US1863571A - Machine and process for generating gears - Google Patents

Description

June 21, E J S 1,863,571

MACHINE AND PROCESS FOR GENERATING GEARS Filed Feb. 12, 1925 ll Sheets-Sheet l INVENTOR.

[ST/W? $47K K 60mm- June 21, 1932. J LE S 1,863,571

MACHINE AND PROCESS FOR GENERATING GEARS Filed Feb 12, 1925 1 sheets-sheet 3 BY v M Z M/-52 #La ATTORNEYS,

June 21, 1932. LEES 1,863,571

MACHINE AND PROCESS FOR GENERATING GEARS Filed Feb. 12, 1925 11 Sheets-Sheet 4 INVENTOR. W- L L 4 v 1 1 ATTORNEY.

E. J. LEES June 21, 1932.

MACHINE AND PROCESS FOR GENERATING GEARS Filed Feb. 12, 1925 11 Sheets-Sheet 8 g awwwazo l6 ATTORNEY,

June 21, J L E v MACHINE AND PROCESS FOR GENERATING GEARS Filed Feb. 12. 1925 11 Sheets-Sheet 9 =-lII14 V I x W.

' IN-VEXTOR.

SEW 2 wan H! s A TToRxEYS.

k r i E June 21, 1932. J LEES 1,863,571

MACHINE AND PROCESS FOR GENERATING GEARS Filed Feb. 12, 1925- v 11 Sheets-Sheet l0 61mm}. 1 INVENTOR.

ATTORNEYS. l

June 21, LEES MACHINE AND PROCESS FOR GENERATING GEARS Filed Feb. 12, 1925 11 Sheet-Sheet 11 INV EN TOR.

16 ATTORNEYS.

Patented June 21, 1932 UNITED STATES )PATENT OFFICE mmssm J. was, or CLEVELAND, OHIO, Assmnoa TO 1:. r. BRADNER, or cmvnmnn,

- onro Y macnmn am) raocnss non ennnna'rme cams Application filed February 12, 1925. Serial m. 8,710.

The present invention relates to the generation of gear teeth on a blank and more particularly to the igeneration of con ugate involute teeth by mi ling or grinding.

5 At the present time, in practice, so far as I am informed, it is customary to perform such operations by rotating the blank and traversing it relative to the tool or generating wheel'in a straight line tangential to some o circle of the gear to be generated.

On of the objects of the present invention is to provide a method and apparatus whereby there may be produced, generated involute or modified involute teeth on a blank I while the blank is held stationary and the tool or tools moved'in a predetermined path and rolled in generating contact with the tooth to be generated, and wherein a continuing rolling action is had until the tool or tools just clear the tooth being ground when an indexing movement of the blank may be ef-' fected and whereby the tool 'maythen operate on the next tooth to be generated.

Another object of my inventionis to accomplish the grinding of gear teeth in a manner whereby, both very small and very large gears can be generated with equal facility.

Another object of my invention is to accomplish the grinding of gears in a more accurate manner by reducing the elements involved in the operation whereby a reduction of the errors due to backlash, tolerances, and like causes is effected.

Another object of my invention is to reduce the many parts and elements usually required to those required for a single rolling action, as a means of tooth generation.

Another object of my invention is to reduce the possible error in generation by the employment of a tool frame unit, or a plurality of such units directed by and preferably suspended on tapes.

Another'object of my invention is to reduce the generating time required to complete a given gear.

The mounting for. and movement of extremely large gears and the controlling of the rotation and traverse of the same has heretofore been a diflicult matter, because of the weight of the parts to be movedand the variable and exact velocity required, whereas, in the present invention-the tool and frame may be comparatively small and much easier to roll on a base circle and only a small amount of relative movement may be -required. The properties of the tool and associate moving parts are constant and those of the work are not. v

' On extremely small gears the accuracy obtained in generating depends largely on the number of working parts, and as the errors incurred due to tolerances in bearings, working slides, and to torque and back lash disturb the accuracy of generation, the reducing of the action to a single rolling action as a means of generation, and the suspending of all of the tool frame units on tapes, reduces these errors to a minimum and to negligibility.

The preferred form of. my invention involves the control of the involute generating action of the tool by rolling it on an involute outline by having a. straight edge element roll on'a circular element corresponding to a base circle or circles, which are arranged axially concentric to the blank to be ground; and moving the tool thus controlled in generating engagement with the teeth being formed. The blank is held stationary without any rotary or traversing action while the generation takes place.

In practicing the preferred form of my invention the tool is only required to roll a minimum distance both' for generation and for indexing clearance as compared with prior methods, requiring both rolling and tangential travel of the gear.

In practicing my invention, I may also impart to the tool or tools a controlled movement in addition to the generating roll so that the tool used may employ either a single line of working contact or a predetermined amount of workin area, the amount of area being governed y the control member.

I may and prefer to use a plurality of tools, su ch as two at the same time, both preferably having the same generating action as described above and both acting simultaneously to generate on opposite sides of different teeth, whereby when a gear of a given number of teeth is indexed a number of times equal to the number of teeth-to be ground, the gear may be completed onboth sides of all the teeth. I reduce the generating time for a given gear down to its minimum by reducing the tool roll to its lowest possible amount to generate the tooth and by limiting the travel past the tooth being generated to just enough to permit the gear to be indexed. The simultaneous use of a plurality of generating tools, such as two tools, still further reduces the generating time required.

In carrying out my invention, I find it of advantage to use thin bands or equivalent elements partly wrapped around base circle elements, which are in axial alignment with the gear blank to be generated, arranging the generating tool or tools with their generating edges at right angles to the intersection of said bands and base circles and to use a planular faced tool controlled by the unwinding and winding of these bands to follow an involute outline to generate a gear tooth whose profile is coincident with the involute.

I also aim to reduce the co-ordinated factors to effect an involute generation, for example, from two or three to one factor only and preferably to a rotating factor. One or two traversing factors may be reduced to one factor of rolling by the use of my invention.

These and other objects of my invention will be apparent from the detailed description of a machine which is at the present time the best form of my invention known to me and which follows.

Referring now to the drawings and diagrams:

Fig. 1 is an end view of a machine embody- 5o ing the invention as set forth.

ig. 2 is a side View of the machine.

Fig. 3 is a plan view of the machine.

Fig. 4 is a lower plan view of the machine taken below the plane A-A of Fig. 2.

Fig. 5 is a. vertical section of the machine taken through the center.

Fig. 6 is a vertical section of one of the swinging frames.

Fig. 7 is a horizontal section of the. swinging frame shown in Fig. 6 taken below plane BB of Fig. 6.

I Fig. 8'is a vertical section of one end of a swinging frame shown in Fig. 7.

Fig. 9 is a view showing the indexing mechanism.

illustrating the basic principle of rolling generation employed.

Figs. 17, 18, 19 and 20 show, diagrammatically, the generating tool lingering on the tooth while generating.

Figs. 21, 22, 23 and 24 show, diagrammatically, the method employed to cause the lingering of the tool while generating, and to effect a quick movement to cause the tool to clear the tooth while indexing.

Fig. 25 is a fragmentary view partly in section and partly in plan of the parts shown in the upper right of Fig. 6'.

Referring now to the various figures of the drawings, in all of which like parts are designated by like characters of reference, I will now describe an embodiment of my invention, comprising a number of co-related mechanisms, describing, under separate heads, the various portions and the various methods and principles employed in the embodiment herein illustrated, to more readily convey an adequate understanding of my invention. In this description, since two movable frames 38 are employed together with duplicate like-operating apparatus for each to actuate each of two gear grinding tools 52, the single description given of one of these units will sufiice to convey an understanding of both.

Power mechanism to roll the swinging frames As shown in Fig. 5, the motor 1 has secured to its shaft a removable spur pinion 2 which drives a removable spur gear 3 secured to a worm shaft 4:, so that gears 2 and 3 may be changed to vary the speed of worm shaft 4 as required. The worm shaft 4 drives a worm 5 secured to the shaft 4 by a key 6. The end thrust of Worm 5 is taken by ball bearings 7. The worm shaft rotates in suitable bearings 8 and 9 secured in a housing 10, which is bolted in place on a sub-housing 11; the subhousing 11 has a projection 12 which carries a sub-base 13 upon which the motor 1 is mounted.

A pulley 14 is mounted on one end of the shaft 4 and is used for driving a pump to supply coolant to the Work and cutter. A tank 15 is provided for the coolant and a removable tray 16 is provided therefor for the sifting out of cuttings on the return of the liquid coolant from the work. The worm 5 thereby returned to their original positions" drives a worm ear 17 which is journalled in housings 10 an 11. The housing 11 is fastened to and supportedbythe main bed of the machine 18. V

Secured to the worm ar 17 by bolts 21 are two cams 19 and 20, ig. 13, which rotate with the worm gear and by their cam faces 22 effect the transverse'travel of slides 23 by engaging the rollers 24, rotatably'mounted on the slides 23 over pins 25, as shown in Figs. 4 and 13. Each slide 23 has ways 26 which reciprocate in a bracket 27 fastened to lower housing 11, as shown in Fig. 2. In Fig. 13, slide 23 is shown to have an abutment face 28 engaging a roller 29 which is carried on a rocking bell crank 30 secured to a trunnion hub 31. The hub 31 carries a projecting lever arm 32 havin a working face 33 to engage a roller'34. Thls roller is journalled upon a shaft 37 in the hub 36 of an arm 35. The arm is secured to the swinging frame 38 which carries the generating toolmechanism which will be later described as a unit.

The above mechanism operates as follows: The motor -1 being run at a suitable speed, will through the pair of .spur gears 2 and 3 of the correct reduction cause the worm gear 17 to revolve at a desired proper rate of speed for the purpose. The worm gear is preferably driven to complete one revolution while each tool operates on one tooth of the work gear and the gear is indexed. The worm gear rotates the cams and throu h the action of their faces which have an e ective motion of radial travel in. and out, cause the slides 23 to push the rollers 29 outwardly and throw the arms 32 upwardly.

A swinging motion is transmitted to each frame 38 through its roller 34 and arm 35, by the movements of the arm 32. The weight of each frame 38 and all mechanism carried by it cause its subsequent return by gravity and all the intermediate moving parts are through the train of movements to the movable cam faces. As the roller 29 is adjustable for radial distance from the axis of 31, it controls the amount of angular swing given to frame 38.

Application of power to operate rotary tool Referring to Figs. 6 and 7 A motor 39 having a shaft 40 extending through two bearings 41 and 42 is secured to spindle 46 is rotatably mounted in a quill 47- axially adjustable in a frame 48 b means of bevel gears 49 and 50 operated by a shaft 51, which is adapted to be rotated byhand in any suitable manner as by a crank applied to the squared end 202 of the shaft 51. The

shaft 46 has a rotary planular faced tool 52 mounted on its upper end. Means to ti hten the belt 44 is provided in a swin 'ng rame 53, carrying a pulley 54, there ing provided a screw threaded into the frame 38 to so adjust the fame 53 that the ulley 54 is pressed against the belt 44 to o tainthe take-up required. The pulley 45 has a fixed relation to the spindle 46 so that when the quill 47 is adjusted by rotation of the shaft 51, the pulley travels with it and the pulley 45 is made long enough axially to permit the belt 44 to be maintained in ahgnment on the pulleys 43 and 54 at all adjustments. The bevel gear 49 is threaded onto a flanged sleeve 57, bolted to quill 47 and is rotatably held in position by a clamping flange 220 of an enclosing case 58; when the ear 49 is rotated the screw 56 moves the quill 47 longitudinally. The flanged sleeve 57 also carriesan adjustable taper actuated Y bushing 59, in

which the lower end of spindle 46 rotates, the

bushing 59 being adj usta le by adjustment of the nuts 60 at its lower end.

Mechanism to adjust the tools to the 'work 40 at bearings 63 and 64; a flanged bearing 65 projects from the frame 48 and rests and slides on the frame 38 and is held in sliding position thereon b means of a gib 66 secured to the frame 38. ecu d to each lower cover 62 is a bracket 67. This bracket is used to control the in-and-out adjustment of the tool and related parts, or cutter head, to the work, the cutter head being carried by the frame 48 as an entirety. This is accomplished as follows:

Referring to Figs. 8, 25 and 6, the frame 38 is constrained to move by gravity, Fi 8, so that the straight edge 72 thereof a uts against the stationary base circle element 74 in a manner and for a purpose described elsewhere herein. The base circle element 74, as will be described, is carried in a support mounted on the main bed of the machine.

And, the gear to be worked being co-axial with the base circle element 74, the tool 52, to be adjustable relatively to the work piece must be adjustable relatively to the base circle element 74, and this is provided for by mak ing it adjustable along or upon the frame 38. To this end a bracket 67 is secured to the lower cover 62 of the tool housing whereby the housing and its tool may be adjusted about the axis of the shaft 40 toward or from the base circle element 74. This bracket is held toward the base circle element 74 b a plunger 75 mounted in the frame 38 an having a thrust compression spring 76 and a compression adjusting screw 77. The force of the plunger on the bracket 67 is taken up by an adjusting screw 68 therein having a hand wheel 69, and the screw 68 in turn abutting upon a projection 71 on a saddle shaped sliding control member 70 adapted to slide upon ways on the frame 38; and the force thus transmitted to the control member 70 is finally transmitted to the base circle element 74 through a projection 73 on the control member 70. Thus the bracket 67 (and therefore the frame 48 and tool 52 all of which move together) is held toward the base circle ele ment 74 (Fig. 8) by the spring 76 and is held against movement by the projection 73 abutting on the base circle element 74, causing the tool 52 to occupy a definite position relatively to the axis of the base clrcle element 74; and it will now be understood that if the hand wheel 69 is turned the bracket 67 will move as a nut thereon and thus move the tool 52 nearer to or farther from the base circle and thus the position of the tool relative to the work may be adjusted by the hand wheel 69.

One method of describing an involute curve is the well known one of rocking a straight edge on a circle and tracing the path of point of the edge, and that method is the one employed herein. Referring to Figs. 14, 15 and 16, which are diagrammatic views, the straight edge 72 is held tangential to a base circle or cylinder 74 and rocked thereon without slipping, the point 81 on the edge as shown in Figs. 15 and 16 thereby generating the involute profile of a tooth 79; a planular faced tool 52 set at right angles to the straight edge 72, and traveling or moving in unison with it so that its face contains the point 81, will generate and describe an involute curve since the point 81 will do the same, and if the tool be a rotating grindingwheel or cutting disc, the face of the wheel or disc will have thereon a circular line of working contact containing the point 81.

Now it is desirable that more than a single point of the tool be employed to generate the gear teeth, or where the tool takes the form of a planular faced grinding wheel, it is desirable to distribute the grinding action over more than a circular lineon such a face. \Vhile distributing the grinding action over a surface instead of a line, it is also desirable to maintain the same effect, in kind, that would be had were the generation confined to a line of contact of tool and work.

Referring to Figs. 17, 18, 19 and 20, these diagrammatic views show my improved method and something of the means for carrying out the method of distributing the cutting action on the face of the planular tool. Fig. 17 shows the base circle straight edge and tool in the same positions as in igs. 14,

but as soon as the rolling action commences the positions subsequently taken apart from those shown. in Figs. 15 and 16 and the tool 52 is not caused to follow the outward movement of the straight edge as in these figures, but is caused to advance on the tool 79 from position Fig. 17 to position Fig. 18 to gradually change the effective cutting circle from point 81 to point 82, and so on, developing an annular area on the wheel, as shown at Fig. 19,

the tool is then drawn out to index the work gear and then is brought forward again as in Fig. 20 to start the generation of the next tooth 80, the planular face of tool 52 always being at 90 with the face 72 of the straight edge. Where I have spoken of a cutting point herein, it is to be understood that this refers to the tool as viewed only in the plane of the paper in the diagrams since the tool 52 is constantly rotating, and the generating point actually, describes a line on the tool. This line is circular in the example described for Figs. 14 to 16 inclusive; and the line developes a flat spiral or in effect an annular surface in the continuing process of Figs. 17 to 20 inclusive.

The action of the control member for regulating the varying diameter of cutter generating contact is as follows: Referring to Figs. 21, 22, 23 and 24, the contactor 73 rests on the base circle 74 so that when the tool on the grinding wheel is adjusted to generate the tooth 79 the contactor and tool have a relative position to each other, as shown in Fig. 21 the generating action now takes place controlled by the action of straight edge 72 on base circle 74 the parts moving to the position shown in Fig. 22. The contactor remaining in contact with the base circle; while the straight edge is rocking on the base circle and controlling the involute generating action, the contactor controls the cutting diameter on the grinding wheel which as Will be seen is less in Fig. 22 than in Fig. 21. The rolling of the tool continues until the control member 70 has come in contact with a block 78 fastened to the base circle, as shown in Figs. 8 and 13. This block throws the control member and contactor away from the base circle carrying the tool and frame 48 along so that the tool 52 just clears the tooth 79 being generated, as shown in Fig. 23. The swinging frame 38 reaching its lowest point, the indexing takes place as will be described later, following which the rolling motion is reversed and the control member, fulcruming on 78 effects the return of the tool 52 inwardly as shown in Fig. 24 to start the generation of the profile of the next tooth, which starts from the outer end of the next tooth and proceeds inwardly with a constantly increasing-diameter of tool contact until it reaches the starting point shown in Fig. 21; then again the generation proceeds outwardly with a constantly decreasing diameter of tool contact as before described. To use a constant diameter of tool contact and the c ntrol member is made with a straight ace parallel with andin line with the straight edge, so that both-edges are tangent to base circle 74 as shown in Figs. 14, 15 and 16; therein 72 is used to designate both the straight edge and the control member, the block 78 is not shown, and the diameter of the tool contact is determined by the point 81 above described. The tool face which generates the profile of the gear tooth is always set at 90 with the edge of the straight edge 72 in contact with'the base circle.

Tapes Referring to Figs. 5, 8, 13 and 25, thin metal tapes 83 are secured to suitable block holders 84 which in turn are fastened to slides 85 controlled by screws 86. The tapes 83 have block holders 84 at each end. Starting at one end their arrangement is as follows: They follow around the rounded end 72 of straight edge 72, thence up the straight edge 72 and over the base circle element 74 and down the other side along the other strai ht ed e 72 around thereunded corner 72' t ereo and to the other block 84. At the top of the base circle elements there are clamps 87 (Fig. 5) held down by two screws 88 to hold the tapes in place.

As the two frames 38 are identical, except being right and left hand, the description herein of one side and its operation is sufficient, the other side having duplicate parts and its operation being identical to that of the parts on the side described.

Main bed and supports The main bed of the machine 18 has at either and upright standards 90, and as shown in Fig. 5 between these end standards a bed 91 is located. Parts 18, 90 and 91 may be integral. As shown in Figs. 1 and 5 the bed 91 has a T slot 92 extending along its full length with the exception of an intermediate open space where the pan 93 is' located to drain the coolant back to the tray 16. On the bed 91 are a V way 94 and a flat way 95, and mounted on these ways are the supports 96 and 97 in which are located the base circles 74; both these supports are held on the bed by T bolts 300 as shown in Fig. 5. Also located on the 3 bed 91 between the supports 96 and 97 is the headstock 99. This also is held in T bolts 301 as shown in Fig. 5.

Slidably mounted on the support 97 is a tailstock 100 for holding the end of work arbors with a center, when required.

H eadatocla and work spindle The headstock 99, Fig. 5, has a work spindle 101 mounted in axial alignment with the two base circle elements 74. Work spindle place by 101 is rotatably supported in the headstock 99 by two taper bushings 102 and 103; a flanged-ta r bearing 104 is keyed to the wor spin lo 101, fittm in the bearin 102 and is adjustable lengthwise or axial y by rotation ofthe nuts 105 to take up all wear in the bushings 102 and 103. A gear,106 is fixedly mounted on the bearing 104, at the rear end of which, the index plate 107is removably mounted by screws 109. The work arbor 110 is held in place in work spindle 101 by a rod 111 heldby a flanged nut 112. The work arbor 110 carries the blank gear 113 to be worked. g

The work spindle 101 and all parts secured ing generated, but when all rotate as one unit.

Indexing nwcha/nz'sm Referring to Figs. 9, 10, 11, 12, the cam 20 has secured to its outer cylindrical face an angular projection located radially to the axis of the cam, and so located with respect to the cam working face 22, that at the time at which the frame 38, Fig. 13, is at its lowest point the projection 120 engages a roller 121, carried in an arm 122 which rocks about an axis of a stationary fulcrum stud 123 secured to the housing 10; at the other end of the arm 122 a connecting link 124 transfers the rocking motion to another rocker arm 126 by means of connecting pins 125 and 127. The arm 122 is held in position by a spring 118 secured at 119 to the housing 10. The arm 126 fulcrums on a stud 128 which is secured to the bed 91; a handle 129 secured to the arm 126 is used to permit hand control of arm 126 when required. Motion from the arm 126 is adjustably transferred to a slide 133 mounted in the headstock 99, by means of a link 130 adjusted in a slot 132 by means of a screw 1.31 and the pin 134. The slide 133 (Fig. 11) actuates a slide 135 through the means of a stud 136 threaded into and secured to the slide 135, and passing through a hole in a lug of the slide 133, a compression spring 137 being interposed between the head at the top of the stud and the perforated lug on the slide 133 which receives the stud shank; the slides 133 and 135 are therefore resiliently held together by the compression spring 137. The slide 135 has a projecting portion 138 which carries a ratchet pawl 139 rocking on a pin 141 and pressed into engagement with the teeth of gear 106 by a flat spring secured to the projection 138. At the upper part of slide 133 is an extended arm 142 having an extension pin 143 which engages a slot in a rocking lever 144. The rocking lever 144 is fulcrumed on a stud 145 secured to frame 146, this in turn being carried on a bracket 147 mounted on the headstock 99. The rocking indexing takes place lever 144 is held against the frame 146 by means of two springs 148 and 149. Shdably mounted in the frame 146 is a plunger 150 having at its lower end a projecting locating finger 151 fitting into one of the slots 152 in the plate, and thereby securely holding the index plate 107 from rotary motion. lhe plunger 150 has at its top a spring 153 held under compression by a screw 154 earned in a bracket 155 which is secured to a bracket 147. The bracket 147 carries a stud 156 carrying an insulator 157 for holding the wires to motors 39.

The plunger 150 has a projecting portion 158, which engages the lever 144 on its upward travel. The frame 146 has a'lateral projection 159 with a chamfered point at its lower portion which meet an oppositely chamfered point at 160 on the arm 144, so that when the arm 144 is rocked upwardly the point 160 engages the chamfered portion of the projection 159 and gradually presses the lever 144 away from the frame 146 compressing springs 148 and 149. The rocking lever 144 engages the projection 158 of the plunger 150 and lifts the finger 151 of the plunger out of engagement with the slot 152 of the index plate 107. The face of the proj ection 159 presses the lever 144 out of engagement with the projection 158 and the spring 153 causes the finger 151 to descend on the index plate 107 until the ratchet 139 has caused sufiicient rotation of the index plate to posi; tion the next notch 152 sufiiicently to engage 151 which then seats itself. The indexing movement as a whole is as follows When the swinging frame 38 carrying the cutter or tool has become lowered so that the tool is out of mesh with the tooth being generated, then the projection 120 lifts the roller 121 to effect the lifting of the slide 133 a pre determined amount as described. This amount is controlled by the distance that the screw 131 is fastened from the fulcruming point 128 which determines the vertical travel of the slide 133. This is purposely set a small amount more than the distance corresponding to the spacing of the notches or slots 152 in the index plate from each other. The object of providing this extra travel is to al-' low the slide 133 to compress the spring 137 a small amount before the finger 151 is withdrawn from the notch 152, thus ensuring that the plunger 150 is lifted before the turning action takes place; another object also is to preferably allow a certain amount of leeway in the setting of the screw 131, of course, only when the movement of 130 is made to be a' little more than required. When the plunger 150 has seated with the finger 151 thereof in the next notch of the plate 107, a little over travel of 133 does no harm but only com presses spring 137.

with the end of the shaft beyond-the spur pinion is a a conical projection 166. This shaft is so located, that the teeth in pinion 162 will mesh gear 106 when the shaft 161 is pushed from the handle end, and also so that the conical point 166 may be projected through a hole in the frame 146 and enga e the edge of a. conical edged hole 167 in tfie plunger-150, shown in Fig. 5, the end 166 of the shaft 161 lifting the plunger 150 so that the finger 151 thereof is released from index plate 107. This permits shaft-161 to be rotated and with it gear 106, which in turn effects the movement of the work spindle 110 and blank 113. Upon the withdrawal of 161 and pin'on 162 the plunger and finger are reseat-ed by the pressure of spring Method of using hand index its other or second face to the other toolwhich generates such second face, and then the tooth is measured for the thickness required, the tool being adjusted until it will cut the tooth to the exact thickness of tooth desired.

The blank may then be indexed to its original position. All blanks generated thereafter with the same setting of machine, wIll be duplicates of the first in regard to thickness of teeth. The handle 129 may also be used for indexing but is rimarily intended for testing out the spaclng from tooth to'tooth when adjusting the indexing mechanism for a given number of teeth. A handle fitted on the end 165 of shaft 161 is located where the operator can see the blank when getting the tooth thickness and is better adapted for indexlng than the handle 129 although each method has its own advantages and each handle is in correct location handy to the operator for its primary intended purpose.

Blank locating device In Figs. 5 and 13, there isshown a swinging arm 168, centrally disposed above the a is o the blank and hinged on the bracket changeabl employed to. suit different -pitches gears to be generated. The locater fits into the space between two teeth. A spring 172, shown in Fig. 2, brings the arm 168 to its outerposition a ainst a stop 173 when not in use. The met 0d of us'ng this device is as follows: As the two gencrating tools are disposed at an equal an lar position on each side of the blank see Fig. 13) it makes no difference whether the blank to be generated has an even or uneven number of teeth. If a space between two teeth is located centrallyabove the axis of the blank there will be an equal angular distance down to a predetermined upper tooth face on either side. Therefore, before the blank, located on the arbor, is fastened, the arm 168 .'s swung down until locater 169 engages this space, and while in this position the blank is secured to the work holder or arbor. The arm 168 being then released, the spring 172 holds it out of the way while generation takes place. All other blanks may be preliminarily located in the same way up to the blank size capacity of the machine, regardless of diameter or number of teeth to e generated.

Connterbalanee and hand adjustment to swinging frames The swinging frame 38 has extension arms 175 located at each end shown in Figs. 1 and 2; rotatably secured to these arms are rollers 176 held in place by bolts 177, and which rollers 176 rest and roll on swinging arms 178, one being pivoted on an arm 179 which is a part of support 96 and the other on an arm 180 which is a part of support 97. See Fig. Secured to standards 90 are brackets 181' having tubular parts 181 containing in their top portions plungers 182 slidably mounted therein, as shown in Fig. 2, an upward pres-.

sure being exerted thereon by springs 183 adjustably controlled by means of screws 184 disposed at the bottom of the tubular parts 181. Plunger 182 is slotted to receive the lower end of a connecting rod 185, held in place by a pin 186, and connected at its upper end to the arm 178 by a pin 187. The arm 178 swings on a pin 188 which connects it to the arms 179 and 180 as shown in Figs. 1, 2 and 3. By this arrangement the weight of the frames 38 may be counterbalanced or as nearly counterbalanced as desired.

Located in brackets 181 are swinging blocks 189, which are used to position the frame 38 in horizontal alignment when setting up the machine for a given sized blank, since they may be swung upwardly so that an adjusting screw 190 supports the arm 178; however, when the machine is generating the blocks 189 are turned down as shown in Fig.1. An upright arni 191 of frame 11 carries a swlnglng rod 192 threaded at its outer end to carry a hook 193 which as seen in Fig. 2 is slidably mounted and controlled by a hand nut 194. This arrangement is such that the rod 192 may be swung. upwardly and the hook 193 hooked onto a projection 195 in frame 38 and then by turning the hand nut 194, the frame 38 will fulcrum on roller 176 and the tool may be suitably raised or lowered. Also the adi'rusting screws 86 may be ad usted as seen in igs. 7 and 8, to accommodate the diameter of the base circle by controlling the block holders 84 and slides 85 to tighten or loosen the tapes 83. Upon completion of the adjustments the rod 192 is then swung down to lower position as shown in Fig. 1, this being its position when generation is taking place.

Modification of tooth form Fig. 1 shows adjustable blocks 205 in su ports 96 and 97 carryin the ends 207 of tl ie base circles. These en s 207 are preferably integral with the base circle element 74 as shown in Fig. 5, and are held in place by caps 208 secured in place by bolts 209. Block 205 is adjustable vertically by interposing shims 206 between it and its supports, thus modifying as desired the center height of base circle, this modification of height effects the modification of the generated tooth form from a true involute as may be desired.

Operation of machine When a gear of a certain number of teeth and pitch diameter is to be generated, two base circles 74 of the diameter for this gear are provided, one at each end, of the machine. Tapes of the right length are arranged in the holder blocks 84.v The tapes are ut over the top of the base circles and the b o'cks secured to the adjusting slides. Handadjustment of frame 38 is used to swing the frame upwards to allow this to be done. An index plate 107 having the same number of spaces as the teeth to be generated is placed in the indexing mechanism. A blank is secured to movement will suflice to adjust this travel correctly as determined by the location of stud 131 in the slot 132. The motors 1 and 39 being now operating, generation is started.

After one side of two difi'erent teeth have been generated, hand ad us tinent is used as described and the blank is rotated so that one of the tools generatesthe second face ofone of the teeth partly generated in the beginning. Measurements are taken and the blank moved to return the tooth to its original position. Allowance is made by tool adjustment, the second face is tried again, and if correct, thereafter blanks of the same size are automatically held to the same tooth thickness thus determined upon. When the tools being used are abrasive wheels for grinding then the diamond truing device on cover 61 is set for this position, the diamond having a stationary location axially to the tool, the tool being adjusted down but the diamond always truing up the wheel in the same place.

The apparatus having thus been set up, the operation proceeds. The motor 1 through the chain of gearing, including 2, 3, 4, 5 and 17, rotates the cams 19 and 20, which effect the swinging of the frames and the rotating tools carried thereby. The arms 32 are swung by the cams through theintermediate mechanism, including the slides 23 and the arms 30. The arms 32 swing the frames about the base circles 74, so that the tools 52 go into and out of the gaps between the teeth, grinding the teeth according to the involute principle as described in detail. The swingin of the frames on the tapes which follow t e straight edges and pass over the base circles 74 ensures the cutting of the faces of the teeth according to the involute principle. The cutting contact circle of the tool is gradually shifted as the swinging proceeds, thus distributing the wear on the tool. When the tool clears the end of the tooth, the indexing is effected through the lug 120 and the associate parts illustrated and described in connection with Figs. 9 and 10. This cycle is repeated until the gear is ground. The operation is both rapid and accurate.

\Vhile I have shown a single embodiment of my invention and certain details of construction which are at the present time the best embodiment and details known to me, I do not wish to be limited either to this particular embodiment or to these details, as it will be understood that the invention may be embodied in other forms and that the details of the-embodiment shown may be varied both in this embodiment and in others without departing from the spirit of the invention.

In the foregoing description of my invention the relative movement between the planular face of the grinding wheel and the gear teeth for generating involute faces on the teeth, is described as produced or controlled by means of the base circle of the gear and a straight edge or line, one rolling on the other. The well known alternative method of rolling a pitch circle of the gear and a straight line one upon the other ma also be employed with my invention. Furt ermore, as is well known, when the circle of the gear which rolls on the line is the base circle, the working plane of the grinding wheel-must be at right angles to the line on which the base circle rolls, and the working zone on the. plane of thewheel is a circular line; and that when the circle on which the gear rolls is another circle such as one of the pitch circles of the gear, the planular face of the wheel must be at an acute angle with the line on which the gear rolls and the working zone on the wheel face is an annular area thereon. Therefore as will be understood by those skilled in this art, when my invention is embodied in a machine in which the said alternative arrangement of rolling' a pitch circle of a gear on a line is employed, the grinding wheel may be caused to work on an annular area thereof without requiring the projecting contactor 73 and the associated parts by which it is caused to slide along on the circle of the gear to shift the working zone on the wheel. To adapt the 'hereinbefore mechanism for rolling the gear on a pitch circle, all that is required, referring to Figs. 13 and 21 to 24 inclusive, is to ad ust the position of the grinding wheel 52 to bring the planular workin face thereof into an'acute angle with the straight edge 72, and to provide circular elements 74 of pitch circle diameter; and

therefore a specific illustration and further description thereof is deemed unnecessary.

What I claim is:

1. The method of generating involute faces on the successive teeth of a gear which includes mounting the gear on a stationary work holder, moving the planular faces of a pair of grinding wheels over the opposite faces of two teeth of the gear simultaneously, controlling the movement of the wheel faces to move on involute paths by causing them to move in unison with a pair of lines rocking simultaneously, on a circle of the gear, the

lines each making a constant pro-determined angle with one of the planular wheel faces and indexing the gear teeth after each pair of faces has been ground by indexing the work holder.

2. The method of generating involute gear teeth which comprises holding a work gear in stationary position, and rolling a rotating cutter upon the base circle of the work gear While maintaining the cutting surface thereof normal to a line tangential to the base circle, the axis of the tool being moved to bring into contact with the work gear different zones upon the surface of the tool.

3. A method of generating involute gear teeth which comprises maintaining a work gear in stationary position, placing a rotating cutter in contact with a tooth thereof, there being a straightedge fixed with respect to the cutter axis, rolling the straightedge CPI eeann upon a base circle equal to the base circle of the work gear and held concentric therewith so that the cutting surface of the cutter is maintained normal to the straightedge, and translating the cutter while maintaining its axis in the same angular relationship to the straightedge.

4. The method of grinding gear teeth which comprises holding a work gear stationary, engaging one toot-h of the work gear with a rotating cutting tool, moving the tool to maintain its axis in a fixed angular relation to a straight line rolling upon the base circle of the work gear until the cutting surface of the tool has traveled across the surface of the tooth, and then rotating the tool about a center outside said base circle to clear the tooth.

5. The method of grinding gear teeth which comprises holding a work gear stationary, engaging one tooth adjacent its root with a rotating cutting tool. moving the tool outwardly while maintaining its axis in a fixed angular relation to a straight line rolling upon the base circle of the work gear until the cutting surface of the tool has traveled across the surface of the tooth, then rotating the tool about a center outside said base circle to clear'the tooth, releasing the work gear, bringing another tooth thereof into position to be engaged by the tool, and repeating the operation for each tooth.

6. The method of generating involute faces on gear teeth which includes mounting the gear on a work holder, moving the flat faces of a pair of grinding wheels over theopposite faces of two teeth of the gear simultaneously, controlling the movement of the wheel faces to move on involute paths by causing them each to move in unison with a line rocking on a circle coaxial with and of the same diameter as a circle of the gear, the lines each making a constant angle of with the plane of one of the wheel faces respectively and causing each wheel to engage the corresponding tooth face on contact zones of the wheel of varying diameter.

7. The method of generating involute faces on the teeth of a gear with a planular faced grinding wheel which includes moving the planular face of the wheel over the face of a gear tooth and controlling the movement of the wheel to cause the working portion of the planular face to follow an involute path on the geartooth, and to cause the wheel to engage the tooth face on a contact zone of varying diameter.

8. The method of generating involute faces on the teeth of agear with a planular faced grinding wheel which includes moving the planular face of the wheel over the face of a gear tooth and controlling the movement of the wheel to cause the working portion of the planular face to follow an involute path by causing it to move in unison with a line rocking on a circle, the line meeting the plane of the wheel face at a constant predetermined ang e.

9. The method of generating involute gear teeth which comprises moving the flat faced grinding wheel in relation to a tooth of the gear so that the flat face of the wheel lies in a single plane normal to a line tangent to the base circle of the gear and simultaneously translating the axis of the wheel in a direction substantially perpendicular to itself and to the axis of the gear.

In testimony whereof, I hereunto afix my signature this 6th day of February, 1925.

ERNEST J. LEES.

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