US2438329A - Method for producing face clutches - Google Patents

Description

March 23, 1948.- E. WILDHABER METHOD FOR PRODUCING FACE CLUTCHES Filed Dec. 21, 1942 8 Sheets-Sheet 1 ERNEST WILDHHBER Zhwcnlor dttorucu March 23, 1948. E, wlLDHABER 2,438,329

METHOD FOR PRODUCING FACE CLUTCHES Filed Dec. 21, 1942 8 Sheets-Sheet 2 Fave F4 15 Fa n 1.9

F: a nvcmor ERNEST' WILDHABER c ttorncg March 23, 1948. E, MLDHABE 2,438,329

METHOD FOR PRODUCING FACE CLUTCHES Filed Dec. 21, 1942 8 Sheets-Sheet 3 Bmaentor ERNES T WILDHHBER Gltomeg March 23, 1948,

E. WILDHABER HETHOD Foa rnonucmc FACE cLUTcHEs File d Dec. 21, 1942 a Sheets-Sheet s Educator ERNES T W/LDHHBER I attorney March 23, .1948. E. WILDHABER 2,438,329

METHOD FOR PRODUCING FACE CIJUTCHES Filed Dec. 21, 1942 8 Sheets-Sheet Inventor Gttorncg March 23, 1948. E. WILDHABER' 3 5 METHOD FOR PRODUCING FACE CLUTCHES Filed Dec. 21, 1942 a She ets-Sheet' a Ffg255 57 58 3m ei1tor ERNEST W/LDHHBER Patented Mar. 23, 1948 v 2,438,329 METHOD FOR monncme FACE oLU'rcms Ernest Wildhaber, Brighton, N. Y., assignor to Gleason Works, Rochester, N. 11., a corporation of New York Application December 21, 1942, Serial No. 469,610

(01. Sill-1.4)

18 Claims. 1

The present invention relates to toothed face clutches and to methods and apparatus for producing such clutches. In a more particular aspect, the invention relates to the construction and production of clash-type toothed face clutches, that is, clutches whose members are adapted to be engaged while the driver, at least, is rotating. The present application is limited to the novel method of producing toothed face clutches forming part of the present invention. The clutch of the invention has been covered in a separate applicationwhich has issued as U. S. Patent No. 2,384,584, granted September 11, 1945. The novel machine of the present invention is covered in pending application Serial No. 5049, filed January 29, 1948.

Since the teeth and tooth spaces of the two engaging members of a clash-type clutch are not always in exact register when the clutch members are moved into engagement, their teeth are chamfered to facilitate engagement. The chamfered parts of the teeth of the clutch members have to carry the loads at the beginning of engagement of the clutch members, and since these loads are high, shock loads, it is important that the teeth of clash-type face clutches be so chamfered that the chamfered portions as well as the main portions of the teeth can stand and carry heavy loads.

A primary object of the present invention is to provide a toothed face clutch which will have correct tooth chamfer and be capable of carrying heavy loads even when only the chamfered portions of the teeth of the mating clutch members are in engagement. To this end, it is one aim of the invention to provide a toothed face clutch whose members have the chamfered portions of their teeth so shaped that they contact midway of the length of the chamfered portions and, if desired. along the whole length thereof in all positions of partial engagement of the clutch members as the clutch members move into full engagement.

A further object of the invention is to provide an improved type of chamfer surface for toothed face clutch members through which contact of the chamfer surfaces midway of the tooth length, or if desired, along the whole of the tooth length may be obtained exactly and without relying on approximate shapes.

Another object of the invention is to provide a method for producing the two members of a clash-type face clutch in which the chamfered portions of teeth of the two membersmay be made conjugate to one another.

A further object of the invention is to provide a method for producing mating clash-type face clutch members in which the chamfered portions of the teeth of one member may be form-cut and the chamfered portions of the teeth of the other member may be generated conjugate to the formcut chamfered portions of the first member.

Another object of the invention is to provide a method for producing clash-type face clutch members with which in the production of either or both members of the clutch a tooth may be chamfere'd in the same operation with the cutting of a side of that tooth.

A further object of the invention is to provide a process for producing toothed face clutch members with which opposite sides of spaced teeth of either or both clutch members may be out and chamfered in a single operation.

Another object of the invention is to provide a simple and relatively efflcient machine that is universal in character and that may be employed for cutting not only clutches of the clash-type but clutches of other types, also.

Still another object of the invention is to provide a new type of tool for cutting the sides and chamfering the teeth of a clutch member in a single operation.

A still further object of the invention is to provide matching tools which will out and chamfer conjugate chamfer surfaces on the two engaging members of a clutch pair.

Other objects of the invention will be apparent hereinafter from the specification and from the recital of the appended claims.

Toothed face clutch members constructed according to the preferred embodiment of the present invention have longitudinally curved side tooth surfaces and longitudinally curved chamfered portions. The side tooth surfaces of both members are surfaces of revolution. The chamfered portions of the teeth of one member are surfaces of revolution coaxial with the side tooth surfaces of that member, while the chamfered portions of the teeth of the other member are helicoidal surfaces conjugate to the chamfered portions of the teeth of its mate. The term helicoidal surface is used in this application in a broad sense to describe asurface enveloped by a surface of revolution which moves along and about an axis, usually with a varying ratio of angular to axial motion.

Preferably, opposite sides of spaced teeth-of each member of the pair are cut and chamfered in a single operation. Opposite sides of spaced teeth of'one member and the chamfered portions scribed cutter.

at the corresponding sides of said spaced teeth may be made parts of coaxial longitudinally con- .cave surfaces of revolution, while opposite sides of spaced teeth of the othermember may be made parts of a common longitudinally convex surface of revolution. The chamfered surfaces at the corresponding sides of the teeth of this latter memer may be made parts of longitudinally convex helicoidal surfaces conjugate to the chamfered surfaces of the mating clutch member.

In cutting each member of a clutch according umn, in turn, is mounted for angular adjustment on 8 sliding base which is reciprocable to effect depthwise feed. vThe cutter spindle isjournaled in a head that is angularly adjustable about an axis intersecting the axis of the cutter spindle so that the cutter-spindle may be positioned parallel to the work spindle or tilted relative thereto in acto the preferred embodiment of this invention,

made concave in shape. a For cutting the teeth 1 and chamfer surfaces of the clutch member, the

depthwise feed movement is effected between the cutter and the work. The side-cutting edges and chamfering edges of the cutter therefore sweep out and form in the cutting operation finished tooth shapes on opposite sides of two spaced teeth of the work which are counterparts of the shape of the cutting tool.

After opposite sides of two spaced teeth have been cut, the cutter is with- 1 drawn from engagement with the work and the work is indexed, and,then the cycle begins anew.

The other member of the clutch may have its side tooth surfaces form-cut but its chamfer surfaces generated, and-the. chamfer surfaces are generated conjugate to the chamfer surfaces-of the first member, A cutter is employed that has chamfering edges adjacent its'tip and side-cutting edges for the remainder of its height. The chamfering edges are of convex shape to match the concave chamfering edges of the first de- During cutting of the chamfer surfaces, the blank is rotated on its axis while a relative depthwise feed movement is produced between the cutter and blank in time with rotation is started again so that as the cutter moves outwardly,it generates the chamfer on the latter side of the spaced tooth; Then the work is indexed and the cycle begins anew.

The cutters employed may'have side-cutting edges of zero pressure angle or of positive pressure angle. Where a cutter of positive pressure angle is employed, it may be tilted with reference to the work to produce the pressure angle desired on the side tooth'surfaces of the work.

For cutting clutches according to the present invention, machines may be employed of the construction illustrated in the accompanying drawing. In this machine, the work spindle is mounted on a column for adjustment thereon in a direction perpendicular to its axis, and the colcutter is rotated on-its axis while the work is held stationary on its axis, and while a relativecordance with the pressure angle of the side-cutting edges of thecutter and the pressure angles of the tooth sides to be cut on the work. The work spindle is driven through a, differential which may be actuated by two Geneva n'ufiranisms that are angularl adjustable relative to one another or by a Geneva mechanism and uniform motion gearing. The combined motions of the driving parts are thereby transmitted through the differential to the 'work spindle to effect the rotation of the work spindle required in production of any given form of clutch. For cutting clutches constructed according to the present invention, the combined motion of the two Geneva mechanisms will drive the work spindle at a varying velocity forthe portions of the cycle during which chamfering is efiected, hold thework spin- (118 against rotation during side-cutting, and rotate the work periodically, when the cutter is out of engagement with the work, for indexing. For cutting other forms of clutches, such as loadreleasing and saw-tooth clutches, the Geneva motion may serve solely to effect indexing of the work while the uniform motion drive may rotate the work during cutting to produce the required-helical tooth surfaces on the work.

tion of the blank. During cutting of the side perpendicular to the clutch axis; d

Fig. 2 is a fragmentary elevational view of the Several diflerent embodiments of the invention are illustrated in the accompanying drawings in which Fig. 1 is a sectional view showing a pair of toothed face clutch members made according to one embodment of this invention in engagement, the section being taken in a mean plane, hereinafter referred to-as the pitch plane, which is pair-of engaging clutch members;

Fig. 3 is a diagrammatic view, showing one of the clutch members partly in section in the pitch plane and partly in plan, and illustrating the principles underlying the cutting and chamfering of the teeth of this member;

Fig. 4 is a part elevational, part sectional view, further illustrating one way in which the teeth of this clutch member may be simultaneously cut and 'chamfered;

Figs. 5 and 6 are views similar to Figs. 3 and 4, respectively, illustrating one way of cutting and chamfering the teeth of the-mating clutch member in a single operation;

. Fig. 7 is a fragmentary elevational view, showing the pair of mating clutch members being moved into engagement and illustrating the principle on which the generating motion employed in producing the chamfered portions of the teeth of one of the'clutch members is based;

Fig. 8 is a fragmentary axial sectional view through the face mill cutters employed for cutting'the two members of the clutch pair, respectively, and showing the relationship which exists between these two cutters;

Fig. 9 is a view on an enlarged scale of matching blades of the two cutters, further illustrating the relationship in construction which exists between the cutters;

Figs. 10 to 19 inclusive are diagrammatic views illustrating successive steps in the chamfering and cutting of opposite sidesof spaced teeth of clutch member;

Fig. is a normal sectional view on an enlarged scale of a tooth of a clutchmember made according to a modification of this invention;

Fig. 21 is a similar view showing a tooth of a clutch member made according to a still further modification of the invention;

Figs. 22 and 23 are views similar to Figs. 3 and 4, respectively, illustrating how a cutter having side cutting edges of positive pressure angle may be employed for chamfering' and cutting the teeth of one member of a clutch pair according to a modification of the invention;

Figs. 24 and 25 are views similar to Figs. 5 and 6, respectively, illustrating how a cutter having side-cutting edges of positive pressure angle may be employed in the chamfering and cutting of the mating clutch member;

Fig. 26 is an axial sectional View of cutter and work piece, and illustrating the chamferin and cutting of one clutch member according to a still further embodiment of the invention;

Fig. 2'7 is a similar view illustrating a similar modification of the process used in the chamfering and cutting of a mating clutch member;

Fig. 28 is a velocity diagram of a simple Geneva motion in which the driver has two rollers spaced 180 apart;

Fig. 29 is a velocity diagram of a simple Geneva motion having a difierent phase from that of Fig. 28;

Fig. 30 illustrates diagrammatically what happens when the two Geneva motions of Figsl 28 and 29 are combined, as they may be in the machine constructed according to the present invention, in order to produce the intermittent rotation of the work required for chamfering and indexing where the chamfer surface is generated;

Figs. 31 to 40 inclusive illustrate diagrammatically a further modification of the process of generating the chamfer and cutting opposite sides of spaced teeth of a clutch member according to this invention, Figs. 31 to 35 inclusive being views of the cutting and chamfering of one side of a tooth of the clutch member, and Figs. 36 to 40 inclusive being views of the cutting and chamfering of the opposite side 'of a spaced tooth of the clutch member;

Fig. 41 is a plan view illustrating more or less diagrammatically a clutch-cutting machine constructed according to one embodiment of this invention;

Fig. 42 is a fragmentary view of the work end of the machine showing the work head upright in elevation and the work head in section in a plane perpendicular to the work spindle;

Fig. 43 is a drive diagram of the machine when arranged for one method of operation;

Fig. 44 is a fragmentary view, showing how the drive may be modified for a modified method of machine operation;

Fig. 45 is a velocity diagram illustrating the rotational movement of the work spindle when the drive is arranged as shown in Fig. 44 for cutting the teeth of a clutch member according to the modified process shown in Figs. 31 to 40 inclusive;

Figs. 46, 47 and 48 are views similar to Fig. 44

illustrating how the drive mechanism of the machine may be iurther modified to permit cutting formed clutches, double-helical and saw-tooth clutches, respectively;

Figs. 49, 50 and 51 are a plan view, a side elevation, and an end elevation, respectively, of a blade of a face mill cutter such as may be employed in cutting and chamfering oi the teeth of one member of a clutch pair according to the process illustrated in Figs. 22 and 23.

Figs. 52, 53 and 54 are corresponding views of a blade of a face mill cutter such as may be em-- ployed in the cutting and chamiering of the teeth of the mating clutch member according to the process illustrated in Fig. 27;

Fig. 55 is a fragmentary axial sectional view, illustrating diagrammatically the relationship which exists between a pair of cutters whose blades are of the construction shown in Figs. 49 to 54 inclusive;

Figs. 56, 5'7 and 58 are plan, side elevational and end views, respectively, of a modified form of cutter blade for cutting one member of the clutch pair; and

Fig. 59 is a fragmentary end elevational view of a similarly modified form of cutter blade for cutting the mating member of the clutch pair.

Reference will be had first to the embodiment of the invention illustrated in Figs. 1 to 19 inclusive. Here 80 and BI denote, respectively, the two members of a clutch pair. The member 60 has teeth 62 which extend generally radially of the clutch axis 63 and whose opposite sides 64 and 65 are longitudinally concave. The mating clutch member 6! has teeth 66 which extend generally radially of the clutch axis 63 and whose opposite sides 51 and 68 are longitudinally convex.

The teeth 62 of member 60 are chamfered along their top edges on both sides as denoted at ill and I I. The teeth 65 of member M are chamfered along their top edges on both sides as denoted at I2 and E3.

The sides of the teeth of both clutch members are of zero pressure angle in the instance shown, that is, the profiles of the sides 64 and 65 and B! and B8 of the teeth of both members extend in the direction of the clutch axis 63. In the instance shown, the sides of the teeth of both clutch members are cylindrical surfaces parallel to clutch axis 63. Moreover, opposite sides of spaced teeth of each clutch member are portions of a common cylindrical surface. Thus, opposite sides 64a and 65b of the teeth 62a and 62b, respectively, of clutch membre 60 are parts of a common cylindrical surface whose axis is at 15 and is parallel to the vclutch axis 63. Likewise, oppositesides 6811 an 6'") of spaced teeth 66a and 661), respectively, of clutch member 6| are portions of a common convex cylindrical surface whose axis is at 16 parallel to clutch axis 63.

The chamfered portions 10 and H of the teeth of the clutch member 60 are surfaces of revolution concentric with the corresponding sides of the teeth. Thus, the chamfered portions 10a and H1; at opposite sides of the teeth 62a and 621), respectively, are longitudinally concave surfaces of revolution of convex profile shape whose common axis is at 15. The chamfered portions '12 and 13 of clutch member 6! are on the other hand helicoidal surfaces of vary lead conjugate to the chamfered portions of the teeth of the clutch member 50. They are of longitudinally convex shapeand of convex profile shape.

For cutting and chamfering the teeth of clutch member 60,9. face'mill cutter (Figs. 4, 8 and position is reached.

9) may be used. The blades 8| of this cutter are arranged circularly about the axis 82 of the cutter and have cutting portions which project beyond one side face of the cutter in the general direction of the axis of the cutter. The blades 8| may be all outside cutting blades, and may have a straight side cutting edge 83 of zero pressure angle, a concave chamfering edge 84, a tip cutting edge 85 and around 86 which connects and keen chamfering edges. .The clearance or non-cutting sides of the blades may be of any suitable shape but preferably are ground as surby generating the chamfered portions 12 and 13 of the teeth of the clutch member 6| so that they have profile shapes conjugate to the profile shapes of the chamferedportions 19 and H of the teeth of the clutch member 69 and so'that their lengthwise shapes match to any desired extent the lengthwise shapes of the chamfered portions of clutch member 69.

faces of revolution as will be described in more detail hereinafter with particular reference to Figs. 56 to 58.

The cutter 89- is preferably positioned to cut simultaneously in two spaced tooth zones of the work. The cutter is so positioned that its axis 82 i is parallel to'the axis 63 of the work and coincides with the axis 15 of the tooth surfaces to be cut i on the work. Cutting is efiected by rotating the cutter 89 on its axis 82 while holding the 1 work 69 stationary on its axis 83 and while effecting a relative depthwise-feed movement between the cutter and the work until full depth ment may be in the direction of the axis 63 of the work or it may be in a direction inclined to said axis. In full depth position, the straight side cutting edges 83 (Fig. 9) of the cutter will sweep out and form opposite sides 64 and 65 on spaced teeth of the work which are coaxial and longitudinally concave cylindrical surfaces, whilethe concave chamfering edges 84 of the cutter will sweep out and form chamfer surfaces 19 and H of convex profile at these same sides of the spaced teeth of the work which are coaxial with one another and with the said sides of the teeth as already described. l9 denotes the path of a point in the chamfering edge of the tool and 11 the path of a point in the side-cutting edge of the tool at full depth. I

When a pair of tooth sides have been cut and chamfered, the cutter is withdrawn from engage ment with the work and the work indexed. Then The depthwise feed movethe cycle begins anew. Thus the tooth sides and chamfer surfaces of .the clutch member 69 may be produced simultaneously in a forming operation and ma rapid and efiicient process.

The form-cutting method used in cutting and chamfering the teeth of clutch member 69 cannot be applied to the cutting and chamfering of the teeth of the mating clutch member SI, for if the .chamfer surfaces of both members were form-cut, the chamfered portions of mating teeth would contact only at the outer ends of the teeth as the clutch members were moved into engagement, and the chamfered portions accordingly could not carry heavy loads. The present invention provides, however, a way for chamfering the teeth of the clutch member 8| so that any desired amount of lengthwise contact can be obtained between the engaging clutch members as they move into engagement. This contact may extend along the whole length of the chamfered portions of the teeth if desired or along any Portion of that length. This contact is obtained For cutting and chamfering clutch member 8 I,

a face mil cutter 90. (Figs. 6, a and 9) may be employed that has a plurality of inside cutting blades 9| which are arranged circularly about the axis 92 of" the cutter and which have cutting portions projecting beyond one side face of the cutter in the general direction of the axis 92 of the cutter. The blades 9| have straight inside cutting edges 93, chamfering edges 94, and tipcutting edges 95. The side cutting edges 93 may be of zero pressure angle or of slight negative pressure angle, that is, of slight negative inclina-- The chamfering edges tion to cutter axis 92.

94 are of convex profile shape, but unlike the chamfering edges 84 of-cutter 89, the chamfering edges 94 of the cutter 99 are arranged adjacent the tips of these blades instead of adjacent the shank portions of the blades. In fact, the chamfering edges 94 of blades 9| connect the sidecutting edges 93 of the blade with the tip-cutting edges 95 thereof. 1

The convex chamfering edge 94 of a blade 9| has .the same profile shape as the convex chamfersurface 19 or H of clutch member 69, that is, it

is a circular arc of the same radius 96 as the concave chamfering edge 84 of a blade 8| of cutter 89. It will be seen, therefore. that when the cutter 99 is rotated on its axis 92, it embodies the chamfered portions of clutch member 69.

To generate the required chamfer on the teeth of the clutch member 6|, the cutter 99 is rotated on'its axisin engagement with the work while a relative feed movement is effected between the cutter and the work about the clutch axis 63 and 'in the direction of said axis. The motion pro duced is as if the clutch member 69 were contacting at various points along the height of the chamfered surfaces of its teeth with the chamfered surfaces of the clutch member 6| as the two clutch members are moving into engagement. In other words, in cutting the chamfered portions of the teeth of clutch member 6|, the cutter 99, which represents the chamfered portion-o1 a tooth of the clutch member 69, assumes such positions relative to the work as are assumed by the chamfered portions of a tooth of the clutch member 69 as the chamfered portion of that tooth engages with and moves over the chamfered portion of a mating tooth of clutch member 6| during movement of the two clutch members into engagement. One of the positions of partial engagement of the two clutch members is shown in Fig. 7.

The relationship of the cutters 89 and 99 for cutting the two clutch members is clearly illustrated in Figs. 8 and 9. It is seen that the convexchamfering edge 94 of a blade 9| of cutter 99 matches the concave chamferingedge 84 of a blade 8| of cutter 89. Moreover, the convex chamfering profile 94 is'an arc of the identical Due to the depthwise feed, the sides edges.

The inside cutting diameter of cutter 90 will be the same as the outside cutting diameter of cutter 80 if the mating chamf er surfaces and mating side surfaces of the two clutch members are to have full length contact, but lengthwise mismatch of mating chamfer and mating side surfaces can be obtained by using a cutter of smaller inside diameter to cut clutch member BI and The cutting and chamfering cycle for clutch member 6| is further illustrated in Figs. 10 to 19 inclusive. Figs. 10 to 14 inclusive illustrate the cutting action which takes place in one zone of cutting engagement, namely, in the cutting and chamfering at one side of a tooth 68b, and these are figures looking from the inside of the clutch outwardly. Figs. 15 to 19 inclusive illustrate the cutting action which takes place in the other zone skipping less teeth between the two tooth zones in which this cutter operates.

In cutting the chamfered portions of clutc member 6|, the rotation about the clutch axis 63 is usually performed by the work and the feed movement in the direction of the clutch axis is also performed by the work. There is a definite coordination required between the rotation about the clutch axis and the feedlengthwise of this axis. The required coordination may be determined to correspond to assumed mean chamfer profiles; for instance, by layout. The chamfered surfaces ll-and I3 produced are helicoidal surfaces, usually helicoidal surfaces of varying lead. The'rotary motion of the work need take place only while a chamfered surface is being cut. The sides 61 and 68 of the teeth may be cut with the work stationary by depthwise feed of the rotating cutter into the work.

In the preferred embodiment of the invention, a face mill cutter 90 is employed which is of sufficiently large diameter to operate in two spaced tooth zones of the work simultaneously. The chamfered part at one side 'of a tooth of the work is cut during in-feed while the blank is being rotated in time with the in-feed movement. Then the rotation of the blank is stopped but the infeed is continued to cause the cutter to cut simultaneously the side of the tooth previously chamfered and the opposite side of a spaced tooth of the work as portions of a, common surface of revolution. Then the cutter is withdrawn and when it has been partially withdrawn, the work rotation commences again so that during the last part of the withdrawal motion, the cutter will chamfer the last named tooth on the same side as has been cut.

Difierent relative angular positions of the cutter about the clutch axis during cutting and chamfering of opposite sides of spaced teeth of clutch member 6| are shown diagrammatically in Fig. 5. The chamfered portion 13b of tooth 66b of clutch member IiI-is being produced when the axis of the cutter is at 92' and the cutter has been partiallyfed into depth. The path of a point in the cutting edge of the tool for this position is denoted at 91'. The side surface 61b of tooth 66b and the opposite side surface 68a of tooth 66a spaced from tooth 6622 are formed when the cutter axis is in mean position 92, and the cutter is moving to full-depth position. The path of said point in the cutting edge of the tool for this position is denoted at 91. The chamfered surface 12a of tooth 66a is beingproduced when the cutter axis is at position 92" and the cutter is being partially withdrawn. 91" denotes the path of the same cutting point when the cutter is at this cutting position. In this way, the chamfered portion of one side of a tooth and subsequently the opposite sides of spaced teeth of clutch member 6| are cut during the in-feed,

of cutting engagement, namely, in the cutting and chamfering at one side of tooth 66a, and these views are looking from the outside of the clutch inwardly. The rounded chamfering edges 94 of the cutting blades 9|, therefore, are at the right in both instances.

Fig. 10 shows the start of the cut on the rounded chamfer surface 13b of tooth 66b. The final shape of the tooth space 69b adjacent this tooth is shown in dotted lines. While the cutter is cutting in the tooth space 6% of the blank, it is also cutting in the tooth space 69a. The start of the cut in the latter tooth space is shown in Fig. 15. As the rotating cutter is fed relatively depth wise into the blank, the blank is rotated on its axis in time with the depthwise feed movement to generate the chamfer surface I3b When the cutter reaches the position illustrated in Figs. 11 and 16, the chamfer surface 73b is completed. Then the turning motion about the clutch axis 63 ceases, but the depthwise feed in the direction of this axis continues. Figs. 12 and 1'? show the position of the cutter at full depth. Here the sidecutting edges 93 will have cut the opposite sides 61b and 68a of the teeth 66b and 66a and the chamfering edges. of the cutter will sweep out and produce the rounded fillets which join these tooth sides with the bottoms of the tooth spaces 69b and 69a. Then the withdrawal motion starts.

At the position indicated in Figs, 13 and 18, the cutter has been withdrawn far enough for the chamfering of the side 12a of tooth 66a to start.

Then the rotation about the work axis begins again, and as the cutter travels outwardly from the position of Figs. 13 and 18 to the position of Figs. 14 and 19, it produces the chamfered surface 12a of tooth 66a. As soon as the cutter has moved clear of the work. the blank is indexed. Then the cutter is fed back into engagement with the work and the cycle of chamfering and cutting opposite sides of spaced teeth of the work begins anew.

In Figs. 10 to 19 inclusive, dotted line I00 denotes the path of the centers 98 of. chamfering edges 94 of cutter at one tooth zone of the work, and dotted line IOI denotes the path of these same centers in the other tooth zone of the work during the cutting and chamfering cycle,

Various types of chamfer may be obtained with the method of the present invention. One form of chamfer surface that can be produced is illustrated in Figs. 1 to 19 inclusive. Other forms are shown in Figs. 20 and 21. In Fig. 20, I05 de- I notes the profile of the chamfered surface at one side of tooth I06. This profile is a circular arc whose center is at I01. Such a chamfer surface joins the straight zero pressure angle tooth side I08 smoothly without angle. The center I01 may be midway between the sides I08 and I09 of the tooth I06 and the top of the tooth may be fully rounded, as shown. In Fig. 21, the chamfer surface I I5 is again of circular arcuate profile shape, but its profile shape is of larger radius being centered at H1. The chamber surfaces H5 and H4 at the sides of the tooth '6 may join the respective tooth sides H8 or H9 at slight angles. Of course, the chamber surfaces need not be of ciraesaeae cular arcuate profile shape but'may-be of any desired profile curvature.

Cutters like the cutters 80 and 00, which have side-cutting edges of zero or negative pressure angle must be relieved radially as well as axially in order to provide cutting clearance, and, after sharpening, the blades must be readjusted radially in order to maintain the cutter diameter. Such an adjustment can be avoided by use of cutters having side-cutting edges of positive pressure angle, 1

Figs. 22 to 25 inclusive illustrate the cutting of a pair of mating clutch members with cutters of positive pressure angle. One member of the clutch is denoted at I and the mating member at I2I. The clutch .member I20 is cut with a face mill cutter I which has a plurality of circularly arranged cutting blades I20. Each blade has an outside cutting edge I27 (Figs. '23, 49, 50 and 51) a chamfering edge I29 and a tip-cutting edge I30. The outside cutting edge is of straight profile and positive pressure angle or inclination to the cut ter axis I28. The chamfering edge I29 is of concave profile shape and lies adjacent to the shank of the blade. The tip cutting edge I30 ispreferably made perpendicular to the side-cutting edge I2! and is, therefore, inclined with reference to the cutter axis I28 at other than right angles. The highest part of the tip-cutting edge is at its outer end. The tip cutting'edge I30 is joined to the side-cutting edge I21 by a suita le round.

For cutting the toothed face clut h member I20 whose tooth sides I34 and I35 are of zero pressure angle, the cutter I25 is tilted inwardly with reference to the work. Opposite sides I34 and I35 of spaced teeth I32 of the clutch member I20 are chamfered and cut in a single cycle of operation by rotating the cutter I25 on its axis I28 while holding thework I20 stationary on its axis and efiecting a relative depthwise feed movement between the cutter and the work preferably in a direction I36 (Fig. 23) slightly inclined to the direction of clutch axis I33.

The tooth sides and the chamfered surfaces produced on the clutch member are counterparts of the chamfering and cutting surfaces of the cutter I25. Both sides of the teeth of the clutch member are of longitudinally concave shape and the chamfered portions at op osite sides oi the teeth are of longitudinally concave shape. The sides of the teeth are of straight profile and zero 3g The tip cutting edges I50 are perpendicular ti the side cutting edges I 41 and therefore incliner. at other than right angles to the axis I48 of the cutter. They are highest at their inner ends. The chamfering edges I are of convex profile shape and connect the side cutting edges I4'I with the tipcutting edges I50 of the blades. The

profile of the convex chamfering edge I49 of a blade I46 of cutter I matches the concave profile of a chamfering edge I29 of cutter I25 so that the convex chamfering portions of cutter I45 represent the chamfered top of a tooth of clutch member I20 as the cutter rotates on its axis.

The cutter I45 may be of the same inside diameter as the outside diameter of the cutter I25,

but if it is desired to have lengthwise mismatch between the contacting surfaces of the two clutch members for localization of tooth bearing, then the inside diameter of cutter I45 is reduced ter I25.

For cutting the clutch member I2I, the cutter I45 is tilted outwardly with reference to the clutch member IZI to out side tooth surfaces of zero pressure angle on the clutch member.

The teeth of clutch member ,I2I are chamfered and have their sides cut in the same way as the teeth of the clutch member iii. The cutter I45 is rotated in engagement with the work and a relative feed motion is produced about and in I the direction of the clutch axis I33 to generate pressure angle, while'the chamfered portions are of convex profile. v a 22 denotes the v The dot-dash line. I31 in Fig. path of a. point in the side cutting edge ofthe tool at full depth position. Opposite sides of spaced teeth as, for instance, the sides I34a and the chamfered portions I50 and I50 of the teeth.

The depthwise feed movement isin the direction of 'the arrow I52 if imparted to the work. When the chamfered portion at one side of a tooth has been completed, the rotational movement of the work is stopped, but the relative depthwise feed movement continues until full depth position is reachced. During this depthwise feed movement, opposite sides of spaced teeth of the clutch member are cut as parts of-a common convex cylindrical surface of revolution coaxial with the cutter axis I48. Then the cutter is withdrawn from engagement with the work. When the cutter has been withdrawn a I35b of the teeth I32a and 132b, are portions of a common conical surface whose axis coincides with the cutter axis I28 in full depth position of the cutter and intersects the clutch axis I33. The chamfered surfaces I36a and l36b at these same sides of these spaced teeth are also por-.

tions of surfaces of revolution coaxial with the conical sides of the teeth. The bottoms I39 of the tooth spaces of the clutch member are inclined' to the clutch axis and are substantially conical surfaces coaxial with the clutch member.

The mating clutch member I2I may be cut with a face mill cutter I45 whose blades- I40 are arranged circularly aboutits axis I48. These chamferingedges I49, and tip-cutting edges I50.-

sure angle and inclined to the cutter axis I48.

suflicient distance from full-depth position, the

' point in the cutter axis I48. When this point is at I55, the chamfered surface 'I'59b of tooth I5Bb is being generated. and the path of a point in the cutting edge of the cutter is at I54. When the said point in the cutter axis is at I55, the

mean cutter path is at I54 and the sides I5'Ib and l58a of spaced teeth I56b and l56a .are

. formed. The chamfer I60a on tooth I560. is genblades (Fig. 25)'have inside cutting edges I41,

,erated during the withdrawal movement of the I v-cutter when the cutter is at partial depth engagement.v When the said point in the cutter axis is at I55" and the path of a point in the 13 cutting surface is at I54", the chamfered portion I60a of tooth I 55a is being generated.

' Preferably, the-smaller diameter cutter I45 is designed so that its axis I48 may be inclined I39 of the tooth spaces of the clutch member Further modifications of clutch members and of the process for producing the same are illustrated in Figs. 26 and 27. For cutting and chamfering the clutch member I10 of Fig. 26, a face mill cutter I15 is employed that has a plurality of cutting blades I16 arranged circularly about its axis I18. These blades have concave chamfering edges I19 and straight outside cutting edges I11. Cutting of the side surfaces of the clutch teeth is really done, however, with the convex rounds vI8I which lie adjacent the tips I80 of the blades and which connect the side edges I11 with the tips. I

The cutter I 15 is tilted inwardly with reference to the work and is rotated on its axis I18 while the work is held stationary on its axis and while a depthwise feed movement is produced in the direction of the clutch axis. If the feed movement is imparted to the work, this is in the direction of the arrow I82. In this feed movement,

to 35 inclusive are views from the inside of a I clutch outwardly at one zone of cutting engagefected about and in the direction of the work axis. The cutter-therefore moves from the position shown in Figs; 31' and 36 to the position,

shown in Figs. 32 and 31. The centers of curvature I95 of the chamfering edges I89 of the blades travel along the path I96 inone tooth zone from position I95a to position I95?) and for the other tooth zone along path I91 from position I95u to position I952). When the cutter attains the position shown in Fig. 32, the chamfer I93 will have been completed. In this embodiment of the invention, as already stated, in contra-distinction to the embodiments previously described, the rotational movement of the work does not cease when the chamfer portion of the tooth has been generated but it continues at a decreased rate through a the protruding convex cutting edges I8I of the cutter blades envelop and generate cylindrical side surfaces I84 and I85 on the clutch teeth. When full depth position is reached, these same convex cutting edges IBI produce the fillets .in the bottoms of the tooth spaces and the chamfering edges I19 produce the chamfer surfaces I83 and I83. v a

The clutch member I10 may be engaged with either the clutch member I2I of Figs. 24 and 25 or the clutch member I1I of Fig. 2'1.

In the cutting of clutch member "I, a facemill cutter I85 (Figs. 27 and 52 to 55 inclusive) is employed whose blades I86 have convex chamfering edges. I89 adjacent their tips I90 and straight side-cutting edges I81 of positive pressure angle. The chamfering of theteeth of clutch member I1I is done, as described with reference to the chamfering of the tooth surfaces of clutch member I2I, namely, by rotation of the cutter on its axis and a feed motion about and in the direction of the clutch axis I13. A tooth is chamfered at one side thereof during the first part of the in-feed movement and a spaced tooth is chamfered at the opposite side thereof during the last part of the outfeed movement. In contradistinction to the embodiments of the invention previously described, one side surface of a tooth is finished before full depth is reached and the other side after full depth by slightly turning the clutch blank toward the cutter, first in one direction and then in the other. This permits of finishing the sides I9I and I92 of the clutch teeth with the side-cutting edges I81 of the cutter in contrast to the action of the cutter I 45, for instance, which cuts the sides of the clutch teeth with the'convex cutting edges I49. Smoother tooth surface finish can be obtained with the embodiment of the invention shown in Fig. 27.

This embodiment of the invention is further illustrated in. Figs. 31 to 40 inclusive. Figs. 31

slightly greater angle. It ceases and is reversed near the full depth position of Figs. 33 and 38.

The position of thecenter of the chamfering edge just before reversal of the work rotation is denoted at I950 and the position after reversal is denoted at Id for one tooth zone of the work while the corresponding positions are denoted at I95w and I95a: for the other tooth zone of the work. Before I reaching the full depth position of Fig. 38, the cutter in its operation in the tooth zone of Fig. 38 will have finished the tooth side I92. The direction of rotation of the work is again reversed soon afterthe cutter leaves full depth. position on the withdrawal movement, the center of the chamfering edge moving to position I95e. This reversal of movement causes the cutter to clean up the stock between the roughed tooth side I9I and the finished tooth side I9I (Fig. 33), and the straight side I9I of a tooth is finished with straight side cutting edge I81. This completes the whole of one side of one tooth as shown in Fig. 34. It will be noted that the profile center of the chamfering edge forms a fiat loop. As the tool moves further out of cutting depth, it produces a chamfered surface I94, the production ofthe chamfer starting when the cutter is in the position shown in Fig. 39 with the center of the chamfering surface at I95y and being practically completed in the position shown in Fig. 40 when the center of the chamfer surface is at I952. Fig. 35 shows the position of the cutter corresponding to that of Fig. 40 for the other tooth zone of the work. Here the center of the chamfering edge is at I959 along path I96. When the cutter has cleared the blank in the withdrawal movement, the blank continues to rotate to present two new tooth sides to the cutting tool andthe cutting cycle thenbegins anew. A machine for cutting and chamfering clutch teeth according to the present-invention is illustrated diagrammatically in Figs. 41 and 42. This machine is also suited to produce face clutches of practically any type and in addition may be employed even for the cutting of bevel or hypoid gears without generating roll.

- The clutch member, which is to be cut, is denoted at 220. It is secured in any suitable manner to a work spindle 22| which is journaled in a vertically adjustable slide 222. Slide 222 is mounted for adjustment in a direction perpendicular to. the axis of thework spindle along the guideways of an upright 223. This adjustment is not required in the cutting of clutches of the type covered by this application, but may be useful in the manufacture of saw tooth clutches and of bevel and hypoid gears.

Upright 223 is angularly adjustable on guideway 224 of sliding base 225 about an axis 225 which is perpendicular to and intersects the axis 221 of the work spindle. The base 225 slides on ways 228 provided on the frame 229 of the machine. The sliding base is used for adjustment of the work in accordance with the height of the cutter blades and it moves, during operation of the machine, to efiect the depthwise feed movement.

The face mill cutter 230 employed on the machine is secured to a spindle (not shown) that is journaled in a swivel head 23! which is mounted on a slide '232 foradjustment angular-1y about an axis 233 which is perpendicular to the axis 234 of the cutter spindle. The slide 232 is mounted on the base 2290f the machine for lateral adjustment in the direction of the arrow 235. The base 229 is provided with ways 231 for this purpose. can be driven in any suitable manner to effect cutting of a desired form of clutch or gear.

Let us now consider the turning motionsto be imparted to the clutch blank when the chamfer surfaces are to be generated and particularly the motions employed in the embodiment of the invention illustrated in Figs. 5, 6, to 19 inclusive, 24 and 25. Here the blank is rotated during chamfering but is held stationary except for its axial depthwise feed while the straight side surfaces of the teeth are being out. As the out starts at the top of a tooth in the chamfer- .ing operation and gradually generates the chamfered surface at one side of a tooth, the speed of rotation of the work should gradually slow down so that it is at zero when the chamfer is completed and the cutting of the sides of the teeth is to begin; The blank is stationary for a time while the sides proper are being cut and during withdrawal. The rotational movement is gradually resumedin the same direction as before with a slow start when the chamfe'rsurface at the opposite side of a tooth spaced from the tooth previously chamfered is being cut on' the way out.

The required turning motions can be derived conveniently from known motions, .as, for in-' stance, a Geneva motion. Fig.- 28 is a velocity The various parts of the machine diagram of a Geneva motion with the angle of 1 rotation of the driver plotted on abscissa X-'X and the turning velocity of the driven member for the instantaneous ratio plotted as the ordinate. This diagram is for a Geneva motion in which the driver carries two pins 180 apart.

The driven member starts to move at point 200.

At point 2:", it has reached the velocity measured by distance 20l-202, assuming that the driver is turning at a constant rate. The velocity increases to its maximum at 204 and then drops down again, reaching zero at point 203. The distance 200-493 corresponds to 90 of rotation of the driver. remains stationary for 90 of rotation of the driver. Then it is driven again unto the maximum velocity and back to rest while the second The driven member then 16 pin is in operation. Distance 205-206 corresponds to of rotation of the driver during operation of the second pin. 7

Fig. 29 is a velocity diagram of a Geneva motionlike Fig. 28 but having a different phase.

When two Geneva motions, such as illustrated in- Figs. 28 and 29, are added together, as can be done by means of a differential, avelocity diagram as shown in Fig. 30 results. 1 The motion here plotted can be used in the cutting of a member 61 or IN. The chamfer cut may start at point 2 and end at point 2H2. Then the blank may remain stationary during rotation of the driver from point 212 to point 213 during which the feed of the cutter to full depth and partial withdrawal of the cutter, and cutting of opposite sides of spaced teeth of the work may take place, and then rotation of the work will start again for the chamfering of theopposite side of the tooth, the chamfering ending at 214. Between 2l4 and 215, the blank will be indexed. Then the cycle will start anew, chamfering at one side of a tooth taking place during rotationof the blank from M5 to 216, cutting of the sides and partial withdrawal taking place while the work is stationary during interval 2|62i1 and chamfering of the opposite side of aspaced tooth taking place during rotation from 211 to 2i8, and the blank being again indexed in the portion 2| 82H of the cycle.

One way in which the machine may be geared 'to effect the work motion of Fig. 30 and cut clutch members of the type shown in Figs. 5, 6, 10 to 19 inclusive, 24 and 25, is illustrated in Fig. 43. Here power is derived from a motor 240. This motor drives the cutter 230 through its armature shaft 24L the bevel gears 242 and 243, the spur change gears 246 and 241, the shaft 248,- and the hypoid gears 249 and 250. The last named gear is secured to the cutter spindle 25L The shaft 253 drives a shaft 255 through spur change gears 245 and 244. There is a bevel gear 256 secured to shaft 255 which drives a mating bevel gear 251 that is secured to a shaft 259. There is a hypoid pinion 262 secured to the shaft 259 and this pinion drives the hypoid gear 263 which is secured to the feed cam 264 of the machine. The feed cam is mounted on a shaft 265 that is journaled in any suitable manner in the base 229 of the machine. It is operatively connected by a suitable follower in known mannerto the sliding base 225 to produce the desired depthwise feed movement. of the work members 213 and 214, respectively, of two Genevamechanisms. The drive member 213 may be fixedly secured to the shaft 212, but the drive member 214 is preferably connected to the shaft by external spur gear 215 and internal gear teeth provided on the drive member 214. The spur gear 2151s fixedly secured to shaft 212. -This clutch permits angularly with reference to the drive member 213 so that a motion may be obtained such as illustrated in the velocity diagram of Fig. 30.

The drive member 213 carries two pins 216 and 211 which engage in the slots of a Geneva wheel 218. The drive member 214 carries two pins 219 and 280 which engage in the slots of a Geneva wheel 281. The two Geneva wheels are rigidly secured to aligned shafts 282 and 283, respectively, whose adjacent ends project into and are journaled in a diiferential housing 284. Journaled on the stud 285 which is secured in the differential housing is a planetary pinion 283. This meshes with the two side gears 281 and 288 of the differential which are secured to the inner ends of the shafts 282 and 283, respectively.

Motion of the differential housing is transmitted to shaft 290 through a spur gear 291, which is secured to or integral with the differentialhousing and a spur gear 292 which meshes therewith and which is secured to the shaft 290. The shaft 290 drives shaft 294 through spur change gears of the drive member 214 being adjusted- 295, 296, 291, and 298. There is a worm 299 fixedly secured to the shaft 294, and this worm meshes with and drives the worm wheel 300 which is secured to the work spindle 221.

The differential serves to combine the two motions of shafts 282 and 283 so that the resultant motion may be transmitted to the work spindle 221. Thus the work spindle may be rotated intermittently in time with the feed motion of the sliding base for chamfering, may be held stationary while the sides of the teeth are being cut and the tool is being partially withdrawn from full depth position, and may be indexed when cutting and chamfering are completed. Known means may be employed to lock the Geneva wheels against rotation when the pins of the driving members are out of engagement with them.

When it is desired to cut a clutch member according to the modification of the invention illustrated in Fig. 29 and in Figs. 31 to 40 inclusive a slight modification in the drive of the machine is required, see Fig. 44. Here the driver 213 is replaced by a driver 303 having four drive pins spaced 90 apart. Three of these are shown at 304, 305 and 306, respectively. Driver 214 is also removed and a spur gear 308 is substituted therefor. This spur gear is keyed to the shaft 212. The Geneva wheel 281 need not be removed from shaft 283, but is, of course, inoperative. A spur gear 309 is secured, however, to the outer end of the shaft 283, and additional spur gears 310 and 311 are mounted on an intermediate shaft, whose axis is indicated at 3 I 2, to mesh with the spur gears 308 and 309, respectively, to transmit motion from the shaft 212 to the shaft 283. The shaft 283 is therefore driven at a uniform velocity and in the same direction as the shaft 212, but in a direction opposite to the intermittent rotation of the shaft 282 under actuation of the Geneva mechanism 303- 218. It is seen, then, that the resultant motion of the differential housing 284 corresponds to subtracting the uniform motion of shaft 283 from the intermittent variable motion of shaft 282.

The motion of the work when the machine is geared according to Fig. 44 is illustrated diagrammatically by the velocity diagram of Fig. 45. The velocity curve 315 has no dwells but consists of a series of successive rises and falls. This results with a Geneva motion when one pin of the driver starts engagement with the Geneva wheel as another pin leaves off engagement. This is the result, in other words, of use of a driver such as the driver 303 which has four pi 1s spaced 90 apart. In the modification of the invention illustrated in Figs. 27 and 31 to 40 inclusive, the turning motion of the work not only stops but is also slightly reversed. To obtain this, a uniform motion must be subtracted from the Geneva motion. This occurs when change gears 308, 310, 311 and 309 instead of a Geneva mechanism, are used to drive shaft 283.

In-the velocity diagram of Fig. 45 the result of the combination of uniform motion on shaft 283 with varying motion on shaft 282 is that the abscissa is raised from a position such as denoted at 316 to the position 311. Distance 318 corresponds to a tooth cycle and to 90 rotation of shaft 212. Point 320 on curve 315.corresponds to the position shown in Figs. 81 and 36 at the start of the chamfering operation on a side of a tooth. Point 321 corresponds to the position shown in Figs. 32 and 37 when the chamfering operation at this tooth side is complete. Point 322 corresponds to the full-depth position shown in Figs. 33 and 38. Point 323 corresponds to the position of Figs. 34 and 39, when the chamfering operation on the opposite side of a spaced tooth is starting, and

point 324 to the position of Figs. 35 and 40 when this chamfering operation is about completed. The opposite side surfaces 191 and 192 of spaced teeth are finished, respectively, at times corresponding to points 325 and 328, respectively, when the blank stands still for a moment.

As previously stated, the machine of this invention may be employed not only for cutting clutch members according to this invention but also for cutting other types of clutch members and for cutting non-generated bevel and hypoid gears. Fig. 46 illustrates diagrammatically the changes that are required in the gear train of the machine in order to adapt it to the cutting of non-generated gears or of fixed-type clutches. The side tooth surfaces of such gears or of such clutches are surfaces of revolution, counterparts of the surface of the cutting tool. For this type of work, the blank remains stationary on its axis during cutting. The only motions required between tool and blank, aside from the cutting motion of the tool, are the depthwise feed movement and intermittent indexing. Hence, all that is required when cutting non-generated gears or the described type of clutch is a simple indexing mechanism. For

' the drivers 213 and 214 there are substituted,

therefore, drivers 333 and 334, respectively, each of which has but a single driving pin, denoted at 335 and 335, respectively. Shaft 212 is here driven at a rate of once per tooth cycle. Accordingly, the work remains stationary on its axis during 270 of rotation of the shaft 212 and is indexed during of rotation of that shaft through operation of the two Geneva mechanisms actuated by the drivers 333 and 334, respectively. The work is fed into the rotating cutter to out its side tooth surfaces, and when these have been cut to full depth, the work is withdrawn from engagement with the cutter, and the work is indexed. Then the cycle begins anew. Clutch members of the type that may be cut with this gearing arrangement are described in my copending application, Ser. No. 444,031 filed May 22, 1942, now Patent No. 2,384,582, granted Sept. 11, 1945.

Fig. 47 illustrates how the drive mechanism of the machine may be modified in order to cut load releasing clutches whose opposite side tooth surfaces are helical surfaces. Fig. 48 illustrates how the drive of the machine may be modified in order to cut a saw-tooth type of clutch which has one side of each tooth straight and parallel to its axis and the other side a helical tooth surface. In each case. a drive member 333 with a single pin 835 is employed to drive shaft 282. The shaft 283, in each case, is driven motion of shaft 282. In the arrangement of Fig.

48, the drive to the shaft 283 is through compound change gears 340, 3,, and 343 so that the intermittent Geneva motion is subtracted from the uniform motion obtained through said change gears. Saw-tooth and double-helical load-releasing type clutches of types that may be cut on the present machine with the gearing arrangements of Figs.- 47 and 48 are described in my copending application Ser. No. 456,894, filed granted April 16, v1946.

For cutting the toothed face clutches of the present invention, as already indicated, new

types of face mill cutters are preferably employed. Figs.'49 to 51 inclusive show on a somewhat enlarged scale one of the blades I25 of the cutter I25 (Fig. 23), whfle Figs- 52 to 54 inclusive show one of the blades I86 of cutter I85 (Fig. 2'7). As already stated, the cutting profile of outside blade I26 consists of a straight side cutting edge I21, of a concave chamfering edge I29 which is of circular arcuate shape and whose center is at 384. of a top cutting edge I30 which extends in a direction perpendicular to the side 1 cutting edge I 21, and of a top round I 3I which chamfering edge I29 of blade I26. Fig. 55 shows diagrammatically the relationship between the two cutters I 28 and I85.

. or 355, respectively.

September 1, 1942, now Patent No. 2,398,570,

Thus, the clearance or non-cutting sides of the blades I 28 and I88, respectively, contain portions of zero pressure angle which are denoted at 352 and 353, respectively. These portions are cylindrical surfaces concentric to the cutter axes I28 and I88 respectively. Such surfaces can be ground without relieving motion.

The point widths of the blades are further limited at all times to a given maximum by thinning down the blades near their shanks by recesses 354 The side surfaces 858 and 359, respectively, formed by these recesses, are

surfaces of revolution concentric with the cutter axes. The clearance side of each blade I28 or I86 may, therefore, be made up of a cylindrical surface parallel to and concentric with the cutter axis and of a circular recess or groove which is also concentric with the cutter axis. The recesses 358 and 355 follow the peripheral direction of the cutter and not the relieved top surface of the cutter.

The front faces 358 and 351, respectively, of the blades are usually made plane and inclined at acute angles to the cutting sides of the blades,- that is, to the outside surface in the case of the blade I26 and to the inside surface in the case of blade I88.

A modified form of blade is shown in Figs. 56 to 58 inclusive. This blade may be used in the cutter 80 of Fig. 4. This blade has an outside cutting edge 360 of zero pressure angle, a straight top cutting edge 35I which is perpendicular to the outside cutting edge, a concave chamfering edge 353 which lies adjacent the shank of the blade, and a round 362 which joins the top and side cutting edges. The blade is radially as well as axially relieved in order to provide cutting clearance. The direction of relief'being denoted by the arrow 389 in Fig. 58.

The non-cutting or clearance side 365 of the blade is ground as a conical surface parallel to the direction of arrow 384. A groove or recess 388 may also be provided in the non-cutting side of the blade to maintain a predetermined maximum point width as the blade is sharpened. This groove or recess extends in the direction of the periphery of the cutter and its profile extends in the direction of side-cutting edge 350. Its side The blades I28 and I88 are axially relievedin the usual manner to obtain cutting clearance as indicated by the dotted lines 0350 and 35I, respectively, which denote the positions of the cutting edges after sharpening. The profiles shown in dotted lines are identical with the original cutting profile and are merely displaced axially therefrom.

Aside from the novel features already pointed out, the blades of Figs. 49 to 54 inclusive are new also in the respect that the clearance or noncutting sides of the blades are not relieved but are formed as surfaces of revolution extending in the direction of relief of the cutting sides of the blades. Further, to maintain the maximum point-width throughout the life of the blades but still prevent the blades from interfering on their clearance sides as they are sharpened, the clearance sides of the blades may be recessed so as to have sides extending parallel to the cutting edges of the blades. The sides of the recesses are also preferably formed as surfaces of revolution.

is a surface of revolution concentric with the cutter axis. Its juncture with the plane shank portion of the blade is a line 868 inclined to the top surface of the blade in Fig. 57.

The front face of the blade is again sharpened as a plane face 389 inclined to the outside surface of the blade at an acute angle to provide the necessary keen cutting action. A cutting edge. such as would appear after repeated sharpenings, is shown in dotted line at 310 in Fig. 58. Its shape and dimension are identical with the original cutting edge. I

A fragmentary view of the matching inside cutting blade 315 is shown in Fig. 59. Blades of this side and top cutting edges. This chamfering edge 318 matches the concave chamfering edge 383 of the blade of Figs. 56 to 58 inclusive. The outside surface 319 of the blade 315 is here the noncutting surface and is made of positive pressure angle to extend in the direction of relief of the inside cutting surface of the blade which here has combined radial and axial relief. The outside surface 319 is, therefore, a conical surface of positive pressure angle whose axis is concentric with the cutter axis.

While the invention has been described in connection with clutch members having longitudinally curved teeth, it will be understood that in its broad aspects it is also applicable to clutches having longitudinally straight teeth. Further it will be understood that it is not limited in application to clutch members having side tooth surfaces of zero ressure angle but may be applied also to clutch members of positive pressure angle although ordinarily its use is confined to clutch members of low pressure angle. Still further it will be understood that while I have described the invention in connection with clutch pairs in which one member has side tooth surfaces that are longitudinally concave and the other member has side tooth surfaces that are longitudinally convex, both members may be made with longitudinally convex side tooth surfaces if quite restricted localization of tooth contact is desired.

Moreover, while the invention has been described in connection with the cutting of clutches, it will be understood that it is applicable also to the grinding of clutches. Instead of a face mill cutter, for instance, an annular grinding wheel may be used, or a cup-shaped oscillatory grinding wheel. The grinding wheels may be shaped and employed in the same way as the cutters previously described. In the specification and claims, therefore, where the term cutting or cutting tool is used, it is to be understood that it is intended to include also grinding and grinding tools.

Indeed, while a number of different embodiments of the invention have been described, it will be understood that the invention is capable of still further modification, and this application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice in the art to which the invention pertains and as may be applied to the essential features hereinbefore set forth and as fall within the scope of the invention or the limits of the appended claims.

Having thus described my invention, what I claim is:

l. The method of chamfering the teeth of a toothed face clutch member or the like which comprises positioning a face mill cutter in engagement with the work so that it will cut along the length of a tooth of the work as the cutter rotates on its axis, and rotating the cutter on its axis while effecting a relative helicoidal movement between the cutter and the work in the direction of the work axis to cause the cutter to produce a helicoidal chamfer surface on the tooth of the work along its length.

2. The method of chamfering the teeth of a toothed face clutch member or the like which comprises rotating a face mill cutter in en agement with the work while effecting a relative movement between the cutter and the work about and in the direction of the clutch axis, the rotational movement being at a varying rate as compared with the axial motion.

3. The method of chamfering the teeth of a toothed face clutch member which comprises moving a cutting tool lengthwise of a tooth of the work from one end thereof to the other while effecting relative rotary movement between the tool and the work and. in time therewith, a relative translator movement in the direction of the axis of the relative rotary movement, said relative movements being at a varying ratio.

4. The method of chamfering the teeth of a toothed face clutch or the like which comprises moving a cutting tool lengthwise of a tooth of the work while effecting relative movement between the tool and the work about the axis of the work and in time therewith a relative depthwise feed movement between the tool and work in the direction of the work axis, the last named relative motion'being at a constant rate and the first named relative motion decreasing with increasing depth of feed.

5. The method of chamfering teeth which comprises positioning a face mill cutter, that has convex cutting edges, in engagement with a tooth of the work so that it will out along the length of the tooth from one end thereof to the other, and effecting a relative rotational movement between the tool and work and a relative depthwise movement between the tool and work in time with said rotational movement, said movements being at a varying ratio.

6. The method of successively chamfering the top and cutting the side tooth faces of a toothed face clutch member or the like which comprises moving a cutting tool lengthwise of a tooth of the work while effecting a relative feed motion between the cutter and the work about and in the direction of the work axis, and then stopping the feed movement about the work axis but continuing the feed movement in the direction of the work axis until the tooth side has been cut for its full depth.

7. The method of successively chamfering and cutting the teeth of a toothed face clutch member or the like which comprises positioning a face mill cutter so that it. will operate in two spaced tooth zones of the work simultaneously, and rotating said cutter in engagement with the work while effecting a relative rotary motion between the cutter and work about the clutch axis and in time therewith a relative depthwise feed motion in the direction of the clutch axis, stopping the rotary motion after one side of a tooth has been chamfered but continuing the depthwise feed motion until full depth position has been reached to cut the corresponding side of the tooth and the opposite side of a tooth spaced therefrom, then withdrawing the cutter from engagement with the work and restarting the relative rotary motion during the latter part of the withdrawal movement to chamfer the said spaced tooth of the work at the side corresponding to that cut, and indexing the work after withdrawal motion has been completed.

8. The method of chamfering the teeth of two mating clutch members which comprises chamfering each tooth of one member by moving a formed cutting tool longitudinally of the tooth to produce a formed chamfer surface, and chamfering each tooth of the other member by moving a cutting tool, which has a chamfering edge complementary in profile shape to the first named tool, longitudinally of a tooth of the work while effecting a relative helicoidal movement between the tool and the work to generate a chamfer surface on the work conjugate to the chamfer surface on the first member.

9. The method of chamfering the teeth of two mating clutch members which comprises chamfering each tooth of one member by moving a formed cutting tool longitudinally of the tooth to produce a formed chamfer surface, and chamfering each tooth of the mating member by moving a cutting tool, which has a chamfering edge complementary in profile shape to the cutting edge of the first tool, longitudinally of the tooth while efi'ecting a relative movement between the tool and work about and in the direction of the clutch axis to generate a chamfer surface on the work conjugate to the chamfer surface on the first named clutch member.

10. The method of chamfering the teeth of two 'mating clutch members which comprises chamfering each tooth of one member by moving a tool, that has a concave chamfering edge along the length of the tooth at the top edge thereof while holding the work stationary on, its axis, and chamfering each tooth of the other member by moving a tool, that has a convex chamfering edge complementary to the first-named concave chamfering edge, along the length of a tooth while effecting a relative movement between the second tool and the work about and in the direction of the work axis.

11, The method of chamfering the teeth of two mating toothed face clutch members which com-' prises chamfering each tooth of one member by rotating a face mill cutter, that has chamfering edges of concave profile shape in engagement with the work while holding the work stationary on its axis, and chamfering each tooth of the other member by rotating a face mill cutter that has chamfering edges of convex profile shape complementary to the concave shape of the chamfering edges of the first cutter, in engagement ting, and chamfering edges, the chamfering edges being of convex profile shape and connecting the side and tip-cutting edges, in engagement with the work so that the cutter will operate simultaneously in two spaced tooth zones of the work,

and rotating the cutter in engagement with the work while effecting a relative rotary motion between the cutter and work about the axis of the work' and in time therewith a relative depthwise feed motion in the direction of the work axis, stopping the rotary motion after one side of a tooth has been chamfered but continuing the depthwise feed motion until full depth position has been reached to cut the corresponding side of the tooth and the opposite side of a tooth spaced therefrom, then withdrawing the cutter' from engagement with the work, and restarting ing the side and tip-cutting edges, in engagement with the work while producing a relative feed motion between the cutter and the work about and in the direction of the clutch axis.

12. The method of cutting and chamfering-the teeth of a toothed face clutch member which comprises cutting each tooth by positioning a face. mill cutter so that it will operate. in twoospaced tooth zones of the work simultaneously and that has side cutting and chamfering edges, in engage-' ment with a work-piece while eflecting a relative rotary motion between the cutter and work and a relative depthwise feed movement between the cutter and work in time with the rotary motion, and decreasing the rate of the rotary motion as the cutter feeds into depth, and reversing the direction of the rotary motibn just before the cutter reaches full depth position, withdrawing the cutter after it has cut to full depth, and reversing the direction of rotary motion again after the cutter has been partially withdrawn, and indexing the work after the cutter is clear of the Work.

13. The method of successively chamfering the tops and cutting the side surfaces of teeth of a toothed face clutch member which comprises positioning a face-mill cutter, that has side-cutting, tip-cutting, and chamfering edges, the chamfering edges being of convex profile shape and connecting the side and tip-cutting edges, in engagement with the work, and rotatingthe cutter on its axis while effecting timed relative motions at a varying ratio between the cutter and work about and in the direction of the work axis until a chamfered surface has been generated on the work, then stopping the motion about the work axis, but continuing the motion in the direction of that axis until a tooth side has been cut to full depth. I

14. The method of chamfering the tops and cutting the' side surfaces of teeth of a toothed face clutch member which comprises positioning a face-mill cutter, that has side-cutting, tip-cutwith the work so that the cutter will operate simultaneously in two spaced tooth zones of the work, and rotating the cutter in engagement with the work while efiecting a relative rotary motion between the cutter and work about the clutch axis and in time therewith a'relative depthwise feed motion in the direction of the clutch axis to successively chamfer a tooth at one side thereof and out said side of the tooth, then reversing the direction of the rotary motion about the work axis and withdrawing the cutter from engagement with the work to cut and chamfer successively one side of a tooth spaced from the first tooth,

and indexing the work after the withdrawal motion has been completed.

16. The method of producing a pair of mating v toothed face clutch members which comprises chamfering the tops and cutting the sides of the teeth of one member by rotating a face-mill cutter, that has tip-cutting, side-cutting, and chamfering edges,-the side-cutting edges being connected with the tip-cutting edges and the chamfering edges being connected with the side-cutting, edges, and the chamfering edges being of concave profile shape, in engagement with the work while efiecting a relative depthwise feed movement between the cutter and work until full depth position is reached, and chamfering the tops and cutting the sides of the teeth of the mating clutch member by positioning a facemill cutter, that has tip-cutting, side-cutting, and chamfering edges, the chamfering edges joining the side and tip-cutting edges and being of convex profile shape complementary to the chamfering edges of the first cutter, in engagement with the work, and rotating said cutter on its axis while effecting a relative rotary motion between the cutter and work about the work axis and in time therewith a relative depthwise feed motion between the cutter and work in the directinuing the depthwise feed motion tion of the work axis until the top of a tooth of the said mating member has been'chamfered,

then stopping the relative rotary motion but conuntil a side of that tooth has been out to full depth.

17. The method of producing a pair of mating

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