Preparing the surface for filing. The workpiece is cleaned with metal brushes from dirt, oils, molding soil, scale, the foundry crust is cut off with a chisel or removed with an old file.
Securing the workpiece. The workpiece being processed is clamped in a vice with the sawing plane horizontally, 8-10 mm above the level of the jaws. The workpiece with treated surfaces is secured by placing jaws made of soft material (copper, brass, aluminum, mild steel) on the jaws.
Filing techniques. The position of the body is considered correct if an angle of 90° is formed between the shoulder and elbow parts of the right arm bent at the elbow with a file mounted on the jaws of the vice (initial position). In this case, the worker’s body must be straight and turned at an angle of 45° to the axis line of the vice.
Leg position. At the beginning of the working stroke of the file, the body weight falls on the right leg; when pressed, the center of gravity moves to the left leg. This corresponds to the following arrangement of legs: the left leg is carried (retracted) forward in the direction of movement of the file, the right leg is moved away from the left by 200-300 mm so that the middle of its foot is opposite the heel of the left leg.
During the working stroke of the file (pull), the main load falls on the left leg, and during the reverse (idling) stroke - on the right, so the leg muscles alternately rest.
When removing thick layers of metal with a file, the file is pressed with greater force, so the right leg is moved back half a step from the left and in this case it is the main support. When there is light pressure on the file, for example when finishing or finishing a surface, the feet are placed almost side by side. These precision jobs are often performed while sitting.
Hand position (file grip) is extremely important. The mechanic takes the file in his right hand by the handle so that it rests against the palm of his hand, four fingers clasp the handle from below, and the thumb is on top. The palm of the left hand is placed slightly across the file at a distance of 20-30 mm from its toe. In this case, the fingers should be slightly bent, but not drooping; they do not support, but only press the file. The elbow of the left hand should be slightly raised; right arm from the elbow to the hand - make a straight line with the file.
Coordination of efforts. When filing, it is necessary to maintain coordination of pressure forces (balancing). This lies in the correct increase in pressure right hand on the file during the working stroke while reducing the pressure with your left hand. The movement of the file must be horizontal, so the pressure on its handle and toe must be changed depending on the position of the file’s fulcrum on the surface being processed. During the working movement of the file, the pressure with the left hand is gradually reduced. By adjusting the pressure on the file, you achieve a smooth sawn surface without blockages at the edges.
When the pressure is weakened with the right hand and increased with the left, the surface may collapse forward; when you increase the pressure with your right hand and weaken your left, you roll back.
You need to press the file against the surface being processed during the working stroke (from yourself). During the reverse stroke, you should not tear the file off the surface being processed: it should only slide. The rougher the processing, the greater the force during the working stroke.
When finishing filing, you should press the file much less than when roughing. In this case, with the left hand, press on the toe of the file not with the palm, but only thumb.
Sawing flat surfaces is a complex, labor-intensive process. Most often, a defect when filing such surfaces is a deviation from flatness. Working with a file in one direction makes it difficult to get a flat and clean surface.
Therefore, the direction of movement of the file, and therefore the position of the strokes (file marks) on the surface being processed should change alternately from corner to corner.
First, filing is performed from left to right at an angle of 30-40° to the axis of the vice, then, without interrupting work, with a straight stroke; finish filing with an oblique stroke at the same angle, only from right to left. This change in the direction of movement of the file provides the necessary flatness and roughness of the surface.
Control of the sawn surface. To control sawn surfaces, straight edges, calipers, squares and calibration plates are used.
The straight edge is selected depending on the length of the surface being checked, that is, the length of the straight edge should cover the surface being checked.
The quality of the surface filing is checked using a straight edge against the light. To do this, the part is released from the vice and raised to eye level; The straight edge is taken by the middle with the right hand and applied with its edge perpendicular to the surface being checked.
To check the surface in all directions, the ruler is first applied to the long side in two or three places, then to the short side (also in two or three places). And finally, along one and the other diagonal.
If the gap between the ruler and the surface being tested is narrow and uniform, then the plane has been processed satisfactorily.
To avoid wear, the ruler should not be moved across the surface; Each time it needs to be lifted and moved to the desired position.
Dimensional processing refers to the processing of a workpiece (part) to give it a given shape, size and roughness of the machined surfaces. The result of processing is ready product, which can have independent use (for example, a chisel, a square), or a part suitable for installation in an assembled product (for example, handles and levers various designs). Dimensional metalworking operations include filing, hole processing (drilling, countersinking, countersinking, counterbore, reaming) and cutting external and internal threads.
Filing is an operation to remove a layer of material from the surface of a workpiece using cutting tool- a file, the purpose of which is to give the workpiece a given shape and size, as well as ensure a given surface roughness. In most cases, filing is carried out after chopping and cutting metal with a hacksaw, as well as during assembly work to fit the part into place. In metalwork practice, filing is used to process the following surfaces:
Flat and curved;
Flat, located at an outer or inner angle;
Flat parallel ones to a certain size between them;
Shaped complex profile.
In addition, filing is used to process recesses, grooves and protrusions.
There are rough and fine filing. Machining with a file allows you to obtain precision processing of parts up to 0.05 mm, and in some cases even more high accuracy. The allowance for filing processing, i.e. the difference between the nominal size of the part and the size of the workpiece for its production, is usually small and ranges from 1.0 to 0.5 mm.
Tools used for filing
The main working tools used for filing are: are files, rasps and needle files.
Files are hardened steel bars, on the working surfaces of which a large number of the notches or cuts that form the cutting teeth of the file. These teeth ensure that a small layer of metal in the form of chips is cut from the surface of the workpiece. Files are made from tool carbon steels of grades U10, U12, U13 and tool alloy steels of grades ShKh6, ShKh9, ShKh12.
The notches on the surface of the file form teeth, and the fewer notches per unit length of the file, the larger the teeth. Based on the type of notches, files with single (Fig. 3.1, a), double (cross) (Fig. 3.1, b) and rasp (Fig. 3.1, c) notches are distinguished.
Single-cut files cut metal with wide chips equal to the entire length of the tooth, which requires a lot of force. Such files are used for processing non-ferrous metals, their alloys and non-metallic materials.
Double-cut files have a main cut (deeper) and an auxiliary cut (smaller) applied on top of it, which ensures that the chips are crushed along the length, which reduces the forces applied to the file during operation. The method for applying the main and auxiliary notches is not the same, so the file teeth are located one after the other in a straight line, making an angle of 5 with the file axis. This arrangement of the teeth on the file ensures partial overlap of the marks from the teeth on the treated surface, which reduces its roughness.
Rasp-cut files (rasps) have teeth that are formed by extruding metal from the surface of the file blank using a special rasp chisel. Each rasp tooth is offset relative to the tooth in front by half a step. This arrangement of teeth on the surface of the file reduces the depth of the grooves formed by the teeth due to partial overlap of the tooth marks on the surface of the workpiece, which facilitates cutting. Rasps are used for filing soft materials(babbitt, lead, wood, rubber, rubber, some types of plastics).
The notches on the file surface are obtained various methods: notching (Fig. 3.2, a) on special machines, milling (Fig. 3.2, b) and broaching (Fig. 3.2, c). Regardless of the method of obtaining the notch, the teeth formed on the surface of the file have the shape of a cutting wedge, the geometric shape of which is determined by the sharpening angle p>, the rear angle a, the front angle y and the cutting angle 5 (see Fig. 3.2, a).
The rake angle is the angle between the front surface of the tooth and the plane passing through its top perpendicular to the axis of the file. The point angle is the angle between the front and back surfaces of the tooth. The clearance angle is the angle between the back surface of the tooth and the tangent to the machined surface. The cutting angle is the angle between the front surface of the tooth and the plane of the machined surface.
Files are classified depending on the number of notches per 10 mm of file length into 6 classes. Notches have numbers from 0 to 5, and the smaller the notch number, the greater the distance between the notches and, accordingly, the larger the tooth. The choice of file number depends on the nature of the work that will be performed by it. The higher the requirements for processing accuracy and roughness of the machined surface, the finer the file tooth should be.
For rough rough filing (roughness Rz 160… 80, accuracy 0.2…0.3 mm), 0th and 1st class files (garnish) are used, having from 5 to 14 teeth per 10 mm of cut part, depending on the length file
To perform finishing processing (roughness Rz 40...20, accuracy 0.05...0.1 mm), files with smaller teeth of the 2nd and 3rd classes (personal) are used, having from 8 to 20 notches per 10 mm of cut length file parts.
For fitting, finishing and finishing work (surface roughness Ra 2.5... 1.25, accuracy 0.02...0.05 mm), chalk files are used, and they are very fine teeth 4th and 5th classes (velvet), having from 12 to 56 notches per 10 mm of the length of the notched part.
Files with double notches, made using the on notching method, are intended for plumbing work. Such files are manufactured with different cross-sectional shapes, which are selected depending on the shape of the surface being processed.
flat files (Fig. 3.3, a, b) - for filing flat and convex wide external surfaces and sawing rectangular holes;
square files (Fig. 3.3, c) - for sawing square and rectangular openings, rectangular grooves and narrow flat outer surfaces;
triangular files (Fig. 3.3, d) - for sawing holes and grooves with angles of more than 60°;
round files (Fig. 3.3, e) - for sawing round and oval holes, as well as concave surfaces with a small radius of curvature, which cannot be processed with a semicircular file;
semicircular files (Fig. 3.3, e) - for filing concave surfaces with a large radius of curvature and fillets;
rhombic files (Fig. 3.3, g) - for filing the teeth of gear wheels, sprockets, for sawing profile grooves and surfaces located at sharp angles;
hacksaw files (Fig. 3.3, h) - for filing internal corners less than 10°, as well as wedge grooves, narrow grooves, gear teeth, flat surfaces and corner finishing in triangular, rectangular and square holes.
Rasps in cross-sectional shape can be flat blunt-pointed (Fig. 3.4, a), flat pointed (Fig. 3.4, b), round (Fig. 3.4, c) and semicircular (Fig. 3.4, d). Rasps are made with small and large notches.
For processing small parts use special files - needle files having a short length (80,120 or 160 mm) and different shape cross section (Fig. 3.5). The needle files also have a double notch: the main one - at an angle of 25 ° and the auxiliary one - at an angle of 45
To provide High Quality When filing, it is necessary to correctly select the cross-sectional profile, length and cut of the file.
The cross-sectional profile of the file is selected depending on the shape of the surface to be filed:
Flat, flat side of semicircular - for filing flat and convex curved surfaces;
Square, flat - for processing grooves, holes and openings of rectangular cross-section;
Flat, square, flat side of semicircular - when filing surfaces located at an angle of 90°;
Triangular - when filing surfaces located at an angle of over 60°;
Hacksaw, rhombic - for filing surfaces located at an angle of more than 10°;
Triangular, round, semicircular, rhombic, square, hacksaw - for sawing holes (depending on their shape).
The length of the file depends on the type of processing and the size of the surface being processed and should be:
100... 160 mm - for filing thin plates;
160…250 mm - for filing surfaces with a processing length of up to 50 mm; 250...315 mm - with a processing length of up to 100 mm; 315... 400 mm - with a processing length of more than 100 mm;
100...200 mm - length: sawing holes in parts up to 10 mm thick;
315...400 mm - for rough filing;
100... 160 mm - during finishing (needles).
The notch number is selected depending on the requirements for the roughness of the machined surface.
For comfortable holding and safety, files are equipped with a handle made of wood or plastic. Pens can be disposable or reusable. Wooden disposable handles (Fig. 3.6) for files are made of birch or linden. The surface of the handle must be clean and smooth. To prevent splitting when installed on the file shank, the handle is equipped with a special metal ring mounted on its neck. A hole is drilled in the handle for the file shank. When fastening, the file shank is inserted into the hole, then, hitting the workbench or vice with the head of the handle, it is ensured that it fits tightly into the hole in the handle. Do not force the handle onto the tip of the file with a hammer, as this may cause injury.
Correct positioning of the body and legs and holding the file when filing
Working movements and balancing when working with a file.
Filing is the operation of processing metals and other materials by removing small layers of metal (material) with files or on filing machines. To file correctly, you need to apply pressure and move the file correctly.
1. The height of the position of the vice is chosen according to the height of the worker so that when the elbow part of the arm is placed on the jaws of the vice, an angle of 90° is formed between the elbow and shoulder parts of the arm (Fig. 96). If the height of the vice does not correspond to the height of the worker, it is adjusted with special stands or the workbench with the vice is raised.
Before starting work, the file should be on the right side of the vice with the handle facing the worker.
2. The upper edge of the block clamped in a vice should be at a height of 5-10 mm above its working surface. The vise jaws should only be clamped by hand.
3. In front of the vice, you must stand straight and firmly half-turn to it (at an angle of 45°). The left leg must be placed near the workbench, and the right leg must be moved back and to the right by approximately a distance of 250 mm, so that the angle between the midlines of the feet is 60°.
Rice. 96. Position of the body and position of the feet when filing
Rice. 97. Position of the right hand on the file handle
4. Grasping the file handle with the right hand is carried out in two steps: the right hand is positioned so that the oval head of the handle rests on the flesh of the palm (Fig. 97, a); the thumb is placed lengthwise
The axes of the handle, and the remaining fingers clasp the handle, pressing it to the palm (Fig. 97, b). placed across the file at a distance of 20-30 mm from its end (Fig. 99, a, b).
5. The file is placed on wooden block and take a working position in which the elbow part of the left arm should take a position close to horizontal.
Practicing working movements and balancing when working with a file consists of two training tasks performed by students to master movement coordination and obtain the primary skill in balancing with a file.
Rice. 99. Training exercises on developing skills in working with a file
Training task 1 for filing two steel plates installed at a distance of 80 mm from each other, consists of mastering the techniques of correct balancing with a file and observing the rhythm of movements (Fig. 99).
1. Marks are applied (along the length) on two steel plates at a distance of 5 mm from the edge.
2. Two steel plates (at a distance of 80 mm from each other) and a wooden spacer are clamped in a vice; the edges of the plates protrude 5 mm above the level of the vice jaws.
3. Take the working position, take the file with your right hand by the handle, place it on the edges of the steel plates, and place your left hand on the file.
4. On the narrow edges of two steel plates, movements are made with a worn-out file in the horizontal plane of the plates.
The movement of the file is carried out with coordinated actions of both hands. Force in the horizontal direction (along the file) is necessary to create its movement during working and idle strokes, and in the vertical direction - to press on the surface being processed only during working stroke. In this case, the vertical force changes depending on the position of the file on the plane being processed: in the middle position the greatest force is applied and in the extreme positions less force is applied (vector arrows in Fig. 99, b). When working with a file from yourself, the body weight will be transferred to the left leg, and when moving the file towards you, the load will move to the right leg.
Training task 2 on filing two steel plates installed at a distance of 50 mm from each other (Fig. 99, c), is performed in the same sequence as the first, and is intended to acquire skills in balancing with a file and with a shorter filing length.
Checking the correct coordination of horizontal movements and balancing with a file is determined by the height of the edges being filed.
If the metal layer is removed evenly, then both edges will have the same height. If the height of the edges is not the same, it means that the forces were distributed incorrectly during filing.
During the initial period of training, the pace of work should be regulated and be no more than 50 double movements per minute. To reduce students' fatigue, they should alternate work (5 minutes) with rest (2-3 minutes). Filing techniques.
The position of the body is considered correct if an angle of 90° is formed between the shoulder and elbow parts of the right arm bent at the elbow with a file mounted on the jaws of the vice (initial position) (Fig. 1.7.4). In this case, the worker’s body must be straight and turned at an angle of 45° to the axis line of the vice. Leg position.
During the working stroke of the file (pull), the main load falls on the left leg, and during the reverse (idling) stroke - on the right, so the leg muscles alternately rest.
When removing thick layers of metal with a file, the file is pressed with greater force, so the right leg is moved back half a step from the left and in this case it is the main support. When there is light pressure on the file, for example when finishing or finishing a surface, the feet are placed almost side by side. These precision jobs are often performed while sitting.
At the beginning of the working stroke of the file, the body weight falls on the right leg; when pressed, the center of gravity moves to the left leg. This corresponds to the following arrangement of legs: the left leg is carried (retracted) forward in the direction of movement of the file, the right leg is moved away from the left by 200-300 mm so that the middle of its foot is opposite the heel of the left leg.
Hand position (file grip) is extremely important. The mechanic takes the file in his right hand by the handle so that it rests against the palm of his hand, four fingers clasp the handle from below, and the thumb is on top. The palm of the left hand is placed slightly across the file at a distance of 20-30 mm from its toe. In this case, the fingers should be slightly bent, but not drooping; they do not support, but only press the file. The elbow of the left hand should be slightly raised; right arm from the elbow to the hand - make a straight line with the file.
Rice. 1.7.4 Coordination of efforts
When the pressure is weakened with the right hand and increased with the left, the surface may collapse forward; when you increase the pressure with your right hand and weaken your left, you roll back.
You need to press the file against the surface being processed during the working stroke (from yourself). During the reverse stroke, you should not tear the file off the surface being processed: it should only slide. The rougher the processing, the greater the force during the working stroke.
. When filing, it is necessary to maintain coordination of pressure forces (balancing). This consists in correctly increasing the pressure with the right hand on the file during the working stroke while simultaneously decreasing the pressure with the left hand. The movement of the file must be horizontal, so the pressure on its handle and toe must be changed depending on the position of the file’s fulcrum on the surface being processed. During the working movement of the file, the pressure with the left hand is gradually reduced. By adjusting the pressure on the file, you achieve a smooth sawn surface without blockages at the edges.
Sawing flat surfaces is a complex, labor-intensive process. Most often, a defect when filing such surfaces is a deviation from flatness. Working with a file in one direction makes it difficult to get a flat and clean surface.
Therefore, the direction of movement of the file, and therefore the position of the strokes (file marks) on the surface being processed should change alternately from corner to corner.
When finishing filing, you should press the file much less than when roughing. In this case, with your left hand you press on the toe of the file not with your palm, but only with your thumb. First, filing is performed from left to right at an angle of 30-40° to the axis of the vice, then, without interrupting work, with a straight stroke; finish filing with an oblique stroke at the same angle, only from right to left (Fig. 1.7.5, A
). This change in the direction of movement of the file provides the necessary flatness and roughness of the surface. K category:
Sanitary work
Metal filing techniques
The layer of rust and scale on the workpiece and the crust of the casting are filed off with an old bastard file so as not to spoil the good one, which quickly wears out. Then they begin roughing the part with a suitable bastard file and after that they finally process it with a personal file.
Rice. 1. Position of the worker at the vice: a - position of the body, b - diagram of the arrangement of the legs, c - position of the body during rough filing
In order not to damage the jaws of the vice during final filing, they are covered with linings made of copper, brass, lead or aluminum.
The frequency and accuracy of filing depend on the installation of the vice, the position of the worker’s body at the vice, working methods and the position of the file.
The top of the vise jaws should be at the level of the worker’s elbow. The correct position of the worker at the vice is shown in Fig. 1.
When filing, the person working should stand on the side of the vice - half-turn, at a distance of about 200 mm from the edge of the workbench. The body should be straight and rotated 45° to the longitudinal axis of the vice. The legs are spaced foot-width apart, the left leg is moved slightly forward in the direction of movement of the file. The feet are placed at approximately 60° to each other. When working, the body is slightly tilted forward. This position of the body and legs provides the most comfortable and stable position for the worker; the movement of the arms becomes free.
During filing, the file is held with the right hand, resting the head of the handle in the palm. Thumb hands are placed on top of the handle, and the remaining fingers support the handle from below. The left hand is placed on the end of the file near his nose and presses the file.
When rough filing, the palm of the left hand is placed at a distance of about 30 mm from the end of the file, with the fingers half-bent so as not to injure them on the edges of the product during work.
When finishing filing, the end of the file is held with the left hand between the thumb located at the top of the file and the remaining fingers at the bottom of the file. The file is moved back and forth smoothly along its entire length.
The product is clamped in a vice so that the sawn surface protrudes above the jaws of the vice by 5-10 mm. To avoid grooves and blockages along the edges, when moving the file forward, it is evenly pressed against the entire surface to be processed. The file is pressed only when moving it forward. When the file moves back, the pressure is released. The file movement speed is 40-60 double strokes per minute.
To obtain a properly processed surface, the product is filed with cross strokes, alternately from corner to corner. First, the surface is sawn from right to left, and then from left to right. In this way, the surface is filed until the required layer of metal is removed.
After the final filing of the first wide plane of the tile, they begin filing the opposite surface. In this case, it is necessary to obtain parallel surfaces of a given thickness.
The second wide surface is filed with cross strokes.
The accuracy of surface treatment and the accuracy of angles are checked with a ruler and square, and the dimensions are checked with calipers, bore gauges, scale rulers or calipers.
When preparing pipelines and manufacturing parts for sanitary systems, the ends of the pipes and the planes of the parts are filed. When filing products, you must strive to avoid defects. Defects during filing are the removal of an excess layer of metal and a reduction in the size of the product compared to the required ones, unevenness of the filed surface and the appearance of “blockages”.
Therefore, before starting filing, the mechanic must carefully mark the product and select the right files. During the filing process, you should use control and measuring tools and systematically check the dimensions of the parts being processed.
To extend the service life of files, it is necessary to promptly clean the file notch from stuck chips and protect it from oil and water. The file is cleaned from dirt or metal particles with steel brushes.
You should not take the working part of the file oily hands and place the files on the oil workbench.
When filing soft metals, it is recommended to first rub the file with chalk. This will prevent it from becoming clogged with metal filings and will make cleaning the sawdust easier.
When filing, it is necessary to perform following rules safety precautions: – the handle must be firmly attached to the file so that during operation it does not come off and injure the hand with the shank; – the vice must be in good working order, the product must be firmly secured in it; – the workbench must be firmly strengthened so that it does not swing; – when filing parts with sharp edges, you must not tuck your fingers under the cap during its reverse motion; – shavings may only be removed with a broom brush; – after work, files must be cleaned of dirt and shavings wire brush; – it is not recommended to place files one on top of the other, as this will damage the notch.
To mechanize filing work, an electric filing machine with a pneumatic drive and a flexible shaft is used. A special device is put on the end of the flexible shaft that converts rotational motion into reciprocating motion. A file is inserted into this device, which is used to file the parts.
- Techniques for filing metal