US2848848A - Cam grinding apparatus - Google Patents

Description

Aug. 26, 1958 E. M. HUTCHINS 2,848,348

CAM GRINDING APPARATUS Filed Jan. 25, 1957 4 Sheets-Sheet 1 INVENTOR ATTORNEY Aug. 26, 1958 Filed Jan.

E. M. HUTCHINS CAM GRINDING APPARATUS 4 Sheets-Sheet 2 Aug. 26, 1958 E. M. HUTCHINS 2,848,848

CAM GRINDING APPARATUS Filed Jan. 23, 1957 4 Sheets-Sheet 3 BY Min-7w ATTORNEY Aug. 26, 1958 E. M. HUTCHINS 2,848,848

CAM GRINDING APPARATUS Filed Jan. 25, 1957 4 Sheets-Sheet 4 I NVENTOR 19-2611 mzazzn ATTORNEY United States atent 2,848,848 Patented Aug. 26, 1958 ice CAl'l l GRINDING APPARATUS Erie M. Hutchins, Winston-Salem, N. C., assignor to Western Electric Company, Incorporated, New York, N. 1., a corporation of New York Application January 23, 1957, Serial No. 635,798

7 Claims. (Cl. 51-101) This invention relates to cam grinding apparatus and more particularly to an apparatus for accurately grinding the surfaces of rotary cams.

It is an object of the present invention to provide simple, novel, and eflicient cam grinding apparatus.

Another object of the invention is to provide new and improved cam grinding apparatus for finish grinding cams for electrical equipment with a very high degree of accuracy.

Cam grinding apparatus illustrating certain features of the invention may include, in combination with a grinding wheel rotatable about a fixed horizontal axis, a movable support block mounted for vertical movement toward and away from the peripheral grinding surface of the grinding wheel, a carriage mounted movably on the support block for horizontal movement substantially perpendicular to a vertical plane including the axis of the grinding wheel, and a rotatable shaft supported by the carriage for movement therewith and oriented substantially parallel to the axis of the grinding wheel. The shaft is designed to support a cam blank for rotation about a predetermined point thereon. Means are provided for urging the block vertically to carry the surface of the cam blank to be ground into engagement with the peripheral grinding surface of the grinding wheel. Actuating means are provided for rotating the shaft during a grinding operation and for shifting the shaft laterally from one side of the aforementioned vertical plane to the other at a predetermined point in the grinding operation. The actuating means operates to prevent rotation of the shaft and cam blank during the lateral shifting movement thereof.

A clear understanding of the invention may be had by reference to the following detailed description, when considered in conjunction with the accompanying drawing, in which Fig. l is a rear elevational view of cam grinding apparatus comprising a preferred form of the present invention;

Fig. 2 is a vertical sectional view taken on the line 22 of Fig. 1, viewed in the direction of the arrows;

Fig. 3 is a horizontal section taken on the line 3-3 of Fig. 1, viewed in the direction of the arrows;

Fig. 3a is a top plan View of the apparatus;

Fig. 4 is a horizontal section, on an enlarged scale, taken along line 4-4 of Fig. 2, viewed in the direction of the arrows;

Fig. 5 is an enlarged perspective view of a detail shown in section in Fig. 4 and used for radially positioning a cam to be ground in the apparatus;

Fig. 6 is an enlarged detailed View of a part of a mechanism, shown in Fig. 4, for holding a cam to be ground in the apparatus;

Fig. 7 is an enlarged detail view of a master cam, shown in Fig. 4, which controls the grinding operation;

Fig. 8 is an enlarged section taken along the line 88 of Fig. 1, viewed in the direction of the arrows;

Fig. 9 is a detailed section, on an enlarged scale, taken along the line 99 of Fig. 8, viewed in the direction of the arrows;

Fig. 10 is a detail view from the front showing a cam which controls the rotation of the cam being ground in the apparatus;

Fig. 11 is a detail view of a cam which controls the shifting of the axis of rotation of the cam being ground in the apparatus;

Fig. 12 is a detail view of a cam which has been ground by the apparatus shown in the other viewsjand Fig. 13 is a vertical sectional view taken on the line 13-13 of Fig. 9, viewed in the direction of the arrows.

Referring now to the drawings, wherein like reference characters designate the same parts throughout the several views, and particularly to Figs. 1 and 2, there is shown an abrasive grinding wheel 15 which may be mounted for rotation on a shaft 16 of a suitable grinding device having a base 17. A plate 18 is mounted on the base 17 in such manner that the plate and all of the apparatus carried by it may be positioned movably with respect to the grinding wheel 15. A reduced portion 19 of a post 20 is set into the plate 13 at an angle. The post 29 carries at its upper end a diamond dressing tool 21, which normally is engaged by a gauge plate 22 mounted upon the upper end of a gauge post 23 that is mounted removably for rotation about its vertical axis on the plate 18.,

The gauge post 23 may be rotated to carry the plate 22 into or out of contact with the dressing tool 21 on the post 21 and serves to gauge the height at which the dressing tool 21 is held. The dressing tool may be adjusted in any suitable manner with respect to the gauge post 23 to move the dressing tool into engagement with the gauge plate 22 in the position shown in Fig. 2. The gauge post 23 may be removed and the plate 18 positioned to carry the diamond dressing tool 21 into engagement with the grinding wheel 15 to dress the wheel 15.

Suitably attached to the plate 18, for example by welding it thereto, is a vertical support plate 27 on which are mounted all of the mechanisms for manipulating a cam-blank 24 during a grinding operation thereon. The vertical support plate 27 has fixed to it a pair of gibs 2828, which serve to guide a main support block 29 for movement vertically with respect to the plate 27 and plate 18. The main support block 29 extends through a rectangular cutout 3G in the vertical support plate 27 and is urged upwardly by a compression spring 31 which bears against its bottom surface and is adjustably mounted in aligned apertures 32 and 33 in the plates 18 and 27. A threaded member 34- is threaded into the plate 18 and may be manipulated to adjust the compressive force exerted by the spring 31 in urging the block 29 upwardly. Mounted on top of supporting plate 27, by means of a nut 37, is a stud shaft 36 which carries at its free end a cam follower roller 38.

The main support block 29 has fixed to it, by means of machine screws 44, a face plate (Figs. 2 and 13) which carries a bearing block 46 that is attached to the face plate 45 by machine screws 47. The bearing block 46 (Fig. 13) is U-shaped in cross section and has in it a suitable bearing 48 which is aligned with a bearing 49 mounted in the face plate 45. The bearings 48 and 49 support a cam shaft 59 which has keyed to it a pair of cams 51 and 52, the cam 52 being mounted in the space between the base of the U-shaped bearing block 46 and the outer or left-hand face of the face plate 45. The shaft has an actuating lever 53 attached to it whereby oscillation may be imparted to the shaft 50. The cam 51 has a cam groove 54 formed in it for cooperation with a cam roller 55. The cam 52 on the other hand is a surface cam and cooperates with a cam roller 56.

From the foregoing it will be apparent that the main supportablocklfi, which is: provided with tapered projections: 61 for cooperation with the gibs 28, may be moved V Fig. 2, hasupper and lower guide bars 62 and 63, re-.

spectively, secured to it by means of machine screws 64. These guide bars: are L-shaped in configuration, the upper bar. 62- being mounted in an inverted'position. The guidebars 62 and 63 receive projecting edges 65 and 66 of a bearing block 67 between their vertically extending legs andthe left-hand face (Fig. 2) of the face plate 45.

Anti-friction bearings 68' and 69 are mounted in the bearing block 67 to rotatably support a shaft 70. The

shaft70, is provided with a head portion 71 (Figs. 3' and 4) inwhich there is mounted. a cam-blank receivingfixture designated generally by the numeral 72. The blank receiving fixture 72 includes a blank holding block 73 which is'fixed, in 'the'head portion 71. The blank holding block 73 has attached to it a locating member 74 which is shownin detail in Fig. and is mounted on the blank holding'block 73 by. means of a machine screw 75. The blank holding block 73 is provided with a shouldered centralaperture 76, against the shoulder of which a tubular 1 plunger77 is urged by a coil spring78 seated between an outer face of the head portion 71 of shaft 70 and the inner end of the plunger 77. This plunger 77 extends freely through an aperture 88 in the locating member 74 and is spring-urged against a clamp plate 79 shown in detail in' Fig. 6. A knurled thumb screw 80 extends througha slot 81' in the clamping plate 79 and through the tubular plunger- 77 and is threaded into the head portion 71- of shaft 70.

By-means of the just described arrangement, a work piece, for example the cam-blank 24 being ground,.may be -mounted on the shaft 70 for movement therewith. It willbe noted that the cam-blank 24 being ground, in addition to-itscentral aperture 82, has a slot 83 formed therein (Fig. 12). This particular cam-blank 24 has two cam surfaces extending from 13 to 90 on opposite sides of the radial centerline of the slot 83 as indicated in Fig. 12. These surfaces must be finish-ground very accurately to give constant rise cam surfaces symmetrically about the radial centerline of the slot 83.

Mounted on the shaft 70 intermediate the outer face of the bearing 69 and the inner faceofthe head portion 71 of shaft 70, is a master cam 91. This master cam 91 isfiired to the shaft.70 and is urged up against the cam follower roller 38, thereby to determine the heights 7 port 94. The rack support 94 hasa projecting rib 95 extending. along its length. which fits slidably into a trackway-96 which in turn is formed in a guide block 97. The guide block 97' is mounted upon a portion of the bearing block 67 and? is threaded to receive a. retainer screw 98, the head of'which rests in a shouldered portion 99 of a guide slot 100formed'in the'racksupport 94. By means of-this' construction'the rack 93 is mounted for movement transversely of the bearing block 67 and when moved will impart rotationthrough the gear 92 to the shaft 70'. The

"rack'suppo'rt Mas-threaded to receive a studshaft 101 on-which the-cam roller 55 is freely rotatable. Fuponcrotationzof cam 51 thexcarn roller- 55 will be-re- Thus ciprocated and will impart reciprocatory motion to the 4 rack 93 which 'in turn will rotate shaft through'the instrumentality of gear 92.

The bearing block 67 is slidable transversely of the apparatus in a horizontal, rectangular slot 105 formed in the main supporting block 29. A horizontal, rectangular slot 106 formed in the faceplate 45 is aligned with, but slightly larger than the slot 105 in the main supporting block 29, clearance being, provided so that the bearing block 67 will slide freely in the slot 105. The face plate 45 hasa rearwardly projecting portion 107 in which there is mounted a headed plunger 108. The plunger 108 bears against the left side (Fig. 3) of the bearing block 67 and isurged to the right (-Fig. 3) by a compression spring 109. The compression spring 109 is seated in a bore 110 and the: pressure exerted by the spring 109 on the plunger 108 may be regulated by a threaded plug 111 threaded into the bore 110. By means of thisjust described mechanism,.the cam .roller 56 ispressed against thecamsurface of. th'ecam52 which is shown in detail in Fig. 11.

Operation:

In the operation" of the apparatus, the cam blank 24', which has been formed approximately tothe configuration' shown in Fig. 12, is mounted between the clamping plate 79 and the clamp holding block 73 in a position where the projecting tang. of the locating member 74 nests-in" the slot: 83 in the cam-blank to be ground in the apparatus. When the: cam-blank is mounted in this position; the surfaces of the cam-blank whichare to be ground are aligned with'a .similar'configuration formed on the ma'stercam' 91;

The cam groove 54 (Fig: l0) formed in the' cam 51 is of a configuration such that during that portion of the rotation of the cam- 51 wherethe cam roller 55' is engaging the cam slot in theme indicated by the letter A, rota tion' will be imparted tothe shaft7'0l Rotation will also be imparted to the shaft 70 when the cam roller 55 is engaging that portion or track. of" the cam groove 54-indicate'd' by the letter B, whereas no rotation' will beimparted-to the shaft 70-during'that arc of rotation of the cam 51 indicated at C. Thus; when the actuating lever 53 is moved through an-arcuate'. course, for-example in the direction indicated by the arrow in Fig."1-, the shaft 70 will be rotated through a predetermined angle in a clockwise direction as viewed in Fig; 1, will rest and then portionzD has been;gr'oundand1the grinding: Wheel 15 is in contact therewith immediately adjacent to the near edge of theyslot 83; .a rise-112 on the cam 52 engages the. cam roller 56, andthe' bearing block 6 7 is indexed rapidly tortherighhas'viewed in Fig-.1, to carrythe shaft 70 and cam-blank 24 la'terally toa: position wherein the grinding .wheel contacts theperipheral:portion E immediately adjacentto the fartedge of therslot 83. The spring 109 providestheforcenecessary to move the bearing block 67 to the right during this indexing movement.

While-the slot 83 :is-moving laterally past the grinding wheel 15. during the last-described indexing movement, there is no rotation imparted/to the shaft 70 and carnblank 24-due to the configuration of-the cams 5:1 and 52. Since the shaft 70, th'e pinion 92, the rack 93, and the cam roller 55 are all carried by the bearing block 67, his manifest that for the. bearing block to shift laterally without rotation of the shaft 7 0,-there can'be norelativen-iovement between the camrollers 55 .an dl56during'the indexingmovement.. Accordingly,.the.portion C. of. the cam slot 54 of the cam 51 has been designed so as to give the same lateral movement to the cam roller 55 as the rise 112 of the cam 52 gives to the cam roller 56.

From Fig. 1, it may be seen that during the grinding of the peripheral portion D of the cam blank 24, the center of rotation of the cam-blank and the shaft 70 is displaced a predetermined distance to the left of the vertical plane including the axis of shaft 16 of the grinding wheel 15. This distance is equal to one half of the rise 112 on the cam 52. After the lateral indexing movement the center of rotation is displaced the same distance on the opposite side of the vertical centerline of the grinding wheel 15.

At all times the main supporting block 29 is urged upwardly under the control of the master cam 91 to cause the grinding wheel to engage the cam-blank 24 being ground until the surfaces of the peripheral portions D and B have been ground to the degree necessary as determined by the master cam, which will then engage the cam follower roller 38. In this manner a cam-blank 24 may be finished to a high degree of accuracy by relatively unskilled operators.

Periodically the grinding wheel 15 may be trued and dressed by simply sliding the plate 18 over to a position where the diamond dressing tool 21 will engage the grinding wheel 15 after the gauge plate 22 has been moved out of association with the dressing tool 21. By means of this dressing tool the distance which the grinding wheel 15 is located above the plate 18 may be accurately controlled.

Although specific mechanisms have been described hereinbefore for effecting the several desirable movements of the cam being ground, it will be understood that various modifications thereof may be made without departing from the invention.

What is claimed is:

l. A cam grinding apparatus comprising a grinding wheel rotatable about a fixed axis, means for supporting a cam blank for rotation, a carriage carrying said supporting means and shiftable to either of two predetermined positions to move the axis of rotation of the cam blank laterally of the axis of the grinding wheel, and a shaft having a pair of cams thereon one of which actuates the carriage for shifting movement and the other of which effects the rotation of the cam blank.

2. A cam grinding apparatus comprising a grinding wheel rotatable about a fixed axis, means for supporting a cam blank for rotation, a carriage carrying said supporting means and shiftable to either of two predetermined positions to move the axis of rotation of the cam blank laterally of the axis of the grinding wheel, a shaft having a pair of cams thereon one of which actuates the carriage for shifting movement and the other of which effects the rotation of the cam blank, a main supporting block for supporting said carriage for movement, and means for urging said main supporting block in a direction to carry the cam blank into engagement with the grinding wheel.

3. A cam grinding apparatus comprising a grinding wheel rotatable about a fixed axis, means for supporting a cam blank for rotation, a carriage carrying said supporting means and shiftable to either of two predetermined positions to move the axis of rotation of the cam blank laterally of the axis of the grinding wheel, a shaft having a pair of cams thereon one of which actuates the carriage for shifting movement and the other of which effects the rotation of the cam blank, a main supporting block for supporting said carriage for movement, means for urging said main supporting block in a direction to carry the cam blank into engagement with the grinding wheel, a cam follower held in a fixed position with respect to said grinding Wheel, and a master cam engageable with said cam follower to control the degree of movement of said main supporting block.

4. A cam grinding apparatus comprising a fixture for supporting a cam blank to be ground in a position for association with a grinding wheel, said fixture including a main support block mounted for movement in a rectilinear path, means for urging said block to move in said path to carry a blank in the fixture into engagement with the grinding wheel, a carriage mounted for movement in said support block in a direction transverse to the direction of movement of the block, a shaft carried by said carriage and having on it means for holding a blank to be ground, means for imparting rotation to said shaft in two steps, and means for imparting movement to said carriage intermediate the two steps of rotation of said shaft.

5. A cam grinding apparatus comprising a fixture for supporting a cam blank to be ground in a position for association with a grinding wheel, said fixture including a main support block mounted for movement in a rectilinear path, means for urging said block to move in said path to carry a blank in the fixture into engagement with the grinding wheel, a carriage mounted for movement in said support block in a direction transverse to the direction of movement of the block, a shaft carried by said carriage and having on it means for holding a blank to be ground, means for imparting rotation to said shaft in two steps, and means for imparting movement to said carriage intermediate the two steps of rotation of said shaft, said last-mentioned means comprising a cam shaft movable with said support block, a pair of cams on said cam shaft, a cam roller carried by said carriage in position to be engaged by one of said cams on said cam shaft, and a cam roller for actuation by the other of said cams on said cam shaft, said second-mentioned cam roller serving upon actuation to impart rotation to the shaft supporting the cam blank.

6. A cam grinding apparatus comprising a fixture for supporting a cam blank to be ground in position for association with a grinding wheel having a grinding surface in a fixed location, said fixture including a main support block mounted for movement in a rectilinear path, a carriage mounted for movement in said support block in a direction transverse to said rectilinear path, a shaft carried by said carriage and having on it means for holding a blank to be ground, means for rotating said shaft including a gear on said shaft and a rack slidable with respect to said carriage, a cam roller mounted on said carriage, and a cam for actuating said cam roller to move said carriage from one position to another, a. second cam for actuating said rack and a cam shaft common to both of said cams.

7. A cam grinding apparatus comprising a fixture for supporting a cam blank to be ground in a position for cooperative association with a grinding wheel, said fixture including a main support block mounted for movement in a rectilinear path, means for urging said block to move in said path to carry a blank in the fixture into engagement with the grinding wheel, a carriage mounted for movement in said support block in a direction transverse to the direction of movement of the block, a shaft carried by said carriage and having on it .means for holding a blank to be ground, a cam shaft movable with said support block, a pair of cams on said cam shaft, a cam roller carried by said carriage in position to be engaged by one of said cams on said cam shaft for moving said carriage, a cam roller for actuation by the other of said cams on said cam shaft, a rack mounted to be actuated by the second-mentioned cam roller and a gear meshing with said rack and mounted on the shaft which holds the blank to be ground.

References Cited in the file of this patent UNITED STATES PATENTS

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