USRE20063E - Machine and method for forming ex - Google Patents

Description

E. w. MILLER Re. 20,063

AGHINE ELEMENTS MACHINE AND METHOD FOR FORMING EXTERNALLY TOOTHED M v 11 Sheets-Sheet l 0riginal Filed Sept. 17, 1929 6 f 6 1 1a 1 2 .5 a 6? J a 6 w Aug. 11, 1936. E. w. MILLER MACHINE AND METHOD FOR FORMING BXTERNALLY TOOTHED MACHINE ELEMENTS H Original Filed Sept; 17, 1929 11 Sheets-Sheet 2 Aug. 11, 1936. E. w. MILLER. Re. 20,063

MACHINE AND METHOD FOR FORMING EXTERNAL-LY TOOTHED MACHINE ELEMENTS Original Filed Sept. 17, 1929 11 sheets-sneei 5 I he? 21 @47 2 24/ 42226? Aug. 11, 1936. E. w. MILLER MACHINE AND METHOD FOR FORMING EXTERNALLY TOOTHED MACHINE ELEMENTS i1 Sheets-Sheet 4 Original Filed Sept. 17, 1929 Aug. 11,' 1936. E. w. MlLLEl Re.20,0

MACHINE AND METHOD FOR FORMING EXTERNALLY 'I'OOTHED MACHINE ELEMENTS 7 Original Filed Sept; 1'7, 1929 ll Sheets-Sheet 5 Aug. 11 1935. E. w. MlLL ER MACHINE AND METHOD FOR'FORMING EXTERNALLY TOOTHED MACHINE ELEMENTS Original Filed Sept; 17, 1929 11 Sheets-Sheet e' Aug. 11, 1936; E. w. MILLER Original Filed Sept; 17, 1929 ll Sheets-Sheet 7 we #2 v Aug. 11, 1936. r i E. w. MILLER Re. 2 6

MACHINE AND METHOD F OR FORMING EXTERNALLY TOOTHED MACHINE ELEMENTS Original Filed Sept. 17, 1929 ll Sheeizs-She et 9 w. MILLER Re. 20,063 MACHINE AND METHOD FOR FORMING EXTERNALLY TCIQTHED MACHINE ELEMENTS no. 3 9 1 L 1 Original Filed Sept; 17, 1929 11 sheets-sheet 1o Zws E. w. MILLER I Re. 20,063-v Aug. 11', 1936.

MACHINE AND METHOD FOR FORMING EXTERNALLY TOOTHED MACHINE ELEMENTS 11 Sheets-Sheet 11 Original Filed Sept. 17, 1929 I 25 gposite direction.

Reissueci Aug. 11, 1936 :UENI TED S TATE S "PATENT oer-Ice MENTS Edward W. Miller, Springfield,

:Vt., assignor to The Fellows Gear 'Shaper Company, Springfield, -Vt., a .corporation .of

.Vermont Original No. 1,953,969, dated April 10, 1934, Serial 'No. 393,291, filed Septe tion for reissue filed March 27,

31 Claims.

.The object of the .present'invention is to provide a. machine-and cutterfor finishing to final .form and'dimensions the teeth of spurgears, ex-

ternal clutch elements and other more or less analogous machine elements, all comprehensively included within the generic title of externally .toothedmachine elements. The operation carried out by the invention consists in cutting all of the teeth simuitaneouslyon one'side by a succession of planing cutsgperformed lengthwise (in the axial direction) of thework piece, with theuse of a cutter having a number of cutting :elements equal to the number of teeth of the work :piece and correspondingly spaced, and'provided .with cutting edges of-a formthe counterpart or complement to the desiredform of the finished '-:teeth of the work piece; and then simultaneously cutting'the'opposite sides of all-the work piece :teethby-a similar series' of planing cuts. In the illustrative embodiment here shown the teeth or cutting elements of the tool are symmetrical on opposite sides, and the tool is operatedwith a rotary feed about its axis, first progressively in one direction and then progressively in the op- However, the invention con- :templates and includes a machine and cutter equipped and operable to act thus on one side only of the workpiece teeth, leaving the second cut- .ting action. to a second, similar but reversed, tool; .or to reverse the work piece after its teeth have :been cut on one side and repeat the operation on the other side of its teeth by the same tool rotated in thesame direction as before.

.Thenspecific machine element chosen herein for illustration of. the principles of the invention is a spur gear of the involute type, the tooth faces of which are involute curves. This illustration, hcwevenis-not a limitation of theinvention to the treatment, orameans for treatment, ofthis .403specific class of machine elements only, but the ,:spur.:gear typifies all the species of the generic .class above defined. In any case, Whatever may bethe specific machine element, the latter is first rough cut to a'more or less near approxima- .'tion. to finished condition, and the finishing tool is thenoperated to bring it to exact and true condition, forming the-work piece teeth to the outline of its own cutting edges.

This invention includes one phase (the formingof external teeth) ofa generic invention, the

mber I7, 1929. .Applica- 1936, Serial 'No.

other phase of which (forming internal teeth) is disclosed in my .Patent -No. 1,927,098, granted September .-19, 1933, -for -Machine -for forming internal clutch elements. "All claims generic to both of these phases are made in said prior patent. The distinctive featuresof the present invention comprise anew cutting tool, the combination of such-toolwith operating'means for eifectingtrelati-ve axial reciprocation and rotary feed movements between thetool and the work pieceand alternative means for effecting relief of :the cutter from the work during the non-cutting strokesvand for. bringing the tool and work into and out of operative relationship.

In the drawings,

'Fig. 1i5 aside elevation 017a machine embody- I 1 ing the foregoing. invention;

Fig. 2 is a vertical section on line 22 of Fig. l and an elevationof the 'parts at-rthe rear of such .line;

Fig.9 is a horizontal section and plan view lZHkGILOD. line .3 3 of. Fig.2;

:Fig. 4.is a'detail vertical section. taken on line :4 4 of Fig. 2;

.Figs.:5-:and 6-:are vertical detail sections'taken on lines 5+5 andzG-Ji respectively of Fig. 1;

iFig..'7=-is-.a fragmentary plan view on an enlargedrsoale of the work holder and work-alining fixture, theparts immediately below line 7-1 of Fig.2;

' Fig. 8isra detail-cross section taken on line 88 "of Fig. 2;

=Fig."9 is a detail cross section on-line 9-9 of -Fig. 2;

Fig. 10 is an elevation of the adjustable cutter feed stop;

Fig. 11 is:a cross section on line I Il l of Fig. 2;

Fig. 12 is an under plan View of the cutter as seen from line |2-l2-of'--Fig. 2 looking upward;

Fig. 1 3 is a perspective view of one of the blades or unit tools of the cutter;

'Figs.14 and 15 aresectional views illustrating the action of specifically different cutters of the sameeharacter on gears of diiferent diameters;

Figs.l6, Hand 18 are fragmentary enlarged views of the cutter-and work in operative relationship;

Fig. 19 is a vertical section showing a form of =machi-ne embodying this invention but having a shiftable turret with a number of work pieces;

Fig. 20 is a transverse section on line 20-2ll of Fig. 19;

Fig. 21 is a section on line 2 |2l of Fig. 20.

Like reference characters designate the same parts wherever they occur in all the figures.

Attention is directed to Figs. 16, 17 and 18 for explanation of the fundamental purpose and accomplishment of the invention. It will be assumed illustratively that the work piece is a spur gear previously cut to an approximation to final dimensions, but having an excess of stock on both sides of its teeth to be removed in a final accurate finishing operation and that the object is to finish it rapidly to final dimensions and form by cutting all its teeth simultaneously. In practice an excess of about ten or twelve thousandths of an inch on each side is suitable for the purpose, but the dimensions of the work piece and cutter and the amount of stock to be removed are not factors of the invention, except that the spaces initially cut in the work piece must be wide enough to admit the teeth or cutting elements of the tool, and the latter must be wide enough for strength. A fragment of such a gear is shown in the above noted figures and designated a. For cutting it according to this invention I provide a series of tool units or tool elements 1) equal in number to the teeth of the gear, having cutting edges b and b at their opposite sides which are counterparts of the forms or curves to be given to the finished gear teeth. Such cutting edges of each tool or cutter element are provided at and adjacent to the extremities of the element and have a relationship to one another like that of the adjacent sides of two contiguous teeth which bound an intermediate space of the gear, except that they are nearer together in order that the tool unit may enter the narrower than standard space of a rough cut unfinished gear. These cutter units are secured to a holder or cutter head and located so that they surround a central open space, and are equidistant from the center of such space and are spaced about a line corresponding to the pitch circle of the gear, equally with the pitch of the gear teeth tobe finished. In other words, the cutter units have the same pitch as the gear to be cut and their edges have the same relation to their pitch circle as the sides of the gear teeth to the pitch circle of the gear, except for the narrow formation of the cutter units previously mentioned.

These cutter units are planing cutters having their cutting edges defined by the intersection of their sides with an intermediate face approximately parallel to the plane of the section on which the section of Figs. 16-18 is taken. They are operated by effecting a relative axial reciprocation between the cutter head and the gear after these parts have been brought into the coaxial relationship shown in Fig. 16. At the same time the cutter head and gear are relatively rotated, one with respect to the other, progressively in one direction between the reciprocative movements until they eventually reach a position somewhat as shown in Fig. 17, when the sides I) of all the cutter units have shaved off the sides of all the gear teeth to the desired depth. Then the direction of relative rotation is reversed and continued until, in the course of their reciprocation, the edges 12 of the cutter units have planed away the opposite sides of the gear teeth to the extent that such teeth have the required finished width.

Describing now the details of an illustrative machine for carrying out these operations, Figs.

1-15 show such a machine equipped with a single work holder. A rigid base or pedestal 2| supports a housing 22 and a guide 23. A cutter spindle or slide 24 is adapted to reciprocate and rotate in the guide 23. It is reciprocated by a connecting rod 25, crank disk 26, shaft 21 and motor 28 which is connected to the shaft by a sprocket drive consisting of sprocket gears 29, 30, and chain 3!. The crank pin, 32 is adjustable radially of the disk 26 in the guideway 33. The connecting rod is coupled to the cutter spindle by a block 34 in which the wrist pin 35 is mounted and in which the spindle has a rotative and end thrust bearing.

The work piece a, which in this instance is the end-most gear element on a gear assemblage of the type used in automobile transmissions, is mounted on a work arbor 36 which has a tapered portion 36a firmly seated in a work carrier 31 by means of a draw rod 3%. The work piece is clamped on the arbor by a nut 38. The carrier is fitted slidingly in a guideway 39 and has rack teeth 40 on one side engaging a pinion t I whereby it is raised to place the work in cutting position and lowered to clear the arbor from the cutter so that the work piece may be placed on and removed from it. Pinion 4| is fast on a shaft 42 (Fig. 9) fitted to a bearing extending through the side of the guide 39, and carrying a hand wheel 43.

The guideway is slotted at one side from its upper end downward and provided with ears 4:3 adapted to be drawn together by a clamp screw 35 (Fig. 8) whereby the carrier is clamped and secured in the working position.

The work piece is positioned angularly by means of an alinement fixture consisting of an arm 35 (Figs. 2 and 7) swiveled on a post 41 which rises from an oil pan 48 fixed on the upper end of the carrier 31. On the arm 46 is a slidable sleeve 49 equipped with a clamping set screw 5!; and carrying a finger 5| which is adapted to enter one of the tooth spaces of the work piece. The work piece is thus positioned before its clamping nut is tightened, after which the nut is screwed down and the fixture arm swung aside out of the way of the cutter.

Angular movement is given to the cutter spindle for effecting the rotational feed described with respect to Figs. 17 and 18, by the following mechanism. A sprocket gear 52 fast on shaft 21 drives, by means of a chain 53, a sprocket gear 54 fast on shaft 55. A carrier 56 is likewise made fast to shaft and carries a pivot stud 51 on which is a planet pinion having two steps 58 and 59 having respectively different numbers of teeth.

The planet element Ell meshes with a stationary internal gear 58 fastened to apart of the frame, and the other planet element meshes with a rotatable internal gear 6! on a shaft 62. By means of this planetary gearing a very slow speed of rotation is given to the shaft 62. By suitable design of the gear elements 53, 59, Eli and 5!, any one of different slow rates of movement within a wide range may be imparted.

One element 53 of a friction clutch is splined on shaft 62 and is pressed by a spring 64 against a complemental clutch element 55 which is free to turn independently of the shaft and is held thereon by a nut 66. A flexible coupling 51 connects the clutch element 55 with an arm E53 keyed to a shaft 69. The coupling here shown is a flat strip of metal screwed to the parts 55 and 68, but this is merely typical of a number of couplings which might be used for the purpose of transmitting rotation from clutch E5 to shaft 59 withzmtrrequirimg sexact refinement. .--A warm MI is splined on shaft 69 and meshes withr avworm :rheel II whichsurroundsithe"cutter-spindle 24 aimi hasa-a hubmortion'flzz occupyinga bearing in athegguide or housing 23. .A guidemember 13 l'elgsi2 and 11).secured to-hubi1-2 and engaging i with the spindle imparts' rotation toithe latter while 1 permitting unimpeded "endwise reciprocav tionithereof. The guiding means here'referred 10 are of thesame character-as illustrated in the patent to E. R.--Fellows.-No. 676227, June 11,1901,

and may be either straight in the direction of ithesspindle -axis, or 'curve'd 1 helically about such :axis, according to whether thewgears being produced are straight or helical. When-helical gears are to be produced; the cutter units may be comi pilementally helical.

'AA slight "angular move'ment 'is given to the "cutter, in=theopposite direction to the-movement gi'venby the feeding mechanism above described,

fitter-each cutting-stroke, in'order toback oiT 'or; relieve itduring its noncutting: returnstrokes,

'so that it will-not then rub onthework. For tl'iisapurpose, the -worm 10 =is -splined to shaft "69 is moved-endwise alternately inopposite directions by a cam'JZI Fig. 4) and a spring 13 I.

"The-springis a'helical one whichsurrounds a sleeve- 14 within the -shaft=housing 15- and exerts 0 -pressure endwise between an abutment' IB on-the heusirig and-a shoulder ll on the-sleeve. The

sleeve isadapted toslide onthe-shaft and transmits pressure endwise-to the-worm through a ringifllp-with which it-has'a spherical contact, and a thrust bearing'M. Theopposite end of the worm-is engaged through an end thrust bearing i0 and a spheiicabsurface ring-8| Witha sleeve '12, which' is slidable on the shaft I0 and splined writhin the housing, from which protrudes. Its protruding end-is thus pressed against hardened bearing 'studs 83 (Fig. 6)

mounted in the branches 84 of the foi'ked arm of a lever 415. "This lever is pivoted on'the'pivot shaft #6 held in lugs'Bl projecting from the *forward -end of the housing. Its forked arm straddles shaft Hi andits "other arm carries an anti-friction -rol1 88 which is held f continuously, by pressure of-the spring I3I,'in contact with the circumference --of the cam.

The cam has a substantially concentric high portion-extending through approximately half its circumferenceand a low portion-throughout the balance of its circumference, the difference in 'height between these portions being "small in amount and-not necessarily more "than enough to shift the cutter througha small-fractionof an ineh. The cam is rotated at the same-anguiar speed-as the cutter-drivingcrank-disk 26 (inother "words'at a one to one-ratio) by means of a gear "88 (Fig. 3) keyed'toshaft "and meshing with gear l 90 on a =paralle1 shaft *9 I a helical gear .92

--alsokeyed to shaft 9|, and amating helical gear 93' (Fig.-5) on shaftfi'dtowhich the'cam is keyed.

flhe-mechanismis so'timed that, while the ro- 35 -tational feed 01' the-cutter is in the direction indicatedby-Fig. 17,'"the high part of thecam is in action during the cutting strokes, holding the cutter elements'up to *the work, and the low part -permits spring 'I-3I"to*back off the cutter at the end-of the -cutting strokes and hold it clear of thework during the-return strokes. When the "direction of 'feedis reversed in 'orderto drive 'thecuttcr' inithe direction indicated by'Fig. 18,

theentiremechanism, including the'worm and 7 the cam, is driven in the opposite'direction and ful one which exerts ffinished on one side, is accomplished by reversing :zthe direction of running of the driving motoria. This motor:is an electric motor of known character having reversible poles enabling itto run in eitherdirection. As-all the mechanisms are driven from this one motoigitsreversal causes ;them all .to run reversely. But as the reciprocation of the cutter isaccomplished through .a

When the cutter has been thus fed rotatably in either direction to a 69. On this carrier disk is fitted a surrounding annular disk 96 having a handle 91. The annular .disk is clamped against a shoulder 98 on the .carrier disk by a ring 99, which is arranged and secured by bolts I09 substantially as shown in Fig.

I02 (Fig. 10) at respectively oppositesides of a=fixed stopI D3 which is secured to the frame.

blocks I04 and I05 respectively, having shanks, one of which passes through a slot I96, and the other through a slot H11, in the disk 96. On the shanks are'mounted clamp screws by which the blocks are made fast at any desired points in the respective slots. :The slots are concentric with the disk, and each block is made with the outer circumference of the clamp ring which is also concentric with the shaft,

pieceisheld stationary. 'Atmost the'helical displacement'fromendto- "endof the teeth-in the --wor k piece is 'a small proportion :of the :total amount" of-rotary-feed occurring between cuts.

Stops I OI-and I02 are After the first series of cuts has been completed as shown in Fig. 17, time may be saved in commencing the second series of cuts with rotation of the cutter in the opposite direction, by the operator rotating the worm shaft 69 in the opposite direction by means of the handle 91. A ball check I08 is mounted in. a socket in the end of stop I03 and pressed outward by a spring I09 in such socket against the rear face of disk 96. A groove or recess III! is formed in the disk to receive the ball when the cutter is in neutral position, that shown in Fig. 16, whereby a yielding impediment is given to the rotation of the disk. After completion of the second series of cuts the operator returns the cutter to neutral position. This yielding impediment, in conjunction with the alinement fixture 46 previously described, enables the work pieces and the cutter quickly to be alined correctly before the commencement of operations.

The cutter is a vital factor of the invention. It is shown in detail in Figs. 12-15. It consists of an annular holder or head III and a series of cutter units or elements I). These units or elements are arranged in the manner of the spokes of a wheel and are first clamped against one face of the holder by screws II2. When they have been correctly located and thus secured, they are additionally and permanently made fast by molten metal, preferably type metal, which is poured into the spaces between and around the cutter elements. and within an outer wall or rib H3 which projects from the peripheral part of the head at one side thereof to an extent approximately equal to the thickness of the shank parts of the cutter elements, the spaces between the cutter elements at the rim of the central hole in the cutter head being then temporarily dammed. The type metal is identified in Figs. 14 and 15 by the numeral IIfl.

While various fusible metals may be used for thus embedding and securing the cutter elements, type metal is preferred because it has a melting point low enough to be used without injuriously heating the cutter elements, and when solid is sufficiently hard and rigid to hold the cutter elements immovable under the stresses to which they are subjected in use. But any other metal or alloy, or nonmetal, having these qualities may be used. A preferred step in this connection is to heat the assembled head and tool elements before pouring in the fusible metal to a temperature high enough to expand the head substantially, although not up to the melting temperature of the fusible metal; say to a temperature between 200 and 300 F. Upon cooling, the shrinkage of the head causes its encircling wall to exert a powerful pressure on the embedding material and thus assures a solid immovable foundation or matrix for the cutter elements.

As previously stated, the inner ends only of the cutter elements have cutting edges. These extremities project over the rim of the central hole in the head and are given greater thickness than the shank portions of the cutter elements, so as to provide stock as shown at b protruding beyond the face of the assemblage and which may be ground away on the outer side for sharpening. The intersections of the outer face with the concave sides of the element form the cutting edges b and b first described. Such concave sides are formed with the desired curvature complemental to the prescribed shape of the gear teeth to be finished and are made somewhat sloping to provide the clearance necessary in metal-cutting edged'tools.

A given cutter assemblage is adapted to cut gears of the same diameter, pitch and tooth forms. Gears varying require different cutters. respectively two such cutters, one designed for the gear a at the end of a gear assemblage of the type used in automobile transmissions, and the other for the next The cutter is connected to the spindle 24 by means of an adapter I15, to which it is secured by screws II6 passing through the adapter into the back of the cutter head, and the adapter in turn is secured by the end of the spindle. The adapter has acentral hole to admit the gear being cut and the nut 38 by which the gear is clamped to the arbor 36. Adapters of different thicknesses are used to accommodate the cutter to gears more or less far removed from the end of the arbor. Thus, for cutting the gear d of the assemblage here shown, a thicker adapter, as well as a cutter having a larger central space than thus shown in Fig. 15, are necessary. When the gear 6 at the opposite end of the assemblage, which is also the largest gear, is to be cut, the assemblage is turned upside down and applied in the that shown in the drawings. cutter substantially larger in than the one shown in Fig. 15, and also an adapt er correspondingly large at the lower end. Preferably the adapter has flanges protruding to both sides to surround the cutter head and the spindle fiange, centering and alining them.

The arbor has an end extension 360 which is guided in a bushing H9 fitted slidingly and adjustable longitudinally in a central recess in the spindle, to maintain the cutter and work in exact alinement, preventing any possible deflection due For that purpose a to the lateral pressure of the rotating cutter against the work.

Figs. 19, and 21 show a different work holder in a machine otherwise the same as hereinbefore described. This work holder consists of a. turret I20 having a large and rigid horizontal pivot I2I rotatable in the frame about an axis in the same vertical plane with the work spindle axis, and having two guideways I22 and I23 radial to the pivot in which are slides I24 and I25 carrying work arbors 36l and 362. The turret is movable manually to place either arbor in alinement with the cutter spindle having a handle I25 forso moving it. A spring pressed locking pin I2I having a knob I28 for retracting it (Fig.

21) enters a socket I29 in the frame for securing the turret in the position shown by full lines in Fig. 20; and enters a second socket I30 for locking it in the dotted line position. A cam I3l is engaged by rolls I32 on the slides, the latter being retracted toward the cam by springs I33 (Fig. 19). The cam is mounted on ashaft I34 to which a crank I35 is secured, by which it may be turned manually. With the turret in either position the finished work piece may be removed from the arbor then out of alinement with the cutter spindle, and a blank work piece substituted. This enables the attendant to unload and load the inoperative arbor while the machine is doing its work. In shifting the work holder, the cam is first turned so as to retract the operative arbor, the turret is then swung over from one position to the other, and the cam again turned to raise the arbor which has just been placed in operative position.-

in any of these particulars Figs. 14 and 15 show gear 0 of the assemblage.

screws II! to a flange IIB on reverse position to diameter is required The foregoing description has been given as,

machine without-departure from the principles of' the invention and within the range of equivalents of the subject matter claimed may be made;

,What. I claim and desire to secure by Letters Patent is:.

'1. A machine for v finishing externally toothed machine elements comprising a cutter having fixed cutting elements arranged complementally to the teeth of such machine element and having cutting edges which are complemental to the prescribed tooth face outlines but nearer together than the finished width of the spaces to be cut, means-for effecting axial reciprocation between said cutter and an alined work piece, and means for efiecting, a relative rotary feed between the cutter and work piece about their common axis.

2. A machine for cutting to final form simultaneously a plurality of teeth of an externally toothed machine element, comprising a. reciprocatable and rotatable cutter spindle, a work holder arranged to hold an unfinished externally toothed machine element in axial alinement with said spindle, .means for reciprocating the spindle and rotating it at a slow rate, and a cutter secured to the spindle and having an .annular series of rigidly fixed cutting elements narrower than'the finished width of the spaces to becut spaced about the axis of the spindle with the same pitch'on a pitch'circle of the same diameter as the teeth of the work piece and having cutting edges complemental to the prescribed finished tooth face forms.

3. A machine for cutting to final form simultaneously anumber of teeth of one and the same machine element, comprising a series of cutting elements located in invariable fixed relation to one another conformably to the tooth spaces of an unfinished roughed out gear and narrow enough to enter such sp-aces,.each having on one side a cutting edge complemental to. the prescribed finished curvature of the gear teeth, and means for efiecting relative reciprocativ-e cutting movement and rotative feed movement between said cutting elements and an unfinished gear located inalinement with the axis of said series.

4. A machine for forming the teeth of externally toothed machine elements, comprising a cutter having a central opening and a series of cutting elements protruding inwardly toward the axis of such opening from the rim of the opening, said cutting elements being provided with cutting edges of prescribed form, nearer together than the finished width of the spaces to be cut, andbeing spaced equidistantly from one another and'at an invariable distance from said axis with a pitch equal to the pitch of the teeth in thework piece, means for holding said outterrand an externally tooth-ed machine element in axial alinement, and means for eifecting relative, movements of axial reciprocation and rotatiorr between the cutter and work piece.

5. A machine for shaping the teeth of externally, toothed gear elements comprising a work holder; a cutter spindle axially alined with the work holder when in operation, a cutter mounted: on; said spindle having adapted to receive the work elements extending inwardly distance from the rim of such a central opening piece, and cutter to an invariable era] cutting edges complemental to the form to opening with latbe given the sides of the teeth of the work piece, said elements being narrower than the tooth spaces of the finished-work piece whereby they are able to enter the spaces between the teeth of a rough cut unfinished work piece, means for reciprocating the cutter spindle, means for progressively rotating said spindle in one direction, and means for giving a limited additional oscillation to the spindle oppositely to the direction of such progressive rotationafter each cutting stroke, and in the same direction as the progressive rotation after each return stroke.

6. A machine for shaping the teeth of externally toothed gear elements comprising a work holder, a cutter spindle axially alined with the work holder when in operation, a cutter mounted on said spindle having a central opening adapted to receive the work piece, and cutter elements extending inwardly ing with lateral cutting edges complemental to the form tobe given the sides of the teeth of the work piece, said elements being narrower than the tooth spaces of the finished work piece whereby they are able to enter the spaces betweenthe teeth of a rough cut unfinished work piece, means for reciprocating the cutter spindle, and means for progressively rotating saidspindle in one direction, said rotation-causing means being reversible to cause action of the cutter elements on the opposite side of the work piece teeth after completion of a series of cuts over one side thereof.

'7. A machine for shaping the teeth of externally toothed gear elements comprising a work holder, a-cutter spindle axially alined with the Work holder when in operation, a cutter mounted on said spindle having a central opening adapted to receive the work piece, and cutter elements extending inwardly from the rim of such opening. with lateral cutting edges complemental to the form to be given the sides of the teeth of the work piece, said elements being narrower than the tooth spaces of the finished work piece whereby they are able to enter the spaces between the teeth of a rough cut unfinished work piece, means for reciprocating the cutter spindle, means for progressively rotating saidspindle in one direction, said rotation-causing means being reversible to cause action of the cutter elements on the opposite side of the work piece teeth after completion of a series of cuts over one side thereof, and means for additionally oscillating the cutter spindle after each reciprocation thereof in such manner that, with rotary feed in either direction, the cutter elements are moved clear of the work piece during each return stroke of the spindle and held in cutting engagement with the work piece'during each cutting stroke of the spindle.

8. A machine for shaping the teeth of externally toothed gear elements, comprising a work holder, a. cutter spindle'axially alined with the work holder when in operation, a cutter mounted on said spindle'having a central opening adapted to receive the workpiece, and cutter elements extending inwardly from the rim of such'opening with lateral cutting edges complemental to the formto be given the sides of the teeth of the work piece, said elements being narrower than the tooth spaces of the finished work piece whereby they are able to enter the spaces between the teeth of a rough cut unfinished work piece, means for reciprocating the cutter spindle, means for progressively rotating said spindle in one direction, a Worm gear coupled from the rim of such open-- to the spindle for imparting rotation thereto, a worm meshing with said gear for rotating it, and means for moving the worm endwise alternately in opposite directions in such timing with the reciprocative strokes of the spindle that an increment of rotation is given to the spindle oppositely to the rotary feed after each cutting stroke and in the same direction as the rotary feed after each return stroke.

9. A machine for forming simultaneously a plurality of 'teeth in a previously partially completed machine element having external teeth, comprising a stationary work holder, a reciprocative and rotatable cutter spindle, a cutter carried on the end of said spindle having fixed cutting elements surrounding a central space and extending inwardly from the boundary of such space, said cutting elements being equal in number and correspondingly spaced to the spaces between the teeth of the work piece and having cutting edges which are complemental to the prescribed finished forms of the tooth faces in the work piece, means for reciprocating said spindle, and means for rotating the spindle comprising a worm gear having rotation transmitting and reciprocating permitting engagement with the spindle, a worm meshing with said gear, and a driving shaft for said worm.

10. A machine for forming simultaneously a plurality of teeth in a previously partially completed machine element having external teeth, comprising a stationary work holder, a reciprocative and rotatable cutter spindle, a cutter carried on the end of said spindle having external cutting elements surrounding a central space, said cutting elements being equal in number and correspondingly spaced to the spaces between the teeth of the work piece and having cutting edges which are complemental to the prescribed finished forms of the tooth faces in the work piece, means for reciprocating said spindle, and means for rotating the spindle comprising a worm gear having rotation transmitting and reciprocation permitting engagement with the spindle, a worm meshing with said gear, and a driving shaft for said worm, the worm being splined on its. driving shaft whereby it is rotated thereby and free to move endwise thereon, combined with a spring exerting endwise pressure in one direction on the worm, and a cam and intermediate lever organized to exert endwise pressure in the opposite direction on the worm, the cam being so timed with respect to the reciprocations of the spindle that it cooperates with the spring in giving endwise movements to the worm such as to relieve the cutting elements from the teeth of the work piece during noncutting strokes of the cutter and return the cutter into cutting position for the cutting strokes.

11. A machine for forming simultaneously a plurality of teeth in a previously partially completed machine element having external teeth, comprising a stationary work holder, a reciprocative and rotatable cutter spindle, a cutter carried on the end of said spindle having external cutting elements surrounding a central space, said cutting elements being equal in number and correspondingly spaced to the spaces between the teeth of the work piece and having cutting edges which are complemental to the prescribed finished forms of the tooth faces in the work piece, means for reciprocating said spindle, means for rotating the spindle comprising a worm gear having rotation transmitting and reciprocation permitting engagement with the spindle, a worm meshing with said gear, a driving shaft for said worm, a friction clutch imparting driving rotation to said shaft, and a positive stop for arresting the rotation of the worm when the rotary feed of the cutter has continued to a predetermined extent.

12. In a machine ofthe character described, a reciprocatable and rotatable cutter spindle, a block having rotatable and end thrust engagement with the spindle, a driving crank, a connecting rod between said crank and block having a wrist connection with the latter, and means for imparting a progressive rotative feed movement to the spindle simultaneously with the reciprocative movements thereof.

13. A machine of the character described, comprising a shaft, a reciprocative and rotatable cutter spindle, means driven by said shaft for reciprocating the spindle, a worm driving shaft, a planetary gearing driven by the first named shaft and organized to transmit slow rotation to the worm driving shaft, a worm on the last named shaft, a worm wheel meshing with said worm and engaged with the spindle to impart rotation to the latter, a friction clutch interposed between the planetary gearing and the worm driving shaft, and a positive step for arresting rotation of the worm driving shaft at a predetermined limit.

14. A machine of the character described, comprising a shaft, a reciprocative and rotatable cutter spindle, means driven by said shaft for reciprocating the spindle, a worm driving shaft, a planetarygearing driven by the first named shaft and organized to transmit slow rotation to the worm driving shaft, a worm on the last named shaft, a worm wheel meshing with said worm and engaged with the spindle to impart rotation to the latter, a friction clutch interposed between the planetary gearing and the worm driving shaft, the worm and its driving shaft having a splined connection whereby endwise movement of the worm on the shaft is permitted, a counter shaft driven from the first named driving shaft, a cam driven from said countershaft, a lever engaged with said cam and having an arm arranged to exert pressure endwise against the worm, and a spring exerting pressure endwise in the opposite direction against the worm.

15. In a machine for finishing gears and the like by a forming cutter having circularly arranged cutting elements adapted to operate simultaneously on a plurality of teeth of the work piece, a reciprocative and rotatable spindle on which the cutter is secured, a work holder in axial alinement with said spindle, and means for moving said work holder back and forth along the axis of the spindle for placing the work piece in and out of operating relationship with the cutter.

16. A machine for shaping and finishing spur gears comprising a normally stationary work holding arbor, a cutter spindle arranged to reciprocate and rotate in and around an axis in alinement with said arbor, and separated therefrom, means independent of the arbor for guiding said spindle, a cutter mounted on the end part of said spindle near the arbor and having cutting elements surrounding said axis with their extremities directed toward the axis, said elements provided with cutting edges at and adjacent to such extremities which are complemental to the prescribed finished tooth faces of the work piece, said arbor having a guiding extension projecting into the spindlean'd in -guided engagement therewith to prevent displacement of the workpiece.

-17.' -A.machine of the character describedcomprisingan alined cutterspindle-and work arbor, means for reciprocating said 'cutterspind-le"in, and=rotating it about-as axis, and a cutter secured to said spindle having cutting elements with cutting edges on corresponding sides which are a counterpart formation to the prescribed finished form of the teeth of a given externally toothed machine element, said cutting elements being arranged to project toward the axis of the cutter from a coaxial circular line with an angular spacing on such line equal to the spacing on a circle of the same diameter between corresponding faces of adjacent teeth of the machine element.

18. The method of forming an externally toothed machine element which consists in, providing a cutter having cutting elements surrounding an open interior space and arranged with spaces between them opening into such interior space and arranged correspondingly to the teeth of such toothed machine element, placing the cutter and a work piece in axial alinement, and effecting an axial reciprocation between the cutter and work piece, together with a rotation of one relatively to the other about their common axis, in such manner that all of the cutter elements are caused to act simultaneously on the Work and form one side of each of the teeth of the work piece by a planing action.

19. The method as set forth in claim 18, including further the step of reversing such relative rotation and causing the cutter similarly to form the opposite sides of such teeth.

20. The method of forming an externally toothed machine element which consists in providing a cutter having cutting elements surrounding an open interior space and projecting inwardly toward the center of such space, and arranged, as to their radial and angular relation to the cutter of such space, in exact conformity with the spaces to be cut in the work, placing the cutter and work piece in axial alinement, and effecting a relative axial reciprocation between the cutter and work piece together with a slow angular rotation progressively in the same direction of one relatively to the other about their common axis, in such manner that all of the cutter elements are caused to act simultaneously on the Work and form one side only of each of the teeth of the work piece by a succession of planing strokes.

21. The method as set forth in claim 20 comprising further the step of reversing such relative rotation and causing the cutter elements similarly to form the opposite sides of the work piece teeth by a succession of planing cuts performed successively in the opposite direction.

22. In a machine for finishing gears and the like by a forming cutter having circularly arranged cutting elements adapted to operate simultaneously on a plurality of teeth of the work piece, a spindle on which the cutter is secured, a work holder in axial alinement with said spindle, means for moving the spindle axially and repeatthe sides of the teeth of the work piece, and means for moving said work holder back and forth along the axis of the spindle through a distance greater than the length of the reciprocativ-e movements of the cutter.

23. In a machine for finishing gears and the like by a forming cutter having circularly arranged cutting elements adapted to operateisimulg taneously on a plurality of eeth on the workpiece, a spindle onwhich the cutter is secured means for reciprocating the cutter axially-throughwa limited distance for acting on the work:p-ie'ce in a succession of cutting strokes, 'a 'work spindle in axial alinement with the cutter, a guide located at a distance from the end of said spindle in which end of the cutter spindle.

24. In a machine as set forth in claim 23, the combination of a work holding arbor secured to said work holder and extending thence into guided sliding engagement with the spindle.

25. A cutter for gear elements, havmg fixed cutting elements arranged complementally to the teeth of a given externally toothed machine element to be finished, said cutting elements being provided with cutting edges which are complemental to the prescribed tooth outlines but are nearer together than the finished Width of the spaces to be cut.

26. A cutter for 27. A gear finishing cutter comprising a series of cutting elements located in invariable fixed relation to one another conformably to the tooth spaces of an unfinished roughed out gear and of less width than the spaces to be out, each element having on one side a cutting edge complemental fto the prescribed finished curvature of the gear eeth.

28. A gear finishing cutter having a central opening and a series of cutting elements protruding inwardly toward a of such opening, said cutting elements vided with cutting edges of in the work 29. A cutter for finishing external 30. A gear finishing cutter comprising an annulus having internal rigid and immovable teeth equally spaced apart from one another on a curved pitch line, said teeth having cutting edges substantially in a plane perpendicular to the axis of the annulus and having sides which converge toward one another away from such plane for cutting clearance, the

finishing externally toothed outlines of such cutting edges being of counterpart curvature to the tooth face curves of a given external gear, and. the distance between cutting edges of each tooth being narrower than the lnterdental spaces of such ex- 5 ternal gear.

31. An annular gear finishing cutter having internal teeth with cutting edges at one end of the cutter which are of counterpart curvature to the tooth face curvature of a. given external gear, the cutter teeth being narrower than the interdental spaces of such external gear.

WARD W. MILLER.

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