US2412144A - Cam grinding machine - Google Patents

Description

Dec. 3, 1946."

'c. J. GREEN CAM GRINDING MACHINE Filed July 16, 1945 3 SheetsSheet l CLARENCE.

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CAM GRINDINGYMACIHINE I Filed July 16, 1945 s sheets-sheet 5 MASTER CAM HELLER MASTER C M ADJUSTABLE Ruck y F/XEJJ F'IVUTE BAR m F'lvuT grwswvbo'b CLARENCE .J. GREEN Mum Patented Dec. 3, 1946 CAM GRINDING MACHINE Clarence J. Green, Worcester, Mass., assignor to Norton Company, Worcester, Mass., a corporatron of Massachusetts Application July 16, 1945, Serial No. 605,339

Claims.

The invention relates to grinding machines,

and more particularly to a machine for grinding ailitomotive cams, oval-shaped pistons and the li e.

One object of the invention is to provide a simple and thoroughly practical cam grinding apparatus for grinding cam shapes, such as automotive cams or elliptical shapes for automotive pistons and the like. Another object of the invention is to provide a grinding apparatus in which the shape of the cam or piston being ground may be varied relative to the shape of the master cam. Another object of the invention is to provide means whereby the shape of the work piece being ground may be varied so as to compensate for differences in diameter of the grinding wheel caused by wheel wear or truing. 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 possible embodiment of the mechanical features of this invention,

Fig. 1 is a fragmentary front elevation of the improved grinding machine;

Fig. 2 is a fragmentary cross-sectional view, on an enlarged scale, taken approximately on the line 2-2 of Fig. 1; V

Fig. 3 is a staggered sectional view, taken approximately on the line 3-3-3 of Fig. 2, showing the relationship of the master cam and follower roller and the supporting parts therefor;

,Fig. 4 is a fragmentary sectional view, taken approximately on the line 4-4 of Fig. 3; and

Fig. 5 is a diagrammatic view, showing the arrangement 'of the master cam and follower roller and the adjustably mounted connecting link between the supports for the master cam and the follower roller.

A grinding machine has been illustratedin the drawings comprising a base I0 which serves as a support for a longitudinally movable work supporting .table II. The table II is slidably supported ona'V-way I2 and .a flat way I3.

'The work table I I maybe moved longitudinally to position it relative to the base I0 either by a the drawings, a manually operable traverse mechanism has been illustrated comprising a manually operable rotatable traverse wheel I-5 which is operatively connected to rotate a gear IS. The gear I5 is mounted on a rotatable shaft I1 which is journalled in suitable bearings (not shown) in the base III. The shaft I! also supports a gear I8 which meshes with a rack bar I3 depending from the under side of the table I I.

A rotatable grinding wheel 20 is supported on a rotatable wheel spindle (not shown) which is mounted in suitable hearings in a wheel slide 2|. The wheel slide 2| is arranged to slide transversely relative to the base I0 on a V-way 22 and a flat way 23 formed on the base III. The grinding wheel 20 is preferably rotated by an electric motor 24 which is mounted on the Wheel slide 2|. The motor 24 is provided with an armature shaft 25 which supports a multi-V-groove pulley 26. The multi-V-groove pulley '26 is connected by multiple V-belts 21 with a multi-V-groove pulley 28 which is mounted on the right-hand end of the wheel spindle (Fig. l).

A suitable wheel feeding mechanism is provided for feeding the grinding wheel 20 and the wheel slide 2| transversely to position the wheel 20 relative to a work piece being ground and to feed the wheel 20 into the work to grind it to the desired and predetermined size. This wheel feeding mechanism has not been illustrated in detail since it is not considered to be a part of the present invention. The wheel feeding mechanism is substantially the same as that which is old and well known in the grinding art such as, for example, 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 disclosure not contained herein. The wheel feeding mechanism may comprise a manually operable rotatable feed wheel 29 which is provided with the usual micrometer feed adjusting mechanism 30. The feed wheel 29 is operatively connected through a gear mechanism (not shown) to rotate a gear 3I which ismounted on the outer end of a rotatable feed screw 32. The feed'screw 32 is arranged to mesh with a half nut 33 depending from the under side of the Wheel slide 2|.

The work supporting table II serves as a support, for a work rotating and driving mechanism comprising a rock bar 35 which is mounted to rock upon trunnion studs 36 and 31 which are journalled in brackets 3-8 and 39. The brackets 38 and 39 are fixedly mounted on the work supporting table I I,

A rotatably mounted headstock spindle 4 0 is provided with a work holding fixture M to sup- ,3 I port one end of a work piece 42. The other end of the work piece 42 is supported by a footstock 4 center 43 carried by a footstock 44. The footstock 44 is adjustably mounted on the rock bar 35.

The headstock spindle 40 is rotatably supported in a manner to be hereinafter described and is surrounded, by meansof a housing 45 which is'fiXed relative to the table I. An electric motor 45 is provided for rotating the head-.

V-groove pulley 50. The multi-V-groove pulley 58 is supported on a shaft journalled' in a suitable bearing bracket 52 which is fixedly mounted on the table II. The shaft 5! is connected by means of a universal joint 53 and a telescopic shaft 54 with a universal joint 55 which is operatively, connected to the left-hand end of the headstock spindle 40. The headstock spindle 40 is rotatably supported in bearings 56 and 51 which are fixedly mounted on the rock-bar 35. r 1

In order to transmit a controlled rocking movement tothe rock bar 35 to generate a predetermined shape on the work piece 42, a master cam 58 is supported on the headstock spindle 40. A master cam roller 60 is mounted on a rotatable shaft 61 which is in turnv carried by a pivotally mounted frame 62. The'frame 62is supported by a pivot shaft 63 which is carried by a bracket 64 mounted in fixed relationship with the housing 45. The follower roller 60 is arranged operatively to engage the master cam roller 58 so that when the master cam 58 is rotated, a controlled rocking motion will be imparted to the rock bar 35 so as to rock the work :piece 42 beinggroundtowardand from the periphery of the grinding wheel to generate a predetermined shape on the work piece.

In grinding automotive cams and pistons of an oval cross-sectional area, themastercam is accurately generated to operate with a grinding wheel of a predetermined diameter. -As the grinding wheel wears away due to grinding and also truing the same, the contour of the cam or piston being ground changes slightly as the wheel diameter is reduced. In production grinding, therefore, it is .common practice to use a wheel'of a given initial diameter and, when the wheel wears away so thatits diameter'is reduced a predetermined amount, to remove the wheel and replace it with a new one in order that the cam or piston contour may be maintained substantially constant. This practice means that only a small portion of a grinding wheel may be used on a given cam grinding operation, after which it must be discarded and replaced with a I i It is, therefore, desirable'to provide suitable adjustments whereby when the grinding wheel Wears away, the rocking movement of the rock bar may be varied so as to compensate for reduction in diameter of the grinding wheel.

In order to facilitate adjusting the motion of the rock bar 35 relative to the master cam roller 60, a connecting link is provided which is connected between an adjustably mounted pivot stud l2 supported by the rock bar 35 and an adjustably mounted pivot stud 1| supported by the frame 62. Adjusting screws 13 and 14 are provided for respectively adjusting the position of the pivot studs II and 12 relative to the frame 62 and the rock bar 35, respectively,

The pivot stud H is slidably supported in an elongated slot Ha (Fig. 3) to facilitate adjustment thereof. Similarly, the pivot stud I2 is supported within an elongated slot 12a. (Fig. 4) to facilitate adjustment of the Stud 12 relative to the rock bar 35.

A. suitable mechanismis provided for maintaining the aster cam '58- in operative engagement with the master cam roller during a grinding operation. This mechanism may comprise a tension spring which is connected at one end by means of a stud 8| with the housin 45. The other ,endof the spring 89 is connected by a stud 82. The stud 82 is conneced by a stud 83 supported adjacent to the upper end of an arm 84 which is fixedly supported relative. to the rock bar 35. The stud 8| is preferably provided with a screw threaded portion 85 which is provided with an adjusting nut 86 by means of which the tension of the spring 80 may bev varied as. de-

sired. V 'J In the diagrammatic view (Fig. 5), a: master cam is shown having a long and a short axis for producing an oval orelliptical shape on a work piece such as a piston, the shape in the drawing being somewhat exaggerated.diagrammatically to illustrate the operation. Dueto the ar rangement of the pivotal axis for the rock bar 35 and the frame 62, thepivot pin 12 at the righthand end of the link 10 is arranged so'that it may be adjusted in'a path'normal'to the axis of the rocking of the rock bar 35. Due to the'linkage arrangement, the stud 12 may be adjusted either toward or from the axis of the spindle so as to vary the shape generated on the periph.- ery of the work piece 42 in such a manner that the long axis, that is, on the line :r y, remains constant while the short axis at right angles thereto, namely cd, may be varied by adjustment of the pivot'stud 12. If it is desired to change the shape of the piston being generated so that the short axis thereofis increased, the pivot stud 12 maybe lowered into position 121), in which case the cam being'ground will have a short axis, as indicated by the frag entary broken line b. If it is "desired to decrease the short axis of the piston being generated, the pivot stud 12 may be raised to position 120,, in which 7 case the short axis of the work beingground will be decreased, as indicated by the broken line 1. During each of these adjustments, due to therelationship of the pivotal supportsfor the rock bar 35, the frame 62 and the link connection. III, the long axis :vy will remain substantiallyconstant. The angular. swingin movement of the I frame 62 is preferably, less than the angular swinging movement of the rockbar 35to facilitate maintaining the master cam 58 in operative Contact with the master cam roller 50. The tension of the spring 80 (Fig. 2) serves to rock the rock bar 35 so as to maintain the master cam 58 in operative engagement with the master cam roller 10'. It will, therefore, be seen that by a precise adjustment of the pivot stud 12, the shape of the piston-being generatedmay be varied soas to compensate for reductionin diameter of the grinding wheel due to wheel wear or tming so that the shape of the piston being groundmay be maintained substantially constantin'shape.

A similar adjustment is provided'for'thej'pivot stud 1| so that it may be adjusted iria path substantially normal to the axispf the pivot stud .613 which supports the frame .62. The pivot stud Il may be raised into position I la or lowered into position Hb to facilitate further adjustment to alter the shape of the cam being produced relative to the master cam, similarly to aid in compensating for the reduction in diameter of the grinding wheel due to wheel wear or tru-ing.

The operation of this improved cam grinding apparatus will be readily apparent from the foregoing disclosure. A cam or piston 42 to be ground is placed in position on the work supporting fixture 4| while the other end of the piston is supported by the footstock center 43. The grinding operation may then be started by starting the motors 24 and 46 and the grinding wheel 20 is fed into grinding engagement with the periphery of the piston 42 while the master cam 58 rotates in operative engagement with the master cam follower roller 60 so that a cam face or oval shape may be ground to the predetermined size and contour. As the grinding operation proceeds and the wheel 20 wears away, or is trued away during truing operations, to a point where the contour of the work piece being ground changes beyond limits, instead of replacing the grinding wheel with a new wheel the operator may adjust the position of the pivot studs 12 and/or H in either an upward or downward direction in a path normal to the axis of the rock bar 35 or the axis of the frame 62, as desired, to compensate for the reduction in diameter of the grinding wheel so that the cam face being produced will be changed relative to the shape of the master cam so that the contour on the finished work piece may be maintained within predetermined limits.

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 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 and not in a limiting sense.

I claim:

1. In a cam grinding machine having a rotatable grinding wheel, a pivotally mounted rock bar, a rotatable work support on said rock bar to support a cam to be ground, a rotatable master cam on said rock bar in axial alignment with the cam to be ground, a rotatable follower roller arranged to engage the master cam, a pivotally mounted frame to support said roller, yieldable means to maintain said master cam in operative engagement with said roller, and a connecting link the ends of which are pivotally connected to said rock bar and said frame, respectively.

2. In a cam grinding apparatus having a rotatable grinding wheel, a pivotally mounted rock bar, a rotatable work support on said rock bar to support a cam to be ground, a rotatable master cam on said rock bar in axial alignment with the cam to be ground, a rotatable follower roller arranged to engage said master cam, a pivotally mounted frame to support said roller, yieldable means to maintain said master cam in operative engagement with said roller, a connecting link, pivotal connections between the ends of said link and the rock bar and the frame respectively, and means to adjust the pivotal connections between the rock bar and the link in a direction normal to the pivotal axis of said rock bar whereby the contour of the cam being ground may be varied relative to the shape of the master cam.

3. In a cam grinding apparatus having a rotatable grinding wheel, a pivotally mounted rock bar, a rotatable work support on said rock bar to support a cam to be ground, a rotatable master cam on said rock bar in axial alignment with the cam to be ground, a rotatable follower roller arranged to engage said master cam, a pivotally mounted frame to support said roller, yieldable means to maintain said master cam in operative engagement with said roller, a connecting link, pivotal connections between the ends of said link and the rock bar and the frame respectively, and means to adjust the pivotal connections between the frame and the link in a direction normal to the pivotal axis of said rock bar whereby the contour of the cam being ground may be varied relative to the shape of the master cam.

4. In a cam grinding apparatus having a rotatable grinding wheel, a pivotally mounted rock bar, a rotatable work support on said rock bar to support a cam to be ground, a rotatable master cam on said rock bar in axial alignment with the cam to be ground, a. rotatable follower roller arranged to engage said master cam, a pivotally mounted frame to support said roller, a connecting link .pivotally connected at its ends at said rock bar and said frame respectively, and means to adjust the pivotal connections at both ends of said link relative to said rock bar and said frame in a direction normal to the pivotal axis of the rock bar and frame respectively to facilitate varying the shape of the cam being ground relative to the shape of the master cam, thereby compensating for reduction in wheel diameter due to wheel wear.

5, In a cam grinding apparatus having a rotatable grinding wheel, a pivotally mounted rock bar, a rotatable work support thereon .to support a cam to be ground, a master cam thereon in axial alignment with said cam, the pivot of said rock bar being located below the axis of the cam and master cam, a rotatable master cam follower roller, a pivotally mounted frame for supporting said roller, the pivot of said frame being located above the axis of said master team roller, a connecting link between said rock bar and said frame, and adjustable pivotal connections between opposite ends-of said link and the rock bar and frame respectively.

CLARENCE J. GREEN.

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