US3925936A

US3925936A - Lapping machine

Info

Publication number: US3925936A
Application number: US542266A
Authority: US
Inventors: Petr Nikolaevich Orlov; Jury Ivanovich Nesterov; Vasily Yakovlevich Kudashov; Alexandr Vasilievich Zimnyakov; Irina Nikolaevna Ermakova; Igor Vasilievich Bogomolov; Efim Matveevich Nirman; Vladimir Dmitrievich Sokolov
Original assignee: Individual
Current assignee: Individual
Priority date: 1974-01-23
Filing date: 1975-01-20
Publication date: 1975-12-16
Anticipated expiration: 1992-12-16

Abstract

A lapping machine in which there is provided a tool or lapping tools, cages accommodating workpieces being lapped, and a central shaft drive rotating a sun wheel which is operatively connected to the cages. The sum wheel is in permanent force transmitting connection with the cages independently of their relative position. Apart from the main motion transmitted from the sun wheel, there is imparted to the cages an additional variable and cyclic motion independent of the sun wheel, whereby the lapping tool and the workpieces or cages will receive at least dual-component compound relative motion so that an imaginary pattern defined by the intersection points between the workpiece surfaces being lapped and the lapping tool become more dense and uniform.

Description

United States Patent 1191 Orlov et a1.

1 Dec. 16, 1975 1 1 LAPPING MACHINE [76] Inventors: Petr Nikolaevich Orlov, ulitsa M. Ulyanovoi, 21, korpus 2, kv. 54; Jury lvanovich Nesterov, ulitsa Moldagulovoi, 28. korpus 4, kv, 19, both of Moscow; Vasily Yakovlevich Kudashov, ulitsa Komsomolskaya 22 E, kv. 30; Alexandr Vasilievich Zimnyakov, ulitsa Schelkovichnaya, 184, kv. 12, both of Saratov; Irina Nikolaevna Ermakova, Scherbakovskaya ulitsa, 58a, kv. 38, Moscow; Igor Vasilievich Bogomolov, ulitsa Koltsovskaya, 38, kv. 29, Voronezh; Efim Matveevich Nirman, Piskarevsky prospekt, 24, kv. 73; Vladimir Dmitrievieh Sokolov, prospekt Shvernika, 10,'kv. 42, both of Leningrad, all of U.S.S.R.

Filed: Jan. 20, 1975 Appl. No.: 542,266

Related U.S. Application Data [63] Continuation of Ser. No. 435.998, Jan. 23. 1974,

abandoned.

[52] U.S. Cl 51/118; 51/120 [51] Int. C13... B24B 5/00; B24B 29/00; 3248 9/00 [58] Field of Search ..51/111R, 117,118,120

[56] References Cited UNITED STATES PATENTS 1,541,001 6/1925 Scarlcs 51/118 2709876 6/1955 lndge t t 51/118 2.973.605 3/1961 Carman et a1. 1. 51/118 3,089,292 5/1963 Hunt 1 1 51/118 3,097,458 7/1963 Richmond t t 51/118 3.541.734 11/1970 Clar 51/111 Primary Examiner-Othell M. Simpson Attorney, Agent, or FirmHo1man & Stern [5 7 ABSTRACT A lapping machine in which there is provided a tool or lapping tools, cages accommodating workpieces being lapped, and a central shaft drive rotating a sun wheel which is operatively connected to the cages.

The sum wheel is in permanent force transmitting connection with the cages independently of their relative position. Apart from the main motion transmitted from the sun wheel, there is imparted to the cages an additional variable and cyclic motion independent of the sun wheel, whereby the lapping tool and the workpieces or cages will receive at least dual-component compound relative motion so that an imaginary pattern defined by the intersection points between the workpiece surfaces being lapped and the lapping tool become more dense and uniform.

4 Claims, 5 Drawing Figures Sheet 1 of 3 3,925,936

US. Patent Dec. 16, 1975 U.S. Patant Dec. 16,1975 Sheet20f3 3,925,936

US. Patent Dec. 16, 1975 Sheet 3 0f 3 LAPPING MACHINE BACKGROUND OF THE INVENTION This is a continuation of application Ser. No. 435,998 filed Jan. 23, 1974, now abandoned.

The invention relates to production methods of the mechanical and instrumentation engineering, and to the machining of precision surfaces of critical machine and instrument parts using free abrasive. More specifically, the invention is concerned with the force transmission systems of actuating mechanisms for the working members of lapping machines.

PRIOR ART Known lapping machines have a complicated and largely variable kinematic system for their working motion. A complicated working motion contributes to improved quality and productivity of the lapping operation since it creates favorable conditions for operation of the abrasive grains. In known surface lapping machines, the working motion is normally obtained by different combinations of two-three rotary motion components of the workpieces and lapping tools, or by combining rotary and reciprocatory motions.

Known in the art are lapping tools having an eccentric cage drive made by Hofman (USA), model PR-3 and others, such as disclosed in US. Pat. Nos. 2,709,876, and 2,944,375. In these lapping machines, the workpieces are accommodated in the sockets of a cage which is eccentrically mounted relative to the central shaft axis.

Also known in the art is a single-disc surface lapping machine of the Lapmaster type disclosed in F.R.G. Pat. No. 1,114,107 of Mar. 29, 1962. In this lapping machine, the workpieces are accommodated in a cage on the base inside a dressing ring which rotates about its own axis due to the tooth gearing with the sun wheel.

The lapping machines having two working laps are the most versatile ones. The lower lap may be used to lap one of the workpiece planes, while the parallel sides of the workpiece are lapped between the two disc laps.

The lapping machines having the stationary working laps ensure higher accuracy of lapping as compared to those having the movable laps, but they are less productive.

During operation, the laps of the lapping machines wear out and lose the initial shape of the working surface, whereby the accuracy of lapping becomes lower.

OBJECTS AND SUMMARY OF THE INVENTION Therefore, it is an object of the invention to provide a lapping tool having an improved productivity of lapping, while ensuring high lapping accuracy.

It is also an object of the invention to provide a lapping machine incorporating the lap dressing feature so as to ensure a long-term maintenance of its flatness and to increase the service life thereof.

Furthermore, it is an object of the invention to provide a lapping machine of the above-described type, in which all the above-mentioned advantages are achieved by making an inexpensive and simple modification of the lapping machine, without adversely effecting its reliability in operation and convenience of its repair and maintenance.

These and other objects are accomplished in a lapping machine comprising a lapping tool, cages accommodating workpieces, a central shaft drive rotating a sun wheel which is operatively connected to said cages, in which according to the invention, said sun wheel is in permanent force transmitting connection with the cages independently of their relative position, and there is provided an adjustable mechanism imparting an additional cyclic motion to the cages, which is variable in speed and amplitude, with said motion being independent of the main motion imparted by the sun wheel and being permanently maintained concurrently therewith, whereby the lapping tool and the workpieces or cages will receive at least a dual-component compound relative orbital motion so that an imaginary pattern defined by the intersection points between the lapping tool and the surface of the workpieces being lapped becomes more dense and uniform.

This structural embodiment generally stated above improves the efficiency and uniformity of the working contact between the lapping surface of the working tool (lap) and the surface of the workpiece being lapped, with the compound cyclic motion making it possible to control the redistribution of the working friction load over the lap surface.

In accordance with one embodiment of the invention, in an eccentric lapping machine, the sun wheel is rigidly fitted on an eccentric shaft, the cages comprise planet gears in an external mesh with said sun wheel, a gear loosely mounted on the eccentric shaft and rigidly connected to a plate coaxial therewith, with the plate having sockets in which said cages are loosely received, and an additional drive for rotating said gear and plate about their common central axis.

In this embodiment, the workpieces will cyclically come in contact with the central and peripheral zones of the lapping tools due to the rotation of the cages with the workpieces, whereby, on the one hand, the taper of the workpieces is prevented, and on the other hand, the laps can be positively dressed in the course of operation of the machine tool using the material of the workpieces. Uniform wear of the laps over the entire working surfaces is thereby ensured.

In order to ensure the positive dressing, the machine tool according to the invention offers an opportunity of a speed adjustment for both the main and auxiliary rotational drives.

In addition, the invention contemplates the provision of a drive system for a positive rotation of said eccentric shaft and sun wheel about their own axis.

This auxiliary drive system, provided in addition to the system for imparting the conventional compound orbital motion to the cages accommodating the workpieces relative to the lap, will add an additional rotation of the cages, while meshing with the sun wheel so as to more uniformly redistribute the working loads over the lap and to offer larger possibilities of the positive dress ing thereof.

In accordance with another embodiment of the invention, a lapping machine for one-side lapping having support rollers for cages or dressing rings provided with outer teeth is characterized in that it is provided with two idle gears mounted on axles which are connected by means of two movable pull rods to the central axis of the lap, to the sun wheel axis and to pull rods forming a parallelogram linkage, with said linkage providing the adjustment of the relative spacing of the gears meshing with the central teeth of the cage dressing ring, and drive means for separating or bringing the gears together, with said means acting upon the pull rods.

This embodiment permits, by varying the angular position of the idle gears relative to the axis of symmetry of the lap and dressing ring, the radial displacement of the latter so as to perform the positive dressing of the working lap directly in the course of lapping.

One modification of the second embodiment of the invention provides that said support rollers are permanently spring-loaded along the common axis of. symmetry of the lap and dressing ring.

This guarantees the reliable tooth meshing between the dressing ring, idle gears and the sun wheel during any possible adjustment displacements of the members of the force transmitting system of the lapping machine as hereinabove described.

The features and advantages of the invention will be better understood from the following detailed description of specific embodiments thereof, which are given as examples only, with reference to the accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatical cross section of an eccentric lapping machine according to the invention and a force transmitting system thereof;

FIG. 2 is a sectional view taken along the line IIII in FIG. 1 showing cages comprising planet gears in external mesh with the sun wheel which is rigidly fitted on the eccentric;

FIG. 3 is a diagrammatical cross section of an eccentric lapping machine according to the invention which is provided with a drive system for rotating the eccentric shaft and sun wheel about the axis of the eccentric shaft;

FIG. 4 is a diagrammatical cross section of a lapping machine with dressing rings according to the invention and the force transmitting system thereof; and

FIG. 5 is a diagrammatical plan view of a lapping machine with dressing rings according to the invention provided with two idle gears meshing with the sun wheel and with the teeth of the dressing ring.

DETAILED DESCRIPTION OF THE EMBODIMENTS Mounted between upper and lower laps 1 and 2 (FIGS. 1 and 2) are cages 3 accommodating workpieces 4. The cages 3 are loosely placed in sockets of a flat support disc 5. The flat support disc 5 is driven by a central shaft 6 and is loosely mounted on an eccentric shaft 7 thereof. The central shaft 6 is driven by a revers ible electric motor 8 via a change gear set 9. Loosely mounted on the same eccentric shaft 7 is a toothed wheel 10 which is a planet gear in of a planetary gear which the eccentric shaft 7 is a carrier. The planet gear 10 meshes with a toothed wheel 11 which is independently driven by a reversible electric motor 12 via a change gear set 13.

A sun wheel 14 is rigidly mounted on the planet gear 10 and meshes with outer teeth of the cages 3. The laps 1 and 2 may be stationary or rotatable.

The lapping machine operates as follows:

After placing the workpieces 4 in the sockets of the cage 3, the upper lap 1 is freely mounted on the surface of the workpieces 4 to be lapped. Then, the electric motors 8 and 12 are activated to rotate the central shaft 6 and the toothed wheel 1 I so as to drive the flat support disc 5, which is loosely mounted on the eccentric shaft 7 and is rotatable thereabout, and the sun wheel 14 rigidly mounted on the planet gear, namely toothed wheel 10. Thus, the cages 3 accommodating the workpieces 4 being will be concurrently rotated by the flat disc 5 and sun wheel 14 to perform a compound planeparallel orbital motion.

Due to the rotation of the cages 3 with the workpieces 4 being relative to the flat support disc 5, the workpieces 4 will cyclically come in contact with the central peripheral portions of the laps 1 and 2. This constitutes an important advantage of the machine tool according to the invention as compared to the known eccentric lapping machines, in which the workpieces occupy a predetermined position relative to the flat disc (plane) and cannot rotate in the sockets (unless the latter are of round shape) about their own vertical axis, so that the workpieces being lapped are tapered. This disadvantage is eliminated in the present lapping machine. The variation of the rotational speed of the central shaft 6 and toothed wheel 11 by means of the change gear sets 9 and 13 permits to largely vary the path and speed of movement of the workpieces 4 and to effect the positive dressing of the laps as it will be generally described hereinbelow.

In the machine tools having stationary laps, the correction of the shape of their working surface to eliminate the defects appearing during the wear in the course of lapping is effected by the positive dressing of the laps.

In accordance with the present invention, the smoothly variable redistribution of the mechanical work of the wear of the abrasive material over the working surface of the laps l and 2 is accomplished by changing the ratio between the angular speeds of rotation of the eccentric shaft 7 and the toothed wheel 10 loosely mounted thereon (or of the toothed wheel 1 l). The radial shape of the working surface of the laps 1 and 2 is preliminarily measured, and the abovementioned ratio between the angular speeds is then selected by adjusting the sets 9 and 13 in such a manner that the wear shape of the working surface of the lap, which will be obtained in accordance with the selected new operating conditions of the machine tool, should represent something like a mirror reflection of the measured wear shape of the working surface of the laps 1 and 2. The superposition of the old wear shape and that newly selected, which represent the mirror reflection of each other, enables the desired correction of the flatness of the lap working surfaces without interrupting the productive operation of the lapping machine due to the self-dressing of the laps by the workpieces.

FIG. 3 shows an embodiment of the invention similar to that shown in FIGS. 1 and 2, in which similar parts are indicated with the same reference numerals.

In this embodiment, there is provided a driving system for positive rotation of the eccentric shaft 7 and sun wheel 14 about their own axis. This system comprises a gear set 15 driven by the motor 8. The relative orbital motion of the workpieces 4 and laps l and 2 becomes thereby more complicated, and additional opportunities are provided for a predetermined positive dressing.

Mounted on a lap 16 (FIGS. 4 and 5) there are dressing rings 17, with each dressing ring 17 accommodating a cage 18 with workpieces 19.

The outer teeth of the dressing ring 17 meshes with two idle gears 20, with their axles being connected by means of two movable pull rods 21 to the axle of a sun wheel 22 meshing with the idle gears 20. The dressing ring 17, on the one hand, meshes with the idle gears 20,

with their axles being connected by means of the pull rods 21 to the axle of the sun wheel 22 meshing with the idle gears, and on the other hand, this ring is supported by movable support rollers 23. A movable joint 24 interconnects, by means of pull rods 25, the axles of the idle gears and a pull rod 26 of a setting means 27 comprising an actuating pneumatic cylinder.

The lapping machine operates as follows:

Prior to the lapping, the workpieces 19 are glued to the cage 18. The cage 18, with the workpieces 19, is mounted inside the dressing ring 17 on the working surface of the lap 16. A weight 28 may be placed on the cage 18 from above, if the weight of the cage 18 is insufficient to exert a required load. After the cage 18 with the workpieces 19 has been so installed, the drive of the lap 16 and sun wheel 22 is activated to rotate them at a predetermined speed via reversible drive means (not shown). The rotational speed of the sun wheel 22 can be varied both by value and direction during the operation. In addition, by feeding compressed air into the chamber of the setting means 27, the radial displacement of the dressing ring 17 is effected relative to the lap 16 due to a change in the angular position of the idle gears relative to the axis of symmetry of the lap 16 and dressing ring 17 (by separating or bringing together the gears 20). This enables the positive dressing of the working surface of the lap 16 during the lapping.

The support rollers 23 mounted on an arcuate member 29 are permanently spring-loaded by means of a spring 30 so as to press the dressing ring 17 against the idle gears 20 along the common axis of symmetry of the dressing ring 17 and lap 16.

The use of the positive operative connection between the dressing ring 17 and the drive of the sun wheel 22, which is effected via the movable idle gears 20, makes it possible to smoothly vary the redistribution of the mechanical work of wear of the abrasive material of the lap 16 over the working surface thereof by varying the ratio between the angular speeds of rotation of the sun wheel 22, and the lap 16, as well as angle a between the pull rods 25, whereby the defects of the lap shape resulting from wear are corrected.

Thus, in using the disc-type lap 16, the lap will have the most intensive wear in the zone located adjacent to the peripheral portion thereof, and, in this case, the ratio between the angular speeds of the sun wheel 22 and lap 16, as well as the value of the angle a will be set in such a manner that the zones of the working surface of the lap located adjacent to its central portion should be in frictional contact with the surface of the workpieces for a longer time as compared to the peripheral zones of the lap working surface. The speed settings of the lapping machine are determined on the basis of measured wear of the lap 16 by caluculations based on the compensation of wear due to the redistribution of the working loads.

Therefore, the lapping machines according to the invention can effect the lapping of the surfaces of workpieces to a predetermined surface finish in the course of continuous operation without interrupting the operation of the machine tool for measurements and dressing of the laps under the idle running conditions as it has been made heretofore.

The arrangement of the measuring device for obtaining the data on the shape of the worn surface of the lap directly during the operation of the lapping machine is disclosed in our co-pending application.

It will be apparent to those skilled in the art that the lapping machines according to the invention are applicable for lapping workpieces of largely variable shape with the use of an appropriate shape of the lapping tools having concave, convex and tapered working surfaces.

While the invention has been described herein in terms of preferred embodiments, numerous variations may be made in the machine tool and parts thereof without departing from the spirit of our invention or the scope of the claims below.

What is claimed is:

1. A lapping machine for a two-side lapping of flat surfaces of workpieces, comprising a fixed disk lapping tool having a central axis, cages in which the workpieces are placed and brought into contact with the working surface of the lapping tool, the cages having axes, a first drive for simultaneously rotating the cages with the workpieces around the central axis of the lapping tool and the axes of the cages, said drive including a shaft eccentric with respect to the central axis of the lapping tool, a sun wheel rigidly mounted on said shaft, said cages having planet gears meshing externally with said sun wheel, and operably connected by a gear train with a main drive rotating the cages and eccentric shaft around the axis of the lapping tool and around the axes of the cages, a flat disk parallel to the lapping tool, sockets in said disk, said cages being placed in said sockets coaxially to the eccentric shaft, a second drive, a central gear located on the axis of the lapping tool operably connected to said flat disk and a train of replacable gears with said second drive for imparting rotation to the flat disk together with the cages around the axis of the eccentric shaft.

2. The lapping machine as claimed in claim 1, in which an auxiliary gear train is provided between the eccentric shaft and the main drive rotating the eccentric shaft around its own axis in addition to said rotation of the eccentric shaft around the axis of the lapping tool.

3. A lapping machine for two-side lapping of workpieces comprising a lapping tool, cages in which the workpieces are placed and brought into contact with the working surface of the lapping tool, a dressing ring, a first drive for rotating the lapping tool around its axis and a second drive for rotating a cage and a dressing ring around a common axis, said dressing ring having outer teeth, support rollers retaining said cage and said dressing ring at one side, said second drive including a sun wheel coaxial to the lapping tool, the sun wheel having an axle, two idle gears, axles on which said idle gears are mounted, two movable pull rods connecting the axles of the two idle gears with the central axle of the lapping tool to the axle of the sun wheel and to pull rods forming a parallelogram linkage for adjusting the relative spacing of said gears meshing simultaneously with the sun wheel and the teeth of the dressing ring, said gears being brought to the dressing ring on the side opposite to the support rollers, and a drive having a pull rod for drawing apart or together said gears connected with the parallolegram linkage.

4. The lapping machine as claimed in claim 3 including a common arcuate number spring loaded along the axis of symmetry of the dressing ring and the support rollers on which said rollers are mounted, and said pull rods for drawing apart and together said gears being adapted for movement along the same axis of symmetry.