pipes of small sizes (pipes of power systems and brake) are bent in a cold state. In order for the pipe walls not to flatten during bending, and the cross section does not change at the bending points, the pipe is pre-filled with fine dry sand, rosin or lead. To get a normal rounding, and the pipe was round at the bend (without folds and dents), you need to choose the right bending radius (a larger diameter of the pipe corresponds to a larger radius). For cold bending, pipes must be pre-annealed. The annealing temperature depends on the pipe material. For example, copper and brass pipes are annealed at a temperature of 600-700 °C, followed by cooling in water, aluminum at a temperature of 400-580 °C, followed by air cooling, steel at 850-900 °C, followed by cooling in air.
Rice. 43. Roller pipe bender
Pipe bending is carried out using various devices. On fig. 43 shows a roller fixture. Mechanical bending of pipes is carried out on pipe bending, edge bending machines, universal bending presses.
metal cutting
When cutting metal, various tools are used: wire cutters, scissors, hacksaws, pipe cutters. The use of a particular tool depends on the material, profile and dimensions of the workpiece or part being processed. For example, wire cutters are used for cutting wire (Fig. 44, a), which are made from tool steel grade U7 or U8. The jaws of the cutting pliers are subjected to hardening followed by low (heating up to 200 ° C and slow cooling) tempering.
Rice. 44. Tools for cutting metal: a - wire cutters, b - chair scissors, c - lever scissors
For cutting sheet material, manual, chair, lever, electric, pneumatic, guillotine, disk shears are used. Thin sheet material (up to 3 mm) is usually cut with hand or chair scissors (Fig. 44, b), and thick (from 3 to 6 mm) - lever (Fig. 44, c). Such scissors are made of carbon tool steel U8, U10. The cutting edges of scissors are hardened. The angle of sharpening of the cutting edges of scissors usually does not exceed 20-30°.
When cutting with scissors, a pre-marked metal sheet is placed between the blades of the scissors so that the marking line coincides with the upper blade of the scissors.
Electric and pneumatic scissors are becoming more and more widely used. In the body of electric scissors there is an electric motor (Fig. 45), the rotor of which, by means of a worm gear, rotates an eccentric roller, to which a connecting rod is connected, which drives the movable knife. The lower fixed knife is rigidly connected to the body of the scissors.
Rice. 45. Electric scissors I-31
Pneumatic scissors work under the influence of compressed air.
Mechanically driven guillotine shears cut steel sheets up to 40 mm thick. Circular shears cut sheet material up to 25 mm thick in straight or curved lines.
For cutting small workpieces or parts, manual and electromechanical hacksaws are used.
A hand saw (Fig. 46) is a steel sliding frame, called a machine, in which a steel hacksaw blade is reinforced. The hacksaw blade has the shape of a plate up to 300 mm long, 3 to 16 mm wide and 0.65 to 0.8 mm thick. The teeth of the hacksaw blade are bred in different directions so that the width of the cut formed during cutting is 0.25-0.5 mm larger than the thickness of the hacksaw blade.
Hacksaw blades come with small and large teeth. When cutting parts with thin walls, thin-walled pipes and thin profile rolled products, blades with fine teeth are used, and for cutting soft metals and cast iron - with large teeth.
The hacksaw blade is installed in the machine with the teeth forward and tensioned so that it does not warp during operation. Before starting work, the workpiece or part to be cut is installed and clamped in a vice so that the marking line (cut line) is located as close as possible to the vise jaws.
During operation, the locksmith should hold the hacksaw by the handle with his right hand, and his left hand should lie on the front end of the machine. When moving the hacksaw away from you, a working stroke is made. With this move, you need to press, and when you move the hacksaw back, i.e., when you move it towards yourself, an idle stroke occurs, at which pressure should not be done.
The work of a manual hacksaw is unproductive and tiring for the worker. The use of electromechanical hacksaws dramatically increases labor productivity. The device of an electromechanical hacksaw is shown in fig. 47. In the body of the hacksaw there is an electric motor that rotates the shaft on which the drum is mounted.
Rice. 47. Electromechanical hacksaw
The drum has a spiral groove along which the pin, fixed in the slider, moves. A hacksaw blade is attached to the slider. When the electric motor is running, the drum rotates, and the hacksaw blade attached to the slider, reciprocating, cuts the metal. The bar is designed to stop the tool during operation.
Hacksaw blade.
Rice. 46. Hacksaw:
1 - machine, 2 - fixed earring, 3 - handle, 4 - hacksaw blade, 5 - magnifying glass, 6 - lamb, 7 - movable earring
Rice. 48. Pipe cutter
A pipe cutter is used to cut pipes. It consists of a bracket (Fig. 48) with three disc incisors, of which the incisors are fixed, and the incisor is movable, and a handle mounted on the thread. When working, the pipe cutter is put on the pipe, by turning the handle, the movable disk is moved until it comes into contact with the surface of the pipe, then, rotating the pipe cutter around the pipe, they cut it.
Pipes and profile material are also cut with band or circular saws. The device of the band saw LS-80 is shown in fig. 49. On the saw bed there is a table with a slot designed for the passage (tape) of the saw blade. In the lower part of the bed there is an electric motor and the drive pulley of the saw, and in the upper part of the bed there is a driven pulley. Using the handwheel, the saw blade is pulled.
In circular saws, instead of a cutting band, there is a cutting disc. A feature of circular saws is the ability to cut profile metal at any angle.
Thin grinding wheels are also used for cutting hardened steel and hard alloys.
filing metal
Filing is one of the types of metalworking, which consists in removing a layer of metal from a workpiece or part to obtain the desired shapes, sizes and surface finish.
This type of processing is performed with a special metalwork tool called a file. Files are made from tool steels U12, U12A, U13 or U13A, ShKh6, ShKh9, ShKh15 with obligatory hardening. According to the shape of the cross section, the files are divided into flat (Fig. 50, a), semicircular (Fig. 50.6), square (Fig. 50, c), trihedral (Fig. 50, d), round (Fig. 50, e ) and etc.
By type of notch, files come with single and double notches (Fig. 51, a, b). Files with a single notch are used for filing soft metals (lead, aluminum, copper, babbit, plastics), files with a double notch are used for processing hard metals. Depending on the number of notches per 1 lin. cm, files are divided into six numbers. No. 1 includes files with a large notch with a number of teeth from 5 to 12, the so-called "bastard files". Files with a notch No. 2 have a number of teeth from 13 to 24, they are called "personal". The so-called "velvet" files have a fine notch - No. 3, 4, 5, 6, are made with a number of teeth from 25 to 80.
Rice. 49. Band saw LS-80
Rice. 50. Files and their application (left):
a - flat, o - semicircular, c - square, d - trihedral, d - round
For rough filing, when it is required to remove a metal layer from 0.5 to 1 mm, bastard files are used, which can remove a metal layer with a thickness of 0.08-0.15 mm in one stroke.
In cases where, after preliminary rough filing with bastard files, clean and accurate processing of the workpiece or part is required, personal files are used, which can be used to remove a layer of metal with a thickness of 0.02-0.03 mm in one stroke.
Rice. 51. Notch files:
a - single, b - double
Velvet files are used for the most precise processing and giving the treated surface a high purity. For finishing and other special work, files called “needle files” are used. They have the smallest notch. For filing soft materials (wood, leather, horns, etc.), files are used, which are called rasps.
The choice of file depends on the hardness of the surface to be treated and the shape of the workpiece or part. To increase the service life of the files, it is necessary to take measures to protect them from water, oil, dirt. After work, the notch of the files should be cleaned with a metal brush from dirt and sawdust stuck between the teeth of the notch. For storage, the files are placed in tool boxes in one row, preventing them from touching each other. To prevent oiling of the file during operation, the notch is rubbed with oil or dry charcoal.
Filing techniques. The productivity and accuracy of filing depend mainly on how coordinated the movements of the right and left hands are, as well as on the pressure on the file and the position of the locksmith's body. When filing, the fitter stands on the side of the vise at a distance of approximately 200 mm from the edge of the workbench so that the movement of his hands is free. The position of the locksmith's body is straight and rotated by 45° in relation to the longitudinal axis of the vise.
The file is taken by the handle with the right hand so that the thumb is located on top along the handle, and the remaining fingers clasp it from below. Left hand should be placed with the palm of your hand across the top surface of the front end of the file.
The movement of the file must be strictly horizontal, and the pressure force of the hands must be adjusted depending on the fulcrum of the file on the surface being processed. If the fulcrum is in the middle of the file, then the pressing force with both hands should be the same. When moving the file forward, you need to increase the pressure of the right hand, and, on the contrary, reduce the left hand. The movement of the file back should be without pressure.
When filing on the surface to be treated, there are traces of the teeth of the file, called strokes. The strokes, depending on the direction of movement of the file, can be longitudinal or cross. The quality of filing is determined by how evenly spaced strokes. To obtain a pra-ail sawn surface, evenly covered with strokes, cross filing is used, which consists in first filing with parallel strokes from right to left, and then from left to right (Fig. 52, a).
After rough filing, the quality of the work is checked against the light with a straightedge, which is applied along, across and diagonally to the processed plane. If the clearance is the same or not at all, the filing quality is considered good.
A more accurate way is to check “for paint”, which consists in the fact that a thin layer of paint (usually blue or soot diluted in oil) is applied to the surface of the test plate and the part is applied to it with a treated surface, and then, by lightly pressing on the part, they move it is all over the plate and removed. If traces of paint are evenly distributed over the entire surface of the part, it is considered that filing is done correctly.
Thin round parts are filed as follows. A wooden block with a trihedral cut is clamped in a vice, in which the sawn part is placed, and its end is clamped in a hand vise (Fig. 52, b). When filing, hand vises, together with the part fixed in them, are gradually turned with the left hand.
When filing several planes located relative to each other at an angle of 90 °, proceed as follows. First, wide opposite planes are processed with cross filing and checked for parallelism. After that, one of the narrow planes is filed with longitudinal strokes. The quality of its processing is checked with a ruler for clearance, the angles formed with a wide plane - a square. Then the remaining planes are sawn off. Narrow planes for mutual perpendicularity are checked with a square.
When filing parts made of thin sheet metal, first they process wide planes on surface grinders, then the parts are combined into packs and their edges are filed using the usual methods.
Sawing straight shaped armholes usually begins with the manufacture of liners, and only after that proceed to the armholes. First, the outer edges of the armhole are filed, then the center and contours of the armhole are marked, after marking, a round hole is drilled so that the edges of the hole are at least I-2 mm away from the marking lines. After that, a preliminary filing of the hole (armhole) is performed and trimming with a needle file is made in its corners.
Rice. 52. Filing surfaces:
a - wide flat, b - cylindrical
Then they proceed to the final processing, filing first two mutually parallel sides of the armhole, after which the adjacent side is filed according to the template, and then the next opposite, parallel to it. Mark the armhole a few hundredths of a millimeter smaller than the size of the liner. When the armhole is ready, make an adjustment (exact fit of the parts to each other) along the liner.
After fitting, the liner should fit into the armhole and have no gaps in the places of contact with it.
Identical parts are made by filing along a copier-conductor. The copier-conductor is a device, the contour of the working surfaces of which corresponds to the contour of the manufactured part.
For filing along the copier-conductor, the workpiece is clamped together with the copier in a vice (Fig. 53) and the parts of the workpiece protruding beyond the contour of the copier are filed. This processing method increases labor productivity when filing parts made of thin sheet material, which are clamped into a vise several pieces at once.
Mechanization of the sawing process. At repair enterprises, manual filing is replaced by mechanized, performed at filing stations. machine tools with the help of special devices, electric and pneumatic grinders. Light portable machines include a very convenient I-82 electric grinder (Fig. 54, a) and a ShR-06 pneumatic grinder (Fig. 54.6), on the spindle of which there is an abrasive wheel. The spindle is driven by a pneumatic rotary motor.
For filing surfaces in hard-to-reach places, a mechanical file is used (Fig. 54, c), powered by an electric drive with a flexible shaft that rotates the tip /. The rotation of the tip is transmitted through the roller and the worm gear to the eccentric 2. During rotation, the eccentric informs the plunger 3 and the file attached to it reciprocating motion.
Sawing safety. The sawn workpiece must be securely clamped in a vice so that during operation it cannot change its position or jump out of the vice. Files must be with wooden handles, on which metal rings are mounted. The handles fit firmly onto the file shanks.
The shavings formed during filing are removed with a hair brush. It is strictly forbidden for a mechanic to remove chips with his bare hands or blow them off, as this can lead to injury to hands and eyes.
Rice. 53. Filing on a copier:
1 - copier strip, 2 - removable layer
Rice. 54. Tools for mechanized filing:
a - electric grinder I-82, 6 - pneumatic grinder ShR-06, c - mechanical file
When working with portable electric tools, you must first check the reliability of their grounding.
scraping
Scraping is the process of removing a very thin layer of metal from an insufficiently flat surface with a special tool - a scraper. Scraping is the final (precise) finishing of the surfaces of mating machine parts, plain bearing shells, shafts, calibration and marking plates, etc. to ensure a snug fit of the connection parts.
Scrapers are made from high-carbon tool steel U12A or U12. Often scrapers are made from old files, having removed a notch from them with an emery wheel. The cutting part of the scraper is hardened without subsequent tempering in order to give it high hardness.
The scraper is sharpened on an emery wheel so that the strokes from sharpening are located across the blade. To avoid strong heating of the blade during sharpening, the scraper is periodically cooled in water. After sharpening, the blade of the scraper is adjusted on grinding whetstones or on abrasive wheels, the surface of which is coated with machine oil.
Scrapers come with one or two cutting ends, the first are called one-sided, the second - two-sided. According to the shape of the cutting end, the scrapers are divided into flat (Fig. 55, a), trihedral (Fig. 55, b) and shaped.
Flat one-sided scrapers come with a straight or bent down end; they are used for scraping flat surfaces of grooves and grooves. For scraping curved surfaces (when processing bushings, bearings, etc.), trihedral scrapers are used.
Shaped scrapers are designed for scraping shaped surfaces, grooves with complex profiles, grooves, grooves, etc. A shaped scraper is a set of steel plates, the shape of which corresponds to the shape of the treated surface. The plates are mounted on a metal holder. scraper and fixed on it with a nut.
The quality of surface treatment by scraping is checked on a surface plate.
Depending on the length and width of the processed flat surface, the scraping allowance should be from 0.1 to 0.4 mm.
The surface of a workpiece or workpiece is treated for machine tools or filing.
After pre-treatment, scraping begins. The surface of the calibration plate is covered with a thin layer of paint (red lead, blue or soot diluted in oil). The surface to be treated is carefully wiped with a cloth, carefully placed on the surface plate and slowly moved over it in a circular motion, after which it is carefully removed.
As a result of such an operation, all areas protruding on the surface are painted and clearly distinguished by spots. Painted areas (spots) together with the metal are removed with a scraper. The surface to be treated and the reference plate are then cleaned and the plate is recoated with a layer of paint, and the workpiece or part is again placed on it.
Rice. 55. Manual scrapers:
a - straight flat one-sided and flat one-sided with a bent end, b - trihedral
Newly formed spots on the surface are again removed with a scraper. Spots during repeated operations will be made smaller, and their number will increase. Scrap until the spots are evenly distributed over the entire surface to be treated, and their number meets the specifications.
When scraping curved surfaces (for example, a bearing shell), instead of a calibration plate, a shaft neck is used, which must be in conjunction with the machined surface of the bushing. In this case, the bearing shell is placed on the shaft neck, covered with a thin layer of paint, carefully turned around it, then removed, clamped in a vise and scraped over the spots.
When scraping, the scraper is set in relation to the surface to be treated at an angle of 25-30° and is held with the right hand by the handle, pressing the elbow to the body, and with the left hand they press the scraper. Scraping is done with short movements of the scraper, and if the scraper is flat straight, then its movement should be directed forward (away from you), with a flat scraper with the end bent down, the movement is done backward (towards you), and with a trihedral scraper - sideways.
At the end of each stroke (movement) of the scraper, it is torn off from the surface to be treated so that burrs and ledges do not result. To obtain a smooth and precise surface to be treated, the scraping direction is changed each time after checking for paint so that the strokes intersect.
The scraping accuracy is determined by the number of evenly spaced spots on an area of 25X25 mm2 of the treated surface by applying a control frame to it. The average number of spots is determined by checking several areas of the treated surface.
Manual scraping is very laborious and therefore it is replaced at large enterprises by grinding, turning, or it is carried out by mechanized scrapers, the use of which facilitates work and dramatically increases its productivity.
Rice. 56. Mechanized scraper
The mechanized scraper is driven by an electric motor (Fig. 56) through a flexible shaft connected at one end to the gearbox and at the other to the crank. When the electric motor is turned on, the crank begins to rotate, imparting a reciprocating motion to the connecting rod and the scraper attached to it. In addition to the electric scraper, pneumatic scrapers are used.
Lapping
Lapping is one of the most accurate methods of final finishing of the treated surface, providing high processing accuracy - up to 0.001-0.002 mm. The lapping process consists in removing the thinnest layers of metal with abrasive powders, special pastes. For lapping, abrasive powders made of corundum, electrocorundum, silicon carbide, boron carbide, etc. are used. Lapping powders are divided into grinding powders and micropowders according to their grain size. The former are used for rough grinding, the latter for preliminary and final finishing.
To grind the surfaces of mating parts, for example, valves to seats in engines, nipples to valve sockets, etc., GOI (State Optical Institute) pastes are mainly used. GOI pastes rub any metals, both hard and soft. These pastes are available in three types: coarse, medium and fine.
Coarse GOI paste is dark green (almost black), medium is dark green, and fine is light green. Lapping tools are made of gray fine-grained cast iron, copper, bronze, brass, and lead. The shape of the lap must match the shape of the surface to be lapped.
Lapping can be done in two ways: with and without a lap. The processing of surfaces that are not mating with each other, for example, gauges, templates, squares, tiles, etc., is carried out using a lap. The mating surfaces are usually lapped together without the use of a lap.
Laps are movable rotating discs, rings, rods or fixed plates.
The process of grinding non-conjugated planes is as follows. A thin layer of abrasive powder or a layer of paste is applied to the surface of the flat lap, which is then pressed into the surface with a steel bar or rolling roller.
When preparing a cylindrical lap, the abrasive powder is poured in an even thin layer on a hardened steel plate, after which the lap is rolled along the lap until the abrasive powder is pressed into its surface. The prepared lap is inserted into the workpiece and is moved along its surface with light pressure, or, conversely, the workpiece is moved along the surface of the lap. Abrasive powder grains pressed into the lap cut off a metal layer 0.001-0.002 mm thick from the lapped surface of the part.
The workpiece must have a lapping allowance of not more than 0.01-0.02 mm. To improve the quality of grinding, lubricants are used: engine oil, gasoline, kerosene, etc.
Mating parts are lapped without lapping. A thin layer of the appropriate paste is applied to the surfaces of the parts prepared for lapping, after which the parts begin to move one over the other in a circular motion in one direction or the other.
The manual lapping process is often replaced by a mechanized one.
Automotive repair shops use rotaries, electric drills, and pneumatic machines to grind valves into seats.
The valve is ground to its seat as follows. The valve is installed in the guide bushing of the cylinder block, having previously put a weak spring and a felt ring on the valve stem, which protects the guide bushing from getting lapping paste into it. After that, the working chamfer of the valve is lubricated with GOI paste and they begin to rotate the valve with a manual or electric drill, making one third of a turn to the left, and then two or three turns to the right. When changing the direction of rotation, it is necessary to loosen the pressure on the drill so that the valve, under the action of a spring put on its stem, rises above the seat.
The valve is usually rubbed first with a coarse paste, and then medium and fine. When a dull gray band in the form of a ring without spots forms on the working face of the valve and seat, the lapping is considered complete. After lapping, the valve and seat are thoroughly flushed to remove any remaining particles of lapping paste.
Drilling is used to obtain round holes in workpieces or parts. Drilling is carried out on drilling machines or a mechanical (manual), electric or pneumatic drill. The cutting tool is a drill. Drills are divided into feather drills, spiral drills, center drills, drills for drilling deep holes and combined drills. In plumbing, mainly twist drills are used. Drills are made from tool carbon steels U10A, U12A, as well as from alloyed chromium steels 9XC, 9X and high-speed P9 and P18.
A twist drill (Fig. 57) has the shape of a cylindrical rod with a conical working end, which has two helical grooves on the sides with an inclination of 25-30 ° to the longitudinal axis of the drill. Through these grooves, the chips are discharged to the outside. tail section the drill is made cylindrical or conical. The angle of sharpening at the top of the drill can be different and depends on the material being processed. For example, for processing soft materials, it should be from 80 to 90 °, for steel and cast iron 116-118 °, for very hard metals 130-140 °.
Drilling machines. In repair shops, single-spindle vertical drilling machines are most widely used (Fig. 58). The workpiece or part to be machined is placed on a table that can be raised and lowered with a screw. The table is fixed on the bed with the handle at the required height. The drill is installed and fixed in the spindle. The spindle is driven by an electric motor through a gearbox, automatic feed is carried out by a feed box. The vertical movement of the spindle is carried out manually by a flywheel.
A hand drill (fig. 59) consists of a spindle on which the cartridge is located, a bevel gear (consisting of large and small gears), a fixed handle, a movable handle and a breastplate. The drill is inserted into the chuck and fixed. When drilling, the locksmith holds the drill with his left hand by the fixed handle, and with his right hand rotates the movable handle, resting his chest on the bib.
Rice. 57. Twist drill:
1 - working part of the drill, 2 - neck, 3 - shank, 4 - foot, l - groove, 6 - pen, 7 - guide chamfer (ribbon), 8 - rear sharpening surface, 9 - cutting edges, 10 - jumper, 11 - cutting part
Rice. 58. Single spindle vertical drilling machine 2135
Pneumatic drill (Fig. 60, a) works under the action of compressed air. It is easy to use due to its small size and weight.
An electric drill (Fig. 60, b) consists of an electric motor, gear and spindle. A chuck is screwed onto the end of the spindle, in which the drill is clamped. On the casing there are handles, in the upper part of the body there is a bib for emphasis during work.
Drilling is carried out either according to the marking, or according to the conductor. When drilling along the markup, the hole is first marked, then it is punched around the circumference and in the center. After that, the workpiece is fixed in a vice or other device and drilling is started. Drilling according to the markup is usually carried out in two steps. First, a hole is drilled to a depth of a quarter of the diameter. If the resulting hole (non-through) matches the marked one, then drilling is continued, otherwise the installation of the drill is corrected and only after that drilling is continued. This method is of the greatest use.
Rice. 59. Hand drill
Rice. 60. Pneumatic (a) and electric (b) drills:
1 - rotor, 2 - stator, 3 - cartridge, 4 - spindle, 5 - gearbox, 6 - trigger
Drilling a large number of identical parts with high accuracy is carried out according to the jig (a template with accurately made holes). The jig is applied to the workpiece or part to be processed, and drilling is performed through the holes in the jig. The jig does not allow the drill to deviate, so that the holes are accurate and located at the right distance. When drilling a tapped hole, use reference manuals to select the size of the drill diameter in accordance with the type of thread, as well as taking into account the mechanical properties of the material being processed.
Causes of drill breakage. The main causes of drill breakage during drilling are: deviation of the drill to the side, the presence of shells in the workpiece or part, clogging of the grooves on the drill with chips, improper sharpening of the drill, poor heat treatment drill, blunt drill.
Drill sharpening. The sharpening of the drill has a great influence on the productivity and quality of drilling. Drills are sharpened on special machines. In small workshops, drills are sharpened by hand on emery grinders. Drill sharpening control is carried out with a special template having three surfaces a, b, c, (Fig. 61).
Hole countersinking - subsequent (after drilling) processing of holes, which consists in removing burrs, chamfering and obtaining a conical or cylindrical recess at the inlet of the hole. Countersinking is carried out with special cutting tools - countersinks. According to the shape of the cutting part, the countersink is divided into cylindrical and conical (Fig. 62, a, b). Conical countersinks are used to obtain conical recesses in holes for rivet heads, countersunk screws and bolts. Conical countersinks can be with an angle at the top of 30, 60 and 120°.
Cylindrical countersinks process the planes of bosses, recesses for the heads of screws, bolts, screws, washers. A cylindrical countersink has a guide pin that fits into the hole being machined and ensures the correct direction of the countersink. Countersinks are made from carbon tool steels U10, U11, U12.
Countersinking is the subsequent processing of holes before reaming with a special tool - a countersink, the cutting part of which has more cutting edges than a drill.
According to the shape of the cutting part, countersinks are spiral and straight, according to their design they are divided into solid, mounted and with plug-in knives (Fig. 63, a, b, c). According to the number of cutting edges, countersinks are three- and four-toothed. One-piece countersinks have three or four cutting edges, mounted ones have four cutting edges. Reaming is performed on drilling machines, as well as pneumatic and electric drills. Zenkers are fixed in the same way as drills.
Reaming is the finishing of a hole, performed by a special cutting tool called a sweep.
When drilling a hole, an allowance for the diameter for rough reaming is not more than 0.2-0.3 mm, and for finishing - 0.05-0.1 mm. After reaming, the accuracy of the hole size increases to the 2-3rd class.
Rice. 61. Template for controlling the sharpening of drills
Rice. 62. Countersinks:
a - cylindrical, b - conical
According to the method of actuation, reamers are divided into machine and manual, according to the shape of the processed hole - into cylindrical and conical, according to the device - into solid and prefabricated. Reamers are made from tool steels.
Cylindrical solid reamers come with a straight or helical (spiral) tooth, and therefore the same grooves. Cylindrical reamers with a spiral tooth can be with right or left grooves (Fig. 64, a, b). The reamer consists of a working part, a neck and a shank (Fig. 64, c).
Rice. 63. Zenkers:
a - solid, b - mounted, i - with plug-in knives
Rice. 64. Cylindrical reamers:
a - with a right helical groove, b - with a left helical groove, c - main parts of the reamer
The cutting, or intaking, part is made conical, it performs the main work of cutting to remove the allowance. Each cutting edge forms with the reaming axis the main angle in plan Ф (Fig. 64, c), which is usually 0.5-1.5 ° for manual reamers, and 3-5 ° for machine reamers - for processing hard metals and 12- 15° - for processing soft and viscous metals. .
The cutting edges of the intake part form an angle at the top of 2 cf. with the revolving axis. The end of the cutting part is chamfered at an angle of 45°. This is necessary to protect the tops of the cutting edges from nicks and chipping during operation.
The calibrating part of the reamer almost does not cut, it consists of two sections: a cylindrical section, which serves to calibrate the hole, the direction of the reamer, and a section with a reverse taper, designed to reduce the friction of the reamer against the surface of the hole and protect the hole from development.
The neck is the section of the sweep between working part and shank. The neck diameter is 0.5-1 mm less than the diameter of the calibrating part. Machine reamers have conical shanks, while manual reamers have square shanks. Reamers come with uniform and uneven tooth pitch. Machine reamers are fixed in the machine spindle with the help of conical sleeves and cartridges, manual reamers are fixed in a wrench, with the help of which the reaming is performed.
Conical reamers are used to ream conical holes for Morse taper, for metric taper, for pins with a taper of 1:50. Conical reamers are made in sets of two or three pieces. A set of three reamers consists of rough, intermediate and finishing (Fig. 65, a, b, c). In a set of two reamers, one is transitional and the other is finishing. Conical reamers are made with a cutting part along the entire length of the tooth, which is also a calibrating part for finishing reamers.
Deployment by hand and on machines. Manual deployment is carried out using a wrench, in which the development is fixed. With manual deployment, small workpieces or parts are fixed in a vice, and large ones are processed without fixing.
After fixing the workpiece or part, the cutting part of the reamer is inserted into the hole in such a way that the axes of the reamer and the hole coincide. After that, slowly rotate the scan clockwise; you cannot rotate the reamer in the opposite direction, as scuffing may result. With machine deployment on machines, they proceed in the same way as when drilling.
Rice. 65. Tapered Reamers:
a - rough, b - intermediate, c - finishing
When reaming holes in steel blanks or parts, mineral oils are used as a lubricant; in copper, aluminum, brass parts - soap emulsion. In cast iron and bronze blanks, holes are drilled dry.
The choice of reamer diameter is of great importance for obtaining the required hole size and surface finish. In this case, the thickness of the chips removed by the tool is taken into account (Table 2).
Using this table, you can choose the diameter of the reamer and countersink.
Example. It is necessary to manually unroll a hole with a diameter of 50 mm. To do this, take a finishing reamer with a diameter of 50 mm, and a rough reamer 50-0.07 = 49.93 mm.
When choosing a machine finishing reaming, one should take into account the size of the development, i.e., an increase in the diameter of the hole during machine reaming.
When processing holes with a drill, countersink and reamer, the following basic safety rules must be observed:
perform work only on serviceable machines with the necessary guards;
before starting work, tidy up clothes and headgear. When working, clothing should fit the body without fluttering floors, sleeves, belts, ribbons, etc., it should be tightly buttoned.
Long hair should be matched with a headdress:
- a drill, countersink, reamer or fixture is accurately installed in the machine spindle and firmly fixed;
- It is strictly forbidden to remove chips from the resulting hole with your fingers or blow them off. It is only allowed to remove chips with a hook or brush after the machine has stopped or when the drill is retracted;
- the workpiece or part to be processed must be installed motionless on the table or plate of the machine in the fixture; you can not hold it with your hands during processing;
- you can not install the tool during the rotation of the spindle or check the sharpness of the rotating drill by hand;
- when working with an electric drill, its body must be grounded, the worker must be on an insulated floor.
Threading
Threading is the process of obtaining helical grooves on cylindrical and conical surfaces. A set of turns located along a helical line on a product is called a thread.
The thread is external and internal. The main elements of any thread are profile, pitch, height, outer, middle and inner diameters.
Rice. 66. Thread elements
The thread profile is the shape of the section of the coil passing through the axis of the bolt or nut (Fig. 66). A thread (coil) is a part of a thread formed during one complete revolution of the profile.
The thread pitch is the distance between two similar points of adjacent turns, measured parallel to the axis of the thread, the axis of the bolt or nut.
Thread height is defined as the distance from the top of the thread to the bottom.
The top of the thread is the section of the thread profile that is at the greatest distance from the axis of the thread (the axis of the bolt or nut).
The base of the thread (depression) is the section of the thread profile located at the smallest distance from the axis of the thread.
The angle of the thread profile is the angle between the two sides of the thread profile.
The outer diameter of the thread is the largest diameter measured at the top of the thread in a plane perpendicular to the axis of the thread.
Rice. 67. Thread systems:
a - metric; b - inch, c - pipe
The average thread diameter is the distance between two lines parallel to the axis of the bolt, each of which is at a different distance from the top of the thread and the bottom of the valley. The width of the turns of the external and internal threads, measured along a circle of average diameter, is the same.
The inside diameter of a thread is the smallest distance between opposite thread roots, measured in a direction perpendicular to the thread axis.
Profiles and thread systems. Various thread profiles are used in machine parts. The most common are triangular, trapezoidal and rectangular profiles. By appointment, the threads are divided into fastening and special. A triangular thread is used to fasten parts together (threads on bolts, studs, nuts, etc.), it is often called a fastener. Trapezoidal and rectangular threads are used on parts of motion transmission mechanisms (screws for locksmith disks, lead screws for screw-cutting lathes, lifts, jacks, etc.). R. There are three thread systems: metric, inch and pipe. The main one is the metric thread, which has a profile in the form of an equilateral triangle with an angle at the apex of 60 ° (Fig. 67, a). To avoid jamming during assembly, the tops of the threads of bolts and nuts are cut off. Metric thread sizes are given in millimeters.
The pipe thread is a fine inch thread. It has the same profile as the inch one, with an angle at the top of 55 ° (Fig. 67, c). Pipe threads are mainly used for gas, water pipes and couplings connecting these pipes.
Tools for cutting external threads. For cutting external threads, a die is used, which is a piece or split ring with a thread on the inner surface (Fig. 68, a, b). The chip grooves of the die are used to form cutting edges, as well as to exit the chips.
By design, the dies are divided into round (lerks), sliding and special for cutting pipes. Round dies are solid and split. One-piece round dies have great rigidity, they give a clean thread. Split dies are used for cutting threads of low accuracy.
Sliding dies consist of two halves, which are called half dies. On the outer sides of the half dies there are grooves with an angle of 120° for fixing the half dies in the die. Each half die is marked with a thread diameter and numbers 1 and 2, which guide them when installing them in a die. Dies are made from tool steel U £ 2 "
Threading by hand with dies is carried out with the help of knobs and screw caps. When working with round dies, special knobs are used (Fig. 68, c). The frame of such a star has the shape of a round die. A round plate is installed in the hole of the frame and fixed with three locking screws having conical ends, which enter into special recesses on the plate. The fourth screw, which is included in the cut of the adjustable die, sets the outer size of the thread.
Rice. 68. Tools for cutting external threads:
a - a split die, b - a sliding die, c - a collar, d - a screw cap with an oblique frame
Sliding dies are installed in a die with an oblique frame (Fig. 68, d), which has two handles. Both half-plates are installed in a frame. With an adjusting screw, half-dies are brought together and set to obtain a thread of the desired size. A cracker is inserted between the extreme half-deck and the adjusting screw, which ensures uniform distribution of the screw pressure on the half-dice.
The thread is cut by hand and on machines. In plumbing, hand tools are more often used. External thread cutting with sliding dies is as follows. The blank of a bolt or other part is clamped in a vice and lubricated with oil. Then, a die with dies is applied to the end of the workpiece and the dies are brought together with an adjusting screw so that they cut into the workpiece by 0.2-0.5 mm.
After that, they begin to rotate the screw, turning it 1-2 turns to the right, then half a turn to the left, etc. This is done until the thread is cut to the required length of the part.
Then the die is rolled along the thread to its original position, the dies are brought closer together with the adjusting screw and the cutting process is repeated until a complete thread profile is obtained. After each pass, it is necessary to lubricate the cut part of the workpiece. Thread cutting with solid dies is performed in one pass.
Rice. 69. Locksmith taps:
a - the main parts of the tap, b - a set of taps: 1 - rough, 2 - medium, 3 - finishing
Tools for cutting internal threads. The internal thread is cut with a tap both on machines and manually. In plumbing, they mainly use the manual method.
The tap (Fig. 69, a) is a steel screw with longitudinal and helical grooves that form cutting edges. The tap consists of a working part and a shank. The working part is divided into intake and calibrating parts.
The intaking part of the tap is called the front conical part, which performs the main cutting work. The calibrating part is used to guide the tap in the hole when cutting and calibrating threads. The teeth of the threaded part of the tap are called cutting feathers. The shank serves to secure the tap in the chuck or in the collar. The shank ends in a square. According to their purpose, taps are divided into locksmith, nut, machine, etc.
Taps are used for threading by hand, they are available in sets of two or three pieces. A set of taps "" for cutting metric and inch threads consists of three pieces: rough, medium and fine (Fig. 69, b). The intake part of the rough tap has 6-8 turns, the middle tap has 3-4 turns and the finishing tap has 1.5-2 turns. With a rough tap, pre-cutting is performed, the thread is made more accurate with a medium tap, and the final cut is carried out with a finishing tap and the thread is calibrated.
According to the design of the cutting part, taps are cylindrical and conical. With a cylindrical design, all three taps of the set have different diameters. Only the finishing tap has a full thread profile, the outer diameter of the middle tap is less than the finishing tap by 0.6 of the thread height, and the diameter of the rough tap is less than the diameter of the finishing tap by the full height of the thread. Taps with a cylindrical design of the cutting part are mainly used for threading in blind holes.
With a conical design, all three taps have the same diameter, full thread profile with different chamfer lengths. These taps are used for cutting threads in through holes. Taps are made from tool carbon steels U10, U12. Threads are cut by hand using a wrench with a square hole.
The workpiece or part is fixed in a vice, and the tap - in the collar. The threading process is as follows. The rough tap is installed vertically in the prepared hole and, with the help of a wrench, they begin to rotate it clockwise with light pressure. After the tap crashes into the metal, the pressure is stopped and the rotation continues.
Periodically, it is necessary to check the position of the tap with a square in relation to the upper plane of the workpiece. The tap should be turned 1-2 turns clockwise and then half a turn counterclockwise. This should be done for
so that the chips obtained during cutting are crushed and thereby facilitate the work.
After the rough tap, cutting is done with a medium tap and then with a finish tap. To obtain a clean thread and cool the tap during cutting, lubricant is used. When cutting threads in steel blanks, mineral oil, drying oil or emulsion is used as lubricating and cooling liquids, in aluminum - kerosene, in copper - turpentine. In cast iron and bronze blanks, the threads are cut dry.
When cutting threads in workpieces made of soft and ductile metals (babbitt, copper, aluminum), the tap is periodically turned out of the hole and the grooves are cleaned of chips.
When working with a tap, various defects are possible, for example, breakage of the tap, torn thread, thread stripping, etc. The reasons for these defects are: a blunt tap, clogging of the tap grooves with chips, insufficient lubrication, improper installation of the tap in the hole and selection of the hole diameter, as well as the inattentive attitude of the worker .
Klepka
When repairing machines and assembling them, a mechanic has to deal with various connections of parts. Depending on the assembly method, the connections can be detachable and one-piece. One of the ways to assemble parts into a permanent connection is riveting.
The riveting is made by means of rivets in the manual or machine way. The riveting is cold and hot.
The rivet is a cylindrical rod with a head at the end, which is called a mortgage. In the process of riveting the rod, a second head is formed, called the closing head.
Rice. 70. The main types of rivets and rivet seams:
heads: a - semicircular, 6 - countersunk, c - semi-secret, d - step of the rivet connection; seams; d - overlap, e - butt with one overlay, g - butt with two overlays
According to the shape of the embedded head, rivets come with a semicircular head, with a semi-counterhead head, with a countersunk head (Fig. 70, a, b, c), etc.
The connection of parts made with rivets is called a rivet seam.
Depending on the location of the rivets in the seam in one, two or more rows, rivet joints are divided into single-row, double-row, multi-row.
The distance t between the centers of the rivets of one row is called the pitch of the rivet connection (Fig. 70, d). For single-row seams, the pitch should be equal to three rivet diameters, the distance a from the center of the rivet to the edge of the parts to be riveted should be equal to 1.5 rivet diameters with drilled holes and 2.5 diameters with punched holes. In double-row seams, the pitch is taken equal to four rivet diameters, the distance from the center of the rivets to the edge of the parts to be riveted is 1.5 diameters, and the distance between the rows of rivets should be equal to two rivet diameters.
Rivet joints are performed in three main ways: overlap, butt with one overlay and butt with two overlays (Fig. 70, e, f, g). According to their purpose, rivet seams are divided into strong, dense and strong-dense.
The quality of the rivet seam depends to a large extent on whether the rivet is correctly selected.
Equipment and tools used in manual and mechanized riveting. Manual riveting is carried out using a locksmith's hammer with a square head, support, stretching and crimping (Fig. 71). Hammers are available in weights from 150 to 1000 g. The weight of the hammer is selected in accordance with the diameter of the rivet rod,
The support serves as a support for the insert head of the rivet during riveting, the tension is for closer convergence of the parts to be riveted, the swaging is used to give correct form closing head of the rivet.
Mechanized riveting is carried out by pneumatic structures. Pneumatic riveting hammer (Fig. 72) is powered by compressed air and is driven by a trigger. When the trigger is pressed, valve 9 opens and compressed air, flowing through the channels to the left side of the barrel chamber, activates the drummer, which strikes the crimp.
Rice. 71. Auxiliary tools used for riveting:
1 - crimp, 2 - support, 3 - stretch
After the impact, the spool blocks the flow of air into channel 3, connecting it with the atmosphere, and compressed air is sent through channel 4 to right side the chamber of the barrel, while the drummer is thrown off channel 4, the gold-in-action is blocked, etc. The work of the pneumo-performs two people, one riveting with a hammer, and the other is an assistant.
Rice. 72. Pneumatic riveting hammer P-72
The riveting process is as follows. A rivet is inserted into the hole and set with a mortgage head on a support clamped in a vice. After that, a tension is set on the rivet rod. The tension head is hit with a hammer, as a result of which the parts to be riveted come together.
Then they begin to rivet the rivet rod with hammer blows, inflicting alternately direct and oblique blows directly on the rod. As a result of riveting, the closing head of the rivet is obtained. To give the correct shape to the closing head, a crimp is put on it and the final processing of the head is performed by hammer blows on the crimp, giving it the correct shape.
For rivets with a countersunk head, the hole is pre-treated with a cone countersink. The countersunk head is riveted with direct hammer blows directed exactly along the axis of the rivet.
The most common riveting defects are the following: bending of the rivet shaft in the hole, resulting from the fact that the diameter of the hole was very large; deflection of the material due to the fact that the diameter of the hole was small; displacement of the insert head (obliquely drilled hole), bending of the closing head, resulting from the fact that the rivet shaft was very long or the support was not installed along the axis of the rivet; undercutting of the part (sheet) due to the fact that the crimping hole was larger than the rivet head, cracks on the heads of the rivets that appear when the material of the rivets is insufficiently plastic.
Safety engineering. When performing riveting work, the following safety rules must be observed: the hammer must be securely mounted on the handle; hammer heads, crimps should not have potholes, cracks, as they can split during the riveting process and injure both the riveting worker and the workers nearby with fragments; when working with a pneumatic hammer, it must be adjusted. When adjusting, do not try the hammer while holding the swage with your hands, as this can lead to serious injury to the hand.
Pressing and pressing
When assembling and disassembling assemblies consisting of fixed parts, the pressing and pressing operations are used, carried out using presses and special pullers.
Pressing out is often done using screw pullers. The puller for pressing out the bushings is shown in fig. 73. It has a grip that is pivotally connected to the end of the screw. To secure the sleeve being pressed out in it, the gripper is tilted and inserted into the sleeve.
Rice. 73. Puller for pressing bushings
Pullers are special and universal. Universal pullers can be used to press out parts of various shapes.
In car repair shops, when disassembling and assembling cars, presses of various designs are used for pressing and pressing out: hydraulic (Fig. 74), bench rack, bench screw (Fig. 75, a, b). Bench rack and bench screw are used for pressing out bushings, fingers and other small parts. Pressing and pressing of large parts is carried out using hydraulic presses.
When pressing and pressing hydraulic press proceed as follows. First of all, by turning the handle (see Fig. 74), a lifting table is installed in such a way that the part being pressed or pressed out passes freely under the rod, and fixed with pins.
By rotating the flywheel, the rod is lowered to the stop with the part. After that, with the help of a lever, a pump is activated, pumping oil from the tank into the press cylinder. Under oil pressure, the piston and the rod connected to it are lowered. Moving, the rod presses (or presses out) the part. After the work is done, the valve is opened and the piston springs up along with the stem. The oil from the cylinder is passed back to the reservoir.
Rice. 74. Hydraulic press:
1 - lifting table, 2 - table lifting handle, 3 - rollers for winding the cable, 4 - lifting spring, 5 - pressure gauge, 6 - cylinder, 7 - release valve, 8 - pump lever, 9 - oil tank, 10 - rod , 11 - flywheel, 12 - pressed part, 13 - frame
Rice. 75. Mechanical presses:
a - bench rack, 6 bench screw
In all cases of pressing, to protect the surface of parts from damage and jamming, they are pre-cleaned from rust, scale and lubricated with oil. On the parts prepared for pressing, there should be no nicks, scratches and burrs.
Soldering
Soldering is a method of connecting metal parts to each other using special alloys called solders. The soldering process consists in the fact that the parts to be soldered are applied one to the other, heated to a temperature slightly higher than the melting point of the solder, and liquid molten solder is introduced between them.
To obtain a high-quality solder joint, the surfaces of the parts are cleaned of oxides, grease and dirt immediately before soldering, since the molten solder does not wet the contaminated areas and does not spread over them. Cleaning is carried out by mechanical and chemical methods.
The surfaces to be soldered are first subjected to mechanical cleaning of dirt, rust with a file or scraper, then they are degreased by washing them in a 10% solution of caustic soda or in acetone, gasoline, denatured alcohol.
After degreasing, the parts are washed in a bath of running water and then pickled. Brass parts are etched in a bath containing 10% sulfuric acid and 5% chromium peak, 5-7% hydrochloric acid solution is used for etching steel parts. At a solution temperature of not more than 40°C, parts g are kept in it from 20 to 60 minutes. ~~ After etching, the parts are thoroughly washed first in cold, then in hot water.
Before soldering, the working part of the soldering iron is cleaned with a file and then tinned (coated with a layer of tin).
When soldering, tin-lead-whist, copper-zinc are of the greatest use. copper, silver and copper-phosphorus solders.
To eliminate the harmful effects of oxides, fluxes are used that fuse and remove oxides from the surfaces to be soldered and protect them from oxidation during the soldering process. The flux is chosen in accordance with the properties of the metals to be soldered and the solders used.
Solders are divided into soft, hard. Soft solders solder steel and copper alloys. Steel parts are tinned before soldering with soft solders. Only under this condition is a reliable soldered connection guaranteed.
The most common soft solders are tin-lead alloys of the following grades: POS-EO, POS-40, POS-ZO, POS-18. Solders are available in the form of rods, wires, tapes and tubes. Zinc chloride, ammonium chloride (ammonia), rosin (when soldering copper and its alloys), 10% aqueous solution of hydrochloric acid (when soldering zinc and galvanized products), stearin (when soldering low-melting alloys) are used as fluxes when soldering with soft solders. lead).
For soldering critical parts made of cast iron, steel, copper alloys, aluminum and its alloys, hard solders are used, mainly copper-zinc and silver of the following grades: PMC-36, PMC-48, PMC-54, PSr12, PSr25, PSr45 (melting point of hard alloys from 720 to 880 °C).
For soldering aluminum and its alloys, for example, solder of the following composition is used: 17% tin, 23% zinc and 60% aluminum. Borax, boric acid and their mixtures are used as fluxes. When soldering aluminum, a flux is used, consisting of a 30% solution of an alcohol mixture, which includes 90% zinc chloride, 2% sodium fluoride, 8% aluminum chloride.
When soldering with hard solders, the parts are fixed in special devices in such a way that the gap between the parts does not exceed 0.3 mm. Then flux and solder are applied to the place to be soldered, the part is heated to a temperature slightly higher than the melting of the solder. The melted solder fills the gap and forms a strong joint when cooled.
Car maintenance
