US2257850A - Generative gear grinding machine - Google Patents

Description

E. W. MILLER GENERATIVE GEAR GRINDING MACHINE Filed March 16, 1939 6 Sheets-Sheet 1 Oct. 7, 1941.

E. w. MIILLER 2,257,850

GENERATIVE GEAR GRINDING MACHINE m 2 /0 9i w f4 T m zz/ m S 6 6 44 4 KW I 'jflwwr Oct. 7, 1941. ,w I I 2,257,850

GENERATIVE GEAR GRINDING MACHINE Filed March 16, 1939 s Shets-Sheet 3 Oct. 7, 1941.[ E. w. MILLER GENERATIVE GEAR GRINDING MACHINE Filed March 16,1939 6 Sheets-Sheet 4 mam 0a. 7, 1941. E; w. MILLER 2,257,850 GENERATIVE GEAR GRINDING MACHINE Filed March 16, 1939 6 Sheets-Shget 5 Oct. 7, 1941. a. w. MILLER ,2 GENERATIVE GEAR GRINDING MACHINE Filed-March 16, 1939 6 Sheets-Sheet 6 Patented Oct. 7, 1941 2,257,850 cam-marry]: orancnmnma momma Edward W. Miller, Springfield, Vt., asslgnor to The Fellows Gear shaper C mpa y, p

field, Vt., a corporation of Vermont Application March 15, 1939, Serial No. 262,125 16 Claims. (o1. 51-123) The subject matter of the present invention is a machine for generating the tooth curves of gears, gear shaper/ cutters and the like, of either spur gear or helical gear characteristics. In the preferred embodiments of the invention, including that illustratively shown and described herein, the operating tool is a grinding wheel; and for that reason the machine is called a grinding machine. But this title is not intended as a limitation to grinding in contradistinction to cutting by tools of other characteristics, (such as milling cutters for instance). Hence, although in the following description I shall generally refer to the action of, the machine as grinding and to the tool as a grinding wheel, it is to be understood that such description is intended to include as well equivalent cutters of specifically different characteristics and the operations performed by their use. Likewise the use of the term "gear in the following description to designate the work piece operated on by the machine is intended to embrace generically also other articles of forms similar to gears, such as gear shaper cutters and all machine elements having curved surfaces capable of generation by combined motions of ro-- tation and translation with reference to a cutting tool.

The main objects of the invention are to increase the speed and accuracy of generating gear teeth to finished form and dimensions; to permit ready adjustment of one machine for generating gear tooth curves based on a wide range of rolling circles easily and with substitution of a relatively small number of interchangeablevparts; to simplify the operation of, and means for, indexing the work, and avoid the tendency to inaccuracy which has accompanied the indexing means of prior machines of the generative grinding type; and to accomplish subsidiary objects related to the foregoing; as will appear from the following description. The nature of the in vention; the principlesancl novel features which it contains, and its utility can best be explained and understood in connection with a full description of a specific embodiment. Such a descrip- Fig. 2 is a vertical section taken on line 22 of Fig. 1' and including'the axis of the work holder;

Fig. 2a is a fragmentary view showing analter native means for holding, clamping and rotating the work supporting arbor tion follows'with reference to illustrative draw- Fig. 3 is a vertical section taken on line 3-3 of Fig. l; v

Fig. 4 is a horizontal section taken on line 4-4 of Fig. 1; 1

Fig. 5 is a vertical section taken on line 5-5 of Fig. 4 showing on a larger scale the details of a braking means for the work indexing motor;

Fig. 6 is a horizontal section taken on line 6--6 of Figs. 1 and 2;

Fig. '1 is a vertical section taken on line 1-1 of Fig. 2 and represented on a larger scale;

Fig. 8 is a fragmentary view similar to Fig. 'l and illustrating a modification of one of the details of the mechanism there shown;

' Fig. 9 is a vertical section taken on line 9-9 of Fi '7;

Fig. '10 is a vertical section of a detail of the mechanism taken on line ill-l0 of Fig. 2 and shown on a larger scale;

Figs. 11 and 12 are detail sectional views taken on lines ll--|l and I2-l2 respectively of Fig Fig. 13 is a detail sectional view of the means for controlling the stop for the indexing mechanism, taken on a plane parallel to that of Fig.

and 1'7;

- Fig. 20 is a diagramillustrating the principles according to which angular 'adJustment of the grinding wheel and of the abutment which controls the translative movement of the work varies the rolling circle with respect to whichthe tooth curves are generated.

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

Describing first the general principles of the machine, with reference to Figs. 1, 2 and 3, the

[frame comprises a base 2i having a recess 22 in its forward side, an annular bed 23 secured to the base 2|, uprights 2| and 25 rising from opposite sides of the base 2|, and a cross beam 26 supported on said uprights 2| and 25; all of these parts being of suitably massive and, rigid construction, The bed 23 supports a table 21 on which is mounted a slide or carriage 28 carrying a work holding head, which includes a work spindle or'arbor 29, by which the work piece 38 is rotatably supported. The tool 3|, here shown as a grinding wheel having a plane operating face, is supported by a tool. head 32 secured adjustably, by means later described, to the cross beam 26 of the frame structure.

In operation the work piece is moved bodily transversely of the plane of the grinding wheel and at the same time is given a component of angular movement such that the ultimate effect is the same as if the workpiece were rolled on a circumference of given diameter over a plane surface toward and away from, or across, the plane of the grinding face, whereby an involute curve is generated in whatever part ofthe work piece engages the grinding face. The following mechanism is provided for imparting these movements to the work.

The carriage 28, which is constrained to travel in a straight line on the table 21, supports a rotatable shaft 33, preferably parallel to the work spindle 29, as here shown, although it is not necessarily so. On this shaft 33 is keyed, a cam holder 34, to which is affixed in a detachable manner a cam 35. The cam has a face 36 of involute curvature bearing on an abutment 31 mounted adjustably on the table 21 in a manner later described. The cam holder 34 includes an arm 38 which is coupled by a connecting rod 39 46, pulley 41, shaft 48 to which pulley 41 is secured, worm 49 on shaft, 48, and worm wheel 58.

on the shaft 5| which carries the crank disk 4|. When the cam 35 is turned in clockwise rotation with respect tov Fig. 1 by this mechanism, the carriage 28 is moved to the left. It is moved in the opposite direction when the cam 35 turns counterclockwise, by a weight 52 suspended from a cord 53 which passes around guides 54, 55, 56 and is secured to the carriage 28. Guide 54 is mounted on the base 2| and guides 55 and 56 are mounted on table 21. The weight 52 maintains a firm engagement between the cam 35 and the abutment 31, takingup backlash, at all times. This mechanism gives the translative component of movement to the work.

The angular component of rolling motion is transmitted through a gear segment '51 keyed to the sha t 33, a compound rack bar 58 and a gear 59 secured to the work holding arbor 29. The element above described as a compound rack bar 58 is so called because it has portions cooperating with the gear elements 51 and 59 in the manner of a rack. It also cooperates with gear 59 in the manner of a screw or worm to cause indexing of the work. This rack bar 58 is mounted for free endwise and rotary movement in a bushing 68 in a housing 6|. It is made with a rack portion 58a of,which the teeth are encircling disconnected ribs without helical lead, which mesh with the gear segment 51, and with a second rack portion 58b of which the teeth have a helical lead and are successive convolutions of a screw thread or a plurality of threads. Angular movement of the segment 51 is transmitted by the rack bar 58 to the gear 59,in equal measure when the pitch radii of the gear segment 51 and gear 59 are the same, as is the case here. Rotation of the rack bar 58 about its own axis rotates the gear 59 in the manner of worm and wheel gearing without rotating the segment -51, and is employed for indexingthe work.

It is not essential that the rack element 58a be a circular rack integral with the bar 58. Fig. 8 shows an equivalent variation in which the rack 58| consists of teeth on one side of a sleeve 62 fitted to a reduced extension 580 of the rackbar 58 so that the latter may rotate within it, and confined from relative endwise movement by anti-friction thrust bearing 63 between a shoulder 64 on the bar 58 and a nut 65 screwed to the end of the bar 58.

Power for indexing the work piece is delivered from an electric torque motor 66 (see Fig. 4 The armature of this motor is coupled to a shaft 61 on which is'a gear 68 meshing with a gear 69 on an upright shaft 18 (see also Figs. 7 and 9). The latter carries on its upper end a gear 1| meshing with a gear 12 on a sleeve 13 which is coaxial with the rack bar 58 and is connected with the end or extension 58d thereof by a cou-,

pling including keys 14 entering longitudinal grooves 15 in the sides of the bar extension 58d.

The torque motor 66 exerts a constant torque tending to rotate the rack bar 58 but is restrained during the grinding operation by a stop plunger 16 and index plate or head 11 (Fig. 10). The index plate 11 is secured to a shaft 18 (Fig. 4) which is driven by the torque motor 66 through shaft 61, a pair of changeable ratio gears 19, 88, shaft 8| on which gear 88 is secured, a change gear 82 on the forward end of shaft 8|, idle gear 83 (Fig. 1) and change gear 84 on shaft 18. By suitable selection of the gears 19, 88, 82, 83 and 84 the ratio of rotation of the index plate 11 to the rotation ofv the rack bar 58 may be varied to cause rotation of the work through any desired angle while the index plate 11 makes a complete rotation. In this illustration the index plate 11 has a single stop shoulder 85, but it may be provided with any number of shoulders.

Release of the locking pin 16 is caused by the carriage driving mechanism when the carriage 28 is at the end of its retracting stroke and the work is clear of the grinding wheel. An arm 86 is secured to the shaft 33 in the same plane with a rod 81 supported by pivotally mounted levers 88, 89 on the table 21 and carrying an adjustable collar 98. The collar 98 is so adjusted that it is engaged by the arm 86 and moved to the right (with respect to Figs. 1 and 10). when the carriage 28 reaches the end of its traverse from left to right or, at least, has progressed far enough in that direction to withdraw the work piece clear of the grinding wheel 3|; and is so moved far enough to cause displacement of the locking pin 16 from the index plate shoulder 85. This movement of the collar 98 swings arm 9| of lever 89 to the left. Said lever arm 9| bears against the end of a rod 93 which is movable in guideways 94 and is pressed toward arm 9| by a spring 95. It extends toward the index plate 11 and carries on its end adjacent to the latter a pusher block or head 96 having a pusher face 91 concentric with the index plate 11. An arm 98 is pivoted at 99 to a bracket I88 in which the stop plunger 16 is slidingly mounted. This arm 98 is acted on by a spring |,8| (which reacts on an anchor pin I82 on bracket I88) so that a roll I03 on its outer end is constantly pressed against the pusher face 91. Arm 98 carries a pivoted pawl H14 in position to act on an arm secured to a shaft I86, which rotates in a bearing in the bracket I88 and carries a pinion 'return of the arm 98.

llI meshing with rack teeth I on the side of the plunger I5. A spring I09 normally holds the pawl I04 against a shoulder on the arm 98 but permits the outer end of the pawl to yield away from the axis of shaft I05. Thus when the pusher head 95 is moved to the left, it swings the arm 95 from the position of Fig. to that of Fig. 13 and causes the pawl I04 to turn arm I05 and thereby retract the stop plunger "I5. The lengths and angular relationship of the pawl I04 and the arm I05 are so made that, when the plunger I5 has been withdrawn clear of the index plate stop shoulder 85, the pawl I04 slips past the end of arm I05, leaving the latter free.

to be moved backward by a spring IIO which constantly forces the plunger toward the index plate 11. As the pawl I04 is then free to yield away from the arm I05, it permits the plunger 15 to'bear on the circumference of the index plate 11 ready to obstruct the plate 'I'I when it has completed its rotation. This is a safety measure which prevents the work from being indexed through more than the prescribed angle in case the indexing movement is completed before the carriage has advanced far enough on the next working traverse to permit turns to normal position (Fig. 10) the pawl I04 is returned to acting position after passing clear of arm I05.

The bracket I00 is secured to a flange III (Fig. 4) on a sleeve II2 which fits rotatably in a bearing in the table 21 and within which the shaft 13 is coaxially supported. Flange III carries a gear segment II3 (Fig. 10) with which is meshed a worm II4 on a shaft II5. 'A face gear H5 is keyed to shaft .II5 and meshed with a pinion III on a shaft II8 which protrudes at the forward side of the carriage and carries a knob II9 (Fig. 2) by which it may be manually turned. This mechanism is a manually operated 5 means for feeding the work to increase the depth of cut. It advances the stop plunger I5 angularly around the axis of the index plate 11, allowing the latter to turn through an incremental angle and consequently permitting the work piece to be turned through a fraction of this angle toward the grinding wheel. When the dethreaded anchor pin I38; and it is so adjusted as to cause substantial retardation of the motor 55,

But when this arm rep drum I24. throughout most of the rotation of the index plate 11. The cam I35 has a depression I35 located so that it releases the arm I34 and permits application of the brake shortly before arrival of the index plate shoulder 85 at the looking bolt I5. The tension of spring I30 may be regulated by adjustment of nuts I31 on the without stopping it. The rise of the cam I35 following the depression I35 releases the brake when the index plate I1 is arrested by the bolt I5, enabling the motor 55 to start when the bolt I5 is retracted. I

The grinding wheel is adjustable vertically for work gears of different diameters, angularly to generate involute curves to difierent base circles, or rolling circles, and pressure angles, and axially to maintain its active face true and in a given plane. These adjustments are made possible and effected by the following means. The

tool head 32 carries the tool spindle I39 (Fig.

14) and an electric motor 0 for driving the spindle I39. The tool head 32 is made as a slide fitted to guideways HI and I42 on a tool head base I43. (Figs. 1 and 2), which constrain the slide to move in a path parallel to the plane of the grinding wheel face. The tool head base I43 is mounted against the plane forward surmaximum angle is determined by the art of gear sired depth of cut has been obtained, the bracket I00 is locked by a clamp I (Fig. 12) which is forced against the flange I I I by a'nut I2I thread ed on a screw stud I22 and carrying a handle In order to soften the shock when the indexing plate 11 is arrested by the locking bolt I5, a brake is-provided and brought into action shortly before the shoulder 85 reaches the bolt I5. The brake consists of a drum I24 (Figs. 4 and 5) on the armature'shaft of the torque motor 55 and a complemental shoe I25. The brake shoe I25 is connected by a pivot pin I26 with a carrier lever I2'l pivoted at I28 to the motor base I29-and connected with a spring I30 which is arranged to exert force tending constantly to press the brake shoe I25 against the brake drum I24. The carrier lever I21 is provided also with a toothed arm I3I constituting a gear segment meshing with a pinion I32 on a rock shaft I33. An arm I34 is secured to this rock shaft I33 and bears at-its free end on a cam I35 secured to the shaft 18 of the index plate 11. The gearing is so arranged, substantially as shown in Fig. 5, that the spring'l30 causes arm I34 to bear on the cam. I35, and the latter is of a radius such that it holds the brake shoe I25 away from the face I44 of the cross beam 25 of the frame, being supported by rolls I resting on the arcuate upper surface of a bar'or ledge I45 secured to said face I44. The base I43 is further provided with an arcuate flange I" which is held against the face I44 by a clamp I45 and releasable bolts 249. The flange I41 and curved face of ledge I45 are coaxial, with the axis of their curvature in or near the plane in which the axis of the work spindle 29 travels and transverse to the di- -'rection of such travel. Upon loosening clamp I48 the tool head base may be tilted. about this axis between the position where the grinding wheel face is vertical (1. e. perpendicular to the plane of travel of work spindle 29) and the maximum practicable angle or inclination. The

manufacture and may be as much as 25 or more from the vertical. The degree of such inclination is measuredby an index "9 on the tool head base I43 with reference to a scale I50 on an adjacent part of the frame. Vertical adjustments, (by which I mean movements of the tool head in the prescribed path, whether such path is exactly vertical or inclined, due to the tilting of the head base), are effected by a hand wheel I5I on the forward end of a shaft I52 mounted in the tool head base I43; This shaft carries a worm I53 meshing with a gear I54 on a shaft I55 which also carries a gear I55 meshing with a rack I5'I on the tool head slide. Correction for wearing of the grinding wheel face, and maintenance of such face in a prescribed plane, is eifected by adjustment of the wheel axially in conjunction with a truing tool I58 carried by an arm I59 which is pivoted to the forward end of the tool head 32 in a positfon such that the truing tool I58 may be passed from a point outside of the circumference of the wheel 3| across the entire width of the active zone thereof. The tool spindle I39 rotates in a sleeve I60 which is movable endwise in a housing I5I forming part of the tool head 32. A screw I52 (Figs. 15 and 16) is mounted rotatably in. a flange I53 of sleeve I50 and engages' the threads of a tapped hole I54 in the adjacent housing wall I6I. A pinion I65 on the shaft of screw I62 meshes with a worm I66 on a shaft I61 which carries a crank I68 on its exposed outer end.

The mounting of the tool spindle, the means for lubricating it, and means for excluding dust from its bearings involve useful features which may well be described at this point. The tool spindle I39 is driven by a belt and pulley drive I69, I10, I1I from the motor I40 and is mounted at its forward end (that to which the wheel is attached) in an internally tapered bearing I12. A bearing I13 at its other end is split and slightly tapered externally so that it can be drawn up within the sleeve I60 to compensate for wear. At the rear end a thrust bearing I14 is provided which is forced outwardly against the rigidly secured pulley I1I by a series of springs I15 reacting against the sleeve I60, whereby a shoulder I16 on the forward end of the spindle is held ti htly against a thrust washer I11 and the latter against a shoulder on the bearing I12.

Lubrication is accomplished by using kerosene oil which occupies a chamber I18 in the tool head to a height sufllcient to enter a filter I19 at the upper end of a pipe I80 which leads to an oil channel I8I in the sleeve I60. Oil grooves and channels conduct the oil between the spindle and its bearings and eventually into a settling basin I 82. From the basin I82 the oil is returned to chamber I18 through a pipe I83 by a pump I84 driven from the motor I40 by a belt and pulley drive I85, I86. The use of a large volume of kerosene or other light oil enables a close fit between the spindle and bearings to be maintained and keeps the bearing surfaces cool.

Dust is excluded from the front bearing by a stationary housing I81 in cooperation with the wheel center I88. The housing I81 is a portion of the structure which contains the settling basin I82 and is extended with a conical formation I89 so as to embrace the shoulder I16 of the spindle I39. The wheel center I88, which is secured by screws I90 to shoulder I16, (and to the peripheral part of which an abrasive annulus is secured), embraces the conical part I89 of the stationary housing I 81. Recesses and grooves are provided at I9I and I92 to contain oil and entrap dust.

Adjustment of the abutment 31 angularly and translatively is accomplished by the following means, shown in Figs. 1, 1'7, 18 and 19. The abutment 31 projects from the open side of a straight channel in the edge portion I93 of a disk or plate I94 pivotally mounted on a stud I95 which projects from a slide I 96 supported movably on a bracket I91 which rises from the table 21 adjacent to the cam 35 and to that part of the carriage 28 on which the cam holder 34 is mounted. The lips of the channel are clamped against the base of the abutment 31 by screws I98, and may be relaxed to permit en'dwise adjustment of the abutment 31. The plate I94 is clamped to the slide I96 by clamp bolts I99 passing through slots 200 in the plate I94 into threaded connection with slide I96, which bolts may be loosened to permit swinging movement of plate I94 about the pivot I95. A toothed segment I is secured to the plate I94 coaxial with pivot I95 and is meshed with a worm or screw 202 on a shaft 203 to which is secured in accessible position a knob 204. Movement of the slide I96 in the path (parallel to the directions in which the carriage 28 travels) prescribed by headed studs occupying guideways 205 in the bracket I91, is effected by a screw 206 carried by the slide I96 meshing with a nut 201 aflixd to the bracket I91. A gear 208 on the screw 206 meshes with a worm 209 on a shaft 2I0 which carries an accessible crank 2I I. Shafts 203 and 2" are both supported in bearings in slide I90. By rotation of knob 204 the abutment 31 may be swung from a position where its contact face (which is a plane face) is vertical, to any desired inclination within the structural and operative limits of the machine; and by rotation of crank 2I I its location may be altered at the same time to accommodate changes of inclination, and also as needed to make contact with one or another of interchangeable cams 35 throughout a range of movement of the carriage 28 which suffices to carry the work piece through any prescribed grinding traverse and clear of the grinding wheel to permit indexing.

Novel features conducive to accuracy by eliminating eccentricity of the work piece are embodied in the work holding head. The arbor. or spindle 29 passes through a sleeve or quill 2I2 fitted to rotate in accurately alined bearings in the head 28 andon which the worm gear.";i9 is keyed and made fast. The outer end portion of spindle 29 is clamped and centered in thequill 2I2, in the construction. shown in Fig. 2,, by, a split taper collet 2I3 and a nut 2 which is screwed into the outer end of the quill 2I2. Otherwise the spindle 29 is clear of the quill 2I2, being smaller in diameter than the interior of the quill 2I2. The 'free end of spindle 29 1s supported by a dead center 2I5 mounted in a bushing 2I6 contained in a tail stock structure 2" on the carriage 28 at the forward side of the space in which the work is located. The bushing 2I6 is centered accurately with the quill 2I2 and secured by screws passing through a flange 2I8 into the tail stock structure 2I1. A knob 2I9 is mounted on a shaft which is rotatably supported in the tail structure and carries a pinion (not shown) meshing with teeth cut in the side of the center 2I5. Thereby the center 2I5 may be moved as required for placing and removing work pieces. The work may be positioned correctly with respect to the grinding wheel by releasing the nut 2I4 and moving spindle 29 endwise to the desired position. This arrangement enables the work to be set accurately concentric with the prescribed axis of oscillation, and in such position lengthwise of its axis as places it in desired relationship to the grinding wheel, and eliminates the use of thickness washers, commonly used heretofore andcontaining sources of error.

Various other means may be used for connecting the arbor 20 to the quill 2I2 with similar effect. One such is shown in Fig. 2a. It consists of a split sleeve 2I3a, secured to the quill 2I2 and furnished with internal teeth, and an external gear 2I3b secured to the work arbor. Gear 2I3b is in effect an external clutch membe'r 'complemental to the internal teeth and grooves o. the sleeve 2I3a. Its teeth are crowned or barreled sufliciently to permit a slight lateral movement in any direction of the end of the arbor 29 which engages the dead center 2I5, while at the same time enabling the split sleeve 2I3a to be clamped on the gear without applying a bending stress to the arbor 29. Except for the connection with the quill 2I2 made through the clutch members 2I3a and 2I3b, the arbor 29 is clear of the quill 2I2 and free to move laterally to the extent necessary to bring the work piece exactly concentric with the axis of rotation. The clutch'sleeve 2I3a is long enough to permit ad- .worm 225 on a shaft travel of the carriage may is given in Fig. 20. This relative positions shown iustment of the workarbor 29 in the axial direction and placement of the work piece in the desired relation to the grinding machine without need of using thickness washers.

The gearing 58b, 59 and the quill 212 are enclosed in a housing 223 and protected from foreign matter by a flexible bushing 22! (which may be of rubber composition) in the end of the housing 220 nearest to the work.

The work spindle axis and the path of movement of the carriage may be adjusted to any desired inclinations with respect to the plane of the grinding wheel as needed to finish helical gears and cutters or to grind the necessary clearance on spur cutters. For this purpose the table 21 is mounted rotatably on the bed 23 and is. engaged therewith by curved guides 222, 223 concentric with a vertical line intersecting or pass-' ing near to the axis of angular adjustment of the grinding wheel; and the crank shaft i and gearing for driving it, including the pulley 41, are mounted in a housing table 21 in the open space 22 of the base 2|. An

' annular gear segment 225 (Fig. 6) isconnected coaxially with the table 21 and meshed with a "221 which is mounted in the bed 23 and projects at its forward end into accessible position for application of a wrench. A scale 228 on the'bed serves in connection with an index 229 on the table to measure the angular adjustments so efiected. The shaft 230 (Fig;

2) on ,which the pulleys shaft drive are secured, is

44 and 45 of the crank coaxial with the table 21; so that when the table ley l1 swings around its driver 45 without affooting the tension of the belt 46.

bearings for the position 3 la where clination, which is indicated by the dotted line position 31a, and the grinding wheel isset in the its face is perpendicular to the line of travel of the work, a curve 0 is gen- .erated of which the base circle is C. Intermediate angular settings of either the abutment or wheel alone, or both in conjunction, produce involutes of base circles between the circles B and C; while with other settings involutes of base circles larger than C and smaller than B may be generated.

The combined generating andindexing control accomplished by the rack bar 58 and associated gears has this conspicuous advantage, that it eliminates all change gears, locking devices,v

etc. from the rolling head, (i. e., the work'spindle and its oscillating means). The rolling head is thus reduced to the extreme of simplicity and it is erfectly balanced. Hence there is nothing to impede rapid oscillation or to cause any lack of accuracy due to unbalance when oscillated rap- 224 suspended from the 1 movement of 21 is rotated, the pul- Other adjustments are effected by lengthening or shortening the two part connecting rod 33 previously described, whereby both limits of travel of the carriage are equally shifted in the same direction, and my moving the crank pin Ill an inch up to twelve inches. Other ranges are ,55

accommodated by machines of the same type having different dimensions.

The capacity for inclining both the grinding wheel and the abutment 31 to any angles between their extreme limits is an important factor in that it enables the same cam to be used through a large fraction of the total range of rolling circles accommodated in the machine.

An indication of the range which the curve 36 represents the involute face of a cam of. which the base circle is A. The curve 12 represents the tooth curve-generated when the abutment and grinding wheel are in the in full lines at 31 and 3| respectively; the face of the abutment being perpendicular to the travel of the gear and the face of the grinding wheel being inclined. The base circle from which the curve b is generated is found by the geometry of involute curves to be is set at a certainin B. when the abutment the face of thecrank substitution of difierent possible wlth'one cam figure is a diagram in machine which I have Perfect equality between the angular the involute cam and the angular movement of the work is assured by the equality in pitch radius of the gear elements 51 and 59 and by absence of backlash between these elements and the rack elements 53a and 53b. It is immaterial whether these gears are equal in radius at their pitch circles to the radius of the idly.

base circle of the cam face or of diiferent radius,

or to-what degree their radius is different. Whatever angle of rotation is imparted to the segment 51 during traverse of the carriage, the same angle of rotation is transmitted to the worm gear 59. If these gear elements are of different radius than the base circle referred to, the rack element is moved endwise at the same time; in the opposite direction to the travel of the carriage if the gear radius is larger, and in the same direction as the carriage if smaller.

An electrically controlled switch board for the motors l2 and Ill is shown at 232 in Fig. 1. It

comprises means of known character for starting and stopping each motor and for causing the motor 42 to operate through any selected number of complete cycles before being stopped. An auxiliary switch 233 includes rotatable contacts 234 driven from the crank shaft Si by gearing 235, 235 (Fig. 2), and set to cause the motor 42 to be stopped only when the carriage 28 is at the extreme rear position away from the grinding wheel 3|.

Although in the foregoing description I have referred to certain parts of the machine as being horizontal or movable horizontally, and other parts and movements as being vertical, it must be understood that these terms are merely descriptive of the particular machine here shown and not limiting as to the invention. Any machine which has similar structural and functional relationships between its parts to those herein described is within the scope of the invention claimed however its corresponding parts may be related to the plane of the horizon.

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

l. A machine of the character described comprising a supporting structure, a cutting tool rotatably mounted on the supporting structure and having an active face, a carriage movable in a path transverse to the active face of the tool, a work spindle mounted rotatably on the carriage adapted to support a toothed work piece with the side of a tooth thereof in contact with said active face, a cammounted rotatably on the carriage, an abutment mounted on the supporting structure in position to receive the thrust of said cam, gear elements connected with the spindle and cam respectively, and a bar having rack element in mesh with said gear elements for transmitting angular movement from the cam to the spindle, the rack element which is meshed with the gear element on the spindle having its teeth in the form of continuous helical convolutions and being rotatable for indexing the work spindle.

2. In a machine of the character described, a carriage, a work spindle and a cam rotatably mounted on said carriage, driving mechanism coupled With the cam for oscillating it, an abutment against which the cam acts to propel the carriage, gears connected to the spindle and cam respectively, a worm and a rack in tandem connection, the worm being rotatable and in mesh with the gear which is connected to the spindle, and the rack being in mesh with the gear connected to the cam, and means for rtating saidworm whereby to index the work spindle.

3. In a machine of the character set forth, a

carriage, a spindle and a cam rotatably mounted on the carriage, gears connected to the spindie and cam respectively, an endwise movable bar having a worm and a rack in tandem arrangement, of which the former is meshed with the spindle-connected gear and the latter with the cam-connected gear, an abutment against which the cam reacts for moving the carriage, driving mechanism connected with the cam to oscillate it, potentially active motive means in geared connection with said bar tending constantly torotate it, an index plate in driven con nection with said motive means, a displaceable stop normally preventing movement of said index plate, and means operable by the carriage for displacing said stop.

4. A machine of the character described comprising a supporting structure, a carriage movly rotated, a cam rotatably supported on ,the

carriage with its axis transverse to said path in a location displaced from the spindle to one side thereof, an abutment on the supporting structure located to receive the reactive thrust of the cam, mechanism for oscillating the cam, and a combined rotation transmitting and spindle indexing means between the cam and spindle for transmitting angular movement from the cam to the spindle and imparting independent angular movement to the spindle for indexing the work.

5. A machine for the purpose set forth having the characteristics set forth in claim 4, combined with a table mounted on the supporting structure and on which the carriage is mounted, said table being angularly movable in a manner to cause generation of spur or helical tooth face curves in the work.

6. A machine for the purposes set forth comprising a supporting structure, an angularly adjustable table mounted thereon, a carriage mounted to move in a path transverse to the axis of adjustment of the table, a power driving train for the carriage including a rotatable machine element concentric with said axis, a work spindle rotatably mounted on the carriage and adapted to hold a work gear, and a rotatable cutting tool mounted on the supporting structure in position to generate tooth curves on such a work gear, said tool being mounted with provision for adjustment to various inclinations to the path of travel of the carriage.

7. In a tooth curve generating machine, a cutting tool mounted for cutting operation in a stationary location, and means for transporting a work piece with a rolling motion toward and away from said location comprising a carriage guided to move in a path transverse to the operating plane of the tool, a work spindle and a cam rotatablymounted on said carriage to rotate about separate axes both transverse to the path of the carriage and spaced apart from one another in the direction of such path, a stationary abutment mounted in position to be engaged by said camand, by reaction, cause movement of the carriage when the cam is rotated inone direction, means for imparting angular movement to the cam about its axis, and means for transmitting rotary movement from the cam to the spindle in a predetermined ratio.

8. The combination as set forth in claim 7, in which the means for transmitting rotary movement from the cam to the spindle is adapted to transmit equal degrees of rotation in the same relative direction.

9. In a tooth curve generating machine, a cutting tool mounted for cutting operation in a stationary location, and means for transporting a work piece with a rolling motion toward and away from said location comprising a carriage guided to move in a path transverse to the operating plane of the tool, a work spindle and a cam rotatably mounted on said carriage to rotate about separate axes both transverse to the path of the carriage and spaced apart from one another in the direction of such path, a stationary abutment mounted in position to be engaged by said cam and, by reaction, cause movement of the carriage when the cam is rotated in one direction, means for imparting angular movement to the cam about its axis, gear elements secured to the cam and spindle respectively, and a. rack bar mounted with freedom to move endwise relatively to the carriage'having teeth engaged with both of said gear elements for transmitting angular movement from one to the other.

10. The combination as set forth in claim 9, in which the gear elements connected to the cam and spindle respectively are of substantially equal pitchradii.

11. The combination as set forth in claim 9, in which the teeth of the rack bar engaging the gear element which is connected to the work spindle are helical and are revoluble about their helix axis, for imparting an increment of rotation to the spindle additional to that imparted by angular movement of the cam.

12. A machine for generating the tooth curves of gears and the like comprising a supporting ternal to the carriage coupled to one of the elements constituted by the cam and spindle for imparting angular movement to said element, an abutment mounted on the supporting structure in position to engage the cam, said cam having an engaging face of involute curvature and the abutment having a plane contact face, means for adjusting the abutment to place its said contact face at different angles to the path of the carriage, whereby to alter the distance traversed by the carriage in consequence of a given angular movement of the cam, a cutting tool. having an active face arranged in position to generate tooth curves on a work piece mounted on said work 13. In a machine ofthe character set forth,

a base, a carriage mounted to reciprocate in a given path on said base, a support adjacent to one end of the path of said carriage, an abutment having a plane face transverse to said path mounted on said support and being adjustable angularly to vary the angle between said plane face and said path, a cam having an involute face mounted on said carriage to-bear at its involute face on the said abutment face and being angularly rotatable about an axis substantially parallel to the axis of angular adjustment of the abutment, a work spindle mounted rotatably on the carriage with its axis substantially parallel to the-axis of said cam and displaced therefrom along the path of travel of the carriage, a tool head base secured to the supporting structure with provision for angular movement about an axis substantially coinciding with one of the positions occupied by the axis of the work spindle in the courseof travel of the carriage, a tool head mounted on saidtool head base, a cutting tool having an active face rotatably mounted on said tool head with its active face substantially in a plane radial to the axis of adjustment of the tool head base and in a position to engage a work piece mounted on said spindle, mechanism between said cam and spindle for transmitting angular movement from one to the other, and means for imparting such angular movement from an external source to one of the elements constituted by the cam and work spindle.

faces of the teeth of such workpieces in contact with the active face of the tool, a cam mounted on the carriage to rotateabout an axis transverse to the path of the carriage and at one side of the work spindle, means for imparting angular movement to the cam, an abutment mounted on the supporting structure in contact with the faceof the cam for receiving the thrust thereof when the cam is turned in one direction, gear elements secured to the cam and work spindle respectively, a rack bar having teeth engaged with both said gear elements and being free to move lengthwise,

the portion of said rack bar which engages the gear element on the work spindle being rotatable about the length dimension of the bar and its teeth being of-helical form, and'means for rotating said portion of the rack bar whereby to give an increment of angular movement to the work spindle additional to that imparted by the cam.

l 15. In a machine of the character described, a supporting structure, a carriage mounted to move in a given path on said structure, a work spindle and a cam mounted rotatably on said carriage on axes beside one another and transverse to the movement of the carriage, gear elements secured to said spindle and cam respectively, a compound rack having helical teeth meshing with the gear element which is secured to the work spindle and other teeth meshing with the gear element which is secured to the cam, that portion of the rack which carries said helical teeth 14. In a tooth curve generating machine, a

supporting structure, a cutting tool having an active face mounted to rotate in a relatively stationary location on said structure, a carriage mounted on said supporting structure and guided to move in a path crossing the plane in which said active face'rotates, a work spindle rotatably supported .on said carriage with its axis transverse to the path of movement thereof adapted to carry a toothed work piece and to roll the being rotatable about the len th dimension of the rack, an electric torque motor mounted on the supporting structure, a gear train between said motor and the rotatable portion of said rack for transmitting rotation to'the rack, a stop normally restraining the motor from rotation, and means operated by the carriage in the course of its travel for displacing said stop.

16. A machine for the purpose set forth comprising a base, a carriage movable translatively on said base, a work spindle rotatably mounted in 'the carriage adapted to hold a work gear element, a cutting tool rotatably supported in position to cut the tooth faces of work gears mounted on said spindle, means for reciprocating the carriage and simultaneously imparting an angular component of movement to the work spindle including a gear secured to the spindle and a rack bar having helical teeth meshing with said gear and being rotatable about the axis of .the helical teeth, a potentially active .motor in geared connection with said rack bar tending constantly to rotate it, an index head in geared connection with said motor provided with a. stop shoulder, a displaceable stop normally engaging said shoulder for preventing action of the motor, and means operated by the carriage at a predetermined point in its travel for withdrawing-said stop, whereby the motor is permitted to act.

EDWARD W. limLER.

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