US2405159A - Method and machine for finishing the teeth of gear shaving cutters and the like - Google Patents

Description

Aug. 6, 194%. mw, LLER 2A09 METHOD AND MAC FINISHING THE TEETH- OF GEAR SHAVING CUTTERS AND THE LI Filed May 15, 1941 Sheets-Sheet l 6, 1946. E. w. MILLER 9 METHOD AND MACHINE FOR FINISHING THE TEETH OF GEAR SHAV'ING CUTTERS AND THE LIKE Filed May 15. 1941 6 Sheets-Sheet 2 Avg 9 3%.. E. MILLER fifififi PZIETHOD AND MACHINE FOR FINISHING THE TEETH QF GEAR SHAVING CUTTERS AND THE LIKE Filed my 1.5, 1941 6 Shasta-sheaf, 3

MILLER 2,

E. w.- v I METHOD AND MACHINE FOR FINISHING THE-TEETH OF GEAR SHAVING CUTTERS AND THE LIKE Filed May 15, 1941 6 Sh'eet-Sheet 4 6 Sheets-Sheet 5 I E. W. MILLER METHOD AND MACHINE FOR FINISHING THE TEETH OF GEAR SHAVING CUTTERS AND THE LIKE Filed May 15 1941 Aug. 6, i946.

- METHOD AND MACHINE FOR FINISHING THE TEETH 0F GEAR SHAVING CUTTERS AND THE LIKE E W NIILLER 2,495,359

Filed May 15, 1,941 6 Sheets-Sheet 6 7 5 /ZZ-a I i l I l I I I z /Z/ V 5% m1 q; W M J w M M I i "i If I. I Immun gumm 4, 4 .1

Patented Aug. 6, 1946 UNITED STATE s PATENT OFFICE METHOD AND MACHINE FOR FINISHING THE TEETH OF GEAR SHAVING CUTTERS AND THE LIKE Application May 15, 1941, Serial No. 393,554

18 Claims. 1

The subject of this invention is concerned with means for performing a finishing operation, by cutting action, on the teeth of shaving cutters and other tools and machine elements having features characteristic of gears. The specific embodiment of the invention here presented for 11- lustration is designed to cut grooves or slots in the tooth faces of gear shaving cutters. Such cutters are well known in the art. gears in having teeth conjugate to the gears which they are designed to finish, but differ from ordinary machine gears in that they are made of a steel composition, or other alloy, sufficiently hard to provide metal-cutting edges, and are provided with a multiplicity of such edges, in the sides of their teeth, in tandemarrangement between the ends of, the teeth.

However, the invention is not limited to means for performing the specific slotting or grooving operation above referred to but may, as will later appear, be used for otherwise finishing gear teeth and the surfaces of other elements similar or analogous to gears.

The particular objects of the invention are to accomplish the result of so finishing teeth in an improved manner, to perform the operation more rapidly than heretofore, and Without need of performing a depth feed in order to extend the cutting efiect to a prescribed depth in the work, and to accomplish other useful results which are explained in the following description.

The principles of the invention are hereinafter explained with reference to drawings of a machine illustrating the preferred embodiment of these principles.

Fig. 1 of the drawings is in part a front elevation, and in part a vertical section of the machine referred to, the plane of section being indicated by the line l-i of Figs. 4 and 8;

Fig. 2 is a sectional View of a detail of the machine taken on line 2-2 of Fig. 1;

Fig. 3 is a section on line 33 of Fig. 2;

Fig. 4 is a vertical section on a front to rear plane on line 44 of Figs. 1, 10 and 11;

Fig. 5 is a detail view of one of the teeth of a shaving tool showing the results of the finishing operation performed by the machine here illustrated;

Fig. 6 is a perspective view of the operating tool with which the machine is equipped to cut the slots illustrated in Fig. 5; V

Fig. 7 is a fragmentary view illustrating an adjustment of the tool for operating on helical teeth;

They are like Fig. 8 is a vertical section of the machine taken on line 8-8 of Fig. 1;

Fig. 9 is a detail sectional view taken on line 9-9 of Fig. 8;

Fig. 10 is a sectional view taken on line Ill-I0 of Figs. 4 and 8, looking from front to rear;

Fig. 1 is a rear elevation of the machine;

Fig. 12 is an elevation of a detail of the indexing mechanism;

Fig. 13 is a plan view of the parts shown in Fig. 12;

Fig. 14 is a horizontal section taken on line l d-I 4 of Figs. 1 and 4;

Fig. 15 is an axial section of a clutching device which appears in elevation, and on a smaller scale, in Fig. 14;

Figs. 16, 17 and 18 are diagrammatic views illustrating the progress of the cutting action on a single tooth of, the work piece.

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

Referring to Fig. 5, there is shown in plan view a tooth t of a conventional gear finishing tool. Such tool is made of metal or alloy of a character suitable for metal cutting tools; it has teeth similar to gear teeth, which may be either straight or helical, and are conjugate to the teeth of the gears which it is designed to shave; and a number of slots or grooves g are cut in the sides of each tooth, extending from the crest toward the root, the intersections of which slots with the side faces of the teeth form cutting edges e. Such slots are produced by the operation of this machine with the aid of acutter C, shown in detail in Fig. 6, which is provided with ribs r of the width prescribed for the slots g, separated by spaces 8. The bounding edges a of the ribs at the extremity of the cutter perform the cutting action. Ordinarily the spaces 8 are deeper than the slots to be cut in the work piece, whereby they leave untouched lands on the side faces of the work piece teeth t, the widths of which are determined by the widths of the spaces s. But the inner boundaries of such spaces at the end of the cutter may likewise be disposed and serve as cutting edges, as when it is desired to shape the lands of the work piece teeth with cutting clearance between the corresponding edges e of adjacent grooves.

The slotting operation is performed by reciprocating the cutter C rapidly endwise while the gear shaving cutter or tool, which will hereinafter generally be referred to as the work and is designated in the drawings by the reference character W, is slowl rolled past it. Cutter .0 is mounted on the upper end of a ram or cutter carrier 1, which reciprocate endwise in guides 2 and 3, suitably mounted in the machine base 4. The ram is thus reciprocated by a main shaft 5, rotated by an electric motor 6 through a belt 1 and pulley 8, the shaft having a crank pin 9 coupled by a connecting rod ID with a lever ll pivoted at 42. A gear segment I3 is carried by lever l I and meshes with encircling rack teeth M on th ram. The connecting od H1 is made of telescopic construction, extensible in length, the crank pin 9 is adjustable radially of the main shaft 5, and the pivot by which the connecting rod is coupled to lever ll may be placed in either of two holes IS in the lever, whereby a wide range of adjustment is made possible, affecting both the length of the cutter strok and the location of its path, to accommodate larger or smaller work pieces.

Provision is made for relieving the cutter so that it will not rub on the work durin its retracting strokes. This is accomplished b mounting the cutter head I! (which is provided with jaws l8 and i9, between which the shank of the cutter is clamped by a screw pivotally on the ram and swinging it about its pivot in time with the reciprocations of the rain. 'The pivotal connection is made by a pin 2| secured in the cutter head and extending at opposite ends into alined bearings in the ram, as shown in Fig. 8. This pivot is perpendicular to the path of the ram and parallel to the width dimension of the cutter. An arm 22, forming part of the cutter head, depends in the hollow interior of the ram and has a cam surface 23 in a plane parallel to pivot 2| and inclined to the path of-the ram. A wedge block 24 is fitted to a guideway in the ram, so that it may move lengthwise of the latter, andha a cam surface complemental to the before mentioned cam surface 23, against which the latter is held in engagement by a spring pressed plunger 25. The wedge block is coupled by a rod 26 with a piston 27 fitted to a cylinder 28 in the lower end of the ram.

Piston 2'5 is moved in opposite directions pneumatically under control of the main shaft 5. Ports opening into opposite ends of the cylinder are connected by flexible tubes 29 and 3D, respectively, with a valve casing 3! mounted in the machine base. A rotary valve 32 in the valve casing is geared to the main shaft by gears 33 and 34 to rotate once with each rotation of the shaft. Passageways 35 and 36 are provided in the rotating valve and other passageways 31 and 38 are provided in the casing, substantially as shown in Figs. 2 and 3, suitably arranged so as to connect the tubes 29 and 3t] alternately with an air supply pipe 39 and an exhaust pipe. These passages are likewise arranged to maintain air pressure on the upper end of piston 21 during the upward or working stroke of the cutter carrier and to maintain pressure on the lower end-of the piston, relieving the pressure from its upper end, during the down strokes of the cutter. Downward force exerted by the piston 21 on wedge block 2 lcauses the arm 22 to be displaced by cam action against an abutment surface in the ram, thereby placing and holding the extremity of the cutter in its cutting path; while upward movement of the wedge allows the spring of plunger 25 to displace the cutter far enough to avoid rubbing on the work during its retracting strokes.

The ram i may be rotated about its longitudinal axisfor adjusting the cutter to work pieces having spur teeth and to those having helical teeth of any degree of helix angle. Hence the ram is of cylindrical form, at least as to those portions which occuply the guide 2 and which contain the teeth 14; and the guide 3 is rotatable in a stationar sleeve bearing 4| and on a thrustsupporting clamp ring 42 mounted in the base; the ram and guide 3 being provided with suitable means 43 (Fig. 14), in the nature of splines, to prevent independent rotation of one relatively to the other. Guide 3 is provided with a flange having worm gear teeth 44 meshing with a worm 45 ona shaft 46 which protrudes from the forward side of the machine base and is adapted to be turned by a wrench or crank mounted on its squared end 47. A clamp screw 48 (Fig, 8) having an operating handle 39 locks the ram in its adjustments by forcing ring 42 toward the toothed flange of the ram guide 3 and thereby clamping said flange against a stationary shoulder 50. Thus the ram may be turned through any angle, the extent of which may be measured by a scale, not here shown. The cutter C is preferabl arranged with the edged portion of its cutting end intersecting the axis of the ram.

The work piece W is secured to one end of a spindle 5i mounted rotatably in a rollin head 52, which is in turn rotatably supported by a carriage 53. The carriage is mounted for reciprocating travel on guideways 54, the latter being supported on the machine base at one side of the upper end of the ram and preferably in a plane inclined to the strokes of the ram and cutter. As appears from the drawings, the spindle 5i and rolling head 52 are coaxial, and their common axis is parallel to the plane above referred to and extends in a direction transverse both to the direction of carriage travel and to the path of the cutter. In one point in the travel of the carriage, this axis intersects and is perpendicular to the directions in which the cutter moves in its path, and in the other positions it is parallel to a line intersecting and perpendicular to said path. One end of the spindle protrudes from the rolling head and carriage, and is provided with work clamping means so located as to secure work pieces within the operating range of the cutter. Rolling movement, compounded of rotation about its axis and translation of its axis in a plane parallel to the guideways 54, is transmitted to the work from the rolling head. The rotary compcnent of this movement is produced by force applied to the rolling head through an arm 5'! (Fig. 10) keyed to the rolling head, (whereby the latter is turned in its bearings in the carriage 53), and is transmitted to the work piece by a retractable locking pin 55 carried by an arm 56 on the rolling head and projecting between adjacent teeth of the work piece; while the translative component is produced in one direction by displacement of the carriage on the guideways 54, effected by a cam or former 58 carried by the rolling head actingagainst a stationary abutment 59. A spring 68, compressed between an abutment 6| on the guideway structure and 3. lug 62 on the carriage, cooperates with the former 58 in displacing the carriage in the opposite direction. By virtue of the arrangement thus shown and described, the reciprocations of the cutter occur in directions crosswise of the work piece teeth, that is, transversely the length thereof or in the crest-to-root direction and vice versa.

Various means may be employed for moving arm 51 to obtain the desired effect, That here illustrated consists of the following mechanism. A worm 63 on the main or drive shaft 5 meshes with a worm gear 64 on a short shaft 65, from which power is transmitted to a shaft 66 through a' pair of changeable gears 61, 68. A worm 69 on shaft 65 meshes with a worm gear (not shown) on a cam shaft Hi, to which a cam H is made fast. Cam ll acts on one arm of a lever 12, pivoted on a supporting shaft 73; and the other arm of lever 12 is connected by a pivot 14 with an extensible and contractable connecting rod 15 which, in turn, is coupled to arm 51 by a pivot 16 adjustably mounted in a radial slot'll in the arm.

In the arrangement as shown in Figs. 1 and 10, upward movement of the lever arm which bears on cam ll turns the rolling head 52 in clockwise rotation, causing the carriage to be moved from left toright and bringing a tooth of the work into operative relation with the cutter, gradually from its crest to its root. The amplitude of rolling movement thus imparted, which may be appropriately varied by adjustment of the radial position of pivot 16 and the length of connecting rod 15, is such as to roll the work wholly clear of the cutter when the carriage is displaced in the opposite direction. The form of cam H is such as to cause the advancing movement of the work in rolling toward'thev cutter to continue during a. major proportion of the rotation of the cam, and the movement away from the cutter to be completed during a minor proportion of that rotation.

The relation between the work and the cutter is similar to that between a gear and the face of a rack tooth lying in the plane in which the cutting edge of the cutter moves; or near that plane. And the relation between the cam or former 58 and the abutment 59 is similar to that between a gear tooth and the relatively opposite side of a rack tooth. Where the teeth of the work piece are involute curves, which is the usual condition, the active face of former 5B is likewise an involute curve, the base circle of which may be the same as that of the work piece teeth, or may differ therefrom within a certain range; and the reactive face of the abutment is a plane surface. Provision is made for substitution of different formers to correspond with work pieces of different diameters having teeth generated from different base circles outside the ranges permitted by the latter-mentioned adjustment of the abutment; the former being detachablysecured by bolts 18 to a hub l9 keyed on the rolling head, as shown in Figs. 4 and 8. These bolts pass through slots 80 in the contiguous part of hub 19, curved coaxially with the rolling head, whereby the former may be adjusted around the same axis. The abutment also is adjustable angularly, its adjustment being such as to alter the inclination of its reactive face with the path in which the carriage travels. Thereby the pressure angle and effective pitch circle of the gear action between the former and abutment are controlled. A pivot stud 8| mounted on the stationary guideway structure supports the abutment in contact with the former, and two set screws, 82 and 83, mounted in a stationary supporting block 84, bear on the abutment at respectively opposite sides of the pivot 8| so that, as either is advanced and the other is retracted, the abutment is tilted more or less. The degree of its inclination to the 'guideways' is measured by an index 85 and scale 86. This latter adjustment enables involutes of a variety of different base circles to be controlled by the same former and, in combination with a series of different formers, enables work pieces 6 with involutes of all base circles withina wide range to be finished on the same machine.

It is not essential in slotting or grooving involute teeth that the bottoms of the grooves be of uniform depth or, in other words, that they be involute curves of the same base circle as the tooth faces. But it is desirable thattheir curvature be approximately the same as that of thetooth facesand be displaced uniformly from such faces. The provisions here made and above described for controlling the rolling motion of the work enable this effect to be secured. They also enable gears and the like to be finished with accurate involute faces when a cutter is used having a continuous straight cutting edge without the interruptions or offsets of such edge caused by the spaces 8 herein shown.

Due to the speed reduction occasioned by the reducing gears 61, 68 and the two worm and wheel couples in the transmission train between the crank shaft 5 and the cam shaft 10, the cutter is caused to make a great many strokes during th rolling traverse of a single tooth of the work. Such number of strokes may be in the order of several hundreds or thousands, and may be widely varied by substitutions of different gear pairs for the change gears 61 and 53. This rapid stroking of the cutter enables the work to be cut to the full predetermined depth in one traverse and without successive depth feeding steps, thus completing the operation more rapidly than in cases where a succession of cuts, with intermediate depth feeding steps, is taken. The progress of the cutting action is illustrated by Figs. 16,17 and 18, in which three different positions of a tooth t of the Work piece are shown. Starting from a'position clear of the cutter, the corner between the outside circumference and the advancing face of the tooth first crosses the path of the cutter and is immediately incised by the cutter. Successive cutting strokes follow before the work has advanced more than the distance of the feasible depth of a single cut; and the speed ratio of such advance is regulated in accordance with the quality of the material of which the work piece is made so as to obtain the most eificient rate of cutting feed.

The length of the cutting strokes is indicated with substantial accuracy by the distance between the full line and broken line positions of the cutter in Figs. 16, 1'? and 13. In these figures the inclined straight dot-and-dash line L represents the pitch line of the imaginary rack with respect to which the path of the cutting edge and the reactive fac of the abutment 59 have the relation of tooth faces, and the arc PC represents the pitch circle of the work piece which rolls in tangent non-slip relation to line L. As there shown, all strokes of the cutter are longer than the tangential extent of the part of any tooth of the work piece that overlaps the cutter path at any instant. They are also preferably always of the same length, with limits at the same points at respectively opposite sides of the pitch line L and so located that the cutting edge, on ach withdrawing stroke, is retracted clear of the work piece tooth on which it is operating. Thus the cutter is caused to remove. in the course of each cutting stroke, all of the stock of the work piece lying across its path; and, in the course of a series of strokes, as a single tooth of the work rolls past, its cutting action progresses gradually along the side of the tooth face toward the root of the tooth until the entire face has been finished. Clearance spaces are left between the roots of adjacent teeth of suiiicient depth to permit chip removal avoid blocking of the cutter. 7 I

Independent manual operation of the :work carriage is made possible to facilitate adjustments and for other purposes. Hence the shaft 65 in the carriage driving train is coupled with gear 66 by means of a clutch, here'shown as a disk clutch 81 of known character, adapted to be relaxed by a clutchshifter arm 88 (Fig. 11) acting through a link 89, arm 80, rock shaft 9I (Fig. 4), arm 92 and sleeves 03 and 94. Arm 92 carrie a pin projecting into a groove in the outer surface of Sleeve 03; whereby it is able to shift said sleeve endwise. The sleeve 93 slides on sleeve 94, which is pinned to the shaft, and carries a pin 95 in position to bear, with cam efiect, on the long arm of a bell crank lever 95, pivoted at El to sleeve 94, the short arm 90 of which bears on the cover disk 99 of the clutch. A shaft I00, which projects from the front of the machine and is rotatable by a crank arm or wrench, carries a pinion IOI arranged to mesh with a face gear I02 onthe extremity of shaft 56. Normally the pinion IOI is held clear of gear I02 by a spring I03.

Indexing of the work to present successive teeth to the cutter is accomplished automatically by withdrawal of the locking pin 55 and by giving a small increment of rotation to the work spindle 5I, every time the work rolls clear of the cutter with movement of the carriage 53 to the left (with respect to Fig. 1). The locking pin is carried by a plunger I which is slidable in a sleeve I carried by the arm 56, and is pressed toward the work by a spring I06 (Fig. 9). Sleeve I05 in turn is mounted in a guideway I01 forming part of a bracket I 08 secured adjustably to the rolling head arm 56. A shank I09, secured to the locking pin, protrudes from the sleeve I05 and carries lock nuts IIO, one of which provides abutments for a forked arm III pivoted to the bracket I08 by'a pivot pin H2 (see also Figs. 12 and 13). Rise of arm IIl retracts the locking pin clear of the work.

A pawl element H3 is carried by arm III on a pivot I I4 and biased by a spring I I5 so that a pin I I6 which it carries is held against a shoulder I I7 on arm I I I. A cam dog I I3 is mounted on a plate I I8, which forms part of the carriage, and is located in the path of pawl H3 to be engaged by the latter near the end of the rolling movement 5 and after the work has rolled clear of the cutter. The inclined cam face of dog IIO raises pawl H3, thereby raising arm I I I, and withdraws the locking pin from the work. Immediately thereafter, the pawl passes the high point I of the cam dog and drops into an open space just beyond, allowing the locking pin to re-engage the work piece. When rolling in the opposite direction, the pawl yields in passing the cam shoulder I 20.

During-the brief time while the locking pin is thus Withdrawn, the work spindle is advanced by a drive consisting of a pulley IZI on cam shaft 70, a belt E22 and a pulley I23 on the work spindle. Pulley I2I constantly rotates while the machine is operating, and the belt slips except when the locking pin 55 is withdrawn. A belt tightener I24, pivoted on the pivot shaft I3 and acted on by a springllifi applies sufiicient tension to the belt for applying constant traction to pulley i23. The belt tightener is likewise arranged, as shown in Fig. 11, to offset the belt, so that a considerable portion of its length is approximately perpendicular to the path in which the Work carriagetravels, thereby compensating for the back and forth movement of the work carriage.

and to The cam dog I I8 is adjustably mounted by bolts I26 passing through a slot in the dog, and which can be set in different ones of holes I21 in the plate II9; said holes being equidistant from the Work spindle and spaced apart at suitable distances to permit placement of the dog in any position between the extreme limits of adjustment. The bracket I08 has a rib on its rear side fitted to an arcuate slot I20-in the rolling head arm 55, and is secured by bolts I28I projecting through slots I29 in the bracket, said slots being coaxial with the work spindle. Stop screws I30 serve'to adjust the bracket and secure it in different positions in order to locate the work piece teeth in exact relation to th cutter.' By this means the work may be set to regulate the depth of cutting, and also to accommodat pieces having different numbers of teeth and different pitches and tooth widths. Furthermore, the sleeve I05 is adjustable endwise in its guide I01 and carries rack teeth I3I meshing with a pinion I32 connected with an adjusting knob I33; By these various adjustments the locking pin 55, and the time of indexing action, may be accommodated to work pieces of all diameters and pitches.

The operation and efiect hereinbefore described are the same whether the work piece has spur teeth or helical teeth. All that difiers is the angular setting of the cutter, one position of which, to operate on a helical work piece W, is shown in Fig. '7. The locking pin 55, when of chisel ended formation as here shown, may be accommodated to helical gear teeth by partial 1 rotation in the plunger I04. It is in screwed connection with theshank I09; and the screw may be tightened to grip an intermediate portion of plunger 104 between a shoulder I34 on the looking pin and a shoulder I35 on the shank,

The fundamental aspects of the invention, which involve methods and means for carrying out a finishing operation on teeth of gear shaving cutters, gears, and other forms of greater or less similarity to gear teeth, by repeated reciprocations of a cutter in a path from the crest toward theroot of the curved form, while a relative rolling movement is carried out progressively, are not limited to the specific means and constructions herein presented for illustration. Different forms of cutter may be used having a greater or less number of ribs, with a greater or less width, spacing and depth than those shown, or having no ribs at all, but a continuous straight or curved edge adapted to finish the work piece by shaving the whole, or any desired proportion, of the width of its face. The term finishing therefore is used in the following claims as designating generically the effect produced on the work, whether that efiect is in cutting slots only, or both cutting slots and shaving the lands between the slots, or simply shaving the surface of the work piece without slotting it. And various different mechanisms may be employed for imparting the prescribed movements to the various instrumentalities; including, for instance, Wholly mechanical means in substitution for the fluid operated means for relieving the cutter on its return strokes; while the inclination of the cam faces and timin of the movements by which relief is effected may be the reverse of those shown and described. Moreover, the invention is not limited to the finishing of involute curves only for, by appropriate modifications of either the former or the abutment, or both, curves departing more or less widely from true involutes may 9 be generated in essentially the manner described.

However, I make; claim to all novel features of the specific embodiment of the invention herein shown.

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

1. A machine for performing a finish cutting operation on the faces of gear teeth and similar objects, comprising a reciprocably mounted cutter having a cutting edge transverse to the direction of its reciprocating movement, means for supporting and rolling a work gear across the plane in which the path of said cutting edge lies with the axis of rolling movement transverse to the direction of cutting movement when crossing said plane, means for reciprocating the cutter a plurality of times durin the rolling advance of a single tooth of the work, and means for shifting the cutter away from the work after completion of each cutting stroke, and into its cutting path prior to making its cutting strokes, whereby to avoid rubbing contact with the work during non cutting strokes.

2. In a machine as and for the purpose set forth, a cutter carrying ram mounted to reciprocate in a given path, a cutter head pivoted on said ram to swing about an axis transverse to the path of the ram, a cutter secured to said cutter head having a cutting edge displaced from said pivot, means for reciprocating the ram, an arm connected to the cutter head extending into the ram, and means carried by the ram operably associated with said arm for swinging said cutter head about its pivot to hold said cutting edge in operating position during its cutting strokes and in a position clear of the work during its non cutting strokes. e

3. In a machine as and for the purpose set forth, a cutter carrying ram mounted to reciprocate in a given path, a cutter head pivoted on said ram to swing about an axis transverse to the path of the ram, a cutter secured to said cutter head having a cutting edge displaced from said pivot, means for reciprocating the ram, an arm connected with the cutter head having a cam surface inclined to the path in which the said cutting edge is carried, a wedge member mounted on the ram engaging said cam surface, and means for moving said wedge member back and forth in time with the reciprocations of the ram to hold the cutting edge in its operativ position during the cutting strokes and to hold it clear of the work during its non cutting strokes.

4. In a machine as and for the purpose set forth, a cutter carrying ram mounted to reciprocate in a given path, a cutter head pivoted on said ram to swing about an axis transverse to the path of the ram, a cutter secured to said cutter head having a cutting edge displaced from said pivot, means for reciprocating the ram, an arm connected with the cutter head, a wedge member mounted on the ram with provisions for" movement back and forth in a definite path, said arm and wedge member having cooperating interengaging cam portions whereby to cause movement of the cutter back and forth when the wedge member is moved in opposite directions in its prescribed path, a fluid operated piston connected to said wedge member and mounted mov-- ably in a pressure chamber in the ram, and means for exerting fluid pressure on opposite endsof said piston at such times, in the reciprocations of the ram, as to cause said cutting edge to occupy its operative position during cutting strokes and to be withdrawn clear of the work during its non cutting strokes.

5. A machine for performing a finish cutting operation on machine elements having spur teeth or helical teeth comprising a carriage, a Work spindlemounted in the carriage adapted to hold a work piece, means for imparting movements of translation to the carriage and rotation to the spindle so as to give the work piece on the spindle a rolling movement equivalent to running in mesh with a stationary rack, a ram mounted to reciprocate, and a cutter carried by said ram in position to travel across and in cuttingrelationship with a face of a tooth of the work piece, said ram being angularly adjustable about an axis lying in the path of reciprocation of the cutter, whereby to adjust the cutter to work piece teeth of spur'or helical formation respectively.

6. A machine for performing a finish cutting operation on gear teeth and similar objects, comprising means for rolling a Work piece in the manner of a gear rolling in mesh with an imaginary rack, a cutter holder mounted with provisions for reciprocation toward and away from the path in which the work piece is rolled, a cutter having a cutting edge secured to said holder in position to act on the face of a tooth of said Work piece, and means for reciprocating the cutter holder a number of times in the course of the action of the cutter on a single tooth; said cutter holder being .angularly adjustable about a line extending in the-directions of said reciprocation, whereby to accommodate the cutter. to

work piece teeth of either spur or helical formation. a

7. A machine for performing a finish cutting action on gear teeth and the like, comprising a reciprocably mounted cutter having a cutting edge on one end, means for reciprocating said cutter endwise in a fixed path, a work carriage, a rolling head mounted rotatably on said carriage, a work spindle" mounted rotatably in said rolling head adapted to carry a work piece so that a tooth thereof rolls relatively to the path of the cutter edge in a manner similar to the rolling of a gear tooth with respect to a rack toothface, a former carried by the rolling head, a stationary abutment, means for rotating said rolling head in a manner to cause translative movement of the carriage by reaction of the former against said abutment, a locking member carried by the rolling head engaging the Work piece to transmit the rotational movement of the rolling head thereto, a retractor for said locking member, means for causing said retractor to withdraw the locking member from the Work piece, and a potentially active spindle rotating means organized to turn the spindle independently of the rolling head when the locking member is so retracted.

3. In a machine of the character described, a carriage, an oscillative rolling head mounted on the carriage, a cam or former secured to said rolling head, a stationary abutment engaged with said former, means for oscillating said rolling head, whereby the former by reaction With the abutment causes the carriage to move back and forth, a work spindle rotatably mounted on the rolling head, potentially active motive means tending constantly to turn said spindle relatively to the rolling head, a locking member carried by the rolling head adapted to engage a work piece secured to the work spindle to cause oscillating movement thereof in unison with that of the rolling head, a retractor for said lockin member,

'a pawl carried by said retractor, a stationary cam 111 .mountedon the carriage in position-to be engaged by said pawl and cause actuation of the retractor. .9. A machine for performing afinish cutting action on gear teeth .andtheflike, comprising a cutting tool, means actuating said tool to perform its cutting. function, a workcarriage, a'rolling headmounted rotatably on said carriage, a work carrier mounted coaxially with said rolling head and being rotatable relatively thereto for indexing, .means for turning said rolling head and simultaneously shifting the carriage so as to roll a work piece supported by said carrier across the operating locationof the cutting tool, a locking member carried by the rolling head forvengaging such a workpiece to transmit the rotational movement of the rolling head thereto, and means for angularly adjusting said lockin member around the axis of the rolling head.

10. A machine for performing a finish cutting operation onzthe-sides of gear teeth and analogous side face of a .racktocth, work supporting means adapted to hold a gearlike work piece with a curved forms, which comprises a. supporting structure, a carriage mounted on said supporting structure for guided movement in a prescribed path, a work spindle rotatably mounted on said carriage adapted to hold a work piece having a projection .of gear tooth character, means for simultaneously shifting th carriage and rotating the'spindle at relative speeds such that a projection of gear tooth character .ona work piece secured to the spindle is caused to roll in the manner of a gear tooth rolling in mesh with a stationary rack, a tool carrying ram supported by said supporting structure for a guided movement in a path transverse to the pitch line of an imaginary rack disposed in tangent relation to the pitch circle on which the work piece projection rolls, a cutting tool protruding from said ram having a cutting edge on its extremity located to reciprocate across said pitch lin when the ram is .reciprocated, and means for reciprocating said ram organized to displace said cutting edge back and forthacross said line a multiplicity of times in the length of time consumedby the work piece projection in rolling into and out of mesh with an imaginary rack tooth coinciding with the path :of the cutting edge.

11. A machine for performing a finish cutting operation on the sidesof gear teeth and analogous curved forms, comprising work holding means adapted to carry work pieces having projections of gear tooth character, means for imparting combined movements of translation and rotation to said work holding means such that a toothlike projection of the work piece is moved in the same manner as though rolling. in mesh with a stationary rack tooth, a cutter having a cutting edge, means for reciprocating the cutter in a path which is transverse to the .axis of rotational movement'and intersects a side of such tooth-like projection so as to perform a, planing action thereon, and through a distance greater than the length of that portion of the; work piece projection which intersects said path when in position to be operated on by the cutter, and means for correlating the rate of cutter reciprocation with the speed of rolling movement of the work holding means so that a multiplicity of cutter strokes are performed while the work piece projection is rolled over the cutter path.

12. A-machine for finishing gear tooth faces and analogous curved forms, comprising a cutter having :a definite cutting edge, means for reciprocating said cutter in directions transverse to its cutting edge so that the path of the cutting edge in space corresponds substantially to one toothlike projection thereof in relation to said path similar to the relation of a gear tooth face with a mating rack tooth face, means for effecting relative movement between the work supporting means and the work piece carried thereby, on the one hand, and the cutter and cutter reciprocating means, on the other hand, analogous to the relative rolling movement between a tooth of a gear rolling in mesh with a rack of which one face of a tooth coincides with said path, and means for correlating the cutter reciprocating means with the means by which said relative movement is effected so that thecutter is reciprocated a multiplicity of times during a single rolling traverse of the work piece, between limits located at respectively opposite sidesof the rolling pitch line of such a rack.

.13. A machine for performing .a finish cutting action on gear tooth faces and analogous curved forms, comprising a supporting structure, a cutter carrying ram mounted for reciprocating movement in a fixed path on said supporting structure, a cutter protrudingfrom said. ram having a cutting edge on its extremity extending transversely of the path of movement of the ram,

work holding means adapted to carry a gearlike workpiece, means for shifting said work holding means in a manner to efiect rolling traverse of the work piece past the cutter in the manner of a gear rolling in mesh with a rack when a tooth of thegear meshes with a rack tooth face which approximately coincides with the path of the cutting edge, while a portion of a side face of one of the work piece teeth intersects such path, said ramand work holding means being relatively disposed so that the reciprocations of the ram are transverse to the axis of the angular component of said rolling traverse, and means for reciprocating said ram and cutter a plurality of times during such rolling traverse of the work piece through distances such that the cutting edge is carried on each stroke beyond the extremities of the before-mentioned portion of the work piece tooth which intersects the cutter path.

14. The method of finishing a curved surface of a Work piece which occupies a relation to such work piece corresponding to that of the side face of a gear tooth to the body of the gear, which comprise imparting a rolling movement to the work piece like that of a gear rolling in mesh with a rack, reciprocating an edged cutter in a direction transverse to the length of its cutting edge and to the translative component of said rolling movement and in the crest-to-root direction of the curved surface of the work piece in a path which intersects said curved surface and the limits of which are outside of the points of intersection of the path with said curved surface, and causing a multiplicity of reciprocation of the cutter to be performed during a single rolling traverse of said surface past such path.

15. The method of finishing gear tooth faces and analogous curved forms, which comprises effecting a rolling movement of a gear-like work piece like that of a gear rolling in mesh with a rack and reciprocating an edged cutter transversely to the translative component of such rolling movement, and so that the edge thereof travels in a path which intersects a side face of a tooth of the work piece, and the direction of reciprocation is in the crest-to-root dimension of the tooth, and the edge of the cutter is carried at each reciprocation beyond the limits of that 13 portion of the work piece tooth which intersects the path.

16. The method of finishing gear tooth faces and the like, which consists in rolling a gearlike work piece in the manner of a gear rolling in mesh with a rack, reciprocating a cutter, having a cutting edge on its extremity, repeatedly during the time required for a tooth of the work piece to roll into and out of mesh with a conjugate rack tooth, and causing the path of the cutting edge to intersect a side face of a tooth of the work piece to a depth suitable for the cutting of a chip in the course of a single uninterrupted stroke of the cutter, and causing the direction of cutting movement of the cutter to extend in the crestto-root direction of the work piece tooth and the limits of each stroke to be outside of the intersection points of the side of such tooth with the cutter path.

17. The method of cutting slots in the side faces of the teeth of a gear shaving tool or the like, which consists in rolling a work piece in the manner of a gear rolling in mesh with a rack, reciprocating a slotting tool, which has a cutting portion on it extremity, in such manner that said cutting portion is carried in a path which intersects a side face of one of the work piece teeth an is transverse to the translative component of such rolling movement, and causing the direction of cutting traverse of the slotting tool to lie in the crest-to-root dimension of the work piece tooth and the limits of travel of the cutting edge to be outside of the points of intersection of the side face of said tooth with the path of the cutting edge.

18. A machine for finishing gear tooth faces and analogous curved forms, comprising a cutter having a cutting edge, a work support, means for eifecting relative rolling movement compounded of translation and rotation between the cutter and a work piece carried by said work support in a manner corresponding to the rolling action between a gear and a rack tooth when a tooth of the gear is in mesh with such rack tooth, the

cutter being reciprocable in a direction transverse both to the translative component of such rolling movement and to the axis of the angular component thereof, means for so reciprocating the cutter a plurality of times during said relative rolling movement, and means for efiecting a relative displacement between the cutter and work piece in time with such relative reciprocations so as to prevent rubbing contact between the cutter and work during the non cutting strokes.

EDWARD W. MILLER.

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