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| The tool used for marking up plumbing. The main types of plumbing work. What is markup |
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Marking is performed using a special marking tool; some control and measuring instruments can also be used, for example: a scale ruler, a level, squares, a compass, a protractor, etc. When carrying out the marking, the following basic tools and devices are used. Marking is used mainly in one-off and small-scale production. At factories of large-scale and mass production, the need for marking disappears due to the use of special devices - conductors, stops, etc. Depending on the shape of the workpieces and parts to be marked, the marking is divided into planar and spatial(volumetric). Plane marking, usually performed on the surfaces of flat parts, on strip and sheet material, consists in drawing on the workpiece contour parallel and perpendicular lines (notches), circles, arcs, angles, center lines, various geometric shapes according to given dimensions or the contours of various holes along templates. Figure 3.1.1 Planar markings (Makienko N.I. General course of plumbing M .: Higher school, 1989.) Even the simplest body cannot be marked out using plane marking techniques if its surfaces are non-rectilinear. At planar marking it is impossible to apply horizontal marks perpendicular to its axis on the lateral surface of the cylinder, since a square and a ruler cannot be applied to this surface. But if a flexible ruler could be found that could be wrapped around the surface of the cylinder, then drawing parallel marks on the cylinder would present great difficulties. Spatial markup is most common in mechanical engineering; in terms of techniques, it differs significantly from planar. The difficulty of spatial marking lies in the fact that it is necessary not only to mark the individual surfaces of the part located in different planes and at different angles to each other, but to link the markings of these individual surfaces to each other. Plane markings are used in the processing of sheet material and profile rolled products, as well as parts on which marking marks are applied in the same plane. Figure 3.1.2 Spatial markup (Makienko N.I. General course of plumbing M .: Higher school, 1989.) Spatial markup- this is the drawing of scratches on the surfaces of the workpiece, interconnected by mutual arrangement. When marking, various measuring and special marking tools are used. To improve the visibility of the marking lines, a number of shallow points should be punched out on them with a center punch at a short distance from each other. Marking is most often done on special cast iron marking plates. In serial production of parts, it is much more profitable to use instead of individual marking copying. Copying(basting) - drawing on the workpiece shape and dimensions according to a template or a finished part. The copy operation is as follows:
Templates are made according to sketches, taking into account all types of allowances. The material for the templates can be sheet steel, tin, cardboard. The method of positioning workpieces of parts on the material is called we will open. There are three main ways to cut sheets:
For mixed nesting, cutting maps are developed, which represent sketches of the placement of parts on metal, drawn to scale on a sheet of paper. Cutting cards are made in such a way as to place on the sheets all the set of parts necessary for the manufacture of units and to ensure the most rational and convenient cutting of blanks. Figure 3.1.3 gives an example of a cyclone cutting pattern, from which it can be seen that the correct cutting provides a straight cut. Figure 3.1.3 Cutting cards: a - correct cutting; b - irrational cutting (Manufacturing technology of the main parts of the equipment, Baku 2010 Directory)
TO Category: Car maintenance The main types of locksmith work Markup Rice. 30. Marking plate Marking is the drawing of boundaries 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 centerlines and centers for drilling holes. If the marking is made only in one plane, for example, on sheet material, then it is called plane. The marking of the surfaces of the workpiece, located at different angles to each other, is called spatial. The workpieces are marked on a special cast-iron plate (Fig. 30), called a marking plate, installed on a wooden table so that its upper plane is strictly horizontal. Tools for marking-to and. When marking out, use various marking tools. The scribe (fig. 31) is a steel bar with sharp hardened ends. With a scribe, thin lines are drawn on the surface of the workpiece using a ruler, template or square. Reismas is used to draw 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 scribe rotating around its axis. The movable collar can be moved along the rack and fixed to it in any position with a clamping screw.
Rice. 31. Scribe The marking compass (Fig. 33) is used to draw circles and roundings on the workpiece to be marked.
Rice. 32. Reismas
Rice. 33. Marking compass For accurate marking, use a height gauge (fig. 34). A rod with a millimeter scale is firmly fixed on a massive base. A frame with a vernier and a second frame of micrometric feed move along the bar. Both frames are fixed to the rod with screws in any desired position. A removable scribe leg is attached to the frame with a clamp. A marking vernier caliper is used to draw large-diameter circles with direct installation of dimensions. A marking caliper (Fig. 35) consists of a bar with a millimeter scale applied on it and two legs, of which the leg is fixed on the bar, and the leg is movable and can move on the bar. The movable leg has a vernier. Hardened steel needles are inserted into both feet. The needle of the movable leg can move up and down and in the desired position can be clamped with a screw.
Rice. 34. Shtangenreismas
Rice. 35. Marking vernier caliper
Rice. 36. Center finder The center finder is designed to determine the center of the end face of a cylindrical workpiece (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 shelves of the square touch the cylindrical surface of the workpiece. A scribe is led along the inner side of the leg, thus drawing a line of diameter, then the center-finder is turned by 90 ° and a second diametrical line is drawn. The point of intersection of these lines will be the center of the end face of the cylindrical workpiece. A scale altimeter (Fig. 37) is used for marking in cases where it is necessary to set the tip of the scribe at a certain height. It consists of a fixed scale ruler attached to a cast-iron square, a movable ruler moving along guide bases, a sighting slider with a thin line. When marking, the targeting engine is installed 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 slider and the distance (height) from the main axis of the workpiece to the other axes is read on the movable ruler. The center punch is used to apply 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 center 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 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. Devices for marking. In order to protect the surface of the measuring 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 along the d-masonry (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 marking process is carried out as follows. The surfaces of the workpieces to be marked are cleaned of dirt, dust and grease. Then it is covered 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 coated with a solution of copper sulfate or quick-drying paints and varnishes. When the applied layer of chalk or paint is dry, you can start marking. The markup can be made according to a drawing or a template.
Rice. 37. Scale altimeter Rice. 38. Kerner The process of marking the workpiece according to the drawing is performed in the following sequence:
Rice. 39. Devices for marking: For planar marking of identical parts, it is more expedient 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 drawn on the workpiece with a scribe. Metal cutting Locksmith's cutting is used to remove excess metal in cases where high processing accuracy is not required, as well as for rough leveling of rough surfaces, for cutting metal, cutting rivets, for cutting keyways, etc. Cutting tools. The tools for cutting metal are chisels and crosscutters, and the hammer is the percussion tool. 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 of 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: Kreutzmeisel (Fig. 40, b) is used for cutting keyways, cutting rivets, preliminary cutting of grooves for subsequent cutting with a wide chisel. To prevent jamming of the cross cutter when cutting narrow grooves, its blade should be wider than the retracted part. The sharpening angles of the crosscutter blade are the same as those of the chisel. The length of the crosspiece is from 150 to 200 mm. Locksmith's hammer (Fig. 40, b). When cutting, hammers weighing 0.5-0.6 kg are usually used. The hammer is made of U7 and U8 tool steel, and its working part is subjected to heat treatment (quenching followed by tempering). Hammers are available with round and square strikers. 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 increase labor productivity, the mechanization of felling has recently begun to be carried out by using pneumatic hammers operating under the action of compressed air coming from a compressor unit. The manual felling process is as follows. The workpiece or part to be chopped off is clamped in a vice so that the cutting line is at the level of the jaws. Cutting is carried out in a chair vise (Fig. 41, a) or, in extreme cases, in a heavy parallel vise (Fig. 41.6). The chisel during cutting should be in an inclined position to the cut-off surface of the workpiece at an angle of 30-35 °. The hammer is hit in such a way that the center of the hammer striker falls into the center of the chisel head, and you only need to carefully look at the chisel blade, which should be moved exactly along the cutting line of the workpiece.
Rice. 41. Vise: When cutting, a thick layer of metal is cut off in several passes of the chisel. To remove metal with a chisel with wide surface grooves are preliminarily cut with a cross cutter, then the formed protrusions are cut with a chisel. To facilitate the work and obtain a smooth surface when chopping copper, aluminum and other viscous metals, the chisel blade is periodically moistened 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, bevels are made on the edges before cutting. The sheet material is chopped on an anvil or on a stove 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 strong, stable table 0.75 m high and 0.85 m wide. The workbench cover must be made of boards with a thickness of at least 50 mm. The top and sides of the workbench are upholstered with sheet steel. A chair or heavy parallel vise is installed on the workbench. The table has drawers for storing locksmith tools, drawings and workpieces and parts. Before starting work, the locksmith must check the locksmith tools. Defects found in tools eliminate or replace the unusable tool with a serviceable one. It is strictly forbidden to work with a hammer with an oblique or knocked-down surface of the striker, work with a chisel with a slanting or knocked-down head.
Rice. 42. Workplace locksmith: To protect the eyes from splinters, the locksmith must wear glasses. To protect others from flying off debris, a workbench is installed metal mesh... The workbench must be firmly set on the floor and the vise well secured to the workbench. It is impossible to work on poorly installed workbenches, as well as on loosely fixed vices, as this can lead to injury to the hand, and besides, it quickly tires. Metal straightening and bending Locksmith's straightening is usually used to smooth out the curved shape of workpieces and parts. Straightening is carried out manually or on straightening rolls, presses, on sheet-straightening and angle straightening machines, etc. Manual straightening is carried out on a right-hand cast-iron plate or on a forging anvil with locksmith's wooden or metal hammers. Thin sheet material is straightened on regular slabs. When straightening sheet material with a thickness of less than 1 mm, wooden or steel bars are used, with which the sheets are smoothed on the right plate. When straightening sheets with a thickness of more than 1 mm, use wooden or metal hammers. When manually straightening sheet material, first identify all the protuberances and mark them with chalk, then the sheet is laid on a regular plate so that the protuberances 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 be not very strong, but frequent. The hammer should be held firmly and strikes against the sheet with the central part of the striker, avoiding any distortions, since dents or other defects may appear on the sheet with incorrect strikes. The strip material is driven on the right slabs with hammer blows; bar material round section ruled on a special straightening-sizing machine. Dents on the fenders, hood and body of the car are first straightened using curly levers, then a blank or mandrel is installed under the dent and the dent is straightened with 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 the pre-marked metal sheet is installed in the device and clamped in a vice, after which blows are applied to the part protruding from the device with a wooden hammer. Pipes are bent manually or mechanically. Large pipes (eg muffler pipe) are usually bent and preheated at the bends. Small pipes (tubes of power supply and brake systems) are cold bent. In order to prevent the pipe walls from flattening 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 obtain a normal rounding, and in the place of the bend, the pipe was round (without folds and dents), you need to choose the right bend 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 pipes at a temperature of 400-580 ° C followed by air cooling, steel pipes at 850-900 ° C followed by air cooling.
Rice. 43. Roller pipe bending device Bending of pipes is carried out using various devices. In fig. 43 shows a roller device Mechanical bending of pipes is carried out on pipe bending, edge-bending machines, universal bending presses. Metal cutting When cutting metal, they use various tools: nippers, scissors, hacksaws, pipe cutters. The use of this or that tool depends on the material, profile and dimensions of the workpiece or part being processed. For example, wire cutting pliers are used (Fig, 44, a), which are made of U7 or U8 tool steel. The jaws of the pliers are hardened, followed by a low (heating up to 200 ° C and slow cooling) tempering.
Rice. 44. Tools for cutting metal: a - nippers, b - chair scissors, c - lever scissors For cutting sheet material, manual, chair, lever, electric, pneumatic, guillotine, circular 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) - with lever scissors (Fig. 44, c). Such scissors are made of U8, U10 carbon tool steel. The cutting edges of the scissors are hardened. The angle of sharpening of the cutting edges of the 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. More and more wide application find electric and pneumatic scissors. In the body of the electric scissors there is an electric motor (Fig. 45), the rotor of which, with the help of a worm gear, drives the eccentric roller into rotation, with which a connecting rod is connected, which drives a movable knife. The lower fixed knife is rigidly connected to the shear body.
Rice. 45. Electric scissors I-31 Pneumatic shears work with compressed air. Using a mechanically driven guillotine shear shears steel sheets up to 40 mm thick. Circular scissors cut sheet material up to 25 mm thick in straight or curved lines. For cutting small workpieces or parts, hand and electromechanical hacksaws are used. A hand saw (fig. 46) is a steel sliding frame, called a machine, in which a steel hacksaw blade... A hacksaw blade has the form 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 set apart in such a way that the width of the kerf formed during cutting is 0.25-0.5 mm greater than the thickness of the hacksaw blade. Hacksaw blades are available with fine and coarse teeth. When cutting parts with thin walls, thin-walled pipes and thin shaped 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 tightened so that it does not warp during operation. Before starting work, the workpiece or part to be cut is installed and clamped in a vise so that the marking line (cut line) is located as close as possible to the vise jaws. During work, the locksaw should hold the hacksaw by the handle with his right hand, and the left hand should rest 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 make pressure, and when you move the hacksaw back, that is, when you move towards yourself, an idle run occurs, at which pressure should not be done. Hand hacksaw work is unproductive and tedious 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 drives the shaft on which the drum is mounted.
Rice. 47. Electromechanical hacksaw The drum has a spiral groove along which the finger, 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, in a reciprocating motion, cuts the metal. The bar is designed to stop the tool during work. Hacksaw blade.
Rice. 46. Hacksaw:
Rice. 48. Pipe cutter A pipe cutter is used to cut pipes. It consists of a bracket (Fig. 48) with three disc cutters, of which the cutters are stationary, and the cutter is movable, and a handle mounted on the thread. During operation, the pipe cutter is put on the pipe, by turning the handle, the movable disk is moved until it touches the surface of the pipe, then, by rotating the pipe cutter around the pipe, it is cut. Pipes and profiles are also cut with band or circular saws. The device of the band saw LS-80 is shown in Fig. 49. The saw frame has a table with a slot for the saw blade to pass (band). At the bottom of the bed is the electric motor and the drive pulley for the saw, and at the top of the bed is the driven pulley. Using the handwheel, the saw blade is pulled. Circular saws have a cutting disc instead of a cutting band. 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 Sawing is one of the types of metalworking, which consists in removing a layer of metal from a workpiece or part to obtain the specified shapes, sizes and surface finish. This type of processing is performed with a special locksmith tool called a file. Files are made of U12, U12A, U13 or U13A, ShH6, ShH9, ShH15 tool steels with mandatory 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), triangular (Fig. 50, d), round (Fig. 50, e ) and etc. According to the type of notch, files are available with single and double notches (Fig. 51, a, b). Single cut files are used for filing soft metals (lead, aluminum, copper, babbitt, plastics), double cut files are used for processing hard metals. Depending on the number of incisions per 1 running meter. cm, files are divided into six numbers. No. 1 includes coarse files with a number of teeth from 5 to 12, the so-called "bastard". # 2 cut files have 13 to 24 teeth and are called "personal" files. The so-called "velvet" files have a fine notch - No. 3, 4, 5, 6, are made with the number of teeth from 25 to 80.
Rice. 49. Band saw LS-80
Rice. 50. Files and their application (left): For coarse filing, when it is required to remove a metal layer from 0.5 to 1 mm, bastard files are used, with which a metal layer 0.08-0.15 mm thick can be removed in one working stroke. In cases where, after preliminary rough filing with brittle files, a clean and precise processing of a 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. Cutting files: Velvet files are used for the most precise processing and giving the treated surface a high degree of cleanliness. For finishing and other special work, files called "files" are used. They have the smallest notch. For filing soft materials(wood, leather, horn, etc.) use files called rasps. The choice of file depends on the hardness of the work surface and the shape of the workpiece or part. To increase the service life of files, it is necessary to take measures to protect them from water, oil, dirt. File notches should be cleaned after work 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 the file from becoming oiled during operation, rub the notch with oil or dry charcoal. Sawing 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 locksmith stands on the side of the vise at a distance of about 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 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 on top along the handle, and the rest of the fingers clasp it from below. The left hand should rest with the palm of your hand across the top surface of the front end of the file. The movement of the file should be strictly horizontal, and the pressure of the hands should be adjusted depending on the point of support of the file on the work surface. If the fulcrum is in the middle of the file, the pressure with both hands should be the same. When moving the file forward, you need to increase the pressure of the right hand, and the left, on the contrary, decrease. The backward movement of the file must be without pressure. When filing, the traces of the teeth of the file, called strokes, remain on the processed surface. The strokes, depending on the direction of movement of the file, can be longitudinal or cross. The filing quality is determined by how evenly the strokes are located. To obtain a correct sawn-off surface, evenly covered with strokes, Cross-cutting is applied, which consists in the fact that first sawing with parallel strokes from right to left, and then from left to right (Fig. 52, a). After rough filing, check the quality of the work in the light with a straight edge, which is applied along, across and diagonally of 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 test "for paint", which consists in the fact that on the surface of the test plate is applied thin layer paints (usually blue or soot diluted in oil) and put the part on it with the treated surface, and then, by lightly pressing on the part, move it over the entire plate and remove it. If the traces of paint are evenly distributed over the entire surface of the part, it is considered that the filing is done correctly. Thin round parts are sawn off as follows. A wooden block with a three-edged cut is clamped into a vice, into which the piece to be sawn is placed, and its end is clamped in hand-held vise (Fig. 52, b). When filing, the hand vise, together with the part fixed in them, is 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 the light, the corners formed with a wide plane - with a square. Then the remaining planes are filed. Narrow planes for mutual perpendicularity are checked with a square. When filing parts made of thin sheet metal, at first, wide planes are processed on surface grinding machines, then the parts are connected in bundles and their edges are sawed using the usual methods. Sawing straight shaped armholes usually begins with the manufacture of inserts and only then proceed to the armholes. First, the outer edges of the armhole are sawn off, then the center and the contours of the armhole are marked, after marking, a round hole is drilled so that the edges of the hole are at least 1-2 mm from the marking lines. After that, preliminary filing of the hole (armhole) is performed and trimming is made in its corners with a file
Rice. 52. Sawing surfaces: Then they proceed to the final processing, first sawing off two mutually parallel sides of the armhole, after which the next 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, they make a fit (exact fit of the parts to each other) along the liner. After fitting, the liner should go into the armhole and have no gaps in the places of contact with it. Identical parts are made by filing on a copier-conductor. A copier-jig is a device, the contour of the working surfaces of which corresponds to the contour of the part being manufactured. 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 sawed off. This method of processing increases labor productivity when filing parts made of thin sheet material, which are clamped in a vice of several pieces at once. Mechanization of the filing process. At repair enterprises, manual filing is replaced by mechanized filing, performed at filing stations. machines with the help of special devices, electric and pneumatic grinders. Light portable machines include a very convenient electric grinder I-82 (Fig. 54, a) and a pneumatic grinder ShR-06 (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 use a mechanical file (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. The eccentric, when rotating, imparts a reciprocating movement to the plunger 3 and the file attached to it. Safety precautions when filing. The workpiece to be sawn must be securely clamped in a vice so that during operation it cannot change its position or jump out of the vice. Files must necessarily have wooden handles on which metal rings are set. The handles fit firmly onto the file shanks. The shavings formed during filing are removed with a hair brush. It is strictly forbidden for the locksmith to remove the shavings with his bare hands or blow them away, as this can lead to injury to the hands and eyes.
Rice. 53. Filing on a copier:
Rice. 54. Tools for mechanized filing: When working with portable power tools, you must first check that they are properly grounded. Scraping Scraping is the process of removing a very thin layer of metal from an insufficiently even surface with a special tool - a scraper. Scraping is the final (precise) finishing of the surfaces of mating machine parts, bushings of sliding bearings, shafts, checking and marking plates, etc. to ensure a snug fit of the joint parts. Scrapers are made of U12A or U12 high-carbon tool steel. Often, scrapers are made from old files by removing the notch from them with an emery wheel. The cutting part of the scraper is hardened without subsequent tempering in order to impart high hardness to it. The scraper is sharpened on an emery wheel so that the strokes from the 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 scraper blade is adjusted on whetstone whetstones or 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 - double-sided. According to the shape of the cutting end, the scrapers are divided into flat (Fig. 55, a), triangular (Fig. 55, b) and shaped. Flat one-sided scrapers are available with a straight or bent down end, used for scraping flat surfaces of grooves and grooves. For scraping curved surfaces (when processing bushings, bearings, etc.), triangular scrapers are used. Shaped scrapers are designed for scraping shaped surfaces, grooves, grooves, grooves with complex profiles, etc. Shaped scrapers are a set of steel plates, the shape of which corresponds to the shape of the surface to be treated. The plates are mounted on a metal holder. scraper and secured to it with a nut. The quality of the surface treatment by scraping is checked on a surface plate. Depending on the length and width of the processed flat surface, the size of the scraping allowance should be from 0.1 to 0.4 mm. The surface of the part or workpiece before scraping is processed on metal cutting machines or filing. After preprocessing start scraping. The surface of the surface of the surface 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 rag, carefully placed on a 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 colored and clearly stand out with spots. Painted areas (spots) together with metal are removed with a scraper. Then the surface to be treated and the surface plate are cleaned and the plate is again coated with a layer of paint, and the workpiece or part is again applied to it.
Rice. 55. Hand scrapers: Newly formed spots on the surface are again removed with a scraper. The spots during repeated operations will be made smaller, and their number will increase. Scrub 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 surface plate, a shaft journal is used, which must be in mating with the surface of the shell to be machined. In this case, the bearing shell is placed on the shaft journal, covered with a thin layer of paint, carefully rotated around it, then removed, clamped in a vice 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 by the handle with the right hand, pressing the elbow to the body, and the scraper is pressed with the left hand. Scraping is done with short scraper movements, and if the scraper is flat straight, then its movement should be directed forward (away from itself), with a flat scraper with an end bent downward, the movement is made backward (towards itself), and with a triangular 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 turn out. To obtain an even and precise work surface, the scraping direction is changed each time after checking the 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 imposing a control frame on it. The average number of stains is determined by checking several areas of the surface to be treated. Manual scraping is very laborious and therefore in large enterprises it is replaced by grinding, turning, or it is carried out by mechanized scrapers, the use of which facilitates labor and dramatically increases its productivity.
Rice. 56. Mechanized Scraper The powered 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 movement 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 grinding process consists in removing the thinnest layers of metal with abrasive powders, special pastes. For lapping, abrasive powders of corundum, electrocorundum, silicon carbide, boron carbide, etc. are used. Lapping powders are divided into grinding powders and micropowders by grain size. The former are used for rough lapping, the latter for preliminary and final lapping. For grinding the surfaces of mating parts, for example, valves to seats in engines, nipples to valve seats, etc., mainly GOI (State Optical Institute) pastes are used. Any metals, both hard and soft, are rubbed with GOI pastes. These pastes are available in three types: coarse, medium and fine. The coarse GOI paste is dark green (almost black), the middle one is dark green, and the thin one is light green. Tools - laps are made of gray fine-grained cast iron, copper, bronze, brass, 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 lapping. The processing of non-mating surfaces, for example, calibers, templates, squares, tiles, etc., is carried out using a lap. Mating surfaces are usually lapped together without lapping. Lap laps are movable rotating discs, rings, rods, or stationary plates. The process of lapping non-mating planes is as follows. A thin layer of abrasive powder is poured onto the surface of the flat lap, or a layer of paste is applied, which is then pressed into the surface with a steel bar or a rolling roller. When preparing a cylindrical lapping, abrasive powder is poured into an even thin layer on a hardened steel plate, after which the lapping is rolled over the rod until the abrasive powder is pressed into its surface. The prepared lap is inserted into the workpiece and with light pressure is moved along its surface or, conversely, the workpiece is moved along the lap surface. Abrasive powder grains, pressed into the lap, cut a metal layer with a thickness of 0.001-0.002 mm from the grinding surface of the part. The workpiece to be machined must have a grinding allowance of no more than 0.01-0.02 mm. To improve the quality of lapping, lubricants are used: machine oil, gasoline, kerosene, etc. The mating parts are lapped without lapping. On the surfaces of the parts prepared for lapping, a thin layer of the corresponding paste is applied, after which the parts begin to move one over the other in circular motions, one way or the other. The manual lapping process is often replaced by a mechanized one. In auto repair shops, rotors, electric drills and pneumatic machines are used to grind valves to seats. The valve is lapped to its seat as follows. The valve is installed in the guide sleeve of the cylinder block, after putting on a weak spring and a felt ring on the valve stem, which protects the guide sleeve from getting lapping paste into it. After that, the working chamfer of the valve is lubricated with GOI paste and the valve is started to rotate 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 release the pressure on the drill so that the valve, under the action of the spring put on its stem, rises above the seat. The valve is usually rubbed in at first with a coarse paste, and then with a medium and thin one. When a matte gray ring-like band without spots forms on the working chamfer of the valve and seat, the lapping is considered complete. After lapping, the valve and seat are thoroughly rinsed to remove any remaining lapping paste particles. Drilling is used to produce 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. By design, drills are divided into feather, spiral, center, drills for drilling deep holes and combined. V plumbing twist drills are mainly used. Drills are made of tool carbon steels U10A, U12A, as well as alloyed chromium steels 9XC, 9X and high-speed P9 and P18. The twist drill (Fig. 57) has the shape of a cylindrical rod with a tapered working end, which has two helical grooves on the sides with an inclination of 25-30 ° to the longitudinal axis of the drill. These grooves guide the chips outward. The tail of the drill is made cylindrical or conical. The sharpening angle at the tip 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 used (Fig. 58). The workpiece or workpiece to be machined is placed on a table that can be raised and lowered using a screw. Using the handle, the table is fixed on the bed at the required height. The drill is installed and secured in the spindle. The spindle is driven in rotation 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 with a handwheel. The hand drill (fig. 59) consists of a spindle on which the chuck is located, a bevel gear (consisting of a large and small gears), a fixed handle, a movable handle and a bib. The drill is inserted into the chuck and secured. 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:
Rice. 58. Single-spindle vertical drilling machine 2135 A pneumatic drill (Fig. 60, a) works under the influence of compressed air. It is easy to use as it has small dimensions and weight. An electric drill (Fig. 60, b) consists of an electric motor, a gear train and a spindle. A chuck is screwed onto the end of the spindle, in which the drill is clamped. There are handles on the casing, in the upper part of the case there is a bib for support during work. Drilling is carried out either according to the marking, or along the conductor. When drilling according to the marking, the hole is first marked, then it is punched around the circumference and in the center. After that, the workpiece to be processed is fixed in a vice or other device and begins to drill. Drilling along the markings 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 (blind) coincides with the marked one, then continue drilling, otherwise, correct the installation of the drill and only then continue drilling. This method has the greatest application.
Rice. 59. Hand drill
Rice. 60. Pneumatic (a) and electric (b) drills: Drilling of a large number of identical parts with high precision is carried out using a jig (a template with precisely made holes). The jig is placed on the workpiece or part to be processed, and drilling is performed through the holes in the jig. The jig prevents the drill from deflecting, so the holes are accurate and spaced. When drilling a hole for a thread, it is necessary to use the 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 to be processed. Causes of drill breakage. The main causes of drill breakage during drilling are: drill deflection to the side, presence of cavities in the workpiece or part being processed, blockage of grooves on the drill by chips, improper drill sharpening, poor heat treatment of the drill, blunt drill. Drill sharpening. Drill sharpening greatly influences work performance and drilling quality. The drills are sharpened on special machines. In small workshops, drills are sharpened by hand on emery sharpeners. Drill sharpening control is carried out with a special template having three surfaces a, b, c, (Fig. 61). Hole countersinking - the subsequent (after drilling) processing of holes, which consists in removing burrs, chamfering and obtaining a tapered or cylindrical recess at the entrance of the hole. Countersinking is carried out with special cutting tools - countersinks. According to the shape of the cutting part, countersinks are divided into cylindrical and conical (Fig. 62, a, b). Tapered countersinks are used to obtain tapered recesses in the holes for the heads of rivets, countersunk screws and bolts. Tapered countersinks are available in 30 °, 60 ° and 120 ° point angles. Cylindrical countersinks process the planes of the bosses, recesses for the heads of screws, bolts, screws, washers. The cylindrical countersink has a guide pin that fits into the hole to be machined and provides right direction countersinks. Countersinks are made of U10, U11, U12 carbon tool steels. Countersinking is the subsequent processing of holes before reaming with a special tool - 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). By the number of cutting edges, countersinks are three- and four-fluted. Solid countersinks have three or four cutting edges, insert countersinks have four cutting edges. Countersinking is performed on drilling machines, as well as pneumatic and electric drills. Countersinks are attached in the same way as drills. Reaming is the finishing of a hole with a special cutting tool called a reamer. When drilling a hole, an allowance for the diameter for a rough reaming is not more than 0.2-0.3 mm, and for a finishing one - 0.05-0.1 mm. After deployment, the hole size accuracy is increased to grade 2-3.
Rice. 61. Template for checking the sharpening of drills
Rice. 62. Countersinks: Reamers by the method of actuation are divided into machine and manual, according to the shape of the hole being machined - into cylindrical and conical, according to the device - into solid and prefabricated. Reamers are made from tool steels. Cylindrical solid reamers are available 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. Countersinks:
Rice. 64. Cylindrical sweeps: The cutting, or intake, part is made conical, it performs the main cutting work to remove the allowance. Each cutting edge forms a main angle with the reamer axis F (Fig. 64, c), which for manual reamers is usually 0.5-1.5 °, and for machine reamers 3-5 ° - for processing hard metals and 12- 15 ° - for processing soft and tough metals. ... The cutting edges of the intake part form an angle at the top of 2 cf with the screw axis. The end of the cutter is chamfered at a 45 ° angle. This is necessary to protect the tops of the cutting edges from nicks and chipping during operation. The calibrating part of the reamer does not cut almost, 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 on the surface of the hole and prevent the hole from being worked out. The neck is the section of the sweep between the working part and the shank. The diameter of the neck is 0.5-1 mm less than the diameter of the calibrating part. Machine reamers have tapered shanks, hand reamers have square ones. Reamers are available with a uniform and uneven tooth pitch. Machine reamers are fixed in the spindle of the machine using tapered sleeves and cartridges, manual reamers - in the wrench, with which the deployment is performed. Conical reamers are used to deploy tapered holes for a Morse taper, for a 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 a rough, intermediate and finishing (Fig. 65, a, b, c). In a set of two reamers, one is transitional and the other is final. 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 manually and on machines. Manual deployment is carried out using a knob, in which the scan is fixed. With manual deployment, small workpieces or parts are fixed in a vice, and large ones are processed without fastening. After fixing the workpiece or part, the cutting part of the reamer is introduced 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 sweep in the opposite direction, as it can cause scoring. With machine deployment on machines, the procedure is the same as for drilling.
Rice. 65. Conical reamers: 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 workpieces, the holes are rolled dry. The choice of the diameter of the reamer is of great importance for obtaining the required hole size and surface cleanliness. In this case, the thickness of the chips removed by the tool is taken into account (Table 2). Using this table, you can select the diameter of the reamer and countersink. Example. It is necessary to manually drill a hole with a diameter of 50 mm. To do this, take a final scan with a diameter of 50 mm, and a rough scan 50-0.07 = 49.93 mm. When choosing a machine finish reaming, one should take into account the amount of development, that is, the increase in the hole diameter with machine reaming. When machining holes with a drill, countersink and reamer, the following basic safety rules must be observed: perform work only on serviceable machines with the necessary fences; tidy up clothes and hats before starting work. When working, clothes should fit the body without fluttering floors, sleeves, belts, ribbons, etc., it should be tightly buttoned. Long hair should be matched to the headgear: Threading Threading is the process of producing helical grooves on cylindrical and tapered surfaces. The set of turns located along a helical line on a product is called a thread. There are external and internal threads. The main elements of any thread are profile, pitch, height, outer, middle and inner diameters.
Rice. 66. Elements of a thread The thread profile is the sectional shape of the thread passing through the axis of the bolt or nut (Fig. 66). A thread (thread) is a part of the thread formed with one full turn of the profile. The thread pitch is the distance between two points of the same name of adjacent turns, measured parallel to the thread axis, the axis of the bolt or nut. Thread height is defined as the distance from the top of the thread to the base. The top of the thread is the section of the thread profile that is at the greatest distance from the thread axis (the axis of the bolt or nut). The base of the thread (root) is the section of the thread profile that is at the smallest distance from the thread axis. The angle of the thread profile is the angle between the two flanks 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. Threading systems: The average thread diameter is the distance between two lines parallel to the axis of the bolt, each at a different distance from the top of the thread and the bottom of the root. The width of the threads of the external and internal threads, measured around the circumference of the average diameter, is the same. Internal thread diameter is the smallest distance between opposite thread bases, 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 purpose, threads are divided into fastening and special. The triangular thread is used to fasten parts together (cutting on bolts, studs, nuts, etc.), it is often called fastening. Trapezoidal and rectangular threads are used on parts of motion transmission mechanisms (screws for locksmith disks, lead screws for screw-cutting lathes, lifters, jacks, etc.). R. There are three thread systems: metric, inch and pipe. The main one is a metric thread, which has a profile in the form of an equilateral triangle with an apex angle of 60 ° (Fig. 67, a). To avoid galling during assembly, the threads of the bolts and nuts are cut off. Dimensions for metric threads are in millimeters. Pipe threads are fine inch threads. It has the same profile as the inch, with an apex angle of 55 ° (Fig. 67, c). Pipe threads are mainly used for gas pipes, water pipes and couplings connecting these pipes. External threading tools. For cutting an external thread, a die is used, which is an efficient or split ring with a thread on the inner surface (Fig. 68, a, b). Chip flutes of the die serve for the formation of cutting edges, as well as for the exit of chips. By design, the dies are divided into round (levers), sliding and special for cutting pipes. Round dies are solid and cut. One-piece round dies have great rigidity and clean threads. Split dies are used for cutting low-precision threads. Sliding dies consist of two halves, which are called half dies. On the outer sides of the half-slabs there are slots with an angle of 120 ° for fixing the half-slabs in the die. Each half-die is marked with the thread diameter and numbers 1 and 2, which are guided when installing them in the die. Dies made of tool steel U £ 2 " Manual threading with dies is carried out with the help of knobs and dies. When working with round dies, special wrenches are used (Fig. 68, c). The frame of such a spindle has the shape of a round plate. A round die is installed in the hole of the frame and fixed with three locking screws having conical ends, which go into special recesses on the die. The outer thread size is set with the fourth screw, entering the cut of the adjustable die.
Rice. 68. Tools for cutting external threads: 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. The half-dies are brought together with an adjusting screw and installed to obtain the thread of the desired size. A cracker is inserted between the extreme half-die and the adjusting screw, providing even distribution screw pressure on half dies. Threads are cut by hand and on machine tools. In plumbing, they often use hand tool... External thread cutting with sliding dies is as follows. The workpiece of the 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 die, 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 up along the thread to its original position, the dies are brought closer with the adjusting screw and the cutting process is repeated until a full thread profile is obtained. After each pass, it is necessary to lubricate the cut part of the workpiece. Solid dies are tapped in one pass.
Rice. 69. Locksmith taps: Tools for cutting internal threads. Internal thread 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 nose of the tap is the front taper that does the main cutting work. The gauge part serves to guide the tap in the hole when cutting and calibrating threads. The teeth of the threaded portion of the tap are called blades. The shank is used to fix the tap in the chuck or in the wrench. The shank ends with a square. By appointment, taps are divided into locksmith, nut, machine, etc. Taps are used for manual threading, they are produced 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 1.5-2 turns. Pre-cutting is performed with a rough tap, the thread is made more accurate with the middle one, and the final cutting is carried out with a finishing tap and the thread is calibrated. By the design of the cutting part, taps are cylindrical and conical. With a cylindrical design, all three taps in 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 one by 0.6 thread height, and the diameter of the roughing tap is less than the finishing diameter by the full thread height. Cylindrical taps are mainly used for tapping blind holes. With a tapered design, all three taps have the same diameter, full thread profile with different taps lengths. Such taps are used for threading in through holes... Taps are made of U10, U12 tool carbon steels. The threads are cut by hand using a knob with a square hole. The workpiece or part is fixed in a vice, and the tap is in the knob. The threading process is as follows. The rough tap is installed vertically into the prepared hole and, using a knob, they begin to rotate it clockwise with light pressure. After the tap hits the metal, the pressure is stopped and the rotation continues. Periodically, you need 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 roughing tap, cutting is done medium and then fine. To obtain a clean thread and cool the tap, a lubricant is used when cutting. When threading in steel workpieces, mineral oil, drying oil or emulsion are used as lubricating and cooling liquids, in aluminum - kerosene, in copper - turpentine. In cast iron and bronze workpieces, threads are cut dry. When threading 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, tap breakage, ragged threads, thread stripping, etc. The reasons for these defects are: blunt tap, clogging of the tap grooves with chips, insufficient lubrication, incorrect installation of the tap in the hole and the choice of the hole diameter, as well as inattentive attitude of the worker ... Riveting When repairing machines and assembling them, a locksmith has to deal with various connections of parts. Depending on the assembly method, the joints can be detachable and one-piece. One of the ways to assemble parts into a permanent connection is riveting. Riveting is done using rivets, either manually or mechanically. Riveting can be cold or hot. A rivet is a cylindrical rod with a head at the end, which is called a rivet. In the process of riveting the rod, a second head is formed, called the closing head.
Rice. 70. The main types of rivets and riveted seams: According to the shape of the insert head, rivets are semicircular head, with a half-countersunk head, with a countersunk head (Fig. 70, a, b, c), etc. The connection of parts made by rivets is called a riveted seam. Depending on the location of the rivets in the seam in one, two or more rows, rivet seams are divided into single-row, double-row, multi-row. The distance t between the centers of the rivets of one row is called the step of the rivet joint (Fig. 70, d). For single-row seams, the step should be equal to three diameters of the rivet, the distance a from the center of the rivet to the edge of the riveted parts should be equal to 1.5 diameters of the rivet with drilled holes and 2.5 diameters with punched holes. In double-row seams, the step is taken equal to four diameters of the rivet, the distance from the center of the rivets to the edge of the riveted parts is 1.5 diameters, and the distance between the rows of rivets should be equal to two diameters of the rivet. Riveted joints are performed in three main ways: overlapping, butt-to-end with one lining, and butt-to-end with two lining (Fig. 70, e, f, g). By design, rivet seams are divided into strong, dense and strong-tight. The quality of the rivet seam depends to a large extent on whether the right rivet is selected. Equipment and tools used for manual and mechanized riveting. Manual riveting carried out using a square hammer, support, tension and crimp (Fig. 71). Hammers are available in weight from 150 to 1000 g. The weight of the hammer is selected in accordance with the diameter of the rivet shank, The support serves as a support for the blind rivet head during riveting, tension - for a closer convergence of riveted parts, crimping is used to give the correct shape to the rivet closing head. Mechanized riveting is carried out by pneumatic structures. The pneumatic riveting hammer (fig. 72) works with compressed air and is triggered by the trigger. When the trigger is pulled, valve 9 opens and compressed air, flowing through the channels to the left side of the barrel chamber, activates the striker, which strikes the crimp.
Rice. 71. Auxiliary tools used for riveting: After the impact, the spool closes the air flow into channel 3, connecting it to the atmosphere, and the compressed air is directed through channel 4 to the right side of the barrel chamber, while the drummer is thrown off channel 4, it closes gold-in action, etc. The pneumatic work is performed by two people , one makes riveting with a hammer, and the other is a helper.
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 riveted parts come closer together. Then they begin to rivet the rivet rod with hammer blows, alternately applying straight and oblique blows directly to the rod. As a result of riveting, a rivet closing head is obtained. To give the correct shape to the closing head, a crimp is put on it and by hammer blows on the crimp, the head is finished, giving it the correct shape. For rivets with a countersunk head, the hole is pre-processed with a countersink on a cone. The countersunk head is riveted with straight hammer blows directed exactly along the rivet axis. The most common riveting defects are the following: bending of the rivet shank in the hole, resulting from the very large hole diameter; deflection of the material due to the fact that the diameter of the hole was small; displacement of the insert head (a hole was drilled obliquely), bending of the closing head, resulting from the fact that the rivet shank was very long or the support was not installed along the rivet axis; undercutting of the part (sheet) due to the fact that the crimping hole was larger than the rivet head, cracks on the rivet heads that appear when the rivet material is not plastic enough. Safety precautions. When performing riveting work, the following safety rules must be observed: the hammer must be securely mounted on the handle; hammer strikers, crimps should not have potholes, cracks, since 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 crimp with your hands, as this can lead to serious injury to the hand. Pressing in and out When assembling and disassembling assemblies consisting of stationary parts, pressing and pressing operations are used, carried out using presses and special pullers. Pressing out is more often done using screw pullers. A puller for pressing out bushings is shown in Fig. 73. It has a catch that is pivotally connected to the end of the screw. To fix the pressed sleeve in it, the gripper is tilted and inserted into the sleeve.
Rice. 73. Extractor for extrusion of bushings There are special and universal pullers. Universal pullers can be used to extrude parts of various shapes. In auto repair shops, when disassembling and assembling cars for pressing and pressing out, presses of various designs are used: hydraulic (Fig. 74), bench rack, bench screw (Fig. 75, a, b). Bench rack and bench screw are used to press out bushings, pins and other small parts. Pressing out and pressing in of large parts is carried out using hydraulic presses. When pressing in and pressing out with a hydraulic press, proceed as follows. First of all, by rotating the handle (see Fig. 74), a lifting table is installed in such a way that the pressed or pressed part passes freely under the rod, and fix it with studs. Rotating the handwheel, the stem is lowered to the stop with the part. After that, using a lever, a pump is activated, pumping oil from the reservoir into the press cylinder. Under oil pressure, the piston and the rod connected to it are lowered. Moving, the stem presses (or extrudes) the part. After completing the work, the valve is opened and the piston rises with a spring together with the rod. The oil from the cylinder is bypassed back to the reservoir.
Rice. 74. Hydraulic press:
Rice. 75. Mechanical presses: In all cases of pressing-in to protect the surface of parts from damage and galling, they are pre-cleaned from rust, scale and lubricated with oil. The parts prepared for pressing must be free of nicks, scratches and burrs. Soldering Brazing is a method of connecting metal parts to each other using special alloys called solders. The brazing process consists in the fact that the parts to be brazed are applied to one another, heated to a temperature slightly higher than the melting temperature of the solder, and liquid molten solder is introduced between them. To obtain a high-quality soldered 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 from dirt, rust with a file or a scraper, then 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 with running water and then etched. Brass parts are etched in a bath containing 10% sulfuric acid and 5% chromic acid; for etching steel parts, a 5-7% hydrochloric acid solution is used. At a solution temperature of not more than 40 ° C, parts g are kept in it for 20 to 60 minutes. ~~ After the end of 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 (covered with a layer of tin). When soldering, tin-lead-like, copper-zinc are most used. copper, silver and copper-phosphorus solders. To eliminate the harmful effects of oxides, fluxes are used, which fuse and remove oxides from the surfaces to be soldered and protect them from oxidation during the soldering process. The flux is selected according to the properties of the metals to be soldered and the solders used. Solders are divided into soft, hard. Steel and copper alloys are soldered with soft solders. Steel parts are tinned before soft soldering. Only under this condition is a reliable soldered connection ensured. 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. As fluxes when brazing with soft solders, zinc chloride, ammonium chloride (ammonia), rosin (when brazing copper and its alloys), 10% aqueous solution of hydrochloric acid (when brazing zinc and galvanized products), stearin (when brazing low-melting alloys lead). For soldering critical parts made of cast iron, steel, copper alloys, aluminum and its alloys, brazing alloys are used, mainly copper-zinc and silver of the following brands: PMTs-36, PMTs-48, PMTs-54, PSr12, PSr25, PSr45 (the melting temperature of hard alloys is from 720 to 880 ° C). For brazing aluminum and its alloys, for example, a 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 brazing aluminum, they use a flux consisting of a 30% solution of an alcohol mixture, which includes 90% zinc chloride, 2% sodium fluoride, 8% aluminum chloride. When soldering with solid solders, the parts are fixed in special devices so 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 point of the solder. The molten solder fills the gap and forms a strong bond upon cooling. After the end of the soldering, the parts are cleaned of flux residues, since the remaining fluxes can cause corrosion of the seam surface. The seams are cleaned with a file or scraper. The main tools for soldering are soldering irons, blowtorches. In addition, when soldering, induction heating installations with high-frequency currents and other devices are used. When soldering with soft solders, soldering irons are usually used (Fig. 76, a, b, c) and blowtorches. A hand-held soldering iron is made of copper and can have different shapes (Fig. 76, a, b). When brazing with solid solders, the parts to be brazed are heated with a blowtorch or in a furnace. TO Category: - Car maintenance Agreed upon: at a meeting of the methodological commission. "__" ___________ 2015 Lesson plan number 1 Study topic by program ... PM 01 marking. Lesson topic. Spatial markup. The purpose of the lesson... Teach the student to correctly mark the parts. Educational and educational purpose... To instill in the student the desire to respect the instrument and materials. Accuracy and care in work. Material and technical equipment of the lesson: Stand, posters, samples, blanks, workbenches, fixtures, reysmass. Lesson progress: 6 hours. 1. Introductory group briefing 50 min. a) knowledge test on the passed material 15 min.
b) explaining new material to students 25 min.
The markup is called - the operation of applying to the workpiece being processed marking lines (marks) defining the contours of the future part or place, to be processed. The markup is performed accurately and accurately, because - because mistakes made during marking will lead to the fact that the manufactured part turns out to be a defect or a large allowance remains. Depending on the shape of the workpieces and parts to be marked, the marking is divided into planar and spatial (volumetric). Planar marking - it is usually performed on the surfaces of flat parts, on strip and sheet parts, it consists in drawing on the workpiece contour parallel and perpendicular lines (notches), circles, arcs, angles, center lines, various geometric shapes. Adaptation to carry out the marking use: marking plates, pads, swivel devices, jacks, etc. Tool - scribe, center punch, compasses, marking vernier caliper, reysmass. Scriber - serves for drawing lines (scratches) on the surface to be marked using a ruler, squares or a template. Kerner - a locksmith's tool, used for drawing recesses (with a core) on previously marked lines. They do so that the risks are clearly visible and are not erased during the processing of the part. Punch pins are ordinary, special, spring and electric. Compass - for marking circles and arcs, for dividing line segments and transfer sizes from a ruler to a detail. The compass consists of: two articulated legs, whole or with insertion needles. Marking vernier caliper - designed for fine marking of straight lines and centers, as well as circles of large diameters. It has a barbell with millimeter divisions and two legs - fixed with a locking screw and movable with frame and cone, locking screw for fixing the frame Reismas - is the main tool for spatial markup. He serves for drawing parallel and horizontal lines, and for checking installation of parts on the plate. Preparing to markup:
3. Examine the drawing of the part (dimensions, machining allowance). 4. Prepare surfaces for painting (chalk, copper sulfate, paint, varnish that dry quickly) 5. Painting surfaces. Plane marking techniques.
Direct risks applied with a scribe at an angle of 75-80 ° away from the ruler. Perpendicular and parallel with a square, carried out once. Nipping marking lines sharp center pins are placed exactly on the marking line in the middle. When installing, first tilt and then place the center punch vertically and apply a light blow with a hammer weighing 100-200 g. Cores for drilling holes are made deeper than the rest, so that the drill is less likely to go away from the marking point. A large number of identical parts are marked out according to the template. Templates - made of sheet material with a thickness of 0.5-1mm. When marking the template or (sample), it is applied to the painted workpiece (part) and the scribe is drawn along the contour of the template, after which the risk is numbered. Safety compliance during marking work
put oiled rags and paper only in special metal boxes.
c) consolidation of the material: A short survey of students. 10 min. 1. How to choose colorants depending on the workpiece material? For painting untreated surfaces (castings, forgings, rolled products), a chalk solution (ground chalk diluted with water) is used. To protect the coloring layer from abrasion and its rapid drying, glue (6OOg chalk + 50g wood glue + 4 liters of water) is introduced into the dye. 2 Drawing marks. Choose a scriber depending on the metal of the distinguishable steel part - when marking rough and pre-processed parts; brass - when marking the polished surfaces of finished parts. Apply risks with a scribe, placing it with an inclination in the direction of movement and with an inclination to the side of the ruler should not change in the process of drawing marks. 3. The order of marking workpieces from the center line. a) Prepare the surface of the workpiece for marking. b) At half the width of the workpiece, i.e. at a distance of 18 mm from the edge, draw an axial longitudinal mark. c) Having deviated from the end of the workpiece by 74 mm, draw perpendicular to the risk. d) On both sides, there are risks at a distance of 15 mm from it. At the point of intersection, apply a root recess and draw a semicircle from it with a radius R of 3 mm. 4. The order of layout by pattern. a) Prepare the surface of the workpiece for marking. b) Place the workpiece on the marking plate so that it fits snugly against it. c) Place the template on the workpiece to be marked so that it fits snugly against it. d) With the fingers of your left hand, press the template against the workpiece, and with the fingers of your right hand, draw risks with a scribe along the outline of the template, strictly keeping the angle of inclination and pressing the scribe unchanged. 5. Punching the marking lines with a simple center punch. a) Take the center punch with three fingers of the left hand and put the sharp end exactly on the marking line so that the sharper center punch is exactly in the middle of the line; tilting the center punch away from you, press it to the intended point, b) Place the center punch vertically, c) Apply a light blow with a hammer. 6. Correct sharpening scribes. a) Prepare the machine for sharpening the tool. b) Take the scriber with your left hand in the middle, and with your right hand - for the opposite end to be sharpened c) Place the scribe on the periphery of the sharpening wheel at the required angle of inclination and keeping this angle constant, with light pressure, evenly rotate the scribe with your right hand; the scribe should be sharpened at an angle of 15-20 °. 7 Sharpening the legs of the compass. a) Bring the legs of the compass so that they are in tight contact. b) Take the compass with your left hand in the middle, and with your right hand for the articulated connection of 2 legs. c) Place the legs of the compass at the required angle to the abrasive wheel. e) First sharpen the end of one leg; after that, changing the position of the legs, sharpen the other end of the leg. d) Bring the sharp ends of the legs of the compass on the donkey and remove the burrs on the lateral edges and inner planes of the legs. 8. Rule of work safety when marking. a) Carefully handle the ends of devils, compasses. b) Place the marker plate securely on the table. c) Handle the copper sulfate solution with care. d) Do not work on a faulty sharpening machine; in the absence of a casing, screen; faulty assistant; the gap between the circle and the handcuff is more than 2-3 mm; the beat of the circle. d) task for the day 1. Make markings on parts and blanks. 2. Independent work of students and current briefing (targeted walks of work places). 4 hours 40 minutes
Typical difficulties and mistakes of students and their a warning. The main difficulties and mistakes of students when performing layout work arise from ignorance of the upcoming locksmith operations. Sometimes the marking is carried out without preliminary processing of the metal and is not always combined with subsequent processing. The first difficulty that students encounter in the plane marking is the poor staining of the previously protected surface of the workpiece with copper sulfate due to its contamination. To ensure good staining, the surface must be thoroughly brushed with a steel brush. Copper sulfate should be diluted in water, and stained with a brush. Avoid wetting the surface of the product with water. In addition, do not rub the surface with a piece of copper sulfate, as it is not harmless. When drawing longitudinal marks with a scribe, students often move the millimeter rulers from their place and the risks are bent. To avoid shifting the ruler, you need to firmly press the ends of the ruler against the workpiece with wide apart fingers of your left hand, and not the middle. Students also make two mistakes when drawing risks: the scriber is tilted strongly, which is why it does not cut into the metal, but only scrapes off the copper sulfate. The scribe must be held at a slight angle to the surface, trying to cut it into the metal; they receive risks not in one pass of the scribe, but in two or three passes; the risk in this case turns out to be wide, and sometimes double. You need to apply risks in one pass of the scribe. Difficulties for students also arise when punching marks and applying core holes exactly at the risk. This is often caused by a center punch sharpened at a high angle. In order for the core grooves to be obtained exactly at the risk, it is necessary to introduce the core punch at risk in an inclined position with a movement directed across the risks. When the center punch enters the risk, it is aligned to a right angle and a hammer is struck on it. Students make the mistake of placing core holes frequently when they are drawing the markings. This makes the markings rough and increases the number of out-of-line core holes. As a result, after processing the edge, the workpiece is mottled with the remaining traces of core depressions. Core depressions should be placed at intervals of 10-50 mm in a straight line and always at the intersections of the marks. Punching should be done with a scoring hammer with the same force so that the core holes are of the same depth. When marking the circles, students have such a difficulty: setting the compasses to the required size, they usually knock it down when fixing the lamb. 3. Cleaning of workplaces. 10 min. 1. Students clean their workplaces, hand over tools and their work. 4. Final briefing. 15 minutes. Analysis of the working day.
5. Home assignment. 5 minutes. Acquaintance with the material of the next lesson, repeat the topic "Metal marking". Textbook "Locksmithing" author Skakun V.А. Industrial Training Master ______________________________ Markup is an operation by drawing on the surface of the workpiece lines (marks) defining the contours of the part being manufactured, which is part of some technological operations. Despite the high costs of manual highly skilled labor, markings are widely used, including at mass production enterprises. Usually marking work are not controlled, therefore, mistakes made during their implementation are revealed in most cases in finished parts. It is quite difficult to fix such errors, and sometimes it is simply impossible. Depending on the characteristics of the technological process, planar and spatial markings are distinguished. Plane markings are used in the processing of sheet material and profile rolled products, as well as parts on which marking marks are applied in the same plane. Spatial markup- this is the drawing of scratches on the surfaces of the workpiece, interconnected by mutual arrangement. Depending on the method of applying the contour to the surface of the workpiece, various tools are used, many of which are used for both spatial and plane marking. Some differences exist only in the set of marking devices, which is much wider for spatial marking. Tools, fixtures and materials used for markingScribblers are the simplest tool for drawing the contour of a part on the surface of the workpiece and represent a rod with a pointed end of the working part. Scribes are made of tool carbon steel grades U10A and U12A in two versions: one-sided (Fig. 2.1, a, b) and two-sided (Fig. 2.1, c, d). Scribes are made with a length of 10 ... 120 mm. The working part of the scribe is hardened at a length of 20 ... 30 mm to a hardness of HRC 58 ... 60 and sharpened at an angle of 15 ... 20 °. Risks are applied to the surface of the part with a scribe using a scale ruler, template or sample. Reismas used for drawing marks on the vertical plane of the workpiece (Fig. 2.2). It is a scriber 2, fixed on a vertical stand mounted on a massive base. If it is necessary to draw marks with a higher accuracy, use a tool with a scale - a height gauge (see Fig. 1.13, d). To set the gauge to a given size, you can use blocks of gauge blocks, and if you do not really need high accuracy markup, then use the vertical scale ruler 1 (see Fig. 2.2). Marking compasses used for drawing arcs of circles and dividing segments and angles into equal parts (Fig. 2.3). Marking compasses are made in two versions: simple (Fig. 2.3, a), which allows you to fix the position of the legs after setting them to size, and spring (Fig. 2.3, b), used for more accurate setting of the size. To mark the contours of critical parts, use a marking caliper (see Fig. 1.13, b). In order for the marking risks to be clearly visible on the marked surface, point depressions are applied to them - cores, which are applied with a special tool - a center punch.
Kerners(Fig. 2.4) are made of U7A tool steel. Hardness along the length of the working part (15 ... 30 mm) should be HRC 52 ... 57. In some cases, center pins of special design are used. So, for example, for drawing core depressions when dividing a circle into equal parts, it is advisable to use a core punch proposed by Yu.V. Kozlovsky (Fig. 2.5), which can significantly increase productivity and accuracy when applying them. Inside the body 1 of the punch, there is a spring 13 and a firing pin 2. Legs 6 to 11 are attached to the body by means of a spring 5 and screws 12 and 14, which, thanks to the nut 7, can simultaneously move, providing adjustment to a given size. Replaceable needles 9 and 10 are attached to the legs with nuts 8. When adjusting the center punch, the position of the striker with the impact head 3 is fixed by the threaded sleeve 4. Marking using this punch is carried out in the following sequence: The point of needles 9 and 10 is set at the risk of a previously drawn circle on the workpiece; Strike the impact head 3, punching the first point; The body of the center punch is turned around one of the needles until the second needle coincides with the marked circle, the impact head 3 is again struck. The operation is repeated until the whole circle is divided into equal parts. At the same time, the marking accuracy increases, since, thanks to the use of needles, the center punch can be adjusted to a given size using a block of gauge blocks. Punching if necessary center holes it is convenient to use on the ends of the shafts special device for punching - with a bell (Fig. 2.6, o). This device allows you to make core grooves on the centers of the end surfaces of the shafts without preliminary marking. For the same purposes, you can use a center-finder square (Fig. 2.6, b, c), consisting of a square 1 with a ruler 2 attached to it, the edge of which divides the right angle in half. To determine the center, the tool is placed on the end of the part so that the inner shelves of the square touch its cylindrical surface and draw a line along the ruler with a scribe. Then the center finder is turned at an arbitrary angle and the second risk is carried out. The intersection of the lines drawn on the end face of the part will determine the position of its center. Quite often for finding centers at the ends cylindrical parts use a protractor centro-finder (Fig. 2.6, d), which consists of a ruler 2, fastened to a square 3. The protractor 4 can be moved along the ruler 2 and fixed in the desired position using a locking screw 1. The protractor is placed on the end surface of the shaft so that the side shelves of the square touched the cylindrical surface of the shaft. In this case, the ruler passes through the center of the shaft end. By installing the protractor in two positions at the intersection of the marks, the center of the shaft end is determined. If you want to make a hole located at a certain distance from the center of the shaft and at a certain angle, use a protractor, moving it relative to the ruler by a given amount and turning it by required angle... At the point of intersection of the ruler and the base of the protractor, the center of the future hole is screwed, which has an offset relative to the axis of the shaft. The punching process can be simplified by using an automatic mechanical center punch (Fig. 2.7), consisting of a body assembled from three parts: 3, 5, 6. Two springs 7 and 11 are placed in the body, a rod 2 with a center punch 1, a striker 8 with a shifting cracker 10 and flat spring 4. Punching is carried out by pressing on the workpiece with the tip of the punch, while the inner end of the rod 2 abuts against the cracker, as a result of which the striker moves up and compresses the spring 7. Resting on the rib of the shoulder 9, the cracker moves to the side and its edge comes off the rod 2. At this moment, the striker, under the action of the force of a compressed spring, applies along the end of the rod with a center punch swipe, after which the spring 11 restores the normal position of the punch. The use of such a punch does not require the use of a special percussion tool - a hammer, which greatly simplifies the work of applying the pits.
For the mechanization of marking work an electric center punch can be used (Fig. 2.8), which consists of a body 8, springs 4 and 7, a striker 6, a coil 5 with a lacquered wire winding, a rod 2 with a center punch 3 and electrical wiring. When you press the center punch point installed on the marking risk, the electric circuit 9 is closed and the current flows through the coil, creating a magnetic field. At the same time, the striker is instantly drawn into the reel and strikes the rod with a center punch. During the transfer of the punch to another point, the spring 4 opens the circuit, and the spring 7 returns the striker to its original position.
For accurate punching use special center punch(fig. 2.9). Kerner shown in Fig. 2.9, a, is a stand 3 with a center punch 2. The indentations of the marks before punching are lubricated with oil, the center punch with the legs 5 fixed in the stand / is installed on the intersecting risks of the part so that two legs located on one straight line fall into the same risk, and the third leg is at risk, perpendicular to the first. Then the center punch will exactly hit the point of intersection of the marks. Screw 4 prevents the center punch from turning and falling out of the body. Another design of a punch for the same purpose is shown in Fig. 2.9, b. This center punch differs from the previous design in that the impact on the core is made with a special weight 6, which, upon impact, abuts against the collar of the center punch. As a percussion tool when performing core recesses, a metalwork hammer is used, which should have a low weight. Depending on how deep the core hole should be, hammers weighing from 50 to 200 g are used. When performing spatial marking, it is necessary to use a number of devices that would make it possible to expose the part to be marked in a certain position and tilt (turn over) it during the marking process. For these purposes, marking plates, prisms, squares, marking boxes, marking wedges, jacks are used for spatial marking. Marking plates(Fig. 2.10) are cast from gray iron, their working surfaces must be precisely machined. On the upper plane of large marking plates, longitudinal and transverse grooves of small depth are planed, dividing the surface of the plate into square sections. Marking plates are installed on special stands and pedestals (Fig. 2.10, a) with boxes for storing marking tools and devices. Small marking plates are placed on the tables (Figure 2.10, b).
The working surfaces of the marking board should not have significant deviations from the plane. The magnitude of these deviations depends on the dimensions of the slab and is given in the corresponding reference books. Marking prisms(fig. 2.11) are made with one and two prismatic recesses. In terms of accuracy, prisms of normal and increased accuracy are distinguished. Normal precision prisms are made of steel grades XG and X or from carbon tool steel grade U12. The hardness of the working surfaces of the prisms must be at least HRC 56. The high-precision prisms are made of gray cast iron of the SCh15-23 grade. When marking stepped shafts, prisms with a screw support are used (Fig. 2.12) and prisms with movable cheeks, or adjustable prisms (Fig. 2.13).
Squares with shelf(Figure 2.14) is used for both planar and spatial markings. In planar marking, the squares are used for making scratches parallel to one of the sides of the workpiece (if this side is pre-processed), and for making scratches in the vertical plane. In the second case, the ledge of the scribe square is installed on the scaffold plate. For spatial marking, the square is used to align the position of the parts in the marking device in the vertical plane. In this case, a marking square with a shelf is also used. Marking boxes(Fig. 2.15) is used for installation on them when marking workpieces of complex shape. They represent a hollow parallelepiped with holes made on its surfaces for fixing blanks. With large sizes of marking boxes, in order to increase the rigidity of the structure, partitions are made in their inner cavity. Marking wedges(Figure 2.16) is used when it is necessary to adjust the position of the workpiece to be marked in height within insignificant limits.
Jacks(Fig. 2.17) are used in the same way as adjustable wedges for adjusting and aligning the position of the workpiece to be marked in height, if the part has a sufficiently large mass. The jack support, on which the workpiece to be marked is installed, can be spherical (Figure 2.17, a) or prismatic (Figure 2.17, b). In order for the marking risks to be clearly visible on the surface of the workpiece to be marked out, this surface should be painted, that is, covered with a compound whose color is in contrast to the color of the material of the workpiece being marked. For coloring the surfaces to be marked, special compounds are used. Materials for painting surfaces are chosen depending on the material of the workpiece, which is being marked, and on the state of the surface to be marked. To paint the surfaces to be marked, use: a solution of chalk in water with the addition of wood glue, which ensures reliable adhesion of the coloring composition to the surface of the workpiece to be marked, and a desiccant, which facilitates the rapid drying of this composition; copper sulfate, which is copper sulphate and, as a result of the ongoing chemical reactions, ensures the formation of a thin and durable copper layer on the surface of the workpiece; quick-drying paints and enamels.
The choice of coloring composition for application to the surface of the workpiece depends on the material of the workpiece and the state of the surface to be marked. Untreated surfaces of workpieces obtained by casting or forging are painted with dry chalk or a solution of chalk in water. Mechanically processed (preliminary filing, planing, milling, etc.), the surfaces of the workpieces are painted with a solution of copper sulfate. Copper sulfate can be used only in cases where the workpieces are made of ferrous metal, since there is no chemical reaction between non-ferrous metals and copper sulfate with the deposition of copper on the surface of the workpiece. Billets from copper, aluminum and titanium alloys with pre-treated surfaces are painted using quick-drying varnishes and paints. |
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