US2315859A - Lapping machine - Google Patents

Description

p 6, 1943. H. s. INDGE 2,315,859

LAPPING MACHINE Filed Jan. 24, 1941 2 Sheets-Sheet 1 HERBERT S. INDG'E Patented Apr. 6, 1943 LAPPIN G MACHINE Herbert S. Indge, Westboro, Mass., assignor to Norton Company, Worcester, Mass., a corporation of Massachusetts Application January 24, 1941, Serial No. 375,828

4 Claims.

The invention relates to lapping machines, and more particularly to a machine for lapping the lapped side faces of piston rings and the like.

One object of the invention is to provide a simple and thoroughly practical lapping machine. Another object of the invention is to provide a lapping machine in which a ringshaped object is rotatably supported while it is lapped by a rapidly reciprocating abrasive lapping element. A further object of the invention is to provide a hydraulically operated reciprocable lapping element which is adjustably supported so that it may lap either a plane side face of a work piece normal to its axis of rotation or an angular or tapered face thereon such as,

for example, a piston ring tapered cross section.

Another object of the invention is to provide a piston ring lapping machine in which a pair of independent hydraulic motors are arranged to reciprocate lapping sticks in engagement with a side face of a work piece, such as a tapered pision ring, in diametrically opposed positions. A further object of the invention is to provide such a lapping machine in which the hydraulic motors and lapping sticks supported thereby are independently and angularly adjustable.

Another object of the invention is to provide a lapping machine having a motor driven rotatable work support and a hydraulically operab'ie slide for supporting a plurality of hydraulically reciprocated lapping elements, in which a manually operable main control valve serves to control the positioning of the lapping sticks and automatically to control the stopping and starting of the work driving motor, Other objects'will be in part obvious or inpart pointed out hereinafter.

The invention accordingly consists in the features of construction, combinations of elements, and arrangements of parts, as will be exemplified in the structure to be hereinafter described, and the scope of the application of which will be indicated in the following claims.

In the accompanying drawings, in which is shown one of various possible embodiments of the mechanical features of this invention,

Fig. 1 is a front elevation of the improved 7 lapping machine, having parts broken away and the lapping heads, taken approximately on the line 3-3 of Fig. 1;

Fig. 4 is a fragmentary sectional view through one of the lapping heads. taken approximately on the line 4--4 of Figs. 1 and 3;

Fig. 5 is a fragmentary cross-sectional viewthrough the lapping head of the machine, taken approximately on the line 5-5 of Figs. 1 and 2;

Fig. 6 is 'a fragmentary cross-sectional view, on an enlarged scale, taken approximately on the line 56 of Fig. 1;

Fig. 7 is a cross-sectional view, taken approximately on the line 'I'l of Figs. 3 and 4;

Fig. 8 is a fragmentary cross-sectional view, taken approximately on the line 8-8 of Fig. 7;

Fig. 9 is a fragmentary cross sectional view of a modified construction, in which the fluid pressure is used to move the lapping element to and from an operative position; and

Fig. 10 is a fragmentary diagrammatic view showing the lapping elements arranged simultaneously to lap adjacent angularly disposed faces on a work piece.

A lapping machine has been shown in the drawings, comprising a base [0 which supports a rotatable work support, such as a work head H. The work head it is mounted on the upper surface of the base l0 and is provided with a rotatable spindle l2 which is supported in antifriction bearings I3 and M. The spindle l2 supports a chuck, such as a face plate l5, which is recessed so as to support a work piece, such as a piston ring is.

The spindle i2 is preferably rotated by a motor driven mechanism, comprising a variable speed electric motor l7 mounted within the work head I I. The motor ii is provided with an armature shaft |8 which supports a V-groove pulley 19. The pulley I9 is connected by means of a V-belt 20 with a V-groove pulley 2| mounted on the end of the spindle 12.

Power is supplied for the motor I! by a suitable outside source, as represented by the power lines 22.(Fig, 1). A snap switch 23 is provided to open and close the circuit controlling the motor I1. A variable speed rheostat 24 is provided for manually controlling the speed of the motor I! so as to thereby regulate and control the speed of rotation of the work piece I 6. A normally closed limit switch 25 is connected in series with the snap switch 23 and the rheostat 24 by means of which the electric circuit controlling the motor ll may be opened automatically to stop the rotation of the work piece l6 after a lapping operation has been completed in a manner to be hereinafter described.

A transversely moveable lap supporting slide 30 is provided for supporting the lapping element to be hereinafter described. Theslide 30 is provided with a dovetailed slideway 3| which mates with a correspondingly shaped way 32 which is fixedly mounted on the upper face of the base H). The slide 30 is arranged so that it may be moved to and from an operative position to facilitate loading of work pieces and removing them from the machine before and after a lapping operation.

In the preferred construction, a hydraulically operated mechanism is provided for moving the slide 30 transversely in either direction, which may comprise a cylinder 33 which is fixedly mounted within the base ll of'the machine. The cylinder 33 contains a slidable piston 34 which is connected to one end of a piston rod 35. The other end of the piston rod 35 is connected to a bracket 35v which projects downwardly from the under side of the slide 35, It will be readily ap parent from the foregoing disclosure that when fluid under pressureis admitted to a cylinder chamber 31 at the left-hand end of the cylinder 33 (Fig. 1), the piston 34 together with the piston rod 35 and the bracket 35 will move the slide 30 toward the right. Similarly, when fluid under pressure is admitted to a cylinder chamber 38 at the right-hand end of the cylinder 33 (Fig. 1), the piston 34 together with the piston rod 35 and the bracket 35 will move the slide 30 toward the left (Fig. 1).

A fluid pressure system is provided for conveying fluid under pressure to the cylinder 33 and also to other fluid pressure actuating mechanisms to be hereinafter described. A box-like reservoir 40 is provided within the base I of the machine. Fluid is pumped from the reservoir 40 by means of a motor driven fluid pump 4|. Fluid is drawn by the pump 4| through a pipe 42 and conveyed through a pipe 43 to a manually operable control valve 44. An adjustable pressure relief valve 45 is connected by a pipe 46 with the pipe 43. The pressure relief valve 45 is adjusted to maintain the desired operating pressure within the fluid pressure system but is so arranged as to allow excess fluid under pressure to exhaust through a pipe 41 into the reservoir 40.

The control valve 44 is a piston type control valve comprising a valve stem 50 having formed integrally therewith valve pistons 52, 53, 54, 55 and 55. The valve 44 is arranged so that it may be actuated manually by means of a manually operable control lever 51 which is pivotally supported on a stud 58 which is in turn fixedly supported on the machine base ID. The lower end of the lever 51 is yoke-shaped and is provided with diametrically opposed studs or pins 59 which engage a groove 60 formed in the valve i stem 50. The valve stem 50 is shown in its extreme right-hand end position (Fig. 1), in which position the slide 30 is moved toward the left into an operative position. In this position of the parts, fluid under pressure passing through the pipe 43 passes through a pipe 6| into a cylinder chamber located between the valve pistons 54 and 55 and passes out through a pipe 62 into the cylinder chamber 38 to move the piston 34, the piston rod 35, the bracket 36, and the slide 30 toward the left to position the lapping elements to be hereinafter described in an operative position for a lapping operation. During the movement of the slide 35 toward the left, fluid within the cylinder chamber 31 exhausts through a pipe 53, through a valve chamber formed between the valve pistons 53 and 54, and exhausts through a pipe 64 into the reservoir 40. A throttle valve 35 is provided in the pipe line 34 to facilitate control of the exhausting fluid from the cylinder 33 so as to control the speed or rate of movement of the slide in either direction. An adjustably positioned stop block 55 is provided to limit the forward movement or movement of the slide 30 toward the left (Fig. l)

After a lapping operation has been completed and it is desired to move the slide 30 to a rearward or inoperative position, the control lever 51 is moved in a clockwise direction (Fig. 1) into the broken line position 51a, which movement is transmitted to shift the control valve 44 toward the left (Fig. 1). In the left-hand end position of the valve 44, fluid under pressure from the pipe 43 passes through the pipe 6| into the valve chamber formed between the valve pistons 54 and 55 and passes outwardly through the pipe 33 into the cylinder chamber 31 to move the piston 34, the piston rod 35, the bracket 36 and the slide 30 toward the right (Fig. l) to an inoperative position.

In the production of work pieces, such as relatively large diameter piston rings for the automotive and aeroplane engines, it is desirable to provide a highly finished surface on the flat side faces of the ring. This is preferably accomplished by mounting the ring |6 in position on the face plate l5 and providing one or more reciprocable lapping elements to reciprocate in a substantially radial path across the side face of the ring l5 as it rotates to provide an ultra-refined surface on the side face of the ring Hi. In the preferred construction, a pair of lapping heads 61 and 68 are provided having reciprocable lapping sticks 69 and 10, respectively, the ends of which are arranged to engage the side face of the piston ring Hi to be lapped at diametrically opposite positions. A single lapping head may be utilized, if desired, or a plurality of heads may be provided, such as the two heads shown in the drawings, whereby an increased lapping action may be produced to increase the productive output of the machine. The lapping sticks 59 and 10 may be of any cross-sectional shape but for the sake of illustration have been shown as being of a square cross-sectional area made of bonded abrasive material and arranged so that the end face of the stick engages for a lapping operation the side face of a piston ring IS.

The lapping stick 10 is adjustably supported in a slide block 1| which is arranged to slide between a pair of opposed guide plates 12 and 13 (Figs. 4 and 7). The lapping stick 10 is held in adjusted position in the slide block 1| by means of a pair of set screws 14 and 15 which are screw threaded into an end plate which is fixed to the slide block 1| The screws 14 and 15 bear against a shim 16 (Fig. '1) which in turn clamps the lapping stick 10 in adjusted position in the slide block 1|.

A hydraulic motor 11 is provided to impart a reciprocatory movement to the lapping stick 10. The motor 11 will not be described in detail, since it is identical with that shown in the prior U. S. patent to Wallace H. Wood, No. 2,212,371 dated August 27, 1940, to which reference may be had for details of disclosure not contained herein. 'The hydraulic motor 11 comprises a cylinder 13 (Fig. '7) which contains a slidabl piston 19.

The piston 19 is connected to one end of a piston rod 80, the other end of which is connected to theslide block II. The motor 11 is provided with a control valve comprising a hollow pilot valve 8| which contains a slidably mounted shuttle type reversing valve 82. The pilot valve 8| is provided with a valve stem 83 having a pair of adjustable dogs 84 and 85 mounted thereon. The dogs 84 and 85 are arranged in the path of a lug 86 which projects from the slide block 1I and serves automatically to shift the pilot valve M to reverse the motor 11. It will be readily apparent from the foregoing disclosure that when the piston 18 is moved back and forth within the cylinder 18, a reciprocatory movement will be imparted to the slide block 1| and th abrasive lapping stick 10.

Fluid under pressure from the control valve 44 passes through a pipe 88 into a chamber 89 (Fig. 8) in the casing surrounding the pilot valve 8| and through ports into a valve chamber. Fluid is exhausted from the motor 11 through a passage 90 and a pipe 9| into the reservoir 40.

and passes out through a pipe 94 which connectswith the pipe 88 to convey fluid under pressure to the hydraulic motor 11 (Fig. 1)

Similarly, the lapping head 61 is provided with a hydraulic motor 91 for reciprocating the lapping stick 69 in operative lapping contact with the work piece IS. The motor 91 is identical with the hydraulic motor 11, consequently it has not been illustrated in detail. For details of disclosure not contained herein, reference may be had to the hydraulic motor 11 and to the prior U. S. patent to Wallace H. Wood, No. 2,212,871 dated August 27, 1940. Th motor 91 is provided with a pilot valve which is actuated by a valve stem 98 (Fig. 1). The valve stem 98 is provided with a pair of adjustable dogs or collars 99 and I which are arranged in the path of a lug IOI which projects from the slide block supporting the lapping stick 69. Fluid under pressure passing through the pipe 94 passes through a pipe I02 to provid pressure for actuating the motor 91 to impart a reciprocatory movement to the lapping stick 69. Fluid is exhausted from the motor 91 through a pipe I03 which exhausts into the reservoir'40. A throttl valve I04 is provided in the pipe line I03 by means of which the speed of the hydraulic motor 91 and the speed of reciprocation of the lapping stick 69 may be readily varied and controlled.

In the position of the parts as shown in Fig. 1, fluid under pressure from the pipe 43 passes to each of the hydraulic motors 11 and 91 continuously to reciprocate the lapping sticks and 69,.

respectively, rapidly across the end face of the piston ring I6 to lap the same during rotation thereof. After a lapping operation has been completed and the valve control lever 51 is shifted into position 51a, the valve piston 52 closes the port at the end of th fluid pressure pipe 93, thus cutting oiT fluid under pressure from the pipe 94 simultaneously to stop the hydraulic motors '11 and 91.

The hydraulic motors 11 and 91, together with the lapping sticks 10 and 69, respectively, supported thereby. ar arranged so that they may be moved to and from an operative position and-so that the lapping sticks 10 and 69 may be maintained yielda-bly in engagement with the surface being lapped. As illustrated in the drawings, the motor 11 is mounted on the end of a piston rod I06. The other end of the piston rod I05 is provided with a piston I06 which is slidably mounted within a cylinder I01. The piston rod I05 is provided with a central aperture I09. A spring I09 is contained within the aperture I08 and is interposed between the end of the aperture I08 and a slidably mounted plug IIO. An adjusting screw III is screw threaded through an end cap H2 and serves to facilitat adjustment of the compression of the spring I09 whereby the pressure of the lapping stick 10 on the piston ring I6 may be varied as desired.

The piston rod I05 is held against any rotary movement by means of a-guide bar H3 which is fixedly mounted on the outer surface 01' the cylinder I01. The guide rod or bar II3 passes through a correspondingly shaped aperture H4 formed in or fixedly mounted on the casing of the motor 11. The guide bar H3 is provided with a depending lug II5 which'supports a stop screw H6. The stop screw H6 is engaged by a portion of the motor casing 11 and serves to limit the forward advancing movement of the motor 11 and the lapping stick 10 so as to accurately limit the advancing movement of the lapping stick 10. After a lapping operation has been completed, fluid under pressure may be admitted through a pipe II1 into a cylinder chamber I18 to cause the piston I06 together with the motor 11 and lapping stick 10 to move toward the right (Fig. 1) against the compression of the spring I09 to move the lapping stick 10 out of operative engagement with the work piece I6 being lapped.

Similarly, the fluid motor 91 is mounted on the left-hand end of a piston rod I 20. The piston rod I 20 is provided with a piston IZI at its other end which is slidably mounted within a cylinder I22. The piston rod I20 is provided with a central aperture I23 which contains a compression spring I24. The compression spring I24 is interposed between the left-hand end of the aperture I23 and an adjustable slidably mounted plug I25. An adjusting screw I26 is screw threaded through an end cap I21 which is fixedly mounted on the right-hand end of the cylinder I22 (Fig. 1). The inner end of the screw I26 abuts against the plug I25. By adjusting the screw I26, the compression of the spring I24 maybe adjusted as desired so as to provide the desired pressure of th lapping stick 69 on the face of the piston ring I6 being lapped.

In order'to prevent rotary motion of the piston rod I20 together with the motor 91, a guide bar I28 is fixedly mounted to the outside of the cylinder I 22. The guide bar I28 extends within a correspondingly shaped aperture I29 formed in or fixedly mounted on the casing of the fluid motor 91 so that the motor 91 may slide with the piston rod I20 without any rotary motion. The guide bar I28 is provided with an upwardly extending lug I30 which carries a stop screw I3I. The stop screw I3I is arranged in the path of a portion of the'motor casing and serves to limit the movement of the engagement with the piston ring 16 being lapped, fluid under pressure is admitted through a pipe I32 into a cylinder chamber I33 to move the piston I2I together with the piston rod I20, the hydraulic motor 91 and the lapping stick 68 in a direction toward the right (Fig. 1). 7

The pipe I32 is connected to the pipe 1 which in turn is connected to a throttle valve I34 (Fig. l). The throttle valve I34 is in turn connected by a pipe I35 with the main control valve 44. In the position of the valve 44 (Fig. l), the pipe I35 connects with a valve chamber located between the valve pistons 52 and 53 which in the position shown is connected to an exhaust pipe I36 leading to the reservoir 40. After a grinding operation has been completed and the valve stem 50 is moved toward the left, the movement of the valve piston 53 toward the left closes the port leading to the exhaust pipe I36 and opens a port so that fluid under pressure within the pipe 43 may pass through a pipe I31 into the valve chamber located between the valve pistons 52 and 53 and passes outwardly through the pipe I35 and the valve I34 simultaneously to move the lapping sticks 68 and out of operative engagement with the piston ring I6 being lapped. The throttle valve I34 located between the pipes I and H1 serves to regulate the passage of pressure to and from the cylinder chambers H8 and I33,

respectively, so that the rate of movement of the lapping sticks 10 and 69, respectively, into engagement with the work may be readily controlled as desired.

It is desirable that the path of reciprocation of the lapping sticks 69 and 10 be angularly adjustable in order that either a fiat or a tapered end face may be lapped on the piston ring I6 as desired. To accomplish this desired result, the lapping heads 61 and 66 are adjustably supported on the transversely movable slide 30. The transversely movable slide 30 is provided with a verti cally extending column I40 which serves as a support for the lapping heads 61 and 68. The column I40 is provided with a plurality of vertically arranged T-slots I5I, I52, I60 and I6I (Figs. 1, 2 and 5). A rectangularly shaped plate I4I (Figs. 1 and 2) is adjustably mounted on the column I40 by means of mounting screws I42, I43, I44 and I45 and serves as a support for the lapping head 68. The cylinder I01 of the lapping head 68 is formed integral with a sector-shaped plate I46 which is pivotally supported by a stud I41 on the plate I. The sector plate I46 may be angularly adjusted in a vertical plane relative to the vertically adjustable plate I4I. A clamping screw I48 and the clamping screw I45 serve to clamp the plate I46 in adjusted position on the plate MI. The clamping bolt I45 has its head slidably positioned in a T-slot I5I formed in the column I40 and passes through a hole formed in the supporting plate HI and passes through an elongated slot I50 formed in the sector plate I46. The clamping screw I48 passes through an elongated slot I49 in the sector plate I46 and is screw threaded into the vertically adjustable supporting plate I (Fig. 6). It will be readily apparent from the foregoing disclosure that the clamping bolt I45 serves jointly as a binding screw for both the sector plate I46 and the vertically adjustable supporting plate I.

Similarly, a vertically adjustable supporting plate I is adjustably clamped on the column I40 by clamping screws I56, I51, I58 and I59. The clamping bolts I56, I51 have their heads supported in a vertically arranged T-slot I60 formed in the column I40, and the clamping bolts I56 and I58 have their heads supported in a T- slot I6I, also formed and arranged vertically on the column I40. A sector-shaped plate I62 is formed integral with the cylinder I22 of the lapping head 61. The sector plate I62 is .pivotally supported on a stud I63. A binder or clamping screw I64 passes through an elongated slot I65 formed in the sector-shaped plate I62 and is screw threaded into the vertically adjustable plate I55. This serves as a means for clamping the sector plate in adjusted angular position so that the path of reciprocation of the lapping stick 69 may be either normal to the axis of rotation of the piston ring I6 being lapped in case a flat side face is desired or at an angle thereto as shown in the drawings for producing a, tapered side face on the ring I6. The clam-ping screw I56 also serves as an additional clamping medium for clamping the sector-shaped plate I62 in adjusted position.- The clamping screw I56 passes through an elongated slot I66 formed in the sector-shaped plate I62 and passes through a hole formed in a vertical supporting plate I55. Its head is supported in the T-slot I6I so that when it is clamped in position it serves jointly to lock the sector plate in adjusted position on the supportingplate I55 and also to lock the supporting plate I55 in position on the column I40.

If desired, the lapping sticks 69 and 10 may be moved into operative engagement with the ring I6 to be lapped and maintained in lapping engagement therewith by means of fluid under pressure. A modification of the lapping head 68 has been illustrated in Fig. 9, in which fluid under pressure may be utilized for moving the piston I06 toward the left (Fig. 9) to move the lapping stick 10 into an operative position. Fluid under pressure from the pump 4| (Fig. 1) in this case is conveyed through a pipe I10 (Fig. 9), through a throttle valve Ill, a pipe I12, and a manually operable control valve I13, and through a pipe I14 into a cylinder chamber I15 at the right-hand end of the piston I06. Fluid under pressure within the pipe I14 may also pass through a pipe I16 to the other lapping head simultaneously to move both of the lapping sticks into an operative position. By regulation of the throttle valve I1I, the speed of movement of the piston I06 may be varied as desired. After a lapping operation has been completed, the valve I13 may be shifted into the dotted line position (Fig. 9) so that fluid within the cylinder chamber I16 may exhaust through the pipe I14 and through a pipe I11 which returns the exhausting fluid to the reservoir 40.

A spring-pressed detent I is provided having an arrow point operative end which is arranged to mate with a V-groove I8I formed in the stem 50 of the control valve 44 so that the lapping sticks 69 and 10 (Fig. 1) may be readily moved to an inoperative position in case it is desired to inspect the work piece being lapped. The contrcl lever 51 is moved into position 511) which shifts the valve stem 50 so that the groove I8I is aligned with and engaged by the spring-pressed detent I80, so that the valve piston 53 moves a sufficient distance 'to cover the port to cut off the pipe I35 from connection with the exhaust pipe I36. The movement also shifts the valve piston 52 toward the left a sufficient distance so that fluid under pressure from the pump 4I passing through the pipe 43 passes through the pipe I31 and through the valve chamber located between the valve pistons 52 and 53 and out through the pipe I35 simultaneously to provide fluid under pressure within the cylinder chambers H8 and I33, respectively, to move the pistons I06 and I2 I, respectively, toward the right (Fig. 1), which movement serves to remove the lapping sticks 10 and 69, respectively, from operative engagement with the piston ring I6.

The detent I80 and groove I8I serve as a locating device so that the operator may readily-shift the valve 44 into the intermediate positionabove mentioned or may shift the control lever 51 into the reverse position 51a by merely overcoming the resistance of the detent I80 after a lapping operation has been completed to facilitate removal of the finish lapped piece of work and the insertion of a fresh piece of work to be lapped.

It is desirable to provide an interconnection between the hydraulic control system for controlling and actuating the lapping sticks and the electrical mechanism for, controlling the rotation of the work piece. As illustrated in Fig. 1, the actuating plunger of the normally closed limit switch 25 is arranged in the path of movement of the valve stem 50 of the main control valve 44. As shown in Fig. 1, the parts are illustrated in an operative position with the work piece I6 rotating and the lapping sticks in reciprocable engagement with the rotating work piece. After the lapping operation has been completed, the control lever 51 is shifted into position 51a to withdraw the lapping sticks 69 and Hi from operative contact with the work piece I6, stop the reciprocation of the lapping sticks I and 69, and move the transverse slide 30 to an inoperative position so that the lapping heads 68 and 61 are moved to an inoperative position.

During the shifting movement of the control lever 51 into position 5111, the end of the valve stem 50 engages and moves the actuating plunger of the normally closed limit switch 25 so as to open the switch, thus breaking a circuit automatically to stop the electric motor I! and thereby stop the rotation of the face plate I and the piston ring I6. Similarly, when a new piece of work has been inserted and it is desired to start a lapping operation, the control lever 51 is shifted from the broken line position 51a (Fig. 1) into the full line position 51, which movement shifts the valve stem 50 toward the right, thus withdrawing it out of contact with the actuating plunger of the normally closed limit switch" which allows the switch to close, thus closing a circuit to start the work driving motor I! to set the face plate I5 and piston ring I6 to be lapped in rotation automatically before the lapping sticks 69 and I0 are in operative engagement therewith.

The operation of this improved lapping machine will be readily apparent from the foregoing disclosure. Assuming all of the adjustments to have been previously made, that is, the sector-shaped supporting plate I46 and I62 angularly adjusted to position the reciprocatory stroke of the lapping sticks I0 and 69, respectively, a work piece, such as a piston ring I6, is inserted in position on the face plate I5, after which the control lever 51 is shifted from broken line position 51a into full line position 51 (Fig. 1). This movement of the control lever shifts the valve stem 50 into the position-shown in Fig. 1, which movement allows the normally closed limit switch 25 to close,thus closing a circuit automatically to start the work driving motor I1 which in turn transmits a rotary motion through the spindle I2 and face plate I5 to the piston ring I6.

The shifting of the valve stem so toward the right into the position illustrating in Fig. 1 first serves to shift the valve piston 52 to uncover the port leading to the pipe 94, thus admitting fluid under pressure through the pipe 88 and I02, re-' spectively, which convey fluid under pressure to the hydraulic lapping stick motors I1 and 91, respectively, to start the reciprocatory movement of the lapping sticks 10 and 69, respectively. The valve piston 55 then uncovers the port leading to the pipe 62 to admit fluid under pressure into the cylinder chamber 38 to move the piston 34 together with the transversely movable lap supporting slide 30 toward the left into engagement with the stop abutment 66 to position the slide in an operative position for a lapping operation. Continued movement of the valve into its righthand end position (Fig. 1) moves the valve piston 53 so as to uncover the port connecting the pipe I35 with the exhaust pipe I36 so as to allow the fluid within the cylinder chambers H8 and I23, respectively, to be exhausted therefrom by means of the released compression of the springs I09 and I24, respectively, which movement serves to shift the lapping heads TI and 91 so that the lapping sticks I0 and 69, respectively, are moved into operative lapping engagement with the piston ring I6 to be lapped. It will be readily apparent from the foregoing disclosure that the lapping sticks I0 and 69 are reciprocating as they are moved into operative engagement with the work piece I6. As previously described, the pressure of the lapping sticks 69 and I0 in engagement with the work may be controlled by adjustment of the compression of the springs I09 and I24, respectively.

After the lapping operation has proceeded to the desired extent, the control lever 51 may be shifted into position 51a, which movement serves first to admit fluid under pressure to the cylinder chambers H8 and I23, respectively, to move the lapping sticks 10 and 69 out of operative contact with the piston ring I 6, after which fluid under pressure is cut off from the pipe 94 to stop the hydraulic motors 11 and 91, respectively. and then finally fluid under pressure is admitted through the pipe 63 into the cylinder chamber 31 to move the piston 34 together with the transversely movable lap supporting slide 30 transversely toward the right (Fig. 1) to an inoperative position to facilitate removal of the piston ring I6 which has been lapped. When the valve stem 50 approaches its left-hand end position, its end engages the actuating plunger of the normally closed limit switch 25 and opens the switch to break the circuit, thereby automatically stopping the work driving motor II, the face plate I5 and the piston ring I6. The lapped piston ring I6 may then be readily removed and a new work piece, such as a piston ring I 6, inserted for the next lapping operation.

It will thus be seen that there has been provided by this invention apparatus in which the various objects hereinabove set forth together with many thoroughly practical advantages are successfully achieved. As many possible embodiments may be made of the above invention and as many changes might be made in the embodiment I claim:

1. In a lapping machine having a base, a rotatable work support thereon, means to rotate said work support, a transversely movable slide on said base, a vertically adjustable support on said slide, an adjustable swivel plate on said adjustable support, a lapping head carried by said plate comprising a piston and cylinder, an adjustable spring to move said piston in one direction, a fluid pressure system whereby the piston may be moved in the other direction by fluid under pressure, a piston rod having one end fixedly attached to the piston, a self-contained fluid motor fixedly mounted on the other end of said piston rod, and a lapping element adjustably mounted to be reciprocated by said motor while in operative engagement with a work piece.

2'. In a lapping machine having a base, a rotatable work support thereon, means to rotate said work support, a transversely movable slide on said base, a vertically adjustable support on said slide, an adjustable swivel plate on said adjustable support, a, lapping head carried by said plate comprising a piston and cylinder, an adjustable spring to move said piston in one direction, a fluid pressure system whereby the piston may be moved in the other direction by fluid under pressure, a piston rod having one end fixedly attached to the piston, a self-contained fluid motor fixedly mounted on the other end of said piston rod, a lapping element adjustably mounted to be reciprocated by said motor while in operative engagement with a work piece, and means to adjust the reciprocatory stroke of said fluid motor and lapping element.

8. In a. lapping machine having a base, a retatable work support thereon, a transversely movable slide on said base which is arranged to move in a direction parallel to the axis of said work support, a pair or lapping heads adjustably mounted on said slide each having a reciprocable lapping element which are arranged to engage a work piece at diametrically opposite points, means independently to adjust each of said heads toward and from the axis of the work support, a fluid motor and a control valve therefor on each of said heads rapidly to reciprocate said lapping elements, andindependent means to adjust each of said heads angularly and in a plane normal to the axis of said work support so that adjacent angularly disposed faces on a work piece may be simultaneously lapped.

4. In a lapping machine having a base, a rotatable work support thereon, a transversely movable slide, a pair of lapping heads on said slide each having a reciprocable lapping element arranged to engage the work piece at diametrically opposite positions, independent fluid motors on each of said heads rapidly to reciprocate said elements in a path substantially normal to the axis of the work support, means independentiy to adjust each of said heads toward and HERBERT S. INDGE.

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