US2167614A

US2167614A - Cam grinding apparatus

Info

Publication number: US2167614A
Application number: US181783A
Authority: US
Inventors: Herbert A Silven
Original assignee: Norton Co
Current assignee: Saint Gobain Abrasives Inc
Priority date: 1937-12-27
Filing date: 1937-12-27
Publication date: 1939-07-25
Anticipated expiration: 1956-07-25

Description

July 25, 1939. H. A. SILVEN CAM GRINDING APPARATUS Filed Dec. 2'7, 1957' 2 Sheets-Sheet 2 Q ww 3% N E V H 5 T R E B R E H Patented July 25, 1939 UNITED STATES PATENT OFFICE 7 Application December 2'), 1937, Serial No. 181,183

10 Claims.

The invention relates to grinding machines, and more particularly to a machine for grinding tapered cams on an automobile camshaft.

One object of the invention is to provide a simple thoroughly practical machine for automatically grinding a plurality of cam blanks on an integral camshaft. A further object of the invention is to provide an automatic cycle control mechanism for controlling the feeding movement of the grinding wheel, the positioning movement of the work table, the rocking movement of the cam toward and from the grinding wheel, and the reciprocation of the truing tool to grind successive cam blanks automatically to a predetermined straight or tapered size and contour. Another object of the invention is to provide an automatic hydraulically actuated truing mechanism for truing the periphery of the grinding wheel in timed relationship with the grinding cycle. A further object of the invention is to provide a truing mechanism which is hydraulically actuated and which is adjustably positioned on a fixed part of the machine and arranged so that it may be swivelled to true a frusto-conical surface on the periphery of the wheel so as automatically to produce cams of a predetermined taper, size, and contour. Other objects will be in part obvious or in part 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 the possible embodiments of the mechanical features of this invention:

Fig. 1 is a fragmentary front elevation of the grinding wheel slide, showing the base and ways in section, and also showing the truing mechanism partly in section and partly in elevation;

Fig. 2 is a left-hand end elevation of the wheel head and truing apparatus asshown in Fig. 1;

Fig. 3 is a fragmentary detail view, partly in section, on a reduced scale, taken approximately on the line 3-3 of Fig. 1;

Fig. 4 is a fragmentary horizontal sectional view, taken approximately on the line 4-4 of Fig. 1, showing the pivotal adjustment of the wheel guard and truing apparatus;

Fig. 5 is a fragmentary view, on a reduced scale, showing the relationship of the camshaft supporting centers, the camshaft, and the tapered face grinding wheel; and

Fig. 6 is a diagrammatic view showing the piping diagram and the electrical control circuit.

A cam grinding machine has been illustrated in the drawings having a base III which supports a longitudinally movable work table II (Fig. 6) on the usual flat and V-ways (not shown). The base III also supports a transversely movable wheel slide l2 on a V-way l3 and a flat way ll for a transverse feeding movement toward and from the work supporting table II. The wheel slide l2 supports a rotatable grinding wheel IS.

The longitudinally movable work table II supports a pivotally mounted rock bar l6 which is supported in bearings l1 (only one of which has been illustrated) at its opposite ends on the table I I and is arranged so that it may be rocked about its axis which is arranged parallel to the axis of the grinding wheel I 5. The rock bar ii is provided with a rotatable headstock spindle (not shown) which carries a headstock center M. The

rock bar also supports a footstock (not shown) having a footstock center IS. The headstock center l8 and the footstock center I! are arranged rotatably to support a camshaft 20 to be ground.

Master cams and roller In order that the cams on the camshaft 20 may be ground to a predetermined size and contour, it is desirable to providea series of master cams 2| for controlling the rocking movement of the rock bar it so as to rock the camshaft 20 being ground toward and from the periphery of the grinding wheel l5 and thereby generate apredetermined shape thereon. A plurality of master cams 2| are mounted on the headstock spindle in axial alignment with the axis of the camshaft 20 being ground. A master cam roller or -follower 22 is slidably mounted on a rotatable shaft 23 which is rotatably supported in brackets 24 which are formed integral with the headstock. The master cam roller 22 is preferably indexed automatically as the table II is moved longitudinally to position the master cam roller 22 opposite the master cam 2| which corresponds to the cam being ground on the camshaft 20.

The details of the master cam roller indexing mechanism have not been illustrated since this feature is not considered to be a part of the present invention. For a detailed disclosure of the automatic shifting of the master cam roller, reference may be had to the prior United States .Patent No. 1,783,755 to Trefethen and Belden dated December 2, 1930, and also to United States Patent No. 2,022,178 to Belden and Silven dated November 26, 1935.

The table traverse and wheel feed mechanisms are substantially identical to the arrangement shown in my prior United States Patent No. 2,- 078,463 dated April 27, 1937, and also similar to that shown in the United States patent to Belden and Silven No. 2,022,178 dated November 26, 1935, to which reference may be had for details of disclosure not contained herein.

Table indexing movement The work supporting table II is traversed or indexed longitudinally, and automatically by means of a fluid pressure system comprising a cylinder 30 which is fixed to the base In. A piston 3| is slidably mounted within the cylinder 30 and is connected by means of a piston rod 32 with a bracket 33 depending from the table II. Fluid under pressure may be admitted to either end of said cylinder in a manner shown in the above mentioned prior patent. The admission of fluid to either a

cylinder chamber

34 or 35 is controlled by a table controlling or reversing valve 36. Fluid is pumped, froma reservoir in the base l0 through a pipe 4| by means of a pump 42 which is preferably motor driven. Fluid under pressure from the pump 42 is conveyed by suitable piping to a main control valve 43 and also to a combined pilot and feed control valve 44.

Wheel feed which may be actuated either manually or hydraulically as desired. In the preferred construe-- tion the wheel slide I2 is provided with a depending nut 60 meshing with a rotatable feed screw 6| which is rotatably supported in the base l6 and is connected so that it may be rotated manually, as indicated in my above-mentioned prior patent. The feed screw 6| is arranged so that it may be moved bodily in an endwlse direction rapidly to move the grinding wheel slide l2 and the grinding wheel I! either toward or away from the work. This is preferably accomplished by connecting the rearward end of the feed screw 6| with a piston rod 63 which carries a piston 64 slidably mounted within a cylinder 66. The fluid pressure wheel feeding mechanism may be supplemented by a hydraulically operated dash pot feed control mechanism (not shown). This dash pot mechanism may be arranged as shown in the patent to Silven No. 2,023,704 dated December 10, 1935. The dash pot feed control mechanism has not been illustrated in the present application, since this feature is not considered to be a part of the present invention. For further details-of the dash pot construction, reference may be had to the above-mentioned patent. By utilizing a dash pot mechanism of this type, the grinding wheel l6 may be advanced rapidly by admitting fluid under pressure into a cylinder chamber 56 to move the wheel slide |2 rapidly up to a position where the grinding wheel is about to contact withthe cam being ground. Then the dash pot piston is picked up by the piston rod 63 and the further advance of the grinding wheel IS in grinding the cam is controlled by the exhausting of fluid from the dash pot cylinder.

In order to move the grinding wheel l6 from contact with the cam 26 after it has been ground to a predetermined size and contour,.the admission of fluid under pressure to the cylinder 65 is reversed and fluid is admitted into a cylinder chamber 68. The pilot or feed control valve 44 anemia serves to control the admission of fluid to the cylinder and also serves as a pilot valve to actuate the main control valve 43.

Rock bar actuating mechanism In order that the master cams 2| may be maintained in operative engagement with the master cam roller 22 during the grinding operation on a cam, a yieldabie pressure device is provided which serves yieldably to maintain the master cam II in contact with the follower roller 22. As shown in the drawings, the rock bar I6 is provided .with an arm 60. A cylinder 6| is pivotally supported on a bracket (not shown) by means of a circular clamping band 62. The cylinder 6| contains a piston 63 which is connected by a piston rod 64 with a stud 65 on the arm 60. A spring 66 surrounds the piston rod 64 and is contained within the cylinder 6| between the piston 63 and a head (not shown) which is fixed in the lower end of the cylinder 6|. sufficient extent to maintain the master cam 2| in operative contact with the master cam roller 22 during the grinding operation.

Hydraulic actuation -rock bar The spring 66 is compressed to a.

through a pipe 13 into a cylinder chamber 14 within the cylinder 16, the piston II moves downwardly and contacts the arm to rock the rock bar l6 and separate the master cam 2| from the follower roller'22.

Grinding wheel driving mechanism The grinding wheel I! may be driven from any suitable source of power, such as an electric motor 80 mounted on the upper surface of the wheel slide I 2. The motor 66 is provided with a rotatable armature shaft 6| which carries a multiple V-groove pulley 62 on its outer end. A multiple V-groove pulley 63 is mounted on the outer end of a rotatable wheel spindle 64 which rotatably supports the grinding wheel Ill. The

pulleys

82 and 63 are connected by multiple V-belts 66 so that when the motor is started, arotary motion is transmitted to rotate thewheel spindle 84 and the grinding wheel l6.

Table indexing movement The table II is traversed-or indexed longitudinally and automatically by a fluid pressure system, above described, which comprises the cylinder 20 containing the piston 3| which is connected by the piston rod 32 to traverse or index the table II longitudinally. The admission of fluid to either the cylinder chamber 34 or 36 is controlled by the table controlling or reversing valve 36. Fluid from the pump 42 passes through a pipe 80, through a pipe 6|, into a valve chamber 82 in the valve 36. A pipe 83 is connected between the valve 36 and the cylinder chamber 36 and a pipe 64 is connected between the valve 36 and the cylinder chamber 34. It will be readily apparent from this disclosure that when the table reversing valve .36 is in the position illustrated in Fig. 6, no fluid is admitted to either of the cylinder chambers and the table II will remain stationary. The valve 99 is provided with a valve stem 95 which is operatively connected to a manually operable control lever 96 mounted on a rock shaft 91. A short lever 99 is mounted on the rear end of the rock shaft 91 and has a pin 99 engaging a spool shaped member 99 on the valve stem 95. It will be readily apparent from this construction that when the lever 99 is moved in a clockwise. direction, the valve stem 99 will be moved toward the left, as viewed in Fig. 6, so as to admit fluid under pressure through the pipe 99 into the cylinder chamber 99 and cause the table II to move toward the right (Fig. 6). Similarly, when the valve stem 99 is moved toward the right (Fig. 6), fluid passes through the pipe 99 into the cylinder chamber 99 to move the table II toward the left (Fig. 6). The lever 99 is normally held substantially in the position illustrated by means of an arrow point 9| formed on the lower end of the lever 99 which is acted upon by a spring pressed roller 92.

An actuating mechanism is provided for the valve 96 so that the movement of the work supporting table II operates to close the valve 96 so that when the table is traversed through a predetermined distance to position the next cam on the product camshaft 29 in operative relation with the grinding wheel ii, the valve 96 is automatically closed to stop further movement of the table. This is preferably accomplished by means of a dog bar (not shown) which is adjustably mounted on the front edge of the table Ii. The dog bar carries a plurality of adjustably mounted dogs which are adjusted along the bar to conform with the spacing of the cams on the camshaft 29 to be ground. In order that the control lever 96 may be moved in the direction of the movement of the table II, it is necessary to provide a secondary actuating lever for cooperating with the table dogs. As illustrated in the drawings, a dog lever 99 is pivotally mounted on a stud 96. The lower end of the dog lever 99 is provided with a projecting pin 91 which rides in a cylindrical aperture (not shown) in the lever 96. These parts have not been completely illustrated in detail since the table operating mechanism of my present case is identical with that shown in my prior Patent No. 2,078,463 dated April 2'7, 1937, to which reference may be had for details of disclosure not found herein. The dog lever 99 is slidably supported on the stud 96 and is arranged to be moved into or out of the path of the table dogs by means of a pivotally mounted lever 99 supported on a stud 99. The lever 99 is actuated in timed relation with the other mechanisms of the machine and is preferably controlled by means of a cylinder I99. A piston i9! is slidably mounted within the cylinder I99 and is connected to a piston rod I92 which is arranged to bear against the lower end of the lever 99. The piston IN is normally held in its rearward position (Fig. 6) by means of a spring. The dog lever 95 may be thrown out of the path of the table dogs by admitting fluid under pressure through a pipe I99, the admission of which is controlled by the main control valve 69. The lever mechanism for controlling the movement of the table control valve 96 as well as the dog lever mechanism has not been illustrated in detail in the present case since these parts are identical with those disclosed in my prior United States Patent No. 2,978,463 to which reference may be had for details of disclosure not found herein.

when the table II is indexed longitudinally,

. surface of the tappet heads.

the longitudinal movement thereof continues until a table dog engages the dog lever 99 and rocks the dog lever and, through' the connecting parts, the control lever 96, so that the arrow point 9! rides up on the spring pressed roller 92 until the control lever 96 assumes the full line position as shown in Fig. 6, in which position the table control reverse valve 96 is in a neutral or stop position, cutting oil fluid under pressure from the cylinder chambers 96 and 99 of the table cylinder 99.

Table pilot valve After the table II has been indexed intermittently for grinding successive cams on the camshaft 29. it is then desirable to shift the table index control valve 96 into a reverse position so that the arrow point 9| rides on the opposite side of the axis of the spring pressed roller 92. This is preferably accomplished by means of a pilot valve I99 which is of a balanced piston type and is normally held in a'neutral or central position by means of a spring I96. When the table II reaches its end position in its movement toward the left, a depending projection on an adjustable truing dog (not shown) mounted on the table II engages the upper end of the pilot valve lever I91 and rocks it so as to -move the pilot valve stem toward the right, as viewed in Fig. 6, so as to admit fluid, which enters a valve chamber I99 from a pipe I99 into a pipe I 19 which passes fluid under pressure into a valve chamber I II at one end of the table reversing valve 96. This pressure moves the valve stem 95 so that the control lever 96 and the arrow points 9! pass over the high point on the spring pressed roller 92 and shift the valve 96 into a reverse position, so that after automatically truing the grinding wheel IS, the table II is ready either for an intermittent traversing or indexing movement in a direction toward the right, as viewed in Fig. 6.

Wheel truing mechanism In a machine of this type, it is desirable that the grinding wheel be trued automatically in between operations so that a trued grinding wheel face will be presented at the start of each grinding operation. It is desirable to provide a truing apparatus which is entirely independent of the table movement so that it may be independently controlled and regulated.

The common practice in automobile engine design has in the past called for a camshaft in which all of the elements of the surface of the cam lie in parallel planes to the axis of rotation of the shaft. In other words, each cam is spaced or of the same dimensions at each end thereof. In the automotive engine employing such a cam-' shaft, it has been found that the tappet engaging the cam is worn away in the path which engages the cam on the camshaft. It is rapidly becoming the standard practice, however, to overcome this difficulty and to provide a tapered cam which engages only one portion of the tappet. The tappet and cam are so arranged that the cam tends to rotate the tappet slowly while in use so that instead of having excessive wear on one portion of the tappet, the cam rotating the tappet causes a more or less uniform wear of the To accomplish this result, it is therefore desirable to provide a grinding face on the grinding wheel l9 which is slightly tapered, that is, a frusto-conical surface which when brought into engagement with the cam being ground serves to grind a slight taper on the cam being ground. The truing apparatus is,

. axis of the grinding wheel so as to produce a slight taper on the face of the grinding wheel which in turn produces a tapered face on the cam being ground. 4

In the preferred construction, the wheel truing apparatus is mounted on a fixed part of the machine, such as the base I0, or as illustrated in the drawings, on a wheel guard I20 which instead of being carried'by the wheel slide I2, as is the usual practice, is fixedly mounted on the base I0 of the machine. The wheel guard I20 is provided with a lower plane surface which rests on a plane upper surface on a transversely adjustable slide I2I. A pivot pin I22 is inter posed between the lower surface of the guard I20 and the slide I2I. arranged so that it may be clamped in position on the slide I2I by means of clamping screws I23, I24, I and I26. The screws I23 and I24 pass through an elongated slot I 21 in the guard I20 and are screw threaded into the slide I2I. Similarly, the screws I25 and I26 pass through an elongated slot I28 in the guard I20 and are ,screw threaded into theslide I2I.

The truing apparatus is preferably rigidly supported on the guard I20 by means of a bracket I30 which is provided with a dovetailed slideway I3I having a reciprocable sliding member I32 carried thereby. The slide I32 serves as a support for a diamond tool holder I33 having a truing tool I34 mounted in the lower end thereof (Fig. 2). The truing tool holder I33 is provided with a threaded aperture which meshes with an adjusting screw I35 carried by the housing I36 which is formed integral with the slide I 32. An adjusting knob I3! is mounted on the outer end of the screw I35 and serves precisely to. adjust the position of the truing tool I34 relative to the slide I32.

The diamond truing tool I34 and the slide I32 are preferably arranged for a reciprocatory move ment to traverse the truing tool I 34 across the face of the grinding wheel I5. The slide I32 is preferably formed as a hollow member which is arranged to slide over a cylinder I30 which is held in a fixed position by a cylinder head and bracket I33.on the supporting bracket I30. A piston I40 is slidably mounted within the cylinder I38. A piston rod I is connected at one end to the piston I40 and at the other end to the slide I32. When fluid under pressure is admitted through a pipe I42 into a cylinder chamber I43 at the right end of the cylinder I38, the piston I40, slide I32 and truing tool I34 will move in'a direction toward the left (Fig. 1). During this movement, fluid within a cylinder chamber L44 will exhaust through a pipe I45. Similarly, when fluid'under pressure is passed through pipe I45 into the cylinder chamber I44, the piston I40, the slide I32, and the truing tool I34 will be moved in a direction toward the right (Fig. 1). The admission of fluid to the cylinder I33 is preferably controlled automatically in timed relation with the automatic cyclic movement of the machine parts by a valve mechanism to be hereinafter described.

To facilitate adjustment of the speed of movement of the truing tool in its travel across the peripheral face of the grinding wheel I5, a suit- The wheel guard I20 is able valve mechanism is provided which in the preferred form, illustrated in Fig. 6, comprises an adjustable throttle valve I46 located in the pipe line I42 and an adjustable throttle valve I41 located in the pipe line I45. By manipulation of the valves I46 and I41, the speed of movement of the truing tool I34 across the operative face of the grinding wheel I5 may be adjusted as desired. Furthermore, by adjustment of these valves, the differential in piston area due to the size of the piston rod within the cylinder chamber I 44 may be compensated for so that the truing tool I34 will travel at a uniform rate of speed when it traverses in either direction.

Slow traverse-truing The normal traversing or indexing movement of the table is comparatively rapid to reduce the loss of time between successive grinding operations on a single work piece. The normal table speed is preferably slowed down before the direction of movement of the table is reversed so as to prevent undue shocks and vibrations of the table. This is preferably accomplished by means of a slow speed valve I50 through which fluid exhausts from the table control valve mechanism. By automatically operating the valve I50 at the end of the table stroke, the passage of fluid through the table indexing mechanism may be throttled to the desired extent to reduce the normal speed of movement of the table II to a slow speed desired to eliminate shocks and vibrations when the table II is either stopped or reversed. The valve I50 is normally maintained in theposition shown in Fig. 6 with the exhaust wide open so that the table II may be indexed at a comparatively rapid rate. A spring I5I is connected at one end to a stud I52 carried by the valve casing and at the other end to a stud I53 carried by a downwardly extending arm of a bell crank lever I54. The lower end of the bell crank lever I54 carries a pin I55 which rides in the groove of a spool shaped member I56 carried on the outer end of the valve stem I 51. The tension of the spring I5I is sufllcient normally to hold the slow speed valve in a normally open or inoperative position.

The bell crank lever I54 is pivotally mounted on a stud I58 and is arranged to be actuated by a collar I59 carried by a vertically movable plunger I60. An adjustable truing dog (not shown) is mounted on the front edge of the work table II and serves to actuate the slow speed valve I50 at the desired time in the cycle of operation. The truing dog for operating this mechanism has not been illustrated in the present case since it is identical with that shown and described in my prior United States Patent No.

2,078,463 dated April 27, 1937, to which reference may be had for further details of disclosure not found herein.

The grinding wheel I5 is preferably automatically trued when in a rearward position after all of thecams on a shaft have been ground. A table feed compensating dog (not shown) serves to actuate a pawl and ratchet feeding mechanism -(not shown) to-cause a rotation of the feed screw 5I to advance the position of the wheel relative to the truing tool justbefore the truing tool passes across the face of the grinding wheel so as automatically to true the wheel to present a fresh face for the next grinding operation. This mechanism has not been illustrated in the present case since it is not considered to be a part of the present invention, and for further attached to the end of the slide I2 I-. By manipulation of the screw I96, theslide may adjusted to position the guard and the truing apparatus relative to the periphery of the wheel when desired. The slide III may be clamped in adjusted position by gib-screws, as indic ted in the drawings, so as to lock the guard -an the truing apparatus in a predetermined adiusted position.

Main control valve In a machine 'of this type, the mechanisms function automatically successively to grind a" plurality of camblanks on a camshaft to a predetermined size and contour, and it is essential that all of the mechanisms be properly timed. Inasmuch as most of the mechanisms of the 'machine are controlled by fluid pressure operated mechanisms, it Is desirable to provide the main control valve 43 having a hollow piston contained therein on which are formed a plurality of valve pistons. A spring I65 interposed'be tween a stud I66 carried by the valve casing 43 and a stud I61 carried by a rock arm I68 are pivotally supported on a stud I69. This valve 1 and its operation is identical with that shown in my prior United States Patent No. 2,078,463.

, Consequently it will not be described in detail herein and reference may be had to the prior patent for details of description not contained herein. Fluid under pressure from the pump 52 passes through the pipe 89 to the main control valve 43 which is in turn arranged to control the admission of fluid under pressure to the table traverse mechanism, the rock bar actuating mechanism, and the truing tool actuating mechanism.

Wheel feedCycle pilot valve "In order that the main control valve 43 may be shifted to control the cycle of operation as desired, a valve is provided to actuate the main control valve. In a grinding machine, while the grinding wheel is in grinding contact with the work piece, there is more or less spring in the various. parts of the machine. Any sudden change in direction of movement of the moving parts of the machine or the sudden shifting of fluid pressure within the system may be sufiicient to set up a vibration which causes the wheel to vibrate and thereby produce inaccuracies in the work piece. It is, therefore, desirable that the grinding wheel be removed from operative contact with the cam being ground before the longitudinal shifting of the table I I or the shifting of the rock bar I6 to an inoperative position. This is preferably accomplished by utilizing the grinding wheel feed control valve 44 as a. control valve to control the admission of fluid to the wheel feed cylinder 55 and also to serve as a cycle pilot valve, whereby fluid under pressure passes through the pipe into the feed control valve chamber I10. In the position of the parts as illustrated in Fig. 6, fluid under pressure passes out through the pipe I'll into a valve chamber I12 at the right-hand end of the main control valve 49 and serves to move the main control valve 43 into the position illustrated in Fig. 6.

A spring I13 serves normally to hold the wheel feed. valve 46 in 'a position toward the right (Fig. 6) so that fluid under pressure entering the feed control and pilot valve chamber I16 passes out through the pipe "I into the wheel feed cylinder chamber 56 to cause a rearward'movement of the grinding wheel I5. When 'the main control valve 43 is moved into the position illustrated by fluid passing through the feed control valve 4], fluid is exhausted from a chamber I14 at the left-hand end of the valve 43, forcing fluid out through a pipe I15, through a valve chamber in the wheel feed and cycle pilot valve H, and out through a pipe I16 into the reservoir 49.

An electric solenoid I80 is provided for actuating the valve 44 in one direction. The armature of the solenoid is pivotally connected to the lower end of a rock arm I9I which is pivotaily supported by a stud I82. A pin I63 carried by the upper end of the'rock arm Illl rides in a spool shaped member I64 carried by' the valve stem I of the valve 44. when the solenoid III! is. energized to shift the wheel feed cycle pilot valve 44 into a reverse position, fluid under pressure from the pipe 80 entering the valve chamber I1ll passes through the pipe I15 into wheel feed cylinder .chamber' 56 tocause a forward feeding movement of the grinding wheel I5 and at the same time passes fluid under pressure through the pipe I15 into the end chamber I14 of the main control valve 43 to move the control valve toward the right (Fig. 6). This movement of the main control valve 43 serves to admit fluid under pressure to the various mechanisms of the machine. The solenoid I611 is preferably connected, in a manner to be hereinafter described, to control the movement of the wheel feed valve 44 which in turn controls the admission of fluid to shift the main control valve 43 after a predetermined time in the grinding cycle.

Cycle control mechanism In order to obtain the maximum eiflciency of the machine, it is desirable to provide a'suitable cycle control device which serves, after a cam has been rotated through a predetermined number of rotations in operative contact with the grinding wheel, to actuate the main control valve 43 and thereby admit fluid under pressure to the cylinder chamber 14 to rock the master cams 2| and product camshaft 20 away from the master cam roller 22 and the grinding wheel ll, respectively, and to admit'fluid to the cylinder chamber 56 to move the grinding wheel I5 rearwardly to an inoperative position and then to admit fluid under pressure to the table traverse cylinder 39 automatically to index the table I I to present the next cam on the camshaft 20 to be ground into operative relation with the grinding wheel I5. This is preferably accomplished by means of a cycle control counting device or mechanism I which is contained within a rectangularly shaped box on top of the bracket 2|. This cycle control counting device is identical with that shown in my prior Patent No, 2,078,463. Consequently it has not been shown in detail herein, nor will any at- This cycle control counting device I90 -Iserves to actuate a mercury tube switch I9I after a predetermined grinding operation has beengt'ompleted, which serves to energize a relay I 52. The

, energizing of the relay I92 in turn closes a circuit to energize the solenoid I55 so as to shift the cycle pilot-wheel feed valve 44 and thereby admit fluid under pressure to shift the main control valve 43 toward the right.

Work rotation Truina apparatus-Control valve It is desirable that the truing tool I34 be passed across the periphery. of the grinding wheel I5 at least by one complete reciprocation of the tool relative to the wheel face, and also that this truing operation occur in timed relationship with the grinding cycle, and preferably after all of the cams on the camshaft 25 have been ground to the predetermined size and contour, so that a fresh wheel face is provided for grinding the next camshaft. In order to simplify the fluid pressure mechanism, the slow speed valve I55 may be utilized to control the admission of fluid to the truing apparatus cylinder I35. The truing valve I is provided with a pair of valve pistons I and I55. The valve I55, in the position illustrated in Fig. 6, covers the pipe I45 which connects the valve I55 with the cylinder chamber I44 of the truing apparatus cylinder I35. The valve piston I55 covers the pipe I42 which connects the valve I55 with the cylinder chamber I43 ofthe truing apparatus cylinder I35. At the end of the stroke of the table II to the left, the truing dog (not shown) operating on the roller I55 rocks the bell crank I54 in a counterclockwise direction and shifts the valve stem I51 of the slow speed valve I55 toward the right (Fig. 6) thereby causing a slow speed traversing movement of the table II and at the same time moving the pistons I95 and I95 toward the right so as to uncover the pipes I45 and I42, respectively, thus connecting the pipes I45 and I42 with the

pipe

54 and 53, respectively, which are in turn connected with the table traversing cylinder 35. In this position of the slow speed valve I55, fluid under pressure passing through the valve mechanisms of the table traverse cylinder 35 also is conveyed through the pipes I45 and I42, respectively, to-

cause a traversing movement of the truing tool I34 across the face of the grinding wheel I5. As illustrated in Fig. 6, when the dog lever 55 is moved out of the path of the table dogs after grinding the last cam on the cam-shaft 25, the valve stem 55 moves toward the right so that fluid under-pressure entering the valve chamber 52 of the table control or reverse valve 35 may pass out through pipe 53 which passes fluid simultaneously to the table traverse cylinder chamber 35 and also through the pipe I42 into truing apparatus cylinder chamber I43 so as to cause the table I I and the truing tool I34 to move toward the left, as viewed in Fig. 6.

During these movements of the table I I and the truing tool I34, fluid under pressure is exhausted from the table traverse cylinder chamber 34 and also from the truing tool cylinder chamber I44. When the table II reaches the end of its stroke after a setting of the truing dog, the lever I01 is rocked is a comm-clockwise direction. which serves to operate the cycle pilot valve III to admit fluid under pressure to the right-hand end chamber III of the table control reverse valve 35 to shift it into a reverse position toward the left, which in turnserves to admit fluid under pressure through the pipe 54 which simultaneously passes fluid under pressure to the table index cylinder chamber 34 and also to the truing tool cylinder chamber I44 to move the table II and the truing tool I34, respectively, simultaneously in a direction toward the right (Fig. 6), making two passes across the face of the grinding wheel I5. The table II is then stopped by the table stop dog 54 (Fig. 6) in a loading position. By manipulation of the adjustable throttle valves I45 and I41, the speed of movement of the truing tool I34 may be varied as desired to produce the desired and predetermined surface on the periphery of the'grinding wheel I5.

By swivelling the wheel guard I25 as hereinbefore described, the diamond may be caused to move in a path either parallel to the axis of rotation of the grinding wheel I5 or at an angle thereto to produce either a straight faced wheel for producing straight faced cams 25, or it may be swivelled in either direction at an angle thereto to true a frusto-conical face on the periphery of the grinding wheel I5 to facilitate the grinding of tapered cams on the camshaft 25 being ground.

Operation The operation of this machine will be readily apparent from the description. the table II to be in its extreme left-hand or loading position, the machine is started into operation and successive cam blanks on the camshaft 25 are ground automatically by the mechanism hereinbefore set forth. The table II is moved longitudinally into operative position relative to the flrst cam to be ground. During this positioning movement, the master cam roller 22 is automatically positioned opposite the flrst master cam 2| and the grinding wheel I5 is then advanced toward the work piece 25. At the same time, the rock bar I5 is rocked to an operative position so that the flrst master cam 2I is in operative contact with the master cam follower 22. The infeed of the grinding wheel I5 continues until the cam blank 25 has been ground to the required and predetermined size whereupon the cycle control counting device I55 actuates the mercury tube switch III to deenergise the relay I52 and the solenoid I55, thereby releasing the compression of the spring Il3-which shifts the cycle pilot valvefeed control valve 44 so as to cause flrst a rearward movement of the grinding wheel I5 and secondly a shifting of the main control valve 43 toward the left (Fig. 6) which in turn serves to cause an indexing movement of the table II which serves to admit fluid to rock the bar I5 to an inoperative position and then to cause a longitudinal indexing movement of the table I I to position the next cam in operative position relative to the grinding wheel and at the same time automatically to position the m'aster cam roller in operative position with relation to the next master cam 2|.

This cycle of operation is continued until all of the cams on the camshaft 25 have been ground to the required and predetermined size, after which a table reversing dog 255 rocks the lever II! to reverse the movement of the table II. When the table II has moved to the left suiliciently, a truing dog actuates the roller I55 which shifts the slow speed-truing apparatm control valve I55 75 a for,

anemia to slow down the table movement and at the same time serves to start a traversing movement of the truing tool I across the periphery of the grinding wheel II, the wheel guard I20 having been previously adjusted so that the truing tool will move in the desired path so as to produce either a straight or a tapered faced wheel, as desired. The truing tool I" continues its traversing movement until the table operating mechanism above described reverses the table movement whereupon the fluid under pressure passing to the truing tool cylinder I38 is reversed to traverse the truing tool I in the reverse direction, after which the machine stops and the finish ground camshaft 20 may be unloaded and a new camshaft inserted in the machine. g

It will thus be seen that there has been provided .by this invention apparatus in which the variousobjects 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 above set forth, it is to be understood that all matter hereinbefore set forth or shown in the accompanying drawings is to be interpreted as illustrative andnot in a limiting sense.

I claim:

1. In a grinding machine, a rotatable grinding wheel, a transversely movable wheel slide there--' a longitudinally movable work table, a longitudinally reciprocable truing tool, each of which is operated by a separate fluid motor, a main control valve in control of the work table and truing tool motors, a feed control valve incontrol of said wheel slide motor and main control valve, a pilot and reversing valve interposed between the main control valve and .the table motor to control the direction of movement of the table, and to control the admission of fluid to said truing tool motor, and a slow speed valve actuated by said table movement to'slow down the table at the end of its travel, said slow speed valve being arranged to serve as a stop and start valve for said truing tool motor.

2. In a grinding machine, a wheel slide, a longitudinally movable work table, a rock bar on said table rotatably to support a camshaft, a longitudinally reciprocable truing tool, each of which is operated by a separate fluid motor, a main control valve in control of the work table and rock bar and truing tool motors, a feed control valve in control of said wheel slide motor'and main control valve, a pilot and reversing valve interposed between the table motor and main control valve to control the direction of movement of said table motor and said truing tool motor, and a stop and start valve which is actuated by said table movement to control the stopping and starting of said truing tool motor so as to true the grinding wheel automatically at the end of its table stroke after a work piece has been completely ground.

3. In a grinding machine, a wheel slide, a work table, a truing tool, each of which is operated by a separate fluid motor, a main control valve in control of the work table and truing tool motors, a feed control valve in control of said wheel slide and main control valve, and a stop and start valve actuated in timed relation with the table movement to stop and start truing tool motor.

4. In a grinding machine, a wheel slide, a rotatable grinding wheel on said slide, a work table,

' a truing tool, each of which is operated by a sep- 7 control valve in control of said wheel slide and main control valve, a stop and start valve which is actuated intimed relation with the table movement to stop and start said truingtool motor, and means angularly to adjust said truing tool and said truing tool motor so that its path of.

travel is either parallel to or at an angle to the axis of said wheel.

5. In a camshaft grinding machine, a rotatable grinding wheel, a wheel slide, a work table, a rock bar thereon rotatably to support a work piece, a

truing tool, each of which is operated by a separate fluid motor, a main control valve in control of the work table and rock bar and truing tool motors, .a feedcontrol valve in control of the wheel slide and main control valve, a stop and start valve which isactuated by said table movement automatically to start and stop said truing tool motor to true said wheel when the table reaches the end of its stroke.

6. In a camshaft grinding machine, a rotatable grinding wheel, a transversely movable wheel slide, a longitudinally movable work table, a rock bar on said table, a longitudinally-movable truing tool, each of which is operated by a separate fluid motor, a main control valve in control of the work table and rock bar and truing tool motors, a feed cntrol valve in control of said wheel slide motor and said main control valve, a stop and start valve which is actuated by said work table automatically to true said ginding wheel at the end of the table stroke, and means to adjust the path of travel of the truing tool and the truing tool motor to an angle relative to the axis of said grinding wheel so as to true a frusto-conical face on'said wheel.

7. In a grinding machine, a base, a rotatable grinding wheel, a transversely movable slide, a wheel guard surrounding said wheel and fixed relative to said base, a longitudinally reciprocable trueing tool on said guard, a fluid operated piston and cylinder on said guard which are operatively connected to reciprocate said truing tool, and a swivel connection between said guard and base whereby the path of travel of the truing tool is either parallel to or at an angle to the axis of the grinding wheel.

8. In a camshaft grinding machine, a rotatable grinding wheel, a transversely movable slide therefor, a longitudinally movable work table, a rock bar thereon rotatably to support a camshaft, means including master cams and a follower to rock said bar to grind a cam blank to a predetermined contour, means to feed said grinding wheel transversely to grind a cam blank to a predetermined size, means automatically to index said table longitudinally to grind successive cam blanks, and means automatically to true said wheel after a camshaft has been ground comprising a longitudinally movable truing tool, a fluid pressure operated piston and cylinder to reciprocate said tool, and a valve actuated by and in timed relation with said table indexing movement to control said truing apparatus.

9. In a camshaft grinding machine, a rotatable grinding wheel having a frusto-conical operative face, a transversely movable wheelslide therefor, a longitudinally movable work table, a rock bar on said table rotatably to support a camshaft to be ground, means to move said wheel slide transversely to grind successive cams on said shaft,

means intermittently to index said table longitudinally, a longitudinally reciprocable truing tool, means including a piston and cylinder automatically to reciprocate said truing tool in timed relation with said table indexing movement, and means angularly to adjust the path of movement of said truing tool so as to produce a rrustoconical face on said wheel.

10. A grinding machine comprising a work support, a grinding wheel support, a grinding wheel,

mounted thereon, mechanism for eii'ecting relative transverse and longitudinal movement between said supports, means for eflecting said dressing device.

T A. SILVER.