US1949062A - Cam tooth generating mechanism - Google Patents

Description

Feb. 27, 1934. F. MARRIOTT r-:r AL 1,949,052

CAM TOOTH GENERATING MECHANISM Filed Sept. 12, 1952 3 Sheets-Sheet 1 47 TOP/WW Feb. 27, 1934.

F. MARRIOTT ET AL CAM TOOTH GENERATING MECHANISM Filed Sept. 12, 1932 3 Sheets-Sheet 2 Feb.27, 1934. F, MARRlOTT Er AL 1,949,062

CAM TOOTH GENERATING MECHANISM Filed Sept. 12, 1932 3 Sheets-Sheet 3 7 j 17 15 W l 13 J '3 r 3 H1 a *0) y 5 q Z 15 Patented Feb. 27, 1934 PATENT OFFICE CAM TOOTH GENERATING MECHANISM Frank Marriott and Constantine Neklutin, Ferguson, Mo.

Application September 12, 1932 Serial No. 632,768

Claims.

This invention relates generally to machinetools and has more particular reference to a certain new and useful improvement in cam-tooth generating mechanism, our invention having for its prime object the provision of mechanism for generating on suitable stock an exact, accurate, and precise helical or spiral cam-tooth having a varying helix-angle, or, conversely, a groove corresponding thereto.

And with the above and other objects in view, our invention resides in the novel features of form, construction, arrangement, and combination of parts hereinafter described and pointed out in the claims.

In the accompanying drawings (three sheets) Figure 1 is a side elevational view of a camtooth-generating mechanism of our invention, shown in connection with fragmental portions of an operating machine-tool and the work being shown with its tooth in process of formation;

Figure 2 is an enlarged end view of the mechanism';

5 views illustrating the corresponding positions of the cutter at similar successive stages of the formation of the tooth on thework.

Referring now more in detail and by reference characters to the drawings, which illustrate a preferred embodiment of our invention, A designates any conventional machine-tool, preferably of the milling-machine type, which, for our pres ent purpose, may be said to include a frame, of which merely fragmentary portions of the spindie-housing a and table-bracket b are shown. From the spindle-housing a, suitably projects a spindle-head l, and projecting from the spindlehousing a" over the spindle-head 1, is an overarm 2, on the outer end of which is mounted a depending so-called arbor-support 3.

Rotarily mounted in the spindle-head l, is a spindle 4, which is provided with a taper-bore 5 in the usual manner, the arbor-support 3 having a hushed aperture 6 in horizontal registration with the spindle 4 and its bore 5, as best seen in Figures '2 and 3.

B designates a bevel-drive attachment or head, which at one end is attached to a hub 7 mounted on a suitably projecting portion 8 of "the spindlehead 1 for rotation about the axis of the spindle 4. The hub '7 carries a bearing 9, preferably of the ball or roller type, disposed registration with the spindle-bore 5. Supported in and through the bearing 9, is a shaft 10, which includes a taper-shank 11 having driving engagement with the taper-bore '5 of the spindle 4.

The shaft 10 projects into the head B and car-- ries a bevel-pinion 12, which meshes with a bevelgear 13 carried by a cutter-shaft 14 supported at a right-angle to the spindle-axis by suitable upper and lower bearings 15, 16, respectively, preferably also of the ball or roller type, the shaft and gear assembly 13- 14 being inserted through the top of the head B and suitably retained therein, as by a closure 17.

At its lower end, the shaft 14 depends below the head B and carries .a cutter 18of the sO-called end-mill type having side cutting edges 56 and end cutting edges 57, the cutter 18 including a taper shank 1'9 engaging a corresponding bore provided in and through the lower end of the shaft 14, as best seen in Figure 3.

Presented from the head 13 toward, and engaging the hushed aperture 6 of, the arbor-support 3, is a shaft 20, which carries a helicalgear 21 normally restrained against rotation by means presently appearing, but actuable during the operation of the machine for permitting revolution of the head B on its horizontal axis. Such movement of the head B is eliected "by a pair of weights 22 suspended from respective flexible cables, chains, or the like '23 trained over pulleys 24 supported from the opposite ends of a beam 25 suitably mounted on, and laterally extending on each side of, the over-arm 2, the chains 23 being attached to a sheave-wheel 26 mounted on the hub '7 for normally biasing the "head B for movement in counter-clockwise direction, reference being made to Figure 1.

conventionally, the machine-tool A includes a table 27, which, in the present instance, is clamped or fixed in position by means not shown, the usual table-feed screw 28, for the purposes of our invention, being disconnected from the table 27.

Mounted on the table 2'7, is a fixture C rotarily supporting an arbor 29 disposed at a right angle to the axis of the spindle 4 and in the vertical plane of swinging movement of the cutter 18, the

arbor 29 including a shaft 30 extending longitudinally of the table 2'7. The arbor-shaft 30 carries a worm-gear 31 meshing with a worm 32 on a cross-shaft 33, the latter, in turn, carrying a worm-gear 34 meshing with a worm 35 on a shaft 36 extending also longitudinally of the table 27 to an end thereof, where the shaft 36 carries a spur-gear 3'7, meshing with a suitably adjustable idler-gear 38 driven by a gear 39 mounted on the adjacent end of the feed-screw 28, whereby the arbor 29 is driven at a suitably reduced speed from and by the feed-screw 28-, the arbor 29 being rotated, in the present instance, in clockwise direction, reference being made to Figure 2.

A cutter-feed shaft 40 is also mounted in the fixture C parallel with the arbor 29, the shaft 40 carrying at one end a gear 41 meshing with the gear 21 on the head B at a one-to-one ratio.

The shaft 40 at its other end carries an index plate or sector 42 provided with an arcuate series of indexing apertures 43, 44, 45, respectively, adapted to be slidably engaged by a pin 45 shiftably supported on a bracket 47 upstanding from the fixture C for retaining the sector 42 in particular shifted positions, the sector 42 during the tooth-generating operation being moved successively in clockwise direction, that is, from left to right in Figure 2.

When the aperture 43 is in registration with, and engaged by, the pin 46, the head B is retained in rotated position in the axial vertical plane of the arbor 29 for disposing the cutter 18 at an angle of 22 to the left of the vertical center of the axis of the head B, or at an angle of 67 to the longitudinal axis of the arbor29, as seen in Figures 1, 2, and 5.

When the pin 46 engages the aperture 44, the cutter 18 is disposed at an angle of 22 to the right of the vertical center of the head B, as seen in Figure 7, and when the pin 46 engages the aperture 45, the cutter 18 is disposed at an angle of 6'7 also to the right of the vertical center of the head B, as seen in Figure 8.

Axially aligned with the shaft 40, is an oscillatory indexing shaft 48, on one end of which is mounted an indexing arm 49 swingable across the face of the sector 42 and carrying a slidable pin 50 disposed for shiftable movement into and out of the respective apertures 43, 44, 45, in the sector 42, as the case may be. The shaft 48 extends parallel with the arbor-shaft 30 and at its other end carries a pinion 51 meshing with a rack 52 slidably mounted for transverse movement in the fixture C. At its inner end, the rack 52 carries a roller 53 for co-operation with a cam 54 mounted on the adjacent end of the arbor-shaft 30, as best seen in Figures 1 and 2.

The cam 54 includes a fall or workingportion a, a rise or return portion is. and a dwell'c. The proportions of the cam 54 will vary according to the work, as presently more particularly appearing; however, in the present instance, the working portion a includes an angle of approximately 200 of arc and is effective for permitting shifting of the rack 52 for rotating the shaft 48 and arm 49 through on angle of 45 in clockwise direction, reference being made to Figure 2. The rack 52 is returned to initial position by the cam return portion b and is retained in such position by the dwell portion 0 of the cam 54.

D designates the work, which comprises a cylindrical-body in which peripherally a helical tooth or thread 55 of irregular or varying helixangle is to be formed by our mechanism, the finished tooth 55 comprising an end or entering helical portion d merging into an annular or non-helical portion 6 at right angles to the axis of the cam and, in turn, merging into an end helical departure portion f, as best seen in Figures 9 to 13, inclusive.

1n the use and operation of our mechanism, the body D may be cut from a bar of solid stock as in the present instance, or the body D may be rough cast and the tooth-form cut from the casting. In either case, the tooth-generating operation is performed by milling or cutting one side face of the tooth 55, then crossing over and cutting the other side face of the tooth 55, the work revolving approximately two revolutions, more or less, during the generating operation.

In setting the mechanism for generating a particular cam tooth, the arbor-shaft 30 is rotated until the roller 53 of the rack 52 engages the cam 54 at the beginning of the cam work-portion a, the arm 49 being then disposed at extreme lefthand position, reference being made to Figure 4. The head B is then manually rotated for swinging the sector 42-at the left until its aperture 43 is in registration with the shifter-pin 50 of the arm 49. The pin 50 is then inserted into the sector-aperture 43 for locking the head B in such rotated position, the cutter 18 being then disposed at an angle of 67 to the left of the vertical Zenter of the head B, as also shown in Fig- A cylindrical body D of suitable length is then mounted on the arbor 29 with its center in vertical registration with the vertical center of the head B.

The machine tool A is then started in operation, which, through the spindle 4 effects rotatory actuation of the cutter 18 and through the feedscrew 28 effects rotatory actuation of the arborshaft 30 and its carried work D.

Rotation of the arbor-shaft 30 likewise rotates the cam 54 for presenting the falling or working cam-portion a to the roller 53, and, since the weights 22 bias the head 13 for rotatory movement tending to press the roller 53 against the cam 54, the rack 52 will shift for permitting the arm 49 and its pin-connected sector 42 to swing clockwise through an angle of 45, as seen in dot-dash lines in Figure 4, for, in turn, allowingthe head B to rotate counterclockwise through an angle of 45 against the work, the work D meanwhile also rotating as the cutter 18 is brought into engagement therewith for forming one side face of the helical end-portion cl of thev tooth 55, as seen in Figures 5 and 10.

Meanwhile, the operator grasps the anchor-pin 46 and quickly shifts the same into the aperture 43 as the latter is broughtinto registration therewith. The pin 46, as it enters the aperture 43 looks the sector 42 to the'anchor bracket 47 and, at the same time, releases the pin 50 therefrom, the head B then being likewise secured against rotatory movement, with the cutter 18 disposed at an ange of 22 from the vertical center of the head B, as seen in Figures 5 and 10. 3

At such time, the return cam-portion b engages the roller 53 and shifts the rack 52 for swinging the arm 49 counterclockwise through an angle of 45 until the shifter-pin 50 is in registration with the sector-aperture 44, as shown by dot-dash lines in Figure 5. The operator then shifts the pin 50 into the aperture 44, thus locking the arm 49 to the sector 42. Meanwhile, the roller 53 engages the dwell cam-portion c for holding the sector 42 against rotation, the operator then withdrawing the anchor-pin 46 from the aperture 43, thus releasing the sector 42 from the bracket 47 in readiness for the next ensuing cycle of cam-released movement of the arm '49.

The head B is in such described manner locked against movement, with the cutter 18, as has been said, disposed at an angle of 22 from the vertical center of the head B, while the cam 54 rotates until the beginning of the working cam-portion a is again brought opposite the roller 53, the work D being correspondingly rotated and the cutter 18 forming one side face of the annular or non-helical portion e of the tooth 55, as seen in Figures 1, 2, 6 and 11. V

The falling or working cam portion a is new again presented to the roller 53, whereby the rack 52 is allowed to shift, responsive to bias of the weights 22, for swinging the arm 49 and sector 42 clockwise through an angle of 45 for, in turn, permitting the head B to rotate counterclockwise again through an angle of 45 against the work, the work D also rotating as the cutter i8 now crosses over to the other side of the tooth portion 6, as shown in dot-dash lines in Figures '6 and 11, the cutter 18 on its one side engaging its cutting edges 56 with one side face of the departure helical end portion 1 of the tooth 55. At the same time on its other diametrically opposite side the cutter 18 engages its cutting edges 56 with the other side face of the entering helical end portion 01 of the tooth 55, as best seen in Figures '7 and 12, the width of the channel or groove 9 between the tooth portions 11 and being thus, as will be seen, equal to the diameter of the cutter 18.

Meanwhile, the operator again grasps the anchor-pin 46 and shifts the same into the aperture 44 as the latter is brought into registration therewith, the shifter-pin 50 being displaced from the sector 42 for releasing the arm 49, while the pin 46 locks the sector 42 and head B against rotatory movement, the cutter 18 being then disposed at an angle of 22 from the vertical center of the head B, as also seen in Figure 7.

Now the return cam-portion b again engages the roller 53 and shifts the rack 52 for swinging the arm 49, as before, through an angle of 45 for bringing the pin 50 into registration with the sector-aperture 45, as shown by dot-dash lines in Figure 7. The operator then shifts the pin 50 into the aperture 45, thus once more locking the arm 49 to the sector 42. Meanwhile, the roller 53 engages the dwell cam-portion c for holding the sector 42 against rotation, the operator withdrawing the pin 46 from the aperture 43 for releasing the sector 42 from the bracket 47 in readiness for the next ensuing movement of the arm 49.

The head B is thus again locked against movement with the cutter 18 in its described position at an angle of 22 from the vertical center of the head B, while the cam 54 rotates until the beginning of the cam-portion a is brought into registration with the roller 53, the work D being likewise rotated while the cutter 18 generates or forms the other side face of the annular portion e of the tooth 55, as will be understood from Figures 8 and 13.

The falling or working cam-portion a is now for a third time presented to the roller 53, the rack 52 then shifting, as before, for swinging the arm 49 and sector 42 clockwise through an angle of 45, the head B rotating counterclockwise through an angle also of 4. and, the work D continuing its revolution, the cutter 18 cuts and generates the other face of the departure helical end-portion f of the tooth 55, the cutter finally being disposed wholly away from the work D at an angle of 67 /2 from the vertical center of the head B, as also seen in Figures 8 and 13.

The machine is then stopped and the finished work D' is removed from the arbor 29. The arbor-shaft 30 is then allowed to rotate for engaging the return cam-pcrtion b with the roller 53 for shifting the arm 49 counterclockwise through an angle of 45, while the operator withdraws the pin 50 from the aperture 45 and manually rotates the head B until the sector-aperture 43 is in registration with the pin 50, the latter then being inserted into the aperture 43 as the beginning of the cam-portion a comes into registration with the roller 53, the several parts being then restored to respective initial positions for repetition of the tooth-generating cycle as described.

While the side-cutting edges 56 of the cutter 18 are generating the tooth 55, the end cutting edges 57 of the cutter 18 are cutting the barrelportions h of the work D. It will be seen that, by varying the projection of the cutter 18 from the horizontal axis of the head 13, the arcuate contour of the barrel-portions it may be varied suitably to the radius of movement of a lever, gear, or other like element to be actuated by the finished worm-cam D. Furthermore, by suitably varying the conformation of the cam 54, and by varying the spacing and number of apertures in the sector 42, correspondingly varying shapes of teeth may be generated on the work D, as may best serve the intended purpose.

It will be understood that other changes and modifications in the form, construction, arrangement, and combination of the several parts of the apparatus may be made and substituted for those herein shown and described without departing from the nature and principles of our invention.

Having thus described our invention, what we claim and desire to secure by Letters Patent is,-

1. Mechanism for generating a helical camtooth having a varying helix-angle comprising, in combination, a rotary spindle, a head mounted for rotatory movement about the axis of the spindle, a cutter carried by the head for rotation by the spindle, an arbor for rotarily supporting the work in co-operation with the cutter, and means having operable association with the head and arbor for intermittently rotarily actuating the head for varying the angular-engaging relation of the rotating cutter with the rotating work.

2. Mechanism for generating a helical camtooth having a varying helix-angle comprising, in combination, a rotary spindle, a head mounted for swingable movement about the axis of the spindle, a cutter swingable with the head and supported by the head for rotation by the spindle, an arbor for rotarily supporting the work in co-operation with the cutter, and means having operable association with the head and including indexing mechanism associated with the arbor for swingably at intervals during the rotation of the arbor and its supported work actuating the head for varying the angular-engaging relation of the rotating cutter with the rotating work.

3. Mechanism for generating a helical camtooth having a varying helix-angle comprising, in combination, a rotary spindle, a head mounted for swingable movement about the axis of the spindle, a cutter swingable with the head and angularly supported by the head for rotation by the spindle, an arbor for supporting the work in co-operation with the cutter, means for rotarily actuating the arbor, and means including indexing mechanism associated with and responsive to actuation of the arbor and having operable connection with the head for rotarily at intervals during the rotation of the arbor swingably actuating the head and its carried cutter for varying the angular-engaging relation of the rotating cutter with the rotating work.

4. Mechanism for generating a helical camtooth having a varying helix-angle comprising, in combination, a rotary spindle, a head mount ed for swingable movement about the axis of the spindle, a cutter swingable with the head and angularly disposed on the head for rotation by the spindle, an arbor for supporting the Work in co-operation with the cutter, means for normally biasing the head for feeding the rotating cutter longitudinally on the work, means for rotarily actuating the arbor, a rotary cam actuable in synchronism with the arbor, and means operable responsively to actuation of the cam for controlling the biased feeding movement of the cutter.

5. Mechanismfor generating a helical camtooth having a varying helix-angle comprising, in combination, a rotary spindle, a head mounted for swingable movement about the axis of the spindle, a cutter swingable with the head and carried by the head for rotation by the spindle, a rotary arbor for supporting the work in cooperation with the cutter, means normally biasing the head for feeding the rotating cutter longitudinally on to the work, means for rotarily actuating the arbor, a rotary cam actuable in synchronism with the arbor, and mechanism for controlling the biased feeding movement of the cutter, said mechanism including an indexing plate having rotative operative connection with the head and a series of indexing apertures, and an oscillatory member actuable responsively to said cam and engageable with successive apertures.

6. Mechanism for generating a helical camtooth having a varying helix-angle comprising, in combination, a rotary spindle, a head mcunted for swingable movement about the axis of the spindle, a cutter swingable with the head and carried by the head for rotation by the spindle, a rotary arbor for supporting the work in cooperation with the cutter, means normally biasing the head for feeding the rotating cutter longitudinally on the work, means for rotarily actuating the arbor, a rotary cam actuable in syn chronism with the arbor, and mechanism for controlling the biased feeding movement of the cutter, said mechanism including an indexing plate having rotative operative connection with the head and a series of indexing apertures, a

rack reciprocatorily actuable by the cam, and an oscillatory arm actuable by the rack and engageable with successive apertures.

'7. In an apparatus for generating a helical tooth of varying helix-angle, the combination with a rotary spindle, of a head for swingable movement about the axis of the spindle, mechanism supported by the head for rotatory actuation by and with the spindle, a rotary shaft disposed angularly with respect to the spindle and actuable by and with said mechanism, a cutter mounted on said shaft, means for rotarily supporting the Work, and mechanism co-operable with said means for eifecting swingable actuation of the head about the spindle for feeding the rotating cutter longitudinally on the work.

8. In an apparatus for generating a helical tooth of varying helix-angle, the combination with a rotary spindle, of a head for swingable movement about the axis of the spindle, mechanism supported by the head for rotatory actuation by and with the spindle, a rotary shaft disposed angularly with respect to the spindle and actuable by and with said mechanism, a cutter mounted on the shaft, means for rotarily supporting the work, and mechanism co-operable with said means for effecting swingable actuation of the head about the spindle for feeding the cutter longitudinally on the work, said last mechanism including a gear on the head, a feed-shaft, a gear on the feed-shaft for co-operation with the first gear, an indexing plate on the feedshaft having a series of indexing apertures, and a member for engaging successive indexing apertures.

9. In an apparatus for generating a helical tooth of varying helix-angle, the combination with a rotary spindle, of a head for swingable movement about the axis of the spindle, mechanism supported by the head for rotatory actuation by and with the spindle, a cutter-supporting shaft disposed angularly with respect to the spindle and actuabie by and with said mechanism, a cutter mounted on said shaft, means for rotarily supporting the work, mechanism co-operable with said means for controlling swingable actuation of the head about the spindle for feeding the cutter longitudinally on the work, and means for biasing the head for actuation thereof responsively to actuation of said controlling mechanism.

ii). In an apparatus for generating a helical tooth of varying helix-angle, the combination with a spindle, of a head for swingablemovement about the axis of the spindle, mechanism supported by the head for rotatory actuation by and with the spindle, a shaft disposed angularly with respect to the spindle and actuable by and with said mechanism, a cutter mounted on the shaft, a gear on the head, an arbor for rotarily supporting the work, a feed-shaft, a gear on the feedshaft for co-operation with the head-gear, an indexing plate on the feed-shaft having a series of indexing apertures, a member for engaging successive indexing apertures for locking the head in selectively swung positions relatively to the spindle, a cam actuable by and with thearbor, an oscillatory indexing shaft for actuation responsively to operation of the cam, and a second member carried by said latter shaft for engaging successive indexing apertures for swinging the head between said selectively locked positions on release of said first member from said indexing plate for feeding the cutter longitudinally on the work.

11. Helical-cam-tooth generating mechanism comprising, in combination, means for rotarily supporting the work, an end-milling cutter, means for rotating the cutter, means for normally biasing the cutter for oscillatory movement, and means for interrupting oscillatory movement of the cutter at predetermined intervals during rotation of the work for varying the helix angle of the tooth being formed upon the work.

12. Helical cam-tooth generating mechanism comprising, in combination, means for rotarily supporting the work, an end-milling cutter, means for rotating the cutter, means for supporting the cutter for swingable movement longit'udinally of the rotating work, means for normally swingably biasing the cutter supporting means, and means for interrupting swingable movement of the cutter at predetermined intervals during rotation of the work for varying the angular relation of the cutter with the work for forming upon the Work a tooth comprising entering and departing helical sections and a central non-helical section.

13. Cam-tooth generating mechanism comprising, in combination, a head disposed for swingable movement, a rotary arbor for supporting the work in registration with the center of the head, a rotary cutter supported for engagement with the work by, and swingable relatively to the work with, the head, means for rotating the cutter, means for normally swingably actuating the head for shifting the cutter for varying the angular-engaging relation of the rotating cutter with the rotating work, and mechanism actuable responsive to and during rotation of the arbor for interrupting swingable movement of the head and cutter at intervals in the rotation of the work for successively cutting upon the work the opposite side faces of the desired tooth.

14. Cam-tooth generating mechanism comprising, in combination, a head disposed for swingable movement, a rotary arbor for supporting the work in registration with the center of the head, a rotary cutter supported for engagement with the work by, and swingable relatively to the work with, the head, means for rotating the cutter, means for normally swingably actuating the head for varying the angular-engaging relation of the rotating cutter with the'rotating work, and means including indexing mechanism actuable responsive to and during rotation of the arbor for interrupting swingable movement of the head at intervals in the rotation of the work for successively cutting upon the work the opposite side faces of the tooth.

15. Cam-tooth generating mechanism comprising, in combination, a rotary cutter, a rotary arbor for supporting the work for engagement by the cutter, an oscillatory head for supporting the cutter for swingable movement in the plane of the longitudinal axis of the work, means for rotating the cutter, means for normally swingably actuating the head for varying the angular-engaging relation of the rotating cutter with the rotating work, and mechanism actuable during and responsive to rotation of the arbor for effecting interrupting at intervals swingable movement of the head and its supported cutter relatively to the work.

16. Cam-tooth generating mechanism comprising, in combination, a swingable head, a rotary arbor for supporting the work in registration with the center of the head, a rotary cutter supported for engagement with the work by, and swingable relatively to the work with, the head, means for rotating the cutter, means for swingably actuating the head for angularly shifting the cutter relatively to the rotating work, and means actuable responsive to and during Irrotation of the arbor for interrupting swingable movement of the head at intervals in the rotation of the work.

17. Cam-tooth generating mechanism comprising, in combination, a swingable head, a rotary arbor for supporting the work in registration with the center of the head, a rotary cutter supported for engagement with the work by, and swingable relatively to the work with, the head, means for rotating the cutter, means for swingably actuating the head for angularly shifting the cutter relatively to the rotating work, and indexing mechanism actuable responsive to and during rotation of the arbor for interrupting swingable movement of the head at intervals in the rotation of the work.

18. Cam-tooth generating mechanism comprising, in combination, a swingable head, a rotary arbor for supporting the work in registration with the center of the head, a rotary cutter supported for engagement with the work by, and swingable relatively to the work with, the head, means for rotating the cutter, means for swingably actuating the head for angularly shifting the cutter relatively to the rotating work, and indexing mechanism including a cam actuable by and during rotation of the arbor for interrupting swingable movement of the head at intervals in the rotation of the work.

19. In an apparatus for generating a helical tooth of varying helix angle, a housing, a spindle having a bearing in the housing for rotation, a head having a hub mounted on the housing for rotation about the axis of the spindle, a cutter-supporting shaft angularly supported by the head with respect to the spindle, meshing gears on the spindle and shaft, and means including opposed weighted flexible members havin operable connection with the hub for rotarily actuating the head.

20. Helical-cam-tooth-generating mechanism comprising, in combination, means for rotarily supporting the work, a rotary cutter, means including a rotarily actuable cutter-supporting head for arcwise shifting the cutter in the plane of the longitudinal axis of the work for varying the angular-engaging relation of the rotating cutter with the rotating work, and means oper- ,:able for restraining rotary actuation of the head at successive intervals in the rotation of the work for temporarily holding the cutter in selected angular positions with respect to the work.

FRANK MARRIOTT. CONSTANTINE NEKLUTIN.

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