US2041244A

US2041244A - Cam grinding apparatus

Info

Publication number: US2041244A
Application number: US10366A
Authority: US
Inventors: Clarence J Green
Original assignee: Norton Co
Current assignee: Saint Gobain Abrasives Inc
Priority date: 1935-03-11
Filing date: 1935-03-11
Publication date: 1936-05-19
Anticipated expiration: 1953-05-19

Description

N E E R G Iv. C.

CAM GRINDING APPARATUS Fi-led March ll, 1955 3 Sheets-Sheet 2 gmc/who@ CLARENCE LJ. GREEN May 19, 1936.

c. J. GREEN l CAM GRINDING APPARATUS Filed March ll, 1955 3 Sheets-Sheet 3 ggmm CLARENCE d. GREEN f lel to each other.

Patented May l 19, 1936 PATENT OFFICE CAM GRINDING APPARATUS Clarence J. Green, Worcester, Mass., assignor to Norton Company, Worcester, Mass., a corporation of Massachusetts Application March 11, 1935, Serial No. 10,366

12 Claims. (Cl. 51-101) This invention relates togrindingl machines, and more particularly to an apparatus for grinding tapered cams on an automobile camshaft.

Heretofore, numerous machines have been de- Y: veloped for the grinding of an automobile camy lthe shifting of the master cam roller have all been distinct manual and individual manual operations. Other machines have been of the automatic type in which it is merely necessary for the operator to place a camshaft in the machine f and start the cycle of operation, and the machine automatically grinds all of the successive cams on the shaft and then stops after the cycle has been completed.

In the. prior methods of grinding and apparatus f used in carrying out these methods, it has been customary to provide a machine in which the master camshaft and the product camshaft are either in axial alignment or in which master camshaft and product camshaft are arranged paral- The former apparatus is preferred dueto the fact that the master shaft in axial alignment with the product shaft may be locked rigidly together so that lost motion in the driving mechanism is entirely eliminated.

Up to the present time, the common practice in the automobile engine design has called for a camshaft in which all 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 straight or of the same dimensions at each end thereof. In the automotive engine employing such a camshaft, it has been found that the tappct engaging the cam is worn away in a path which engages the cam on the camshaft. It is rapidly becoming the standard design, 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 head, the cam ro- .tating the tappet causes a more or less uniform wear on the surface of the tappet head.

It is the primary object of this invention to provide a simplified method and apparatus for of the camshaft being ground is swivelled at an angle to the axis of the grinding wheel by an amount corresponding to the taper desired to be produced on the cams being ground.

It is a further object of this invention to mount the camshaft to be ground with its axis at an angle to the axis of the grinding Wheel and to provide master cams of varied or steppeddiameters Which allows the cams on the camshaft to be ground while rocking the rock bar through a greater or lesser distance in grinding successive cams, so that all of the cams may be successively ground by utilizing a single stop on the wheel feeding mechanism.

Other objects will be apparent from the foregoing disclosure.

One embodiment of this invention has been illustrated in the accompanying drawings, in which like reference numerals indicate like parts:

Fig. 1 is a somewhat diagrammatic top plan view of a simplified form of a machine embodying this invention;

Fig. 2 is av front elevation of a machine embodying this invention, on a reduced scale, and having parts broken away to mo-re clearly show the construction; and

Fig. 3 is a fragmentary perspective view illustrating the mechanism for indexing the master cam roller.

The present invention relates to a method and apparatus for grinding a, plurality of tapered cams on a camshaft by a simple method which permits the use of a single feed stop on the wheel feed mechanism and employs a cylindrical wheel which permits a reciprocation of the wheel during grinding to take up the grinding line and Y produce the desired ne finish on the cam being ground.

Broadly, this invention comprises a cam grinding machine in `which the axes of the grinding Wheel and the camshaft being ground are set at an angle to each other so that the cylindrical operative face of the grinding wheel will grind a. predetermined taper on the periphery of the cam being ground. A set of master cams or forms of successively varying or stepped sizes serve to cause a relative approaching and receding movement between the grinding wheel and the cams being ground, the variations in the size of the successive master cams being such as to compensate for the angular position of the axes of the camshaft and grinding wheel.

As illustrated in the drawings, a machine embodying this invention comprises a base IIJ having a longitudinally traversable work supporting table Il which is supported on ways I2 and I3 55 on the base I0. A rotatable grinding wheel I5 is supported on a wheel spindle I6 which is journaled in bearings I1 and I8. The bearings I1 and I8 are integral with a transversely movable wheel slide I9 which is supported on the base I0 by a V-way 20 and a flat way 2l.

Wheel spindle reciprocaton The grinding wheel spindle I6 and bearings I1 and I8 are preferably so arranged that the spindle may be reciprocated within its bearings during the grinding operation. A Wheel spindle reciprocating mechanism 22 is xedly mounted on the wheel slide I9. A control lever 23 serves to stop and start the reciprocation of the spindle as desired. Details of the mechanism have not been illustrated since this mechanism is not a part of the present invention. For details of construction of this mechanism, reference may be had to the prior patent to Belden and Flygare No. 1,584,717 dated May 18, 1926.

Wheel feed The grinding wheel slide I9 is arranged for a transverse feeding movement relative to the base in order that the grinding wheel may be fed toward the work to the required extent to accurately size the work being ground. Any of the well-known feeding mechanisms may be employed to cause a precise transverse movement of the slide I9. Since the feeding mechanism in itself is not a part of the present invention, the actual wheel feed mechanism has not been shown in detail. The feeding mechanism, aS

illustrated, is identical with the wheel feedingl mechanism shown in the U. S. Patent to Trefethen and Belden No. 1,783,755 dated December 2, 1930, to which reference may be had for )details of the wheel feeding mechanism not shown in the present drawings. The Wheel feeding mechanism consists of a. half nut 25 depending from the wheel slide I9 and engaging a feed screw 26 which is rotatably mounted in the base of the machine. The outer end of the feed screw 26 carries a gear 21 which in turn meshes with a gear 28 rotatably mounted on a stud 29. A manually operable feeding wheel is also rotatably mounted on the stud 29 and is preferably fixed to gear 28 so 'that rotation of the hand wheel 30 serves to cause a transverse movement of the Wheel slide I9 either toward or from the work, as desired, depending on the direction of rotation of the feed wheel 36. The usual micrometer adjusting mechanism 3l is provided on hand wheel 30 which serves to accurately position a stop abutment 32. The abutment 32 cooperates with a stop arm 33 which is pivotally mounted on a stud 34 and serves to positively llimit the rotary movement of the feed wheel 3) so as to stop the infeeding movement of the grinding wheel I5 when the work piece has been ground to the required size. Details of the micrometer adjustment 30 have not been illustrated, since this feature is not part of the present invention. This construction is substantially that shown in the prior U. S. Patent to Norton No. 762,838 dated June 14, 1904, to which reference may be had for details of construction.

The grinding wheel may be rotated by any suitable source of power (not shown) by means of a pulley 40 mounted on the wheel spindle I6. The pulley 49 may be operatively connected to an electric motor on the wheel slide or by means of a belt to an overhead driving shaft.

'-Such illustration has been omitted, since this drive does not constitute any part of the present invention.

The work table I I serves as a work support and in the present construction serves as a support for a swivel table 45 which is pivoted on a stud 46 and arranged to be swivelled, about the vertical pivot stud 46, to the desired extent and then locked in adjusted position. The swivel table 45 in turn serves to support the work holding apparatus which comprises a rock bar 49. The rock bar 49 has reduced end portions or trunnions 56 and 5I journaled in

brackets

52 and 53 which are xedly mounted on the swivel table 45. The rock bar 49 is provided with a headstock member 55 and a footstock 56 which are arranged to rotatably support a camshaft 51 for a grinding operation. A master camshaft 54 is rotatably supported in the headstock 55 and is located in axial alignment with the headstock center 58 and footstock center 59 so that the master camshaft and the product camshaft are in axial alignment with each other. A driving dog 66 is operatively connected to the camshaft being ground and serves to form a rigid driving connection between the master camshaft 54 and the product shaft 51.

In order that a rocking motion may be transmitted to the rock bar 49 so as to produce the desired contour on the cams being ground, a rotatable masterV cam follower 65 is slidably mounted on a shaft 66 which is rotatably journaled in brackets 61 and 68. The brackets 61 and 68 are rigidly xed to the swivel table 45. The master camshaft 54 is in turn operatively connected with a drive shaft 10 which may be rotated by a pulley 1I (Fig. l) from any suitable source of power, such as an overhead drive shaft or the like.

Traverse mechanism In order that the table II may be traversed longitudinally relative to the base I0, a traverse mechanism is provided which may comprise a manually operable hand wheel 80 mounted on a shaft 8l and carrying a gear 82. The gear B2 meshes with a gear 83 mounted on shaft 84. The shaft 84 carries a gear 85 meshing with a rack bar 86 depending from the under side of the table II. It will be readily apparent from the foregoing disclosure that rotation of the traverse wheel 8 9 serves to cause a longitudinal traversing movement of the table II.

Master cam follower-Index mechanism In the preferred construction, the master cam follower or roller 65 is arranged for automatic indexing so that when the work table Il is traversed longitudinally to present a given cam in operative relation with the grinding wheel, the master cam roller or follower 65 is indexed automatically into operative relation with the corresponding master cam 12 on the shaft 54. The automatic indexing mechanism in the present illustration is identical with that shown in the prior United States Patent to Trefethen and Belden No. 1,783,755 dated December 2, 1930. Details of this construction have not been illustrated completely, since reference may be had to the prior patent for details not readily disclosed in the present case. This mechanism, as shown in Fig. 3, may comprise a yoke 13 which serves to engage the side faces of the roller or follower 65 so as to slide it longitudinally on the shaft 66. The yoke 13 is fixed to a rack bar 14. The rack bar 14 is slidably mounted in a support 15. XA pinion 16 meshesiwith the ra'ck 14 and is mounted on a stud 11 which carries a gear 18 meshing with a gear 19. The gear'19 meshes with a gear 81 which in turn carries a star Wheel (not shown) arranged to be engaged by adjustable dogs 88 which are adjustably positioned on a bar 89 carried by a bracket 90 xed'to the base i9. It will be readily appreciated from the foregoing disclosure that when the table v|| is moved longitudinally, the star wheel engaging the dogs 98 on dog bar 99 serves torotate the train of gears 91, 19 and 18 to transmit a longitudinal movement to rack 14 so as tor automatically index the master cam roller 65 as the table is moved longitudinally to position it in operative relation with the master cam corresponding with the product cams to be ground. For further details of the automatic indexing mechanismfor the master cam follower 55, reference may be had to the above-mentioned patent.

Rock bar actuating mechanism The rock bar 49 is normally held in an operative forward position by means of a spring (not shown) so that the master cam opposite the master cam roller 65 is held in engagement with the roller E5 as`the master camshaft is rotated so as to cause a rocking of the rock bar 49, causing a corresponding movement of the cam being ground relative tothe operative face of the grinding wheel, so that a Adesired and predetermined contour will be generated on the cam being ground.

It is desirable that a suitable mechanism be provided to rock the bar 49 to an inoperative position, thereby separating the master cams from the follower and the product cams from the grinding wheel before the table traversing movement is started. To accomplish this result, a fluid pressure mechanism may be utilized, such as that shown in the prior Patent No. 1,783,755. 'I'his mechanism comprises a cylinder |00 connected by a pipe I 0| with a valve |02 whichis connected by a rack |03 with a gear train |04 which is rotated by the wheel feeding mechanism. The gear connection between the rack |03 and the feed mechanism is such that when the feed wheel 30 is turned in a clockwise direction to cause a rearward feeding movement of the grinding wheel, this movement serves to shift the valve |02 from the position indicated in Fig. 2 of the drawings and move the valve piston |06 toward the left so as to admit fluid under pressure from pipe |01 through Valve |02 and into pipe ||l| and cylinder |00, causing a downward movement of the piston (not shown) within the cylinder |00 so as to rock the rock bar 49 to an inoperative position so that the table may be readily traversed to position another cam in operative relation with the grinding wheel. For further details of the rock bar actuating mechanism, reference may be had to the prior patent above referred to.

Taper adjustment-Work support As illustrated in the drawings, the rock bar 49 is supported in

brackets

52 and 53 which are rigidly supported on a swivel table 45, so that the rock bar may be readily adjusted to position the axis ofthe work parallel to or at an angle with the axis of the grinding wheel spindle. Such a construction permits the angle between the work axis and the wheel axis to be readily varied so that the desired taper may be produced on the cam being ground. If desired, the machine may be built for a xed taper, in which case the swivel table 45 may be dispensed with.

In this case, the

brackets

52 and 53, which support the rock bar 49, are fixedly mounted on the upper surface of table I and are positioned so that the axis of the camshaft 51 is positioned at an angle relative to the axis of the wheel spindle I6, so that when the grinding wheel |5 is brought into operative contact with a cam to be ground, the cylindrical operative face of the grinding wheel will grind the cams with a desired and predetermined taper thereon.

Stepped master cams With the axis of the camshaft set at an angle relative to the axis of the grinding wheel, it will be readily appreciated that if the successive cams on the camshaft 51 are ground from the headstock end toward the footstock, due to the angular positioning of the axis of shaft 51 relative to grinding wheel spindle I6, the rock bar must be rocked through a greater angle when successive cams are ground if it is desired to rely upon the same fixed feed stop abutment to acf curately size each of the successive cams as they are ground. To permit the desired additional rocking of the rock bar so as to enable the machine to be operated by a feed mechanism employing a single stop, the master cams 12 are stepped or varied in size from the left-hand end to the right-hand end, as illustrated in Fig. 1. The left-hand master cam is the largest in diameter or size and each successive master cam is smaller in size than the preceding master cam.

It will-be readily apparent from the illustration in Fig. l that when the table II is moved toward the left to position cam ||0 into operative relation with the grinding wheel l5, the master cam roller 65 will be moved longitudinally toward the right, as viewed in Fig. 1, and into operative relation with master cam lll. The master cam is smaller in diameter than master cam ||2 and will allow the rock bar to rock through a greater distance toward the periphery of the grindingwheel so that by utilizing a single adjustment of the stop 33 and stop abutment 32 of the feed mechanism, the cam I0 may be accurately ground to the desired shape and size. The difference in diameter or size of successive master cams is calculated and determined by the amount of taper and spacing of the cams to be ground. It will be readily appreciated from the foregoing disclosure that a plurality of tapered cams may be ground on an integral camshaft by utilizing a true cylindrical grinding wheel without the necessity of providing a complicated multi-stop feed mechanism for controlling the size of the various cams as they are ground.

If desired, the grinding wheel may be readily trued by means of a diamond truing tool |20 which is adjustably positioned on a bracket IZI which is in turn fixed to the swivel table 45 (Fig. 2) or to theA longitudinally movable table When it is desired to true the grinding wheel, the operator merely traverses the work table II toward the right to bring the diamond into operative contact with the periphery of the grinding wheel so as to true the surface thereof.

The operation of this machine will be readily apparent from the foregoing disclosure. The camshaft to be ground is mounted on

centers

58 and 59 and the swivel table is adjusted to the desired angle or the

brackets

52 and 53 are rigidly xed on the table so that the axis of the shaft 51 bears the proper angular relation with the axis of the wheel spindle I6. The operator then traverses the table II by manipulation of the manually operable traverse wheel 80 to bring the first cam on the left-hand end of the camshaft 51 into operative relation with the wheel I5. During this positioning movement, the automatic master cam roller indexing mechanism, as shown in Fig. 3, causes the master cam roller to be moved into operative relation with the left-hand master cam H2. The operator then feeds the grinding wheel I5 toward the camshaft 51, by rotating the feed wheel 30, to grind the left-hand end cam tc the required diameter. After the first cam has been ground to a predetermined size, the operator rotates the feed wheel 30 in a clockwise direction to move the grinding wheel I5 rearwardly and also to actuate valve H32, admitting fluid under pressure through pipe IOI into cylinder I0!) yto rock the bar 49 so as to separate the camshaft 51 from the grinding wheel and the master cams 12 from the follower roller G5. The operator then, by manipulation of the traverse wheel 80, traverses the table I I in a direction toward the left, as viewed in Figs. 1 and 2, to bring the second cam IIO into the position as illustrated in Fig. 1 in operative relation with the grinding wheel I5. This traversing movement of the table II automatically indexes the master cam roller 65 into operative relation with the master cam I I I, and the operator may then by turning the feed wheel 30 in a counterclockwise direction (Fig. 2) cause the grinding wheel to be led into cam IIU to grind the same to a predetermined shape and size. The master cam I II being of smaller diameter than the preceding master cam II2, allows the rock bar to rock to a greater extent so as to compensate for the angular relation of the shaft 51 and permit the grinding wheel to reduce the cam to a required and predetermined size when abutment 32 engages stop arm 33. This sequence of operation is continued until all of the cams on the shaft are ground to the desired extent without the necessity of resetting or adjusting the stop abutment 32 of the wheel feeding mechanism.

While the present invention has been described as applied to a manually operable cam grinding machine, I do not desire to be so limited in interpreting the scope of my invention. My invention is equally ap-plicable to an automatic cam grinding machine of the types shown in the U. S. Patents Nos. 1,840,088 and 1,945,588 and the copending application Serial No. 605,707.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A grinding machine comprising a rotatable grinding wheel, means for rotatably supportingl a multiple camshaft with its axis at an angle to the wheel axis, and means for moving the wheel and shaft longitudinally relative to each other and parallel with the wheel axis to position successive cams in operative relation with the grinding wheel and means for moving them relatively towards and from each other, so as to grind a predetermined taper on a plurality of cams thereon while in said angular relationship.

2. A grinding machine comprising a rotatable grinding wheel, means for rotatably supporting a camshaft with its axis at an angle to the wheel axis, and means for moving the wheel and shaft longitudinally relative to each other and parallel with the wheel axis and means for moving them relatively towards and from each other, so as to grind a plurality of cams thereon while in said angular relationship, said means including a set of master cams of successively variable size and a follower cooperating therewith to move the camshaft and wheel through successively greater distances in grinding the successive cams on the shaft.

3. A grinding machine comprising a rotatable grinding wheel, means for rotatably supporting a multiple camshaft with its axis at an angle to the wheel axis, and means for moving the wheel and shaft longitudinally and transversely relative to each other and parallel with the wheel axis and means for moving them relatively towards and from each other, so as to grind a plurality of cams thereon while in said angular relationship, said means including a set of master cams of successively variable size and a follower cooperating therewith to move the camshaft and wheel through successively greater or successively lesser distances to grind a predetermined tapered surface of a predetermined contour on successive cams on the shaft.

4. A grinding machine comprising a transversely movable slide, a rotatable grinding wheel on said slide, a longitudinally movable work supporting table, means for rotatably supporting a camshaft on said table with its axis arranged at I an angle to the wheel axis, and means for moving the wheel and table longitudinally and transversely relative to each other to grind a predetermined tapered surface of a predetermined contour on a plurality of cams thereon while in said il angular relationship.

5. A grinding machine comprising a transversely movable slide, a rotatable grinding wheel thereon, a longitudinally movable work supporting table, means for rotatably supporting a camshaft on said table with its axis arranged at an angle relative to the wheel axis, and means for moving the slide and table longitudinally and transversely relative to each other to grind a plurality of cams on said shaft while in said angular relationship, said means including a set of master cams of successively variable size and a follower cooperating therewith to move the camshaft and wheel to successively greater or lesser distances in grinding the successive cams on the shaft.

6. A cam grinding machine comprising a base, a transversely movable slide thereon, a rotatable grinding wheel on said slide, a longitudinally movable table on said base, a rock bar pivotally mounted on said table, a rotatable work support on said bar which is arranged `to rotatably support a camshaft thereon, said rock bar and rotatable work support being so positioned and arranged that its axis makes an angle to the path of travel of said table and also with the axis of the grinding wheel, said angle being such as to produce the desired taper on a cam being ground, and means including a master cam roller and a plurality of rotatable stepped master cams arranged to rock said bar and camshaft toward the operative face of the grinding wheel through a greater distance for each successive cam as it is ground.

7. A camshaft grinding machine comprising a base, a transversely movable slide mounted thereon, a rotatable grinding wheel on said slide, a longitudinally movable table on said base, a rock bar pivotally mounted on said table, a rotatable work support on said bar which is arranged to rotatably support a camshaft thereon, said rock bar and rotatable work support being so positioned and arranged that their axes of rotation are set at an angle to the path of travel of the table and the axis of the grinding wheel, said angle being such as to produce the desired taper on a cam being ground, a master camshaft on said rock bar arranged in axial alignment with the camshaft being ground, a master cam follower rotatably and slidably mounted on said table, and a plurality of stepped master cams on said shaft, said master cams varying in size so as to allow the rock bar and camshaft to rock a greater distance toward the wheel periphery for each successive cam being ground.

8. A camshaft grinding machine comprising a base, a transversely movable wheel slide mounted thereon, a rotatable grinding Wheel on said slide, a longitudinally movable table on said base, a rock bar pivotally mounted on said table, a rotatable work support on said bar which is arranged to support a camshaft thereon, said rock bar and rotatable work support being so positioned and arranged with its axis at an angle to the path of travel of said table and the axis of said grinding wheel, said angle being such as to produce the desired taper on a cam, a master camshaft on said rock bar arranged in axial alignment with the camshaft to be ground, and a plurality of master cams of stepped sizes on said shaft to allow the camshaft to rock to a greater distance toward the wheel periphery while grinding successive cams on the shaft being ground.

9. A camshaft grinding machine comprising a base, a transversely movable slide mounted thereon, a rotatable grinding wheel on said slide, a longitudinally movable table on said base, a rock bar pivotally mounted on said table, a work support on said bar which is arranged to rotatably support a camshaft thereon, said rock bar and rotatable work support being so positioned and arranged that its axis is setl at an angle to the path of travel of the table and the axis of the grinding wheel, said angle being such as to produce the desired taper on a cam being ground, a master camshaft on said rock bar arranged in axial alignment with the camshaft being ground, a master cam follower rotatably and slidably supported on said table, and a plurality of stepped master cams on said shaft, said master cams varying in size so as to allow the rock bar and camshaft to rock a greater distance toward the wheel periphery for each successive cam being ground.

10. A camshaft grinding machine comprising a base, a transversely movable slide thereon, a rotatable grinding wheel on said slide, a longitudinally movable table on said base, means to traverse said table longitudinally, a rock bar pivotally mounted on said table, a rotatable camshaft support on said bar, the axes of the rock bar and rotatable support being positioned and arranged at an angle to the path of travel of said table and also with the axis of the grinding wheel, said angle being such as to produce the desired taper on a cam being ground, and means including a master cam roller and a plurality of rotatable stepped master cams arranged to rock said bar and camshaft toward the operative face of the grinding wheel through a greater distance for each vsuccessive cam as it is ground.

11. A camshaft grinding machine comprising a base, a transversely movable slide mounted thereon, a rotatable grinding wheel, a longitudinally movable table on said base, means to cause a relative transverse movement between the wheel and said table, means to cause a longitudinal traversing movement between the wheel and said table, v

a rock bar pivotally mounted on said table, a rotatable work support on said bar which is arranged to rotatably support a camshaft thereon, said work support being so positioned that its axis makes an angle to the path of travel of the table and the axis of the grinding wheel for producing the desired taper on the cam being ground, a master camshaft on said rock bar having a plurality of stepped master cams thereon, and means to cause a relative indexing movement between said follower and master camshaft as the table is moved longitudinally, said master cams being of successively varying sizes so that in grinding successive cams, the camshaft and rock bar may be rocked through a varying distance and the cam being ground may be accurately sized by utilizing a single stop on the wheel feeding mechanism.

12. A cam grinding machine comprising a base, a transversely movable slide thereon, a rotatable grinding wheel, a longitudinally movable table on said base, a rock bar pivotally mounted on said table, a rotatable work support on said bar which is arranged to rotatably support a camshaft thereon, said rotatable work support being so positioned and arranged that its axis makes an angle to the path of travel of the table and the axis of the grinding wheel for producing the desired taper on the cam being ground, means to traverse said table longitudinally to position Successive cams opposite to the grinding wheel, a wheel feeding mechanism arranged to feed the grinding wheel relatively toward and from the work to reduce the cam to a predetermined size, a stop to limit the forward feeding movement of the grinding wheel, and means including a plurality of rotatable stepped master cams and a follower which are arranged to rock said bar and camshaft relatively towards and from the operative face of the grinding wheel, said cams being of successively varying sizes so as to rock the camshaft to a greater or lesser distance in grinding successive cams, whereby each cam may be accurately sized by utilizing a single stop of the wheel feeding mechanism.

CLARENCE J. GREEN.