Finishing operations - polishing, lapping, rolling, rolling, smoothing and rolling are performed to reduce roughness, increase dimensional accuracy to the wear resistance of a previously processed surface or to apply corrugations of a certain pattern to it.

Polishing

Polishing is performed to reduce the roughness and increase the gloss of the surfaces of the part. On lathes, it is carried out with sanding skins on paper or canvas. Steel and non-ferrous metals are processed with corundum sands 15A-25A, cast iron and other brittle materials - with sandpaper 54C- 64C silicon carbide.

In the process of work, a strip of skin, holding it with both hands, is pressed against the rotating polished surface and moved back and forth along it. It is impossible to hold the skin with your hand in a girth, as it can wrap around the part and pinch your fingers. It is necessary to stand at the machine with the body turning to the right at an angle of 45 ° to the center axis. Polishing is usually carried out sequentially with several abrasives with a gradual decrease in their grain size.

It is convenient to polish cylindrical surfaces with a "press" consisting of two hinged wooden bars. A sandpaper is placed in the radius grooves of the bars, which is pressed with a press to the surface to be treated. Holding the press handles with the left hand, and with the right supporting the hinge, carry out a reciprocating longitudinal feed.

Polishing can also be carried out by attaching the abrasive cloth in the caliper holder using wooden block and metal bar .

The inner surfaces are polished with a sandpaper fixed and wound on a wooden frame.

The polished part gets very hot and lengthens. Therefore, when it is pressed in by the center, it is necessary to periodically check how tight it is clamped, and, if necessary, loosen it a little.

To get a better surface, it is necessary to increase the rotation frequency of the part as much as possible. In addition, chalk is recommended for final polishing.

Debugging

Finishing is carried out to improve the accuracy of the surface (up to the 5-6th grade) and reduce its roughness. Special tools - lapping - together with abrasive materials, the smallest irregularities are removed from the surface of the part.

Abrasive and bonding materials. Working surface lapping is saturated with hard abrasive materials: electrocorundum powders - for finishing steels and silicon carbide - for cast iron and other brittle materials.

The grain size of the powders is selected depending on the required roughness. Preliminary finishing is performed with M40-M14 micropowders, finishing-M10-M5 (the number of the micropowder corresponds to the grain size in microns).

Of the finishing pastes, GOI pastes are most often used, made on the basis of a soft abrasive material, chromium oxide, mixed with reactive and binding substances. According to the finishing ability, such pastes are divided into coarse, medium and fine.

Kerosene or mineral oil are used as binders and lubricants for fine-tuning.

Lap bushings with a longitudinal cut, allowing them to be adjusted in diameter to compensate for wear.

Pre-lapping laps have longitudinal or helical grooves that collect abrasive residues during operation. Final finishing is carried out by lapping with a smooth surface.

Finishing of the outer surface is carried out with a lap, which is installed in the press and is adjusted as necessary with a screw .

To process the holes, the lap is installed on a tapered mandrel and adjusted by axial movement with nuts. The lapping material is chosen depending on its purpose and the abrasive material used.

When lapping with hard abrasive materials, the grains of which are pressed into the lap, the material of the latter should be softer than the material of the workpiece. In addition, the larger the grains of the powder used, the softer material should be chosen for lapping. For coarse lapping, lapping made of mild steel, copper, brass is recommended, and for preliminary and finishing - from fine-grained gray cast iron medium hardness.

To work with GOI pastes, the lap must have a greater hardness than the finished part. In this case, good results are obtained by using laps made of hardened steel or gray cast iron of increased hardness.

The peripheral speed of the part or lapping is taken with preliminary finishing 10-20 m / min, with finishing - 5-6 m / min in order to reduce the heating of the part.

Rolling

Appointment and tools. Rolling is performed to create on the surfaces of some parts (handles, screw heads, etc.) a specially provided roughness, made in the form of corrugations of a certain pattern. To do this, use knurling, consisting of a knurling roller and a holder.

To apply a straight pattern, a single-roll knurling is used, a mesh-two-roll knurling, respectively, with the right and left directions of the corrugations.

Knurling rollers are made from tool steels and hardened to high hardness. On their cylindrical surface, corrugations are made with a profile angle of 70 ° for steel parts and 90 ° for non-ferrous metal parts with a pitch of 0.3 to 1.6 mm.

The knurling is fixed with the smallest overhang in the caliper tool holder so that the generatrix of the roller is strictly parallel to the axis of the part. Check this on the surface to be treated in the light. The axis of the single-roll knurling roller must be level with the centerline of the machine. For double-roller knurling, the height adjustment accuracy is not essential, since in

In this case, the rollers are self-aligning on the processed surface due to the articulated connection of the holder with the holder .

Rolling techniques... When rolling, the metal is squeezed out, therefore, the surface of the part is ground to a diameter that is less than the nominal by about 0.5 step of corrugations.

The rollers are brought close to the rotating part and manually pressed into the work surface to a certain depth. Turning off the rotation of the part, check the accuracy of the resulting pattern. Then turn on the spindle rotation and longitudinal feed and perform rolling to the required length in several passes in both directions until the full height of the corrugations is obtained. At the end of each pass, without breaking contact with the workpiece, the knurling is fed transversely to

required depth. The knurling rollers should be periodically cleaned with a wire brush to remove trapped metal particles from the grooves.

The longitudinal feed is taken to be approximately equal to the doubled step of the corrugations (1-2.5 mm / rev), the rotation speed of the part is in the range of 15-20 m / min.

The surface to be treated is lubricated with oil.

To main

section five

Basic operations and works,
performed on a lathe

Chapter XI

Turning external cylindrical surfaces

Lathes can handle parts whose surfaces are in the form of bodies of revolution. Most parts used in mechanical engineering have cylindrical surfaces such as rollers, bushings, etc.

1. Cutters for longitudinal turning

For longitudinal turning, straight cutters are used. Through cutters are divided into rough and finishing.

Rough cutters (Fig. 99) are designed for rough grinding - roughing, made in order to quickly remove excess metal; they are often called stripping. Such cutters are usually made with a welded or brazed or mechanically attached plate and are equipped with a long cutting edge. The tip of the cutter is rounded off along the radius r = 1-2 mm. In fig. 99, a shows the cutter of the rough straight line, and in Fig. 99, b - bent. The bent shape of the cutter is very convenient when turning the surfaces of parts located near the chuck jaws, and for trimming the ends. After turning with a rough cutter, the surface of the part has large risks; the quality of the finished surface is therefore low.

Finishing cutters are used for the final turning of parts, i.e. for obtaining accurate dimensions and a clean, flat surface processing. There are different types of finishing cutters.

In fig. 100, a shows a finishing cutter, which differs from the rough cut mainly in a large radius of curvature, equal to 2-5 mm. This type of cutter is used for finishing work, which is carried out with a shallow depth of cut and low feed. In fig. 100, b shows a finishing cutter with a wide cutting edge parallel to the axis of the workpiece. This pick allows for fine chip removal at high feed rates and produces a clean and smooth surface. In fig. 100, c shows V. Kolesov's cutter, which allows obtaining a clean and smoothly processed surface when working with a high feed (1.5-3 mm / rev) at a cutting depth of 1-2 mm (see Fig. 62).

2. Installing and securing the cutter

Before turning, you need to correctly install the cutter in the tool holder, making sure that the part of the cutter protruding from it is as short as possible - no more than 1.5 times the height of its shank.

With a larger overhang, the cutter will tremble during operation, as a result, the processed surface will turn out to be uneven, wavy, with traces of crushing.

In fig. 101 shows the correct and incorrect installation of the cutter in the tool holder.

In most cases, it is recommended to set the tip of the cutter at the same height as the center of the machine. To do this, use pads (no more than two), placing them under the entire supporting surface of the cutter. Lining is a flat steel ruler with a length of 150-200 mm, having strictly parallel upper and lower surfaces. The turner must have a set of such shims of different thicknesses in order to obtain the necessary height for setting the cutter. You should not use random records for this purpose.

Shims should be placed under the cutter as shown in fig. 102 on top.

To check the position of the tip of the cutter in height, bring its tip to one of the preliminarily calibrated centers, as shown in Fig. 103. For the same purpose, you can use the risk drawn on the tailstock quill, at the height of the center.

The fastening of the cutter in the tool holder must be reliable and strong: the cutter must be fixed with at least two bolts. The bolts holding the cutter must be evenly and tightly tightened.

3. Installation and fixing of parts in centers

A common way of processing parts on lathes is processing in centers(fig. 104). With this method, center holes are pre-drilled at the ends of the workpiece - center detail. When installed on the machine, the points of the centers of the headstock and tailstock of the machine enter these holes. To transfer rotation from the headstock spindle to the workpiece, a driver chuck 1 (fig. 104) screwed onto the machine spindle, and yoke 2, fixed with a screw 3 on the workpiece.

The free end of the clamp is captured by the groove (Fig. 104) or by the finger (Fig. 105) of the chuck and rotates the part. In the first case, the clamp is made bent (Fig. 104), in the second - straight (Fig. 105). The pin chuck shown in fig. 105, poses a hazard to the worker; safer is the drive chuck with a protective cover (Fig. 106).

Essential accessories lathe are centers... Typically, the center shown in Fig. 107, a.

It consists of a taper 1, on which the part is mounted, and a tapered shank 2. The shank must fit exactly the tapered bore of the headstock spindle and the tailstock quill of the machine.

The front center rotates with the spindle and workpiece, while the tailstock center is in most cases stationary and rubs against the rotating workpiece. From friction, both the conical surface of the center and the surface of the center hole of the part are heated and worn out. To reduce friction, the rear center must be lubricated.

When turning parts at high speeds, as well as when machining heavy parts, working on a fixed center of the tailstock is impossible due to the rapid wear of the center itself and the development of the center hole.

In these cases, apply revolving centers... In fig. 108 shows one design of a revolving center inserted into a tapered hole in a tailstock quill. Center 1 rotates in ball bearings 2 and 4. The thrust pressure is taken up by a thrust ball bearing 5. The tapered shank 3 of the center housing corresponds to the tapered bore of the quill.

To reduce the time for fastening parts, instead of clamps with manual clamping, they are often used grooved front centers(fig. 109), which not only center the part, but also act as a leash. When pressed by the rear center, the corrugations cut into the workpiece and thereby transfer rotation to it. For hollow parts, external (Fig. 110, a) are used, and for rollers, internal (reverse) corrugated centers (Fig. 110, b).

This method of fastening allows you to grind the part along its entire length in one installation. Grinding the same parts with a conventional center and yoke can only be done in two sets, which significantly increases the processing time.

For light and medium turning work, use self-tightening clamps... One of these clamps is shown in Fig. 111. In the housing 1 of such a collar, a cam 4 is installed on the axis, the end of which has a corrugated surface 2. After the collar is installed on the part, the corrugated surface of the cam is pressed against the part under the action of the spring 3. After installation in the centers and starting the machine, the pin 5 of the driver chuck, pressing on the cam 4, jams the part and drives it into rotation. These self-tightening clamps significantly reduce the downtime.

4. Setting up the machine for processing in centers

To obtain a cylindrical surface when turning the workpiece in the centers, it is necessary that the front and task centers are on the axis of rotation of the spindle, and the cutter moves parallel to this axis. To check the correct location of the centers, you need to move the rear center to the front (Fig. 112). If the center points do not match, the tailstock body must be adjusted to the plate as indicated on page 127.

Center misalignment can also be caused by dirt or swarf entering the tapered bores of the spindle or pi-zero. To avoid this, it is necessary to carefully wipe the spindle and quill holes, as well as the tapered part of the centers, before installing the centers. If the center of the headstock and after that, as they say, "hits", then it is faulty and must be replaced by another.

When turning, the part heats up and lengthens, while creating an increased pressure on the centers. To protect the part from possible bending and to prevent the rear center from jamming, it is recommended to release the rear center from time to time and then press it back down to its normal state. It is also necessary to periodically additionally lubricate the rear center hole of the part.

5. Installation and fastening of parts in cartridges

Short parts are usually mounted and secured in chucks, which are classified as simple or self-centering.

Simple chucks are usually made with four-jaw (Fig. 113). In such chucks, each cam 1, 2, 3 and 4 moves with its screw 5 independently of the others. This allows you to install and fix in them various parts of both cylindrical and non-cylindrical shapes. When installing a part in a four-jaw chuck, it must be carefully aligned so that it does not hit when rotating.

The alignment of the part during its installation can be done using a planer. The scribe of the scraper is brought to the surface to be checked, leaving a gap of 0.3-0.5 mm between them; turning the spindle, watch how this gap changes. According to the observation results, some cams are squeezed out and others are pressed until the gap becomes uniform along the entire circumference of the part. After that, the part is finally fixed.

Self-centering chucks(Fig. 114 and 115) in most cases, three-cam are used, much less often - two-cam. These chucks are very convenient to use, since all the cams in them move at the same time, due to which a part with a cylindrical surface (outer or inner) is installed and clamped exactly along the spindle axis; in addition, the time for setting up and fixing the part is significantly reduced.

In it, the cams move with a wrench, which is inserted into the four-sided hole 1 of one of the three bevel gears 2 (Fig. 115, c). These wheels are coupled with a large bevel wheel 3 (Fig. 115, b). On the reverse flat side of this wheel, a multi-turn spiral groove 4 is cut (Fig. 115, b). All three cams 5 enter the individual turns of this groove with their lower protrusions 5. When one of the gears 2 is turned with a key, the rotation is transferred to the wheel 3, which, rotating, by means of the spiral groove 4, moves all three cams along the slots of the chuck body simultaneously and evenly. When the disk with a spiral groove rotates in one direction or the other, the cams approach or move away from the center, respectively, clamping or releasing the part.

Make sure that the part is firmly fixed in the chuck jaws. If the chuck is in good condition, then a strong clamping of the part is ensured by using a key with a short handle (Fig. 116). Other clamping methods, such as clamping with a wrench and a long tube that fits over the handle, should never be allowed.

Chuck jaws... The cams are used hardened and raw. Hardened cams are usually used due to their low wear. But when such cams are clamped on parts with cleanly machined surfaces, traces in the form of dents from the cams remain on the parts. To avoid this, it is recommended to use wet (non-hardened) cams as well.

Raw cams are also convenient in that they can be periodically bored with a cutter and eliminate the beating of the chuck, which inevitably appears during its prolonged operation.

Installing and securing parts in a chuck with rear center support... This method is used when processing long and relatively thin parts (Fig. 116), which are not enough to fix only in the chuck, since the force from the cutter and the weight of the protruding part can bend the part and pull it out of the chuck.

Collet chucks... For quick fastening of short parts, do not large diameter for the outer treated surface apply collet chucks... Such a cartridge is shown in fig. 117. Tapered shank 1 chuck is installed in the tapered bore of the headstock spindle. A split spring sleeve 2 with a cone, called a collet, is installed in the groove of the chuck. The workpiece is inserted into the hole 4 of the collet. Then nut 3 is screwed onto the chuck body using a wrench. When the nut is screwed in, the spring collet is compressed and fixes the part.

Pneumatic chucks... In fig. 118 shows a schematic diagram of a pneumatic chuck that provides fast and reliable clamping of parts.

An air cylinder is attached to the left end of the spindle, inside which there is a piston. The compressed air flows through the tubes to the central channels 1 and 2, from where it is directed to the right or left cavity of the cylinder. If air enters through channel 1 into the left cavity of the cylinder, then the piston displaces air from the right cavity of the cylinder through channel 2 and vice versa. The piston is connected to a rod 3 connected to a rod 4 and a slider 5, which acts on the long arms 6 of the crank levers, the short arms 7 of which move the clamping jaws 8 of the chuck.

The cam stroke length is 3-5 mm. The air pressure is usually 4-5 am. To actuate the pneumatic cylinder, a distribution valve 9 is installed on the gearbox housing, which is turned by a handle 10.

6. Screwing in and out of jaw chucks

Before screwing the chuck onto the spindle, carefully wipe the threads at the end of the spindle and in the bore of the chuck with a rag and then lubricate them with oil. A light chuck is brought directly to the end of the spindle with both hands and screwed on until it stops (fig. 119). It is recommended to put a heavy chuck on a board (Fig. 120), bringing its hole to the end of the spindle, screw the chuck to failure, as in the first case, manually. When screwing on the chuck, make sure that the axes of the chuck and the spindle are strictly aligned.

To prevent cases of self-unscrewing of cartridges in machines for high-speed cutting, additional fastening of the cartridge to the spindle using various devices is used

(screwing on an additional nut, securing the cartridge with shaped breadcrumbs, etc.).

The screwing of the chuck is done as follows. Insert the key into the chuck and use both hands to make a jerk towards you (fig. 121).

Other screwing methods, associated with sharp blows to the chuck or to the jaws, are unacceptable: the chuck is damaged, the jaws in its body are loose.

It is better to screw and screw on a heavy chuck with the help of an auxiliary worker.

7. Techniques for turning smooth cylindrical surfaces

Grinding of cylindrical surfaces is usually carried out in two steps: first, roughly remove most of the allowance (3-5 mm per diameter), and then the rest (1-2 mm per diameter).

To obtain the specified diameter of the part, it is necessary to set the cutter to the required depth of cut. To set the cutter to the depth of cut, you can use the test chip method or use the cross feed dial.

To set the cutter to the depth of cut (by size) by the method of trial chips, you must:
1. Inform the details of the rotational movement.
2. By turning the handwheel for the longitudinal feed and the handle of the cross feed screw, manually bring the cutter to the right end of the part so that its tip touches the surface of the part.
3. Having established the moment of contact, manually move the cutter to the right of the workpiece and by turning the handle of the cross feed screw move the cutter to the required cutting depth. After that, the part is turned with manual feed at a length of 3-5 mm, the machine is stopped and the diameter of the turned surface is measured with a vernier caliper (Fig. 122). If the diameter turns out to be larger than the required one, the cutter is retracted to the right and set by a few great depth, again grind the belt and again take the measurement. All this is repeated until the specified size is obtained. Then turn on the mechanical feed and grind the part along the entire specified length. At the end, turn off the power feed, take the cutter back and stop the machine.

Finishing turning is performed in the same order.

Using the cross-feed screw dial... To speed up the setting of the cutter to the depth of cut, most lathes have a special device. It is located at the handle of the cross feed screw and is a bushing or ring, on the circumference of which there are divisions (Fig. 123). This graduated bushing is called a limb. The divisions are counted according to the risk on the fixed screw sleeve (in Fig. 123, this risk coincides with the 30th stroke of the dial).

The number of divisions on the dial and the pitch of the screw can be different, therefore, the magnitude of the lateral movement of the cutter will also be different when the dial is rotated by one division. Suppose the limb is divided by 100 equal parts, and the cross feed screw has a thread with a pitch of 5 mm. With one full turn of the screw handle, i.e. 100 divisions of the dial, the cutter will move in the transverse direction by 5 mm. If you turn the handle one division, then the cutter movement will be 5: 100 = 0.05 mm.

It should be borne in mind that when the cutter moves in the transverse direction, the radius of the part after the passage of the cutter will decrease by the same amount, and the diameter of the part by doubled. Thus, in order to reduce the diameter of the part, for example, from 50.2 to 48.4 mm, i.e., by 50.2 - 48.4 = 1.8 mm, it is necessary to move the cutter forward by half, i.e. . by 0.9 mm.

When setting the cutter to the cutting depth using the cross feed screw dial, it is, however, necessary to take into account the gap between the screw and the nut, which forms the so-called "backlash". If you lose sight of this, then the diameter of the machined part will differ from the specified one.

Therefore, when setting the cutter to the cutting depth using the dial, the following rule must be observed. Always approach the required setting along the dial by slow right-hand rotation of the screw handle (Fig. 124, a; the required setting is the 30th division of the dial).

If you turn the handle of the cross feed screw by an amount greater than the required reverse side, and then rotate the handle again to the right until the required division along the dial (Fig. 124, c). The same is done when you need to take the cutter back; turning the handle to the left, the cutter is withdrawn more than necessary, and then by right rotation it is brought to the required division of the limb.

The movement of the cutter corresponding to one division of the dial is different on different machines. Therefore, starting to work, it is necessary to determine the amount of movement that corresponds to one division of the dial on this machine.

Using the limbs, our high-speed turners achieve a given size without trial chips.

8. Processing parts in rests

Long and thin parts, the length of which is 10-12 times their diameter, bend during turning both from their own weight and from the cutting force. As a result, the part receives irregular shape- it turns out to be thicker in the middle, and thinner at the ends. This can be avoided by using a special support device called lunette... When using rests, you can grind parts with high accuracy and remove larger chips without fear of deflection of the part. Lunettes b, stitch motionless and mobile.

Fixed steady rest(Fig. 125) has a cast-iron body 1, with which a hinged cover 6 is fastened by means of a pivot bolt 7, which facilitates the installation of the part. The rest housing at the bottom is processed according to the shape of the frame guides, on which it is fixed by means of a strap 9 and a bolt 8. In the housing holes, using adjusting bolts 3, two cams 4 move, and on the roof - one cam 5. Screws 2 are used to fix the cams in the required position Such a device allows shafts of various diameters to be installed in the steady rest.

Before installing the rough workpiece in a fixed steady rest, it is necessary to grind in the middle of it a groove for the cams with a width slightly larger than the width of the cam (Fig. 126). If the workpiece has a large length and small diameter, then its deflection is inevitable. To avoid this, an additional groove is machined closer to the end of the workpiece and, having installed a steady rest in it, the main groove is machined in the middle.

Fixed rests are also used for cutting ends and for cutting ends of long parts. In fig. 127 shows the use of a fixed steady rest when trimming the end face: the part is fixed at one end in a three-jaw chuck, and the other is installed in the steady rest.

In the same way, you can process precise hole from the end of a long part, for example, bore a tapered hole in a lathe spindle or drill such a part along its entire length.

Movable steady rest(fig. 128) is used for finishing long parts. The steady rest is fixed on the carriage of the support so that it moves along with it along the turned part, following the cutter. Thus, it supports the part directly at the point of application of the force and prevents the part from bending.

The steady rest has only two jaws. They are extended and secured in the same way as the cams of a fixed steady rest.

Steady rests with conventional cams are not suitable for high speed machining due to rapid wear of the cams. In such cases, apply steady rests with roller or ball bearings(fig. 129) instead of conventional cams, thereby facilitating the operation of the rollers and reducing the heating of the workpiece.

9. Techniques for turning cylindrical surfaces with ledges

When machining a batch of stepped parts (stepped rollers) with the same length for all parts of individual steps on lathes, innovators use a longitudinal stop, limiting the movement of the cutter, and a longitudinal feed limb in order to reduce the time for measuring the length.

Using the longitudinal stop... In fig. 130 shows a longitudinal stop. It is bolted to the front frame guide as shown in fig. 131; the place of fixing the stop depends on the length of the part to be turned.

If there is a longitudinal stop on the machine, it is possible to process cylindrical surfaces with steps without preliminary marking, while, for example, stepped rollers are turned in one setup much faster than without a stop. This is achieved by laying between the stop and the support of the length limiter (measuring plate) corresponding to the length of the roller step.

An example of turning a stepped roller using a stop 1 and measuring plates 2 and 3 is shown in Fig. 131. Grinding step a 1 is carried out until the caliper rests against the measuring plate 3. Having removed this tile, you can grind the next step of the roller with length a 2 until the caliper rests against tile 2. Finally, removing tile 2, grind step a 3 ... As soon as the caliper reaches the stop, you must turn off the power feed. The length of the measured tile 2 is equal to the length of the ledge a 3, and the length of the tile 3 is, respectively, the length of the ledge a 2.

It is possible to use rigid stops only on machines that have an automatic cut-off of the feed in case of overload (for example, 1A62 and other new machine systems). If the machine does not have such a device, then turning on the stop is possible only if the mechanical feed is turned off in advance and the caliper is manually brought to the stop, otherwise the machine will inevitably break down.

Using the longitudinal feed limb Using the longitudinal feed limb... To reduce the time spent on measuring the lengths of workpieces, modern lathes are equipped with longitudinal feed limb... This dial is a large diameter rotating disc (Fig. 132) located on the front wall of the apron and behind the longitudinal feed handwheel. Equal divisions are marked on the circumference of the disc. When the handwheel rotates, the limb, which is connected by a gear train to the longitudinal feed wheel, also rotates. Thus, a certain longitudinal movement of the caliper with a cutter corresponds to the rotation of the dial by a certain number of divisions relative to the stationary risks.

When processing stepped parts, the use of a longitudinal feed limb is very rational. In this case, the turner, before processing the first part from the batch, pre-marks the length of the steps with a cutter using a vernier caliper, and then begins to grind them. Having turned the first step, he sets the longitudinal limb to the zero position with respect to the stationary risks. Grinding the next steps, he remembers (or writes down) the corresponding readings of the dial regarding the same risks. When turning subsequent parts, the turner uses the indications established when turning the first part.

Using the cross stop... To reduce the time spent on measuring diameters when machining stepped parts, it is possible to use a cross stop on a number of lathes.

One of these stops is shown in Fig. 133. The emphasis consists of two parts. The fixed part 1 is installed on the carriage and secured with bolts 2; the thrust pin 6 is stationary. The movable stop 3 is installed and fixed with bolts 4 on the lower part of the support. Screw 5 is set exactly to the required size of the part. The end of the screw 5, abutting against the pin 6, predetermines the required size of the part. By placing measuring tiles between the pin 6 and the screw 5, it is possible to grind the part with steps of various diameters.

10. Cutting conditions for turning

Choice of cutting depth... The depth of cut when turning is selected depending on the machining allowance and the type of machining - roughing or finishing (see p. 101-102).

Selecting the feed amount... The feed is also chosen depending on the type of processing. Usually, feed is taken for rough turning from 0.3 to 1.5 mm / rev, and for semi-finishing and finishing from 0.1 to 0.3 mm / rev when working with normal cutters and 1.5-3 mm / rev when working with cutters designs by V. Kolesov.

Choice of cutting speed... The cutting speed is usually selected according to specially developed tables depending on the tool life, quality of the work material, material of the tool, depth of cut, feed, type of cooling, etc. (see, for example, Table 6, page 106).

11. Rejection when turning cylindrical surfaces and measures to prevent it

When turning cylindrical surfaces, the following types of rejects are possible:
1) part of the surface of the part remained untreated;
2) the dimensions of the turned surface are incorrect;
3) the turned surface is conical;
4) the turned surface is oval;
5) the cleanliness of the treated surface does not correspond to the instructions in the drawing;
6) combustion of the rear center;
7) mismatch of surfaces when processing the roller in the centers on both sides.

1. Defect of the first type is obtained due to insufficient dimensions of the workpiece (insufficient machining allowance), poor straightening (curvature) of the workpiece, improper installation and inaccurate alignment of the part, inaccurate location of center holes and offset of the rear center.
2. Incorrect dimensions of the turned surface are possible due to inaccurate setting of the cutter to the depth of cut or incorrect measurement of the part when removing test chips. It is possible and necessary to eliminate the causes of this type of marriage by increasing the attention of the turner to the work performed.
3. The taper of the turned surface is usually obtained as a result of the displacement of the rear center relative to the front center. To eliminate the cause of this type of marriage, it is necessary to correctly install the rear center. A common cause of a rear center offset is dirt or small chips getting into the tapered bore of the quill. Cleaning the center and tapered bore quill can eliminate this cause of marriage. If, after cleaning, the points of the front and rear centers do not coincide, it is necessary to move the tailstock body on its plate accordingly.
4. Ovality of the turned part is obtained when the spindle beats due to uneven wear of its bearings or uneven wear of its journals.
5. Insufficient surface finish during turning can be due to a number of reasons: high feed of the cutter, use of a cutter with incorrect angles, poor sharpening of the cutter, small radius of curvature of the cutter tip, high viscosity of the part material, jitter of the cutter due to long overhang, insufficiently strong attachment of the cutter in the tool holder, increased gaps between the individual parts of the caliper, shaking of the part due to its fragile fastening or due to wear of the bearings and spindle journals.

All of the above reasons for marriage can be eliminated in a timely manner.

6. Burning of the rigid center of the tailstock can be caused by the following reasons: the part is too tightly fixed between the centers; poor lubrication of the center hole; incorrect centering of the workpiece; high cutting speed.
7. The mismatch of the machining surfaces when turning on both sides in the centers is obtained mainly as a result of the beating of the front center or the development of center holes in the workpiece. To prevent scrap, it is necessary to check the condition of the center holes of the workpiece during finishing, and also to ensure that there is no beating of the center of the headstock.

12. Safety precautions when turning cylindrical surfaces

In all cases of machining on lathes, it is necessary to pay attention to the firm fixing of the workpiece and the cutter.

The reliability of fastening the workpiece machined in the centers largely depends on the condition of the centers. Do not work with worn centers, since the part under the action of the cutting force can be torn out of the centers, fly off to the side and injure the turner.

When machining parts in centers and chucks, the protruding parts of the clamp and chuck jaws often grip the worker's clothes. These same parts can also cause injury to hands when measuring a part and cleaning the machine while on the move. To prevent accidents, use protective shields at the clamps or use safety clamps, and protect the jaw chucks. A perfect type of safety collar is shown in fig. 134. The rim 3 covers not only the head of the bolt 2, but also the pin 1 of the driver chuck.

To protect the turner's hands and clothes from protruding parts of the chuck or faceplate, a special guard is used on modern lathes (Fig. 135). The casing 1 of the device is pivotally connected to the pin 2 fixed on the headstock housing.

When installing parts in the centers, you need to pay attention to the correctness of the center holes. If their depth is insufficient, the part can break off the centers during rotation, which is very dangerous. In the same way, after fixing the part in the chuck, you need to check if the key is removed. If the key remains in the chuck, then when the spindle rotates, it will hit the bed and fly off to the side. In this case, both the breakdown of the machine and the injury to the worker are possible.

Accidents are often caused by shavings, especially drain chips, which when high speeds cutting comes off with a continuous belt. Such shavings should never be removed or torn off by hand, they can cause severe cuts and burns. Should be in all possible cases use chip breakers. In extreme cases, when chip breaking is not achieved, it should be removed with a special hook.

When processing materials that give short bouncing chips, you must use protective goggles or use safety guards made of safety glass or celluloid (Fig. 136), attached on a hinged stand to the carriage. It is necessary to sweep away small shavings resulting from the processing of brittle metals (cast iron, hard bronze), not with your hands, but with a brush.

Hand injuries are possible when installing and securing the cutters as a result of the wrench breaking off the heads of the tool holder fixing bolts. The key breaks off when the key jaws and bolt heads are worn out. Often, however, breakage also occurs when the turner uses a wrench that does not match the size of the bolt.

The installation of the cutter along the center height using all kinds of pads that are not suitable for this (metal scraps, pieces of hacksaws, etc.) does not provide a stable position of the cutter during its operation. Under the pressure of the shavings, such shims are displaced, and the setting of the cutter is unstable. In this case, the fastening of the cutter is also weakened. As a result, the shims and the cutter can jump out of the tool holder and injure the turner. In addition, during the installation of the cutter and during work on the machine, hands can be injured on the sharp edges of the metal pads. Therefore, it is recommended that every turner have a set of shims of different thickness, with well-machined reference planes and edges.

Control questions 1. How to correctly install the tool in the tool holder?
2. How to check the position of the cutter tip relative to the center line?
3. How are parts set and secured when turning cylindrical surfaces?
4. What is the difference between the working conditions of the front and rear centers?
5. How is the rotating center arranged and in what cases is it used?
6. How does the grooved front center work and what are its advantages?
7. How to check if the centers for turning a cylindrical surface are correctly set?
8. How does a self-centering chuck work? Name its details, rules for installing and preparing it for work.
9. How to align a part when installing it in a four-jaw chuck?
10. What is the purpose of the cross feed screw dial?
11. What is the longitudinal feed limb for? How does it work?
12. What are lunettes used for and in what cases are they used?
13. What is the structure of a fixed steady rest?
14. How is the movable steady rest arranged?
15. How is the billet of the shaft prepared for installation in the steady rest?
16. Give an example of using a longitudinal stop; cross stop.
17. What types of rejects are possible when turning cylindrical surfaces? How to eliminate the causes of marriage?
18. List the basic safety rules when turning cylindrical surfaces.

Current trends in the integration of combined machining have led to the fact that grinding can also be carried out on lathes. When quality issues come to the fore, they always pay attention to the process finishing, which is called grinding - performing mechanical action in several passes to reduce the initial errors. Spend finishing with a turning tool with the same quality as when using grinding heads, it is not possible due to the rounding of the cutting edge. Also, do not forget that vibration can occur on a lathe at low feed rates, which will lead to errors. For this reason, even with the emergence of new materials that can withstand strong impacts for a long time and not change their shape, grinding remains the main method used to obtain a surface of a high roughness class.

The need for grinding heads

Obtaining bodies of revolution on lathes has been carried out over the past several decades. As a rule, grinding was carried out on other equipment. This moment determined the following technological process:

1. performing rough turning to remove a large layer of metal;
2. finishing turning to prepare the part for the finishing stage of the technological process;
3. finishing on a cylindrical grinding machine.

Such a technological process determines the increase in costs due to the installation of a special machine for finishing. When creating a large batch of products, the purchase grinding machine pays off, but with small-scale production, its purchase will lead to an increase in the cost of one product. A way out of the situation can be called the use of special grinding heads, which can also be used to obtain a surface with a high roughness class.

Design features

The grinding heads are a special design that is used to significantly expand the capabilities of the turning group machine. This mechanism is conventionally referred to as a snap. TO design features can be attributed:

1. the presence of its own electric motor, the power of which can be from 1 kW or more. this moment determines what the head can become a snap for different models lathes. as a rule, turning equipment has a closed gearbox and does not have a separate drive for connecting the equipment in question;
2. the installed electric motor is connected to the lathe circuit, which determines the versatility of the entire structure. there is also a three-phase plug for connection to a separate power circuit;
3. the head has its own bed, which during modernization can be fixed rigidly instead of the standard tool holder. this moment determines that the equipment allows obtaining high-quality surfaces with high mechanization of the process. in the manufacture of the bed, steel is used, which prevents vibration during operation by increasing the rigidity of the structure;
4. the transmission of rotation is carried out using a belt drive to reduce the speed.

The construction is pretty simple. When considering it, it is worth paying attention to the type of bed. This is due to the fact that only a certain type of bed can fit a certain model of a lathe instead of a tool holder.

Grinding head VGR 150

There are several popular models of cylindrical grinding heads, among which we note VGR 150. It has the following features:

1. Supplied with external grinding spindle with a wheel diameter of 125 mm;
2. the VGR 150 version can also be used for grinding internal surfaces with a wheel with a diameter of 8 to 40 millimeters;
3. the setting of the model can be carried out on a lathe with a stud diameter under the tool holder no more than 22.5 millimeters. the frame of the VGR 150 has a contact surface 202 by 102 millimeters;
4. for external grinding, the spindle speed is Idling is 5000 rpm, for internal - 16 800 rpm at idle. during operation, the indicator can significantly decrease, which depends on the value of the cross feed. with a strong feed, there is a possibility of the belt slipping on the installed pulleys, which makes it possible to exclude the possibility of displacement of the output shaft of the electric motor relative to the windings, as well as its deformation;
5. VGR 150 drive shafts are mounted on precision bearings;
6. the spindle sleeve and the motor base have the ability to adjust, which to a greater extent increases the versatility of the device;
7. using a belt drive, you can adjust the speed of rotation of the wheel depending on the tasks set, as a rule, there are 2 gears;
8. VGR 150 can be used to obtain dimensions with an accuracy ranging from 0.01 to 0.02 millimeters. this point determines that Model 150 and 200 can be used to obtain a high surface finish.

The maximum diametrical size of the workpiece when using VGR 150 is limited by the longitudinal movement of the support and depends on the features of the lathe.

Steel and cast iron using the tooling in question can go through the finishing process on a lathe. In this case, you can achieve the same roughness index as when using cylindrical grinding equipment. Model 200 differs from the considered power of the installed electric motor and the maximum diametrical dimensions of the wheels installed. Similarly, you can reduce the cost of manufacturing parts by increasing the versatility of the equipment used. At the same time, we note that the tooling is suitable for old and new turning equipment, as it has a universal application.

The most common tools for turning and grinding are centers, jaw and collet chucks, which are also used in other works (for example, drilling).

In fig. 122 shows the designs of the centers of the lathe: normal (Fig. 122, α), with a spherical end (Fig. 122, b), used when the center line of the workpiece is displaced relative to the line of the centers of the machine, half-centers (Fig. 122, c), allowing to combine the outer longitudinal turning and trimming of ends. To increase the wear resistance of the centers, they are reinforced with hard alloy or the surface of the cone is metallized.

Clamping force changes due to heating during cutting, causing elongation of the workpiece. In order for the clamping force to be constant, compensators of various designs are located in the tailstock: spring, pneumatic and hydraulic, which allow the quill to be slightly displaced when the workpiece is heated. Such expansion joints are usually used when fixing the workpiece in rotating centers.

To prevent deflection of non-rigid shaft blanks, use as additional supports lunettes movable or fixed type. Conventional designs of stationary universal rests do not meet the requirements for high-speed machining, since the cams of the rest, made of bronze or cast iron, wear out quickly and a gap forms in their mating with the part, which leads to vibrations. VK Seminsky proposed to modernize the lunette (Fig. 123).

At the base 1 of the steady rest, instead of cams 7, ball bearings are installed, and the nest for the cam in the cover 2 is bored and a rod 4 with a spring 5 is inserted into it. An earring 6 with two ball bearings is attached to the rod. The ball bearings of the steady rest base are adjusted to the diameter according to the control roller installed in the centers, or according to the workpiece itself being processed.

Then, cover 2 of the steady rests is put on and the nut 3 is used to adjust the position of the rod 4 so that the gap between the base and the cover was 3 ... 5 mm, after that eccentric 8 press the cover. In this case, the spring 5 is compressed and the ball bearings installed in the shackle begin to forcefully press the workpiece to the base ball bearings.

The beating due to ovality and unequal thickness of different sections of the workpiece being processed with this design of the steady rest is perceived by the spring 5, which works as a shock absorber.

The most common devices for transmitting torque to workpieces on the headstock spindle are levers: clamps, staples, driver mandrels, driver faceplates, driver chucks, cam chucks, collet chucks.

Conventional and self-clamping clamps are of limited use, since they require a significant amount of time for installation, therefore, self-clamping driver mandrels are more often used. In this case, it is possible to install and remove workpieces while rotating the spindle. The workpiece installed in the centers is moved to the left by pressing the quill, the tailstock, while the teeth of the driver are pressed into the end of the workpiece, which ensures the transfer of torque from the spindle to the workpiece.

Of the chucks used to mount and clamp workpieces on lathes, the most common are self-centering three-jaw chucks. To fix asymmetric workpieces, usually four-jaw chucks are used with an independent movement of each cam using a screw.

When basing the workpiece to be processed on the inner surface, expanding mandrels with a pneumatic drive are used. The most typical design of a pneumatic drive chuck is the chuck shown in Fig. 124. In this design, the workpiece can be installed and removed without stopping the machine spindle. The chuck is equipped with an automatically locking floating center. Plungers 7 are installed in the holes of the body of the device, in the grooves of which there are gears 5 rotating on axes 6 pressed into the plungers 7. , move the pads with eccentric cams to the workpiece being clamped. Cams 1 rotate on axes 2 fixed in pads 3. In the middle of the chuck there is a sleeve 14 with a floating chuck 16 rigidly connected to the chuck body. The head 10 is connected to the rod of the pneumatic cylinder of the rocker 9.

When clamping, the head 10 pushes the plungers 7 and feeds the sleeve 15 forward, sitting on the sleeve 14. The cams 1 by the spring plungers 11 are pressed against the stop screws 12, which ensure contact between the middle part of the cam surface and the workpiece to be clamped. When the cams 1 abut against the workpiece to be processed, the gear wheels 5, rolling over the teeth of the rack wedges 8, move the sleeve 15, which, with its body and three balls, clamps the center 16. Pads 3 with cams 1 in the idle state are held by spring plungers 13 at the same distance from the center of the chuck ...

In fig. 125 shows the design of a lathe tailstock with a built-in rotating center and a pneumatic cylinder for moving the quill. This device allows you to reduce the time required to move the quill. Quill 2 moves with a rotating center 1 by means of rod 3 and piston 5 of pneumatic cylinder 4. When compressed air enters the right cavity of the cylinder, the piston, moving to the left, pushes the quill rod to the workpiece with the rod.

Pneumatic cylinder 4 is rigidly fixed to the tailstock housing. The control valve 6 is used to control the drive.

For processing workpieces on lathes, pneumatic three-jaw chucks with adjustable jaws are used. The use of adjustable cams is due to the need to machine workpieces of various sizes. Frequent rearrangements of the cams (or pads) make it necessary to grind or grind them, which, of course, makes it difficult to changeovers, especially during the working day. Shown in fig. 126 design allows not only adjusting the cams depending on the shape of the workpiece or its dimensions, but also quickly readjust the chuck to work in. centers. In the body 2 of the cartridge there is a coupling 1, which is threaded to the pull rod of the pneumatic drive. The long ends of the three levers 3 enter the groove of the coupling, and their short ends go into the grooves of the sliders 4, connected with screws 5 to the cams 6. An annular risk 7 is applied to the end surface of the chuck, and there are divisions on the cams that allow pre-setting the cams. When changing the chuck for work in the centers, a transition sleeve with a normal center is inserted into the central hole, and one of the cams is used as a leash.

In some cases, it is advisable to center the workpieces with beads or flanges on short rigid pins or grooves and clamp them along the axis. In fig. 127 shows the structure of a pneumatic tool for axially clamping a thin-walled collar bushing. The sleeve is centered in the groove of the disk 7, attached to the body 1, and clamped along the axis by three levers 6, set on the axis 5. The levers are actuated by a rod connected to the screw 2, during the movement of which the rocker 4 moves together with the levers 6 clamping the workpiece to be processed ... When the thrust moves from left to right, the screw 2 by means of the nut 3 moves the rocker arm 4 with the levers 6 to the side. The fingers on which the levers 6 are seated slide along the oblique grooves of the disc 7 and thus, when unclamping the processed workpiece, they rise somewhat (as shown by the thin line), allowing the workpiece to be released and a new workpiece installed.

The collar fastening allows for the processing of both external and internal surfaces.

Enterprises also use pneumatic devices with replaceable clamping levers, ensuring concentricity of the outer and inner surfaces to be treated. The design of such a device is shown in Fig. 128 and is a housing 5, inside of which levers 2 and 4 are installed on the hinge axes. The short ends of the levers protrude outward, and the long ones are installed in the rectangular groove of the stem 3. B threaded hole rod screwed in rod 1, connected to the rod of the pneumatic cylinder (not shown in the figure). The body of the device is centered on the faceplate 7 of the machine by the sleeve 6.

When the rod 1 moves with the rod 3 from right to left, the short ends of the levers 2 and 4 clamp the workpiece.

Cartridges are also used with the installation of blanks on processed bases. In fig. 129 shows the design of the chuck with the installation of the workpiece along the central hole and the clamp by the flange. When fastening, the cams 3, sitting at the ends of the rods 1, with their projections rest on the bar 2, relieving the rods from bending forces. When unfastening the machined part, the cams 3 with the lower outer projections 4 abut against the bar 2, freeing the part, and with the inner projections 5 push it off the locating pin.

For processing on mandrels, various types of expanding pneumatic devices are used. In fig. 130 shows the structure of a three jaw expanding mandrel. It consists of a body 2 with a cast iron threaded bushing 3 screwed onto the machine spindle. The workpiece is clamped with three cams 4 located at an angle of 120 ° in the holes of the mandrel body and extended by means of a sleeve 5 with three wedges. The bushing is moved by the rod 1 from the pneumatic drive. Cams 4 return to their original position when the machined part is released with spring rings 6.

The main disadvantage of placing a pneumatic drive at the rear end of the spindle is the impossibility of processing bar stock. In fig. 131 shows the construction of a pneumatic collet that allows the processing of workpieces from a bar passing through the holes of the machine spindle. In this design, compressed air is supplied through a junction box mounted on the rear end of the machine spindle. The air duct from the junction box to the cartridge is located in two metal pipes 1 soldered into the grooves of the pipe 2.

When clamping the workpiece, compressed air is directed into the right cavity of the cartridge, moving the piston 3 with the ring 5 screwed in it. This ring, pressing on the cams 6, moves them along the tapered surface of the sleeve 4, thereby clamping the workpiece. To loosen the machined part, compressed air is directed into the left cavity of the cartridge, moving the piston 3 to the right, while the cams 6 diverge under the influence of the spring ring 7.

When, according to the terms of the drawing, it is required to obtain a smooth and shiny mirror surface of the part, but the dimensional accuracy can be rough, polishing of this surface is used; if, in addition to cleanliness and shine, it is required to obtain the exact dimensions of the part, fine-tuning or lapping is used.

1. Polishing

Polishing is carried out on lathes using emery cloth... Depending on the size of emery grains, the following skin numbers are distinguished: No. 6, 5 and 4 - with coarse emery grains No. 3 and 2 - with medium grains, No. 1, 0, 00 and 000 - with small ones. The cleanest polishing is given by sandpaper no. 00 and 000. The sandpaper should be handled as shown in fig. 232, otherwise it may wrap around the part and pinch your fingers.

Polishing is done much faster with simple adaptation, called benches (Fig. 232, b). The press consists of two wooden bars connected at one end by a leather or metal hinge and having indentations in the shape of the part. Emery cloth is laid in the benches or emery powder is poured. It is recommended to grease the polished surface with machine oil or mix powder with oil, then the surface is more shiny.

The use of presses eliminates the risk of injury to the turner's hands and the capture of the sleeve by a rotating part, clamp or chuck.

Polishing is carried out with light pressure of the presses and large numbers turns of the workpiece.

2. Finishing or lapping

Lapping or lapping is used for finishing external and internal cylindrical and conical, shaped and flat surfaces of parts in order to obtain exact dimensions and high quality (cleanliness) of the surface or tightness of the connection.

This processing method has become widespread in tool production (finishing the cutting edges of carbide cutters and reamers; finishing the calibers of cylindrical, conical, threaded; finishing the measuring plates).

This processing method is also widely used in mechanical engineering, for example, finishing the journals of crankshafts, nozzle plungers, wheel teeth, etc. The surface finish after finishing can be obtained from 10 to 14.

Finishing the outer cylindrical surfaces produced by cast iron, copper, bronze or lead bushings (laps), machined to the size of the workpiece. The sleeve is cut on one side as shown in fig. 233.

Bushing 1 is lubricated from the inside with an even thin layer of corundum micropowder with oil or finishing paste. Then it is inserted into the metal press 2 and put on the part. Slightly tightening the press with bolt 3, evenly drive the lap along the rotating part. When finishing, it is useful to lubricate the part with liquid machine oil or kerosene.

The allowance for finishing is left about 5-20 microns (0.005-0.020 mm) per diameter.

Part rotation speed during finishing - from 10 to 20 m / min; the cleaner the surface must be, the lower the speed must be.

Hole finishing made with cast iron or copper bushings (laps), also cut on one side. The sleeves are set to the exact size using shallow tapered mandrels onto which they are fitted. In fig. 234 shows a sleeve 1 fitted on a tapered mandrel 2 fixed in a self-centering chuck. For finishing, the part is put on the sleeve 1, which, during finishing, rotates with the mandrel 2; the details impart a slow rectilinear-return movement along the sleeve.

Finishing of the outer and inner surfaces is carried out with corundum micropowder mixed with oil, or with special finishing pastes GOI. These pastes give the best results in both surface quality and performance. They have on the metal not only mechanical, but also chemical action. The latter is that, thanks to the paste, the thinnest oxide film is formed on the surface of the part, which can then be easily removed.

3. Rolling

Cylindrical handles of various measuring instruments, gauge handles, micrometric screw heads and round nuts are not made smooth, but grooved, so that it is more convenient to use them. Such a corrugated surface is called knurled, and the process of obtaining it - rolling... Knurling can be straight and cross.

For rolling, a special holder 1 is fixed in the tool holder of the machine support (Fig. 235), in which one is installed for simple knurling, and two rollers 2 and 3 made of tool hardened steel with teeth applied to them are installed for cross-rolling.

Roller teeth have different sizes and differently directed (fig. 236), which allows you to get knurled different patterns.

During rolling, the holder is pressed against the rotating part. The rollers rotate and, pressing into the material of the part, form a knurling on its surface. It can be large, medium or small, depending on the size of the teeth on the rollers.

When rolling, feed is performed in two directions - perpendicular to the axis of the part and along the axis. To obtain sufficient rolling depth, rolling can be carried out in 2-4 passes.

Rolling rules: 1) when starting rolling, you should immediately apply a strong pressure and check whether the teeth of the roller fall into the notches made by them at the next revolutions;
2) the rollers must match the required pattern of the part;
3) double rollers must be exactly positioned one below the other;
4) before work, the rollers must be thoroughly cleaned with a wire brush from the remnants of the material;
5) during rolling, the working surfaces of the rollers should be well lubricated with spindle or machine oil.

Rolling modes... Table 10 and 11 show the peripheral speeds and longitudinal feeds when rolling on lathes.

Table 10

Peripheral speeds when rolling

Table 11

Roll feed

Checking the correctness of the knurling is carried out by eye.

4. Rolling the surface with a roller

To harden the surface layer of a part that has been pretreated, for example, by finishing turning, the cylindrical surface is rolled with a hardened roller with a polished surface.

The rolled part is given a rotational movement at a speed of 25-50 m / min, and the holder with a roller is given a longitudinal feed movement. Feed rate 0.2-0.5 mm / rev - depending on the required surface finish. The rolling is carried out with a slight pressure of the roller on the rolling surface. The number of roller passes is 2-3. To reduce the wear of the roller, apply abundant lubrication of the roller surfaces and parts with spindle or machine oil mixed in equal amounts with kerosene.

Control questions 1. How is the surface polished?
2. What materials are used for surface polishing?
3. What is the difference between finishing and polishing?
4. What tool is used to roll the surface?
5. How is the surface rolling with a roller?