US3911707A

US3911707A - Finishing tool

Info

Publication number: US3911707A
Application number: US532002A
Authority: US
Inventors: Anatoly Petrovich Minakov; Petr Ivanovich Yascheritsyn; Gennady Mikhailovich Mironov; Jury Khonanovich Golant; Viktor Vladimirovich Bogachev; Evgeny Nikitovich Blinov; Stanislav Vladimiro Sokolovsky
Original assignee: Individual
Current assignee: Santrade Ltd
Priority date: 1974-10-08
Filing date: 1974-10-08
Publication date: 1975-10-14
Anticipated expiration: 1992-10-14
Also published as: AU8100575A

Abstract

A tool according to the invention is to be used for finishing internal surfaces of revolution in blanks by the method of plastic deformation. The tool body is provided, at its peripheral surface with a groove for accommodation of deforming members which are caused to move under the action of fluid under pressure. For supplying fluid under pressure, passages are made in the body of the tool communicating the groove with a source of fluid under pressure. Thus, each deforming member performs a compound movement during the machining, whereby the force required for finishing of the surface by the method of plastic deformation is reduced.

Description

United States Patent Minakov et a1.

[4 1 Oct. 14, 1975 [54] FINISHING TOOL Filed: Dec. 12, 1974 Appl. No.: 532,002

[52] US. Cl 72/76; 72/120 [51] Int. Cl. B21D 41/02 [58] Field of Search 72/75, 76, 112, 120, 53;

Primary Examiner-Lowell A. Larson Attorney, Agent, or FirmHolman & Stern ABSTRACT A tool according to the invention is to be used for finishing internal surfaces of revolution in blanks by the method of plastic deformation. The tool body is provided, at its peripheral surface with a groove for accommodation of deforming members which are caused to move under the action of fluid under pressure. For supplying fluid under pressure, passages are made in the body of the tool communicating the groove with a source of fluid under pressure. Thus, each deforming member performs a compound movement during the machining, whereby the force required for finishing of the surface by the method of plastic deformation is reduced.

3 Claims, 13 Drawing Figures US. Patent Oct. 14, 1975 Sheet 1 of4 3,911,707

FIE. 2

FIE]

US. Patent Oct. 14, 1975 Sheet 2 of4 3,911,707

' FIG. 7

US. Patent Oct. 14, 1975 Sheet 3 of4 3,911,707

U.S. Patent Oct. 14, 1975 Sheet 4 of4 3,911,707

FINISHING TOOL The present invention relates to tools to be used for machining by the method of plastic deformation of metallic blanks, and in particular to tools for finishing internal surfaces of revolution in blanks.

The present invention may be widely used in the mechanical engineering for machining internal surfaces of actuating cylinders, cylinder liners for engines, precision cylinders for measuring equipment, internal surfaces of bearing races.

The invention may be the most advantageously used in machining internal surfaces of thin-walled blankshaving cylindrical, elliptical, spherical and conical surface with a curvilinear or undulated generatrix, as well as in machining blanks having a comparatively low stiffness.

Known in the art is a tool for finishing internal surfaces of revolution in blanks by the method of plastic deformation mounted for a linear displacement along the geometrical axis of the surface being machined comprising a body in the form of a body of revolution having at the peripheral surface thereof at least one annular groove for accommodation of deforming members each comprising a body of revolution mounted for rotation about their geometrical axes and for displacement along the groove.

In this known tool, the body comprises a stepped cylinder provided with a bush with a tapered outer periphery fitted on one of the steps of the cylinder having an intermediate diameter. Mounted on the step of the body of the largest diameter is a cylindrical bush which is axially movable relative to the body. The portion of the body adjacent to the end thereof has the smallest diameter and is provided with a sleeve axially movable relative to the body, the outside diameter of the sleeve corresponding to the outside diameter of the cylindrical bush fitted on the body.

The portion of the body adjacent to the other end thereof is adapted for clamping the tool in the tail spindle of a lathe.

A plurality of deforming members are uniformly circumferentially spaced between the opposite end faces of the cylindrical bush and sleeve forming a groove, the deforming members resting against the conical surfaces of the bush fitted on the body during the operation with the tool.

In order to maintain equal spacing between the deforming members, the latter are mounted in a cage, and thrust bearings are placed either side of the cage. The outer race of one bearing rests against the end face of the sleeve, and the outer race of the other bearing is supported at the end face of the cylindrical bush.

The body is provided with a centrally located hole through which a drawbar is passed. One end of the drawbar has a threaded portion for fastening the sleeve having a hole in its bottom wall for passing the drawbar therethrough. The other end of the drawbar has a hole drilled normally to the axis thereof, and a pin is pressfitted into the hole. The tool body is provided with a recess normal to the longitudinal axis thereof for accommodating the pin, the recess having the width allowing an axial displacement of the pin together with the sleeve and drawbar relative to the body. The pin ends are received in holes made in the cylindrical bush.

The sleeve and cylindrical bush are fastened by means of nuts, one nut being screwed on the end of the drawbar extending beyond the sleeve and the other nut being screwed to the body. The body is also provided with a passage for supplying cooling lubricant to the deforming members and to the thrust bearings.

The deforming members comprise balls.

During the operation with the tool, the deforming members come in contact with the surface of a blank being machined which is clamped in the lathe chuck. The tool in this case is mounted in the tail stock spindle of the lathe in coaxially with the surface being machined. Since the diameter of a circle enveloping the deforming balls is greater than that of the surface being machined by a predetermined amount of the interference fit, the deforming balls are jammed between the conical surface of the bush and the surface being machined upon the axial displacement of the tool to work down microscopic irregularities thereof. The feed force is transmitted to the tool body and thence to each deforming ball via the cylindrical and conical bushes and the thrust bearing.

At the points of contact of the deforming balls with the surface being machined, surface of the conical bush and the race of the thrust bearing there are developed pressures resulting in considerable friction forces and temperature rise. In order to decrease friction forces and temperature rise, as well as to improve the finish of the surface being machined, coiling lubricant under pressure is supplied to the contact points through the hole in the body.

During the machining of the surface by the deform ing members, the surface is cold-worked and strengthened.

Upon the completion of machining, the tool is retracted into the initial position. During the return stroke of the tool, the balls are first urged against the surface being machined to be slightly displaced under the action of this force along the generatrix of the conical bush in the direction towards the portion thereof of a smaller diameter so that during further movement of the tool the balls will never engage the machined surface.

The above-described prior art tool has a number of disadvantages one of which consists in the permanent rigid contact of the deforming members with the surface being machined, surface of the conical bush and the cage which is due to the fact that the deforming members are received in the bore being machined with an interference fit. This results in important radial forces whose value depends on a fit, initial finish of the surface being machined amount of the tool feed and required finish class, characteristic of the material being machined. Where the deforming member is made in the form of a ball, the amount of the radial force exerted to each ball is within the range from 0.75 to 3.0 kN, and for the rollers from 1.8 to 7.0 kN. The development of such forces results in a rapid wear of the conical surface of the bush and of the deforming members themselves. This requires frequent replacement of these parts since their worn surfaces negatively affect the quality and precision of the machined surface.

In addition, the above-mentioned values of the radial forces developed during the machining create the conditions in which only blanks having sufficient stiffness and strength can be machined.

The known construction of the tool allowing for the development of constant radial forces only to be applied to the surface during the machining, there is no opportunity of obtaining various performances as regards the precision and quality of different portions of the surface being machined. This also constitutes a disadvantage of the known tool.

Another disadvantage of the known tool resides in the fact that it permits to machine parts of one and the same diameter only for which the amount of projection of the deforming members has been once adjusted.

Still another disadvantage of the known tool consists in that during the return stroke of the tool into the initial position the deforming members are displaced along the generatrix of the conical bush in the direction towards the smaller diameter thereof without contacting the surface being machined, whereby only the direct stroke of the tool can be used to machine the surface.

Since during the operation friction is developed at the points of contact of the deforming members with the surface being machined, surface of the conical bush and cage, as well as with the thrust bearing race resulting in a temperature rise, cooling lubricant should be employed to prevent the effects thereof changes in the structure of the material of the deforming members and the wear thereof, and the quality of the surface being machined. This complicates the construction of the tool.

Furthermore, rather stringent requirements are imposed on the precision and geometrical shaped of the deforming members so that standard balls or rollers cannot be used independent on the precision grade thereof.

It is an object of the present invention to provide a tool for finishing internal surfaces of revolution in blanks having such a construction which permits to obtain parts of a high precision and to machine blanks having a comparatively low stiffness and strength and high hardness, as well as thin-walled blanks.

Another object of the invention is to provide a tool which permits to improve the productivity of machining, is more reliable and simple in operation.

The above objects are accomplished in a tool for finising internal surfaces of revolution in blanks by the method of plastic deformation mounted for an axial movement along the geometrical axis of the surface being machined and comprising a body in the form of a body of revolution having at the peripheral surface thereof at least one annular groove for accommodation of deforming members each comprising a body of revolution, the deforming members being mounted for rotation about their own geometrical axes and for displacement along the groove, wherein, according to the invention, the body is provided with a centrally located axial hole communicating with at least one passage ex tending in a plane passing transversally with respect to the bottom wall of the groove, the passage being directed substantially tangentially with respect to the bottom wall of the groove and serving to supply fluid under pressure to the deforming members which are displaced along the annular groove and rotate about their axes under the action of the fluid.

Due to the free accommodation of the deforming members in the groove and due to the fact that they are moved therein under the action of fluid under pressure and perform oscillations in the radial direction with respect to the surface being machined and therealong, as well as rocking motions each about its own center of gravity. This contributes to the reduction of a force required for plastic deformation of the blank material.

In addition, during the operation of the tool, the pressure of fluid supplied to the deforming members can be varied so that thin-walled blanks may be machined, and portions having different quality of finish may be obtained on one and the same surface being machined.

Since the deforming members in the tool according to the invention are radially movable, it is now possible to machine elliptical and conical surfaces, as well as surfaces of revolution with a curvilinear or undulated generatrix.

During the operation of the tool, fluid under pressure fed to the deforming members is concurrently used as coolant whereby the effects of the temperature changes on the surface being machined and deforming members are completely eliminated.

According to one embodiment of the invention, the body is made composite of three parts: a sleeve and two disks fitted thereon having their opposite flat ends defining the side walls of the groove, at least one disk being mounted on the sleeve for an axial movement relative thereto so as to vary the width of the groove.

This embodiment permits to employ deforming members of different diameters in one and the same tool depending on specific application and on the requirements to the quality of the surface after the machining.

In another embodiment one of the disks is provided, at the peripheral portion of its flat end facing the end face of the other disk, with an annular projection for retaining the deforming members within the groove after the tool is retracted from the blank. While the amount of projection of the deforming members in the radial direction is somewhat limited in this embodiment of the tool, the tool becomes more convenient in operation.

Where a blank has a comparatively low stiffness and strength, balls are preferably used as deforming members. The ball has a point contact with the surface being machined so that high contact pressures can be developed sufficient to machine the blank.

Where each deforming member comprises a roller, it is possible to improve the productivity of machining of the surface due to the fact that a roller has a line contact with the surface being machined so that the feed of the tool may be increased. However, the radial forces on the part of the deforming rollers applied to the surface being machined are considerably greater than in the case of balls.

In all applications of the tool according to the invention for machining surfaces, the construction of the tool permits to utilize both the direct and return stroke of the tool due to the fact that the contact of the deforming members with the surface being machined is provided by feeding fluid under pressure to the deforming members.

The invention will now be described with reference to specific embodiments thereof illustrated in the accompanying drawings, in which:

FIG. 1 shows a partial axial section of a tool for finising internal surfaces of blanks according to the invention;

FIG. 2 is a sectional view taken along the line IIII in FIG. 1;

FIG. 3 shows a partial axial section of another embodiment of the tool according to the invention;

FIG. 4 is a sectional view taken along the line I\/IV in FIG. 3;

FIG. 5 shows an axial section of the tool according to the invention with means for catching the deforming members;

FIG. 6 is a sectional view taken along the line VIVI in FIG. 5;

FIG. 7 shows a partial axial section of still another embodiment of the tool according to the invention;

FIG. 8 is a further embodiment of the same tool;

FIG. 9 shows a sectional view taken along the line IX-IX in FIG. 8;

FIG. shows a partial axial section of an embodiment of the tool according to the invention;

FIG. 11 is a sectional view taken along the line XI-Xl in FIG. 10;

FIG. 12 is a partial axial section of another embodiment of the tool according to the invention;

FIG. 13 is a sectional view taken along the line XIII- xn1 in FIG. 12.

The tool for finishing internal surfaces of revolution in blanks by the method plastic deformation comprises a body 1 (FIG. 1) in the form of a cylinder.

An annular groove 2 for accommodation of deforming members 3 is made on the peripheral surface of the body I normally to the axis thereof. In this example the deforming members comprise balls. The diameter of balls is taken depending on the blank material, class of finish of the surface being machined, its shaped and other factors influencing the operating conditions for the machining. The side walls of the groove 2 are flat, and the distance therebetween, that is the width of the groove 2 is selected to be sufficient for free accommodation of the deforming members 3 therein. Thus, for a tool of 80 mm diameter with the diameter of the deforming members of 12.7 mm, the space between the ball and one of the side walls of the annular groove is of I mm when the ball is in contact with the other side wall.

The depth of the annular groove 2 is selected to be slightly greater than the dimension of the deforming member 3. The circumferential spacing of the deforming members 3 is selected in such a manner as to eliminate the possibility of the accommodation of the members 3 without a spacing therebetween during the operation of the tool. The deforming members 3 are mounted in the groove 2 for rotation about their geometrical axes and for displacement along the groove.

The body 1 is provided with a cylindrical shank 4 adjoining the body I and aligned therewith. The shank 4 is adapted to fix the tool in a mandrel 5 which is, in turn, mounted in the tail spindle ofa lathe (not shown). The mandrel 5 has a blind cylindrical bore 6 for accommodation of the shank 4, the bore having one portion with a flat surface and the other portion with a thread.

According to the invention, the body I and the shank 4 are provided with a centrally located axial hole 7. The hole 7 communicates with passages 8 (FIG. 2) extending in a plane passing transversally with respect to the bottom wall of the groove 2 and directed substantially tangentially with respect to the bottom wall of the groove. The passages 8 serve to supply fluid under pressure to the deforming members 3.

The mandrel 5 is provided with a passage 9 (FIG. 1) comminicating with the bore 6 thereof for connecting a flexible hose thereto (not shown) to communicate the hole 7 of the body 1 with a source of fluid under pressure (not shown).

In order to facilitate the manufacture, the axial hole 7 of the body 1 is made as through hole and is plugged at 10. The plug 10 has a conical thread for preventing it from loosening during the operation of the tool. A heat 11 of the plug 10 projecting beyond the body 1 is of a hexagonal shape for screweing the shank 4 of the body 1 into the mandrel 5.

The outside diameter of the body 1 of the tool is selected to be slightly smaller than that of the bore of a blank 12 to be machined, the blank being clamped in the chuck of a lathe (not shown).

FIG. 3 shows another embodiment of the invention. In this embodiment, the tool comprises a body 13 which is also made in the form of a body of revolution. The body 13 is made composite of three parts: a sleeve 14 and two disks 15 fitted thereon. The flat ends of the disks 15 facing each other .define side walls of the groove 2. The disks 15 are mounted for displacement along the axis of the sleeve 14 to vary the width of the groove 2. For assembly of the disks 15, the outer periphery of the sleeve 14 is provided with an annular flange 16, the disks 15 being arranged at either side of the flange along the sleeve and resting with their flat ends against flat laterla sides of the flange 16. The width of the groove 2 is selected depending on the diameter of the deforming balls 3 accommodated therein. The width of the groove 2 is varied by selecting the thickness of an annular washer 17 mounted between the adjacent flat surfaces of one of the disks l5 and lateral side of the annular flange 16. The disks 15 are fixed to the sleeve 14 by means of nuts 18 and a locking nut 19, and for that purpose a thread is made on corresponding portions of the outer peripheral surface of the sleeve 14.

The sleeve 14 is made integral with the shank 4 which is also used to fix the tool in the mandrel 5. A centrally located axial hole 20 is made in the body of the sleeve and in the shank 4 communicating with the bore 6 in the mandrel 5 and, hence, with the passage 9 serving to supply fluid under pressure to the deforming members 3. For that purpose the sleeve 14 has passages 21 (FIG. 4) extending in a plane passing transversally with respect to the bottom wall of the groove 2 communicating with the hole 20.

To facilitate the operation of the tool, one of the disks 15 (FIG. 3), which is the left one in this example (as show in the drawing), is provided, at the periphery of its flat end facing the end of the other disk 15, with an annular projection 22 of a triangular cross-section serving to retain the deforming members 3 within the groove 2 during the retraction of the tool from the blank 12. It should be, however noted that in this embodiment of the tool the amount of projection of the deforming, member-s 3 is somewhat smaller than in the tool shown in FIG. 1.

To facilitate the operation of the tool, there is provided means 23 (FIG. 5) for catching the deforming members 3 during the retraction of the tool from the bore being machined. Where the surface of a blank 23a being machined has an undulated generatrix, only the tools having flat side walls of the groove can be used, and the amount of projection of the deforming balls 3 beyond the outlines of the body 13 should approximate one half of the diameter of the ball 3 during the machining. In machining surfaces with an undulated generatrix, the height of the undulation generally should not be greater than one half of the diameter of the ball 3. The diameter of the ball 3 is selected to be such that the minimal radius of curvature of a curvilinear of undulated generatrix of the surface does not exceed the radius of the ball.

The above-mentioned means 23 prevents the balls 3 from leaving the groove 2 during the retraction of the tool from the blank 12. This means 23 comprises a cylindrical bush 24 having the inside diameter which is slightly smaller than the maximum diameter of the body 13 of the tool. The bush 24 is provided at both ends thereof with annular projections 25 for mounting thereon the ends of two diametrically opposed leaf springs 26 arranged inside the bush 24. In order to accommodate the springs 26, the internal surface of the bush 24 is provided with rectangular slots 27 (FIG. 6) extending along the generatrix of the bush. During the operation, the bush 24 (FIG. is mounted coaxially with the tool and the bore being machined and is fixed in a bracket 28 by means of a lock screw 29 mounted in a through hole of the bracket 28 normal to the axis of the bush 24. The end of the lock screw 29 is received in a recess in the peripheral surface of the bush 24. The bracket 28 is rigidly fixed to the stand of a lathe (not shown).

In case when one pass of the tool is insufficient to obtain the surface with a required class of finish and precision, a multiple tool is used which is illustrated in FIG. 7. The tool has a body 30 with two grooves 2 on the periphery thereof, each groove being formed by the lateral side of an annular rib made on the periphery of the body 30 and separating one groove 2 from the other groove, and a disk fitted on the body 30. Deforming members 3 of different diameter are accommodated in the grooves, the diameters being selected depending on the size of a blank, stiffness and strength thereof, geometrical accuracy of the surface to be machined, with due consideration of the requirement of the permanent contact with the surface. As to the remaining points, this construction of the tool is identical with that shown in FIG. 3.

In all the abovedescribed embodiments balls are used as the deforming members 3. Such tools may be used to create high specific pressures applied to the surface being machined with comparatively low radial forces acting on the balls, thus contributing to the efficient machining of blanks having relatively low strength and stiffness. For machining stronger and stiffer blanks, it is advantageous to employ a tool in which the deforming members comprise rollers, because in this case, due to their line contact with the surface being machined, greater linear feeds of the tool are possible, whereby the productivity of the machining in improved. However, the rollers can be used only for machining surfaces with the rectilinear generatrix. In addition, the rollers develop considerably greater radial forces transmitted to the surfaces being machined as compared to the balls, whereby very strong and stiff blanks may be machined.

FIG. 8 shows the construction of a tool with the deforming members 3 comprising rollers. This construction does not substantially differ from the construction of the tool shown in FIG. 1, with the only difference that the passages 8 (FIG. 9) are arranged in two relatively parallel planes extending through the bottom wall of the groove 2 (FIG. 8). The shape of the groove 2 is selected in such a manner as to provide for free displacement of the rollers 32 along the groove 2, and the space between the surface being machined and the outer surface of the body 1 is selected such that the 5 jamming of the rollers 32 therebetween is prevented.

In machining spherical surfaces, such as raceways of bearing races, the tool shown in FIG. 10 is preferably employed. The tool has a body 33 in the form of a stepped cylinder with an annular groove 2 of a rectangular cross-section made in the portion of the cylinder having the largest diameter. The plane, in which the groove 2 is arranged, is inclined with respect to the longitudinal axis of the body 33. The diameter of this portion of the body 33 is selected to be slightly smaller than the smallest diameter of the spherical surface of a bearing race 34 being machined as measured normally to the body axis. The angle of inclination of the groove 2 is equal to one half of the angle of arc of the spherical surface being machined with the center located substantially at the axis of the tool body 33. Passages 35 (FIG. 11) communicating with the hole 7 of the tool body 33 serving to supply fluid under pressure to the deforming members 3 are of an arcuate shape so that the outlet portion thereof is tangential to the bottom wall of the groove 2. The remaining features of this construction of the tool are identical with those of the tool shown in FIG. 1.

For machining conical surfaces, including those having an undulated generatrix, a tool of the construction shown in FIG. 12 is used. The tool comprises a body 36 whose outer periphery is made conical with the taper angle about equal to the taper angle of the surface being machined of a blank 37 which is vertically mounted on the table of a drill stand (not shown).

Three annular grooves 38 for accommodation of the deforming members 3 are provided on the peripheral surface of the body normally to the axis thereof. The width and depth of the grooves 38 are selected based on the same conditions as those considered for the grooves 2 of the tool shown in FIG. 1. Depending on the selected diameter of the deforming members 3, the distance between the adjacent grooves 38 is selected in such a manner that the difference in the diameters of the sections of the conical body 36 normally to the axis thereof passing through the middles of the bottom walls of the adjacent grooves 38 does not exceed the diameter of the deforming member 3.

A cylindrical shank 39 made integral with the body 36 is located adjacent thereto at the side of the larger base of the cone, the free end of the shank being tapered for insertion into a mandrel 40 which is clamped in the chuck of a drill stand (not shown). A hole 41 is made in the body 36 and in the shank 39 which is plugged at 42 adjacent to the smaller base of the cone. A passage 43 communicating with the hole 41 is made in the wall of the shank 39 and serves to supply fluid under pressure from a source (not shown). For feeding the fluid to the deforming members 3 from the hole 41, there are provided passages 44 communicating therewith and extending in planes passing through the bottom walls of the grooves 38. The arrangement of the passages 44 in one of such planes is shown in FIG. 13.

In order to retain the deforming members 3 within the grooves 38 of the tool body 36 during the retraction thereof from the machined blank, an annular recess 45 is provided in the side wall of each groove located closer to the cone apex, the defonning members 3 being received in this recess after the deforming members 3 being received in this recess after the interruption of the supply of fluid under pressure. In order to retain the deforming members 3 withing thegrooves 38 in the initial position before the beginning of the operation, there is provided a cylindrical bush 46 mounted above the blank 37 coaxially therewith. The tool operates as follows. The tool is mounted in alignement with the bore of the blank 12 being machined in such a manner that the lower deforming members 3 (as shown in the drawing) contact the surface being machined and are partially received in this bore at a height corresponding to onehalf of the diameter. The blank 12 is caused to rotate, and a linear motion is imparted to the tool. At the same time, fluid under pressure is fed from a source thereof to the bore 6 of the body 1 and further, via the passage 8, into the groove 2 to the deforming members 3. Fluid under pressure comprises compressed air. Under the action of compressed air, the deforming members 3 start moving along the groove 2, while rotating about their own geometrical axes. In addition, the deforming members 3 are displaced in the radial direction away from the axis of the tool until they contact the surface being machined. During the rotation, each of the deforming members is acted upon by a centrifugal force applied to the surface being machined at the points of contact to plastically deform the material. The deforming members 3 work down microscopic irregularities of the surface being machined. It has been found by way of experiments that the deforming members 3 also perform axial and radial oscillations along with the rocking movement each about its own center of gravity under the action of fluid under pressure.

This compound motion contributes to the reduction of the radial force required for plastic deformation of material of the blank 12. During the operation with the tool, compressed air is also utilized as coolant thus eliminating the effects of the temperature on the material of the blank 12 and deforming members 3. This is particularly important in manufacturing parts with high precision. In machining surfaces with such tool, a relief pattern of the surface also may be obtained for parts operating under thermal loads, eg in engine cylinder liners.

The use of fluid under pressure for moving the deforming members 3 permits to control the value of the centrifugal force acting thereon by varying the pressure of fluid depending on the requirements imposed on the surface being machined. This provides an opportunity of obtaining a plurality of portions of one and the same bore having different quality of finish.

Upon the completion of machining of the blank 12, the tool is returned into the initial position. For that purpose, the supply of compressed air to the bore 6 of the body 1 is interrupted. Where the return stroke of the tool should be used for repeated machining of the surface, the interruption of compressed air supply is effected after the tool is completely retracted from the bore being machined.

When using means 23 (FIG. the linear displacement of the tool continues until all the deforming members 3 are inside the cylindrical bush 24. If the tool is to be removed from the machine, the tool body I is introduced into the bush 24 until the projection of the leaf spring 26 enters the groove 2, whereafter the lock screw 29 is screwed out of the recess of the surface of the bush 24. Then the tool is removed along with the means 23. v

' 'The operationof the tools shown in FIGS. 3, 7 and 8 is substantially indentical with that of the tool shown n no. 1.

In machining surfaces with an undulated generatrix, thedeforming members 3 (FIG. 5) contact the surface being machinedover the entire profile thereof and are urged thereagainst under the action ofa centrifugal force developed due to their rotation about the tool axis, that is their displacement along the groove 2. The amount of projection of the deforming members 3 is, in this case, variable in conformity with the shape of the surface. The height of undulation does not exceed one half of the diameter of the deforming member 3.

The machining of a spherical surface is performed with no linear movement of the tool, since during the rotation of the race 34 (FIG. 10) all points of the inner spherical surface thereof will contact the deforming members 3. For that purpose, the tool is introduced, prior to the operation, into the race 34 until the center of the spherical surface thereof coincides with the center of a circle described by the deforming members 3 during their displacement along the groove 2.

Upon the completion of machining, the tool is retracted from the machined race 34, and the deforming members 3 are catched by the means 23 as described above.

In machining conical surfaces the tool and the blank 37 are mounted in the vertical position, and the tool is introduced into the bore being machined moving it downwards at an amount corresponding to the distance between two adjacent grooves 38. Then compressed air is fed through the passage 43 into the hole 41, wherefrom it is admitted, via the passages 44, into the grooves 38, and hence, to the deforming members 3. The bush 46 retains the deforming members 3 from leaving the grooves 38. As the tool moves axially in the bore being machined, the amount of projection of the deforming members 3 is gradually changed from the value about equal to one half of their diameter to the value equal to one half of the difference in the diameters of the body 36 and the bore being machined in one and the same section. Therefore, the machining of the whole bore is effected within the limits of the displacement of the tool defined by the distance between two adjacent grooves 38.

Upon the completion of machining, the supply of compressed air to the deforming members 3 is interrupted, whereby they roll down under their own gravity into the recesses 45 to the bottom wall of their respective groove 38. Then the tool is moved upwards until the complete retraction from the part being machined.

What is claimed is:

l. A tool for finishing internal surfaces of revolution in blanks by the method of plastic deformation mounted for a linear displacement along the geometrical axis of the surface being machined comprising: a body in the form of a body of revolution; at least one annular groove in the peripheral surface of said body; deforming members, each comprising a body of revolution accommodated in said groove for displacement therealong and for rotation about their own geometrical axes; said body having a centrally located axial hole; at least one passage communicating with said hole in said body, said passage extending in a plane passing transversally with respect to the bottom wall of said being mounted on the sleeve for displacement along the axis of the sleeve so as to vary the width of the groove.

3. A tool as claimed in claim 2, wherein one of the disks is provided, at the peripheral portion of its flat end facing the end of the other disk, with an annular projection for retaining the deforming members with the groove during the retraction of the tool from the blank.

Claims

1. A tool for finishing internal surfaces of revolution in blanks by the method of plastic deformation mounted for a linear displacement along the geometrical axis of the surface being machined comprising: a body in the form of a body of revolution; at least one annular groove in the peripheral surface of said body; deforming members, each comprising a body of revolution accommodated in said groove for displacement therealong and for rotation about their own geometrical axes; said body having a centrally located axial hole; at least one passage communicating with said hole in said body, said passage extending in a plane passing transversally with respect to the bottom wall of said groove, the passage being directed substantially tangentially with respect to the bottom wall of said groove and serving for supplying fluid under pressure to said deforming members which are displaced along said groove and rotate about their own geometrical axes under the action of the fluid.

2. A tool as claimed in claim 1, wherein the body is made cOmposite of a sleeve and two disks fitted thereon, the flat ends of the disks facing each other defining the side walls of the groove, at least one disk being mounted on the sleeve for displacement along the axis of the sleeve so as to vary the width of the groove.