US2421548A

US2421548A - Apparatus foe grinding articles of

Info

Publication number: US2421548A
Authority: US
Publication date: 1947-06-03
Anticipated expiration: 1964-06-03

Description

June 3,. 1947. 2,421,548

APPARATUS FOR surname ARTICLES 0F IRREGULAR FORM R. DAVIES Filed June 20, 1945 5 Sheets-Sheet 1 I Ir] UIIJIIIII I 41! 11 II l I] u n Inventor Ilh Attorney R. DAVIES 2,421,548

APPARATUS FOR GRINDING ARTICLES OF IRREGULAR FORM June 3, 1947.

Filed June 20, 1945 5 Sheets-Sheet 2 I n venlor 32,4 @zdzm'es A ttbrney June 3, 1947. R, DAVlEs 2,421,548

APPARATUS FOR GRINDING ARTICLES OF IRREGULAR FORM Filed June 20, 1945 5 SheetsSheet 5 7 12E 7 I 22 F/GS. v

Attorney June 3, 1947. R. DAVIES 2,421,548

APPARATUS FOR GRINDING ARTICLES OF IRREGULAR FORM Filed June 20, 1945 5 Sheets-Sheet 4 I nventor z Attorney June 3, 1947. DAVlEs 2,421,548

- APPARATUS FOR GRINDING ARTICLES OF IRREGULAR FORM Filed June 20', 1945 s Sheets-Sheet 5 I n ventor A llomey Patented June 3, 1947 APPARATUS FOR GRINDING ARTICLES F IRREGULAR FORM Rowland Davies, 'Gerrards Cross, England, as-

signorto The Metal Box Company Limited, Perrywood, Worcester, England, a company of Great Britain Application'June 20, 1945, Serial No. 600,458 In Great'Britain July 3, 1944 15 Claims.

This invention relates to methods of an apparatus forgrinding articlesof irregular form, such as male and female dies,cams, and other irregularly shaped objects which have to be precision ground to size.

A main object. of the invention is to: provide a method of grinding articles of irregular form which is "simple and convenient. to carryout.

-A further object of the invention is to provide a method of and apparatus for grinding irregularly shaped objects which will permit adjustment for wear of the grinding wheel to be made during the grinding operation.

Another object of the invention istoprovide means by which both male and female work pieces, not. necessarily of the same size but of parallel shape, may be ground truly, using only theone master cam, thus insuring perfect correspondence. I

In order that the invention may be more completelyunderstood reference is directed to the following description and the accompanying drawings, wherein Fig. 1 .illustratesa set-up for internal profile grinding in whichthe. grinding wheel axisis ver-- tical, the figure being a front elevation, partly in section;

Fig. 2 is a side view of the cam driving mechanism;

Fig, 3 is a plan of thecam and its drivingmechanism i Fig. 1 is a fragmentary View similar to Fig. 1 but showing a setup for external profile grindin Fig. -5 illustrates in front elevation a modified formof apparatus in whichthe grinding-wheel axis is horizontal;

Fig. 6 is an end elevation in section on the line VIVI in Fig. 5, the driving mechanism for themaster cam being omitted;

. Fig. 7 isan end elevation in section on the line VIIVII in Fig. 5, the driving mechanism for the grinding wheel and the lever supporting the master cam and workpiece being omitted, and Figndis a plan, and Figure 9illustrates a further modification.

In the embodiment illustrated by Figs. 1 to 4 inclusive, which is intended for grinding a male or female workpiece by usin a master female earn the apparatus comprises a camplate l0 having arallel faces and formed with an internal cam contour H which is parallel to and larger thancthe workpiece to be ground, the external contour l2 of the cam plate In beingsubstantially parallelto the internal contour ll. thereby providing an irregularly shaped ring of approximately uniform wall thickness.

The cam plate lllrests freely on the worktable l3 of the machine and. the grinding wheel [41s mounted above the cam plate lil on an axisat right angles to the table. [3. The grinding wheel head may be made to reciprocate by anyknown form of mechanism to ensure even wear over the whole face of the wheel. The internal contour ll of, the cam engagesa follower roller l5 having a conical bore 1.6 through which passes the conical head ll of an adjusting spindle 18' mounted coaxially with the grinding wheel Hi, the head ll of the spindle l8 being of maximum diameter at. its upper end and tapering downwardly. The cam H! is driven by a friction roller 22 engaging the external periphery of the cam and driven in a manner described later. As the cam lllfis caused to gyrate around the roller I5, the point of contact between cam I0 and friction roller I5 is always approximately on a line passing through the axis of the adjusting spindle l8. and the centre of the friction .roller 22. Thus the thrust from the cam .driving roller 22 passes approximately through the axis of the grinding wheel l4.

If the adjusting spindle I8 is lowered theconical head I! thereof will displace the roller l5 and the cam l0 horizontally against the pressureexerted by the driving roller 22 which is mounted so that it can move while maintaining contact with the cam l0, and the centre of the follower roller I 5 will move along the line joining the axis of the grinding wheel l4 and the point of contact between the cam l0 and roller, whereby the distance between said point of contact and the grinding wheel axis is increased. Conversely, if the adjusting spindle I8 is raised said distance will be reduced.

The cam driving roller 22 is secured to the lower end of an axle pin 23 mounted vertically in aboss 24 formed at one end of a pivoted lever 25, the pivot pin 26 of the lever, 25 upstanding from a block 21 secured to the worktable I3 and passing through another boss 28 provided at about the middle of the lever 25. On the upper end of the pivot pin 26 are two sprocket wheels 29, 3!! which rotate in unison, the lower wheel 29 being drivingly connected by a chain 3| to another sprocket wheel 32 secured to the upper end of the axle pin 23 of the cam driving roller 22, whilst the upper wheel 30 .is driven by chain (not shown) from any available source of rotary motion. The end 33 ofthe pivoted lever 25 is pierced with a hole 34.for connecting to the lever a spring or a cable leading to a balance weight whereby the lever 25 is pivoted to maintain the driving roller 22 in frictional engagement with the external contour of the cam 10. The lower end of the axle pin 23 may ride over the face of the worktable [3, as shown, to afford support to the outer end of the lever 25.

The cam plate l carries a number of upstanding pillars 35 on the top ends of which is fixed a centre plate 35 which is thus secured to and above the cam plate Ill and in a plane parallel thereto. Conveniently the centre plate 39 is approximately the same shape as the cam plate l0 and of the same size as the outside dimensions thereof. The centre plate 36 is provided with a number of tapped holes 3! in which may be engaged bolts 33 for attaching the workpiece 39 thereto in a plane above and parallel to the centre plate 36. Assuming that the workpiece 39, has an interval contour to be ground in a given position relative to the other dimensions of the workpiece, it will be provided with holes, 4| for the reception of bolts, as these holes being arranged so that the workpiece is fixed in this relationship to the already located internal contour, ll of the cam plate, ID. The bolts 38 pass through spacing collars 42 which support the workpiece 39 a suitable distance above the centre plate 36.

It will thus be seen that, the workpiece 39 being fixed to the centre plate 39, which is in turn fixed to the cam plate It), the workpiece 39 will execute the same gyratory motion as that of the cam plate I3, the position in which the cam lll'and workpiece 39 gyrate being controlled by the adjusting spindle I3 with the conical head A suitable choice of cam follower roll and grinding wheel diameters will allow the grinding whee] l4 to pass inside the contour 40 to be ground. By raising the adjusting spindle I8 by turning the handwheel 43 the effective diameter of the cam follower roller I5 is reduced and thus the distance from the axis of the grinding wheel M to the internal contour 43 of the workpiece 39 is reduced, whereas by lowering the adjusting spindle l8 said distance is increased. Accordingly by raising or lowering the adjusting spindle I8 the grinding out can be put on or reduced.

In using the above described apparatus the adjusting spindle I8 is lowered until sufficient clearance is obtained between the grinding wheel l4 and the contour 4!] to be ground to permit the wheel to be lowered inside said contour. The cam l9 and workpiece !3 are then caused to gyrate by the driving roller 22 and the grinding wheel I4 is set in motion. The adjusting spindle 8 is then raised until the contour 49 to be ground comes into contact with the rotating grinding wheel l4, the shape ground thereby being parallel to the cam I!) for any given setting of the adjusting spindle l8 and the size of this shape being increased by raising the adjusting spindle I8 to put on the cut.

In order to determine when the workpiece has been ground to a predetermined size it is only necessary to measure one dimension thereof, e. g., the length or a diagonal.

If a male workpiece or the male profile of a ring-like article (as in Fig. 4) is to be ground by the above described apparatus the workpiece 39 is attached to the centre plate 33 in exactly the same manner as before and then the adjusting spindle I8 is raised to push the workpiece 39 away from the grinding wheel [4a until suflir 4 cient clearance has been obtained to permit the wheel to be lowered outside the contour to be ground; in thi case the cut is put on by lowering the adjusting spindle I8.

In general it will be necessary to change the follower roller |5a to one of smaller diameter when changing from internal to external grindmg.

In order to operate the adjusting spindle 18 the following mechanism may, for example, be provided.

The spindle I8 is mounted in a sleeve 44 having a flange 45 at one end so that the sleeve 44 may be inserted through a hole 43 in the worktable [3 to depend therefrom by its flange 45, the sleeve 44 being provided with an externally screwthreaded portion below the flange 45 to receive a nut 41 for clamping the sleeve 44 to the table [3. At its lower end the sleeve 44 is internally screw-threaded to receive a screw-threaded portion of the adjusting spindle l8 and on the lower end of the spindle I8 is fitted the handwheel 43 graduated on its periphery to indicate the extent of out put on for a given rotary movement of the handwheel 43, the graduations travelling past a pointer 48 fixed to the sleeve. The externally screw-threaded portion of the spindle is provided with a locking nut or ring 49 for fixing it securely in the adjusted position, and the upper end of the sleeve 44 is coned internally as indicated by reference 59 to clear the conical form of the spindle head I! when in its lowest position.

In the modification shown in Figs. 5 to 8 the apparatus is constructed to operate with the grinding wheel axis horizontal instead of vertical, the conical headed adjusting spindle being, of course, horizontal and coaxial with the grinding wheel. y

In this construction the female cam I0 is fixed by bolts (not hown), having distance pieces 35, to a face plate 69 fixed to one end of a spindle 6| rotatably mounted in the end 62 of a lever 63, the centre plate 64 to which the workpiece 39 can be attached, by bolts having distance pieces 42, being secured to the other end of the spindle 6|, and the spindle being prevented from axial movement by the two

plates

69 and 64. At its other end the lever 63 is freely pivoted on a spindle 65 carried in bearings 66 mounted on a carriage 6! having wheels 61a running between fixed guide rails 68 at right angles to the axis of the grinding wheel 14 in the horizontal plane and so that the end of the lever 63 carrying the cam I 0 is completely free to follow the movement of the cam. The lever 63 is balanced about the pivot 65 by means of an adjustable weight 6311..

The cam I0 is, as before, rotated by a friction roller 22 secured to a spindle 69 mounted in a bearing 10 formed in one end of an arm I! pivoted at 12 to a fixed support 13, whereby the roller 22 yieldably engages the external periphery of the cam l0. Mounted on arm H is a motor 14 which drives the roller 22 through a belt 15.

With the internal contour ll of the cam I9 engages the follower roller l5 through the conical bore [6 of which passes the conical head I? of the adjusting spindle I8, which, as in the construction shown in Figs. 1 to 4, is mounted coaxially with the grinding wheel 14, and is there fore, in the construction of Figs. 5 to 8, mounted horizontally.

If the adjusting spindle I8 is moved to the 5 leftin'Fig. 5 the conical head I! thereof will displace the roller 15 and the cam in vertically upwards against the pressure exerted by the weight of lever II acting through the driving roller 22, the lever 1|. risingin Fig. 7. Accordingly the centre of the follower roller l5 :will, as in thecon'struction shown in Figs. 1 to- 4, move along the linev joining the axis of thegrinding :wheel 14 and the point of contact between the cam HI .and the roller 15, whereby the distance between: said point of contact and the grinding wheel axis is increased.

Conversely if the adjustinglspindle i8 is .moved to the right in Fig. 5 the weight of lever H, actingthrough the roller .22 will .push; the: cam l'll 'ventically downwards, maintaining the follower roller l5lin contact with the conical head [1. Accordingly the distance between .the' grinding wheel axis and the point of contactsbetweencam Hland roller l5 will be reduced.

1 In order to move the spindle is inandzout .the outer end thereof is screw-threaded .and engages a fixed nut 44a, .the spindle being. providedrwith ahand'wheel..43a,:and;a looking nut (notshown) similarto, the lockingnut 49.

The grinding wheel I4 is secured to adrive spindlewalfi'mountedcon a slide H which also car riest the motor 18 which drivesthe wheel 14 through a belt 18 and pu1leys80. The slide H may be moved in and out in the: usual manner by means of a rack 8| and pinion 82 operated by a handwheel 83.

With the vertical and horizontal for-ms of apparatus just described the "distance between the inner and outer walls of the followerroller is the important dimension rather than the actual outsidewdiameter and this fact renders it possible to use rollers with the same outside diameterforboth internal and external grinding so that any slight errors in the cam are reproduced in both con-tours to the same extent. It is here pointed out that a small roller will clearly be more sensitive to slight irregularities in the cam than a roller of larger diameter.

Figure 9 illustrates a further embodiment of the invention in which instead of employingan internally conical roller, a roller [15 having a cylindrical bore is provided. The roller I15 runs on a pin 215 fixed to and concentric with a rich low support 315 freely disposed overthe conical head 11 of the adjusting spindle Hl, saidhead [1 extending through'a conical bore M5 formed in the base 5i5 of the support 3I5 whichrcsts freely on the flange 45.

The template ID has a depending "annular rib H whereby itis freely supported on the worktable 13 with its internal contour ll maintained in engagement with the roller M5, by the friction roller 22 which is .driven by the means already described with reference to the construction shown in Figures 1 to 4.

The grinding wheel I4 is mounted coaxi'a lly with the adjusting spindle l3 andthe latter is raised and lowered by the mechanism shown in Figure l. Lowering of the spindle1l8 displaces the hollow support 3| 5, roller H and cam il'll horizontally against the pressure exerted by "the drivingroller 22, the centre of the latter moving along the line joining the axis of the grinding wheel 14 and the point of contact between the cam H] and the roller, whereby the distance be,- tween said .point of contact and the grinding wheel axis is increased. Conversely, if the adjusting spindle i8 is raised said'distance will'ibe reduced.

Asinthe construction. shown in. Figures 1- to; 4, the workpiece 39 is; secured byvbolts SB-toaqentre plate 36 which is secured to .and aboveqthe cam plate l0 and in aplane; paralleltheretosby means of pillars 35 upstanding from theplate H1. Sucha construction has the advantage that the roller is more free to rotate and is cheaper to manufacture, while thelchange from one roller to. another ofdifferent size is more easily. efi'ectecl, since it is necessary to. change the outside diameter of the cylindrical rollers only.

The method of grinding according to the inventiomhas the advantage that by adjusting the effective :diameter of the roller, grinding wheel wear is compensated for and the-actual diameter of the wheel becomes unimportant within wide limits, while;the same adjustment alsoaffords a means of puttingon the out. At :all times .during'grinding operation, solongas the face being ground has cleaned-up and the cut is allowed to run out, the form of theworkpiece will be parallel to that of the cam therefore the grinding operation is continued until by measurement of any convenient dimension, it isascertained that the workpiece is .of the size required.

From the' foregoing it will be understood that a single master cam having an internal contour can be used to grind both male and female workpieces such as dies of irregular form, and that also the master cam for a particular job, internal, or external can be ground on the same machine using a female template of the actual. jobrequired as the controlling cam. Such irregular dies'when ground on a machine according to the invention will have the sameaccuracy as dies of circular form.

In the construction described above boththe master camand the workpiece although rigidly connected together are floating as a unit in relation to the grinding wheel and the follower roller. If desired however the master cam and work piece could be mounted to rotate about a fixed bearing while the grinding wheel head and the adjusting spindle with its follower roller could be rigidly connected together and movable. as a unit relatively to thework.

Constructions according to the invention, are particularly suitable for grindingdies of irregular shape such as those employed in the manufacture of sardine tin bodies and ends. Further any'number of such dies all alike within. the limits usual for dies of circular form may be ground bymeans of apparatus according to the invention. By the employment of formed grinding wheels radii could be put on parts which require them, such as punch bores and die centre blocks.

The invention may also be .used to grindcams of any contour whether internal or external, and re-entrant curves may also :be ground within limits depending on the practical sizecof the grinding wheel.

The invention also includes articles of irregular form, such as dies employed in the manufacture of sardine tin bodies and ends, ground in accordance with the method hereinbefore set forth.

I claim:

1. Apparatus for grinding articles of irregular form, comprising in combination, a grinding wheel, a cam for supporting the article and, havinga contour parallel to the contour to-be ground, means for causing the cam to gyrate in a plane perpendicular to the grinding wheellaxis and an adjustable abutment. consisting of an element axially aligned with the grinding wheel axis and 7 a second element with which the cam contacts as it gyrates and which is movable for adjustment relative to the first element.

2. Apparatus for grinding articles of irregular form comprising in combination a grinding wheel, a cam for supporting the article and having a contour parallel to the contour to be ground, means for causing the cam to gyrate in a plane perpendicular to the grinding wheel axis, a follower roller disposable to co-operate with said cam, means for varying the effective diameter of said roller while its effective centre remains coincident with the grinding wheel axis, and means for maintaining the gyrating cam in contact with said follower roller.

3. Apparatus for grinding articles of irregular form comprising in combination a grinding wheel, a cam for supporting the article and having a contour parallel to the contour to be ground, means for causing the cam to gyrate in a plane perpendicular to the grinding wheel axis, an adjustable abutment device comprising two elements having mutually engaging inclined planes, a parallel sided roller mounted on one of said elements to contact the gyrating cam, and means for moving the other of said elements relatively to the roller-carrying element to vary the position of the roller relatively to the grinding wheel axis.

4. Apparatus for grinding irregular male and female profiles from a single master, comprising in combination, a grinding wheel, a cam ring with one of its profiles having a contour parallel to the male and female profiles to be ground, means for supporting the male or the female workpiece on the cam ring, in fixed relation thereto, a rolling abutment, means for maintaining the cam profile which is parallel to the profile to be ground in contact with a point on said abutment while the effective centre of said abutment remains coincident with the grinding wheel axis, means for moving the abutment to adjust the position of said point in relation to the axis of the grinding wheel, and means cooperating with the other profile of the cam to effect gyration of aid cam.

5. Apparatus for grinding articles of irregular form comprising in combination a grinding wheel, a cam, means for freely supporting said cam in a plane through which the grinding wheel axis passes at right angles, means for attaching a workpiece to said cam in a plane parallel to that of the cam, an axially displaceable conical member coaxial with the grinding wheel, an internally conical follower roller rotatable about said conical member, means for restraining said follower against axial movement, means for pressing the cam against said follower roller, means for rotating the cam while pressed against said follower roller, and means for displacing the conical member axially, whereby the follower roller is displaced in its own plane, thereby varying its effective radius, that is, the distance between the grinding wheel axis and the point of contact between cam and roller.

6. Apparatus for grinding irregular male and female profiles of complementary form from a single master, comprising in combination a grinding wheel, a cam ring having one of its profiles with a contour parallel to the male and female profiles to be ground, means for supporting the male or the female workpiece above and parallel to the cam in fixed relation thereto, two members disposed in the same plane, one within the other, the inner one of said members having a conical external surface and the outer one of said members having a conical internalsurface' coacting with said conical external surface of said inner member, resilient means for maintaining the cam profile which is parallel to the profile to be ground in contact with the outer one of said members, means for displacing the inner one of said members axially, whereby the outer member is displaced to positions of varying eccentricity relative to the inner member as the latter is displaced axially, and means cooperating with the other profile of the cam ring to impart a driving movement thereto to cause gyrating of the cam and the workpiece supported thereon.

7. Apparatus according to claim 1 characterised in that the cam is freely slidable during its gyratory movement upon the flat top of a worktable situated at right angles to the axis ofthe grinding wheel.

8. Apparatus for grinding articles of irregular form comprising in combination a grinding wheel, an adjustable abutment having its efiective centre coincident with the grinding wheel axis, means for adjusting the abutment face of said abutment during grinding to vary the distance of said face from the effective centre of the abutment, a cam ring for supporting the article to be ground and having one of its profiles parallel to the profile to be ground, means for maintaining said cam ring with said parallel profile in' contact with the abutment face during a gymtory movement of the cam and a rotary driven member yieldably mounted in frictional engagement with the other cam profile to eifect gyration of the cam and the attached workpiece.

9. Apparatus for grinding articles of irregular form comprising in combination a grinding wheel, a cam ring for supporting a workpiece to be profile ground, said cam ring having one of its profiles Parallel to the workpiece profile when in its finished form, a sleeve disposed in axial alignment with the grinding wheel axis, a spindle within said sleeve, said spindle having a conical head,

a roller having a bore of a conical form complementary to that of the spindle head, said roller being disposed about said head, means maintaining the cam profile which is parallel to the profile to be ground in contact with said roller while driving the cam by its other profile, and means for displacing said spindle axially Within the sleeve whereby displacement of the cam-contacted roller at right angles to said spindle is effected.

10. Apparatus for grinding articles of irregular form comprising in combination a grinding Wheel having its axis horizontal, a lever, a support to which said lever is pivoted at one end with its axis parallel to the grinding wheel axis, a mounting for said support, said mounting permiting free reciprocation of said support but constraining the reciprocation of a direction at right angles to the grinding wheel axis, a spindle parallel to the grinding wheel axis, and carried by the other end of said lever, a cam ring having one of its Profiles parallel to the profile to be ground, said cam ring being mounted on said spindle, means for mounting the workpiece in fixed relation to said cam, a follower roller, means for varying the effective diameter of said follower roller While maintaining its effective centre coincident with the grinding wheel axis, and means for maintaining the cam profile which is parallel to the profile to be ground in contact with said roller, while driving the cam by its other profile.

11. Apparatus for grinding irregular male and female profiles from a single master, comprising in combination a grinding wheel having its axis horizontal, a carriage freely movable horizontally at right angles to said grinding wheel axis, a substantially horizontal lever pivoted at one end to said carriage, a horizontal spindle parallel to the grinding wheel axis and. freely rotatable in the other end of said lever, a cam ring with one of its profiles having a contour parallel to the male and female profiles to be ground, means securing said cam ring to one end of said spindle, means for fixing the article to be ground to the other end of said spindle, a rolling abutment, means for maintaining the cam profile which is parallel to the profile to be ground in contact with a point on said abutment, means for moving the abutment to adjust the position of said point in relation to the axis of the grinding wheel, and means co-operating with the other profile of the cam to effect gyration of said cam while maintained in contact with said point.

12. Apparatus for grinding irregular male and female profiles from a single master, comprising in combination a grinding wheel having its axis horizontal, a carriage freely movable horizontally at right angles to said grinding wheel axis, a substantially horizontal lever pivoted at one end to said carriage, a horizontal spindle parallel to the grinding wheel axis and freely rotatable in the other end of said lever, a cam ring with a profile having a contour parallel to the male and female profiles to be ground, means securing said cam ring to one end of said spindle, means for fixing the article t6 be ground to the other end of said spindle, an axially displaceable conical member coaxial with the grinding wheel, an internally conical follower roller rotatable about said conical member, means for restraining said follower roller against axial movement, means for pressing the cam against said follower roller, means for rotating the cam while pressed against said follower roller, and means for displacing the conical member axially, whereby the follower roller is displaced in its own plane, thereby varying its effective radius, that is, the distance between the grinding wheel axis and the point of contact between cam and roller.

13. Apparatus for grinding articles of irregular form comprising in combination a grinding wheel, a cam ring for supporting a workpiece to be profile ground, said cam ring having one of its profiles parallel to the workpiece profile when in its finished form, an interally screw threaded sleeve disposed in axial alignment with the grinding wheel axis, a spindle disposed within said sleeve, and having a screw thread cooperating with the internal screw thread thereof, said spindle having a conical head, a roller having a bore of conical form complementary to that of the spindle head, said roller being disposed about said head, means for maintaining the cam profile which is parallel to the profile to be ground in contact with said roller while driving 'the cam by its other profile, a hand control member, and an operative connection between said control member and said spindle to rotate the spindle on operation of the control member whereby the spindle is axially displaced within the sleeve with consequent displacement of the cam-contacted roller at right angles to said spindle.

14. Apparatus for grinding articles of irregular form comprising in combination a grinding wheel, a cam ring having one of its profiles with a contour parallel to the male and female profiles to be ground, means for separating the male or the female workpiece in fixed relation and parallel to the cam ring, an axially displaceable conical member coaxial with the grinding wheel axis, a support having an internal conical bore disposed over said conical member, a cylindrical pin mounted on said support, a roller havin a cylindrical bore rotatably mounted on said pin, means for maintainin the cam profile which is parallel to the profile to be ground in contact with said roller while driving the cam by its other profile and means for displacing said conical member axially during a. grinding operation.

15. Apparatus for grinding articles of irregular form comprising in combination a grinding wheel, a cam ring having one of its profiles with a contour parallel to the male and female profiles to be ground, means for supporting the male or female workpiece in fixed relation and parallel to the cam ring, a support, an externally conical roller axially displaceable and rotatably mounted on said support with its centre coincident with the grinding wheel axis, means for maintaining the cam profile which is parallel to the profile to be ground in contact with said roller while driving the cam by its other profile, and means for displacing said roller axially during a grinding operation.

ROWLAND DAVIES.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 300,277 Maloy June 10, 1884 660,642 Keyes Oct. 30, 1900 2,088,737 Forbes Aug. 3, 1937 2,259,472 Johnson Oct. 21, 1941 2,118,806 Brown May 31, 1938 2,365,302 Shutt et al. Dec. 19, 1944