US1540898A - Relieving machine - Google Patents

Description

June 9, 1925. 1,540,898

F. MULLER RELIEVING MACHINE Filed Dec. 14, 1921 10 Sheets-Sheet l June 9, 1925. v

F. MULLER RELIEVING MACHINE Filed Dec. 14, 1921 10 sheets shet 2 June 9, 1925.

F. MULLER RELIEVING MACHINE Filed Dec. l4,

10 Sheets-Sheet 5 June 9, 1925.,

F. MULLER RELIEVING MACHINE Filed Dec. '14, 1921 10 Sheets-Sheet 4 June 9, 1925.

. F. MULLER RELIEVING momma Filed Dec. 1.4, 1921 10 Sheets-Sheet v QWN ' June 9, 1925.

1,540,898 F. MULLER RELIEVING MACHINE Filed Dec. 14, 1921 10 Sheets-Sheet a June 9,1925. 1,540,898

F..MULLER v RELIEVING MACHINE Filed Dec. 14, 1921 10 Sheets- Sheet 1o Patented ,Junet9, 1 925. v

1 UNITED STATES rm-comm; or nnwyonx,

RELIEVING MACHINE.

Application filed December 14, 1921. Serial- No. 522,394.

-, To all whom it may concern:

- new and usefullmprovements Hartford, in the county of Be it known that I, Fnmnnmcrr MtiLmm, a

citizen of the United States, residing at Hartford and State of Connecticut, have invented certain in Believing Machines, of which the following is a specification.

,My invention relates to relieving 'machines and particularly to rel eving machines for operating on cutter blanks having helical teeth. a One object of my invention is to provide a relievingmachin'e that shall cut a blank,

" having helical teeth provided either with radially arranged or non-radially arranged cutting faces, rectilinear contour While relieving-the teeth along lines extending backwardly, inwardly and to the right or to the'left, as desired,-

- and compensating such relieving operation at different blank diameters in case the cutting faces of the blank teeth are non-radially arranged. 1

' Another object of my invention is to pro- 1 vide a relieving machine that shall form a blank, having helical teeth provided with either radially or non-radially arranged cutting faces, to the contour of a former member while varying the length of the contour formed on the blank relative to the length of the contour of the former member to compensate for changes inlen Another -ob ect-ofmy invention is to provide a relieving machine of'the above indicated character that shall control a'plurality" of cutting tools to cute plurality. of cutter-3 blanks in accordance with a former member,- whil'e ef-' having a predetermined contour, fecting relieving movements of the tool, in-

' conformlty with helical teeth 9n the blank and compensating such'relieving. operationof the tools at :difierent blank diameters in case the helical teeth of the blanks have non-radially arrangedcutting faces:

Another object of vide a relieving machine forshapm ter blank, having h'elieally inchne to. any predetermined: contour that shall vary the rotative'movement oi the blankcarr'yin-g spindle by means of a'r'ack and" pinion in accordance with the inclination of the teeth of the blank and that shall pro to a rectilinear 'or to a nonth oi the blank contour which are eflected uring the hardening process.

my invention to pro:

teeth,

PATENT OFFICE. j

connnc'rrcu'r, Assmnon; 'ro mm a wrrri 1:. Y., A conronnrron or new mnsmr.

'vide means for resetting the rack in case a very-long blank is being-cut.

A further object ofmy, invention is toprovide a relieving machine for shaping a cutter blank to any predetermined contour that shall be provided with a slide forwithdrawing the tool from engagement with the blank at predetermined intervals, means in cluding a cam bar for raising the slide upon each withdrawal to permit free movement thereof, and means comprising oil cylinders and valves alined therewith for retarding the return movement of the tool.

More specifically my invention comprises a relieving machine for-forming a blank,

'which is provided either with helical "or straight teeth having radially arranged or non-radially arranged cutting faces, to any predetermined contour. The machine is provided with mechanism for eflecting reheving movements of the-tool along lines which extend backwardly, inwardly and to the right or ,left, as desired. The relieving movements are effected in accordance with the shape of the teeth on the blank and in case the blank teeth are, provided with nonradially arranged putting faces compensation is effected for the relieving movements.

The cutting tool is guided in accordance 'member. The cutting tools may operate simultaneously on one blank or mav'operate on a corresponding number of blanks. Each cutting tool is-provided with a" rear face Which'is formed to the sameangle as the relief on the front of the tool. By so constructing each cutting tool, itmay be'sharp- .ened by grinding the top faces and may then be reinserted in position without disturbing the. relative position of the cutting tool to the blank. v The mechanism disclosed in this ap lication includes some features ofthe mac es Ill . view of the machine.

of Fig. 14. v

Fig. 17 is a sectional view taken along.

' form and disclosed in my patentsNos. 1,429,617 and 1,443,638 respectlvely dated September 19, 1922 and January 30, 1923, and is adapted to cut a cutter such as is described and claimedin my co ending application Serial No. 524,586 -filed ecember 24, 1921.

In the accompanying drawings:

Figure 1 is a front elevational view of a machine constructed in accordance with my invention, certain parts being broken away and others being shown in section, Fig. 2 is a plan view with certain parts shown in section. In this view the covers for the head stock and other gearing are removed for the sake of clearness.

Fig. 3 is a vertical longitudinal sectional Fig. 4 is a rear View partly in section along the line 44 of Fig. 2.

Fig. 5 is an end view .taken from the left of Fig. 1.

Fig. 6 is a .transverse vertical sectional view taken along lines 66 of Figs. 1, 2 and 3.

Fig. 7 is a transverse vertical sectional view taken along the lines 77 of Figs. 1, 2 and 3.

Fig. 8 is a transverse vertical sectional view taken along the lines 8-8 of Figs. 1, 2 and 3. I

Fig. -9 is a fragmentary plan view showing certain. parts of the tool-carryingslides.

Fig. 10 is a fragmentary vertical sectional view taken along the lines 10 10 of Figs. 2 and 7.

Fig. 11 is a fragmentary vertical sectional view taken along the lines 11-11 of Figs. 1 and 2.

Fig. 12 is a horizontal longitudinal sectlonal view taken along the lines 12-1 2 of Figs. 1 and 7.

Figs. 13 and 14 are detailed views 'of the mechanism for varying the movements ofthe blank-carrying spindle, the views being taken from opposite sides. Fig. 15- is a transverse sectional view taken along the lines 1515 of Figs. 13 and 14. Fig. 16 is a fragmentary transverse sect1onal view take along, the lines 1616 the line.1717 of Fig. 2.

Figs. 18, 19 and 20 are diagrammatic views illustrating one operation that may be followed in cutting cutters with undercut cutting faces.

Fig. 21 is an enlarged sectional view showing the mechanism for effecting side relieving movements by the tool.

Fig. 22 is an end shown in Fig. 21. .Fig. 23 is va detailed sectional view show- 111g.

view of the mechanism the ball-bearing guides forone-of the slides. 3

Fig. 24 is an enlarged plan view of the mechanism used for operating on blanks having non-radially arranged cutting faces.

Fig. 25 is a side elevational view, partially in section, of the mechanism shown in Fig. 24.

Fig. 26 is an end elevational view, partially in section, of the mechanism shown in Fig. 24.

Fig. 27 is a diagrammatic view showing the relation of, the levers illustrated in Figs. 24, 25 and 26.

Fig. 28 is a diagrammatic view showing in development a cutter having teeth provided with non-radially arranged cutting faces.

Figs. 29 and 30 are detail views of the adjusting bar.

Figs. 31 and 32 are detail views of the correcting lever.

Figs. 33 and 34 are respectively plan and end elevational views of a modified tool post carring a plurality of cutting tools.

Fig. 35 is a section along the line .3535 of Fig. 33.

Figr36 is a section along the line 3636 being moved longitudinally along the blank in the manner tobe presently set forth. When the machine is so constructed, the

headstock 2 is fixedly preferably being formedin part integrally therewith, as shown. The tailstock 3 is adjustable along the bed to accommodate blanks or blank arbors of different lengths.-

The headstock 2 is provided with arotatsecured to the bed,

Inn

able spindle 5' mounted in suitable .bearings 6 and 7. Secured to the spindle 5, in

any suitable manner, is a collet chuck 8 which may be of any usual or preferred which is adapted -to grip either the shank of the tool to be formed and relieved or an arbor upon which the tool is mounted. As illustrated, there is a blank YA mounted upon an arbor B, the arbor being engaged by the chuck 8. A drive mechanism including a driving member in the form of a worm wheel 9, which meshes with a worm member 10 on a transverse rotatable shaft 11, spindle 5.

The tailstock 3 may be of any usual or preferred construction, and is adjustable is provided -for rotating the along ways 12 and 13. The tailstock 3 can be secured in adjusted position by means of a clamp 14 which is controlled by a lever 15. The tailstock spindle 16, which carries a center 17, can be moved longitudinally by means of a screw 18 under the control of a hand wheel 19. A handle 20 is provided for clamping the sleeve in adjusted position. As shown in Fig. 2, the center 17 is adjusted into engagement with the end of the arbor B.

The tool mechanism 4 includes a carriage 21 which is longitudinally movable along Ways 22 and 23 on the bed 1. A slide 24,

which is mounted for transverse movement with respectto the carriage 21, carries the cutting tool. In Figs. 2, 7 and 8 of the drawings I have shown a non-rotary lathe tool 25, and such a tool is preferable for many classes of work. However, when preferred a rotary tool can be used.

As stated at the outset, a machine ada t-.

ed to practice my invention is adapted or cutting a blank having a varying diameter. The diameter may .vary uniformly from end to end of the blank, thus providing a uniform taper,.or it'may vary in any desired way so as to provide the blank with any predetermined contour differing from a straight line. The variations in the diameter of the blank are determined by moving the slide 24 together with the tool transversely, and preferably, for regulatin and controlling the transverse movements, provide a former and a former pin, one car- I ried in fixed position on the bed 1, and the other carried by the slide 24. As illustrated, a former member 26 is carried by the bed 1 and a former pin 27 is carried by the slide 24. The former 26 has exactly the same contour with which the blank isto be formed and the former pin 27 has exactly the same shape as the cutting tool 25. The pin is detachably secured to the slide in a manner to be hereinafter set forth, so that it can be removed and another pin be substituted corresponding to atool difiering in shape from the tool which is shown.

A bracket 28, which is rigidly secured to the bed 1, is provided for supporting the former member 26. In order to ermit adjustment, the former 26 is secure to a slide 29 which is longitudinally movable along 'a suitable guideway 30 on the bracket, a

' screw 31 being provided for efiecting longitudinal movement. The slide can be locked in adjusted position by means of screws 32, 32 which enga'e a gib member 33. The slide 29 is rovi ed wlth'a T-slot 34, which is adapte to receive T-bolts 35 passing through the former member. Such {arrangement isprovided to permit the ready adjustment of the former member. To further assist in holding the former member in place and to prevent any possible nally the slide 24 with the tool 25 is moved transversely so as to keep the former pin 27 in en agement with the former 26.

In on ler that the tool may be given a relieving movement along lines extending backwardly and inwardly to properly relieve the several teeth on the blank, it is not rigidly secured to the slide 24 but is transversely movable thereon. A slide '37, which is transversely movable along a suitable guideway is mounted on the slide 24. A mechanism, for efiecting regular reciprocating relieving movements of the slide 37 and the tool in suitable timed relation with the rotative movement of the blank, is carried in part by the slide 24. In order that the tool may be adjusted for blanks of difierent sizes, a tool-carrying slide 38 is provided which is transversely movable on the slide 37. 1A screw 39, which is rotated by means of a hand wheel 40, is provided for moving the slide 38.- The slide 38 is provided with a transverse guideway 41 and a tool post 42 is mounted on a slide 43 which operates. in the guideway 41. Preferably to effect adjustment of the cutting tool but 1 also serves to efiect side relieving movements of the tool in .a manner to be hereinafter set forth. The tool post has a toolreceiving aperture p'rovided'with a horizontal top wall 44 exactly at the level of the axis of the blank. The tool 25 is positioned 'Witl'f'its top surface engaging thehorizontal wall 44 of thetool vpost and is held in this position by means of a wedge 45. The rear end of the cutting tool 25 isformed with an angle exactly corresponding to the relief angle on the vfront end of the tool. The rear endof the tool is engaged by a bolt 25 which serves to adjust the cutting end of the tool relative to the blank A.- When the bolt 25 is adjusted, the tool may be removed, ground on the top face for sharpening, and returned into exact 'osi- 1 tion without changing the setting 0 the bolt 25. e

It will be observed that, with the construction described, the tool is maintaine in parallelism as it moves ,longitudinall for feeding or inward and outward to 0 slide 37 together with the tool includes a rotatable relieving cam 46 which ismounted on the slide 24 so as to be bodily movable therewith. As shown, the cam is mounted -on a. .longitudinal rotatable shaft 47 which is mounted in bearings 48 and 49 on abracket 50 depending fromthe front of the slide 24. A lever 51 is pivoted between its .ends on the slide 24 and at its lower end is provided with a roller engaging the cam 46.

r The upper end of the lever 51 engages an abutment 52 on the slide 37. A coil spring 53 is interposed between the slide 37 and the slide 24, this spring tending to press the slide '37 forward, thus holding the abutment 52 in firm contact with the upper end of the lever 51. It will be seen that, when the cam 46 is rotated, the lever 51 will be oscillated, thus giving a reciprocating movement.

to the slide 37 and'to the tool 25. The shape of the cam 46 is such that the slide 37 is moved forward relatively slowly at a uniform rate so that the tool may effect a re lieving cut, and is then drawn back relative.

ly rapidly so as to Withdraw the tool and position it for another cut.

The cam 46 is driven in timed relation with the blank rotation, as beforestated. For rotating the cam; I make use of the aforesaid transverse shaft 11. A shaft 54,

which is mountedpartly in the main frame" 1 and partly in a bracket 55 secured thereto, is positioned immediatelybelow the shaft 11.v The two shafts 1-1 and 54 are connected by means of a gear wheel 56 on the shaft 11, a gear w'heelj57- on the shaft 54 and an idler gear wheel 58 meshing with the two gear wheels56 and 57. The idler gear wheel is mounted on a bearing stud 59 which is carried by an adjustable slotted arm 60. The arm 60 is carried by a hub 61 which assists in supporting the shaft 11. The speed ratio between the two shafts 11 and 54 can be changed by removing one or both of the gear wheels 56 and 57 and substituting other gear wheels of different diameters, it being clear that the idler gear wheel 58' can be adjusted to mesh with such differently diametered gear wheels. A vertical shaft 62 is mounted in the bracket 55 and is driven from the shaft'54 by means of bevel gearing 63. The shaft 62 serves to drive a.longitudinal splined shaft 65 by means of bevel gearing 64. The shaft is supported-partly" in a bearing 66 secured to the bed and partly in bearings 67 on a depending bracket 68 secured to the carriage 21.

A worm 69, which is mounted onthe shaft 65 between the bearings 67, is splined to the shaft. Theworm 69 meshes witha worm' wheel 70 which is connected with a transverse shaft 71.- The worm wheel 70 and the shaft 71 are rotatably mounted in a bearing 72 formed inthe bracket68, and in a bearing 73 formed-on a supplemental bracket 74 secured to the bracket 68. A bevel gear wheel 75 is slidably mounted on the shaft 71 and is engaged by a bearing 76 on the afore-.

said bracket. 50 depending from the front end of the slide 24. The bevel gear wheel 75 meshes with a bevel gear wheel 77 on the shaft/l7. The bevel gear wheel 75 and the shaft 71 are splined or otherwise'suitably constructed so that the bevel gear wheel is rotated, but is at the same time free to move transversely of the machine when the slide 24 is moved. Inasmuch as the bevel'gear wheels 75 and 77 are both supported by the bracket 50, they are at all tlmes held in mesh. It'willbe seen that with this construction power .is transmitted from the shaft 11, through the several parts thathave been described, to the shaft 65, and is trans- -mitt ed from the shaft 65 to the shaft 47 and the cam member 46, the connection between the shaft 65 and the shaft 47 being such that free transverse movements of the cam mem- .ber and associated parts is permitted. The

cam member 46 is given one complete rotation for each tooth of the blank. The machine can be adjusted for blanks with different numbers of teeth by changing the gear wheels '56 and 57, as already explained.

As has already been stated, the machine is adapted for cutting blanks -having helical teeth. In order that blanks with such teeth may be properly relieved, it is necessary to effect the relieving movements of the tool in of the blank. For this purposeImakeuse of a mechanism which is in many respects similan'to that set forth in my Patent No. 1,429,611 dated September 19, 1922, 1 The present construction differs, however,'in that I have so arranged the mechanism that the aforesaid relationship is varied by changing the rotative movement of the blank rather than by changing-the relieving movements of the tool.. While I prefer to change the blankrotation, it will be understood that my present invention in itsbroader aspects is not limited in this res ect.

In the construction i ustrated, the driving member or worm-wheel 9 is not connected directly withpthe spindle 5 but isconnected indirectly by means of suitable gearimgv 78 which can be supplementally moved to change the spindle rotatlon. By

preference, this gearing is bodily rotatable and includes .a rack and pinion, the rack being longitudinally slidable in accordance with the longitudinal movements of the carriage 21. A sleeve 79 is coaxially mounted with the spindle and is supported by bearings 80 and 81 in the headstock. The inner end of the sleeve 79 preferablyextends into and has a'bearing in the outer end of the spindle 5. A frame 82 is recessed to receive the outer end of the spindle 5 and to engage the outer surface thereof. The aforesaid worm wheel 9 is rigidly secured to the sleeve 79. A shaft 83 having rack teeth formed thereon at 84 is slidably mounted in the sleeve 79. The shaft 83 is splined-to the sleeve 79 so as to be rotatable therewith. A transverse shaft 85, which is provided with teeth 86 meshing with the rack teeth 84, is rotatably mounted in bearings in the. frame 82. A trans verse shaft 87 is also rotatably mounted in the frame 82. The two shafts and 87 are connected by spur gear wheels 88 and 89. A third rotatable shaft 90 is rotatably mounted in the frame .82. A worm 91, which meshes with worm teeth 92 formed in the periphery of the spindle 5 near the end'thereof, is secured to the shaft 90. A gearing isprovided at the side of the bracket 82 opposite from the gears 88 and 89 for connecting the shafts 87 and 90.- A gear wheel 93 is mounted on the shaft 87, and aigear wheel 94 is mounted on the shaft 90. An adjustable'slotted bracket 95 is mounted on the frame 82 and this carries adjustable bearing studs 96 and 97 on which are mounted, respectively, idler gear wheels 98 and 99.

An annularly grooved collar 100 is carried by the shaft 83 near the outer end thereof. A longitudinal cent the shaft .83. A bracket 102 having a fork 103 entering the groove in the collar 100 is slidably mounted on the stud 101. The bracket 102 is apertured to receive. a longitudinal rod 104, .which is connected at its right-hand end with the-carriage 21'. i

The bracket 102 may be clamped to the rod 104 in any desired relative position and preferably by means of screws 105, 105 provided with handles 106.

It will be seen that, when the carriage 21 is moved longitudinally along the bed, the rod 104, together with the bracket 102. will be moved at t .same time and to the same extent. By reason of the engagement of the fork 103 with the cellar 100 the shaft 83 is similarly moved,=thus moving the rack teeth 84. When the rack slides longitudinally the pinion 86 is turned and this serves, by means of the gearing and the several shafts that have been described,

to turn the worm 91. The retative move ment of the worm 91 serves to turn the I ide stud 101 is. rigidly secured to the main frame 1 adjaspindle 5 relatively to the frame, 82 and the sleeve 79. Itwill be understood, as before stated, that the entire gearing 78 rotates bodily with the spindle 79. Itwill therefore be clear that the relative move ment of the spindle 5 with respect. to the sleeve 79 simply serves to either increase or decrease the spindle rotation to a certain extent. However, the relative move ment of the spindle 5 isdetermined by the longitudinal movement of the rack 84, which in turn is determined by the longitudinal movement. of the carriage 21 and of the cutting tool 25 carried thereby; Inasmuch as the relieving cam 46 reciprocates the tool Wlth a frequency which is normally uniform, and lnasmuch as the spindle 5 and the blank are given a changed rotation which is in exact proportion to the lon itudinal movement. of the carriage and t e tools it is clear that the relieving movements are. effected-in such relation to the'blank as to be in conformity with helical teeth.

In case a very long cutter is being formed in the machine, the rod 83 may be so moved to the left, as shown in Fig. 3 of the draw ings, as to move the rack teeth 84 beyond the gear teeth 86. In order to permit the cutting of extremely long blanks, the gear wheel 88' is detachably connected to the shaft 85 which carries the gear teeth 86. The shaft 85 is preferably provided with a flange 85 to which the gear wheel 88 is connected by means of a removable pin or bolt 88'. J I

If the end of the rod 83 carrying the rack teeth 84 approaches the'shaft 85 carrying the gear teeth 86'during the operation on a cutter blank, it is necessary to discounect the gear wheel 88 from the shaft 85 for resetting the rod 83. The pin 88" is removed for disconnecting the gear wheel 88 from the shaft 85 and. the screws 105 operated by the handles 106 are loosened to release the clamp 102 from the rod 104. The rod 83 carrying the rack teeth 84 is moved forward or to" the right as shown in Fig. 3 of the drawings until the, opposite end of the rack teeth approach the shaft 85. The 'pin 88 is inserted in position for con-nectmg thegear wheel 88 to the shaft 85 and the clamp 102 is fastened to the rod 104.. By such means, it is ap arent the machine may be accommodate to operate on blanks of-extremely long lengths.

The amount of variation of the s indle 5 and blank rotation can be change .in accordance with the degree of inclination of the helical teeth by removing one orv the other orboth of the gear wheels 93 and 94 and substituting other, gearwheels of different diameters. The idler gear wheels 98 and 99 can be properly adjusted to mesh with such differently diametered gear wheels, It is also possible to cause the relative movements of the spindle to take place -in either direction in conformity with helical teeth inclined in either direction. As

helical teeth, the gearing is rendered ,inef

fective, as for instance by loosening the clamping. screws 105, thus permitting the rod 104 to slide freelyth'rough the bracket 102. By loosening the clamping screws 105 it is possible to preliminarily adjust the carriage without effecting the position of the spindle 5 and blank. When the cutter and the blank have been properly adjusted relatively, the handles 106 are turned to connect the carriage with the mechanism for controlling the spindle rotation.

From the foregoing description it will be observed that in following helical teeth as described, the blank is rotated in'each instance through a little more or a little less than one revolution, as required for righthand or left-hand helices. It will. further be seen that during each rotative movement of the spindle 5 and blank a whole number of relieving movements areefi'ected.

The blank A, shown in Fig. 7 is pro-- vided with teeth having their front cutting faces arranged exactly-radially. Frequently, however, it is desired to provide a cutter I with undercut or hooked teeth; that is, teeth having their front cutting faces inclined with respect to radial lines. Such a cutter is set-forth in my patent for milling cutters, No. 1,443,641 dated January 30, 1923. For cuttingv a blank with undercut faces, it is necessary to vary the ordinary relation between the relieving movements'of the tool and the rotative movement of the blank as the cutting tool moves inward or outward to conform to different blank diameters.

-When such blanks are to be cut, the mechanism heretofore described may be somewhat modified.

One way of varying the relation will be understood by reference to the diagrammatic Fig. 18. In this view if may be considered to be a-fragmentary sectional view taken at'the maximum radius ref a cutter '0 having undercut faces. Under the control of the former and the former pin, the cut-ting tool 25 is at a distance r from the blank axis and is in position to engage the poilit of the tooth shown and to cut the proper relief line dd thereon. The tooth section at a small radius 1" is shown at t.

i For this radius, without special provisionbeing made, the tool 25 Would be in the position indicated by dotted lines at the distance r from the blank axis. However, by

reason of the inclined cutting face on the blank, the blank tooth would not be in engagement with the tool but; would be separated therefrom by the angle m. The tool,

however, would lmmediately start its inward relieving movement notwithstanding v separated from the tool by a greater angle m", with the result that the incorrect relief line d"d would be further from the correct relief line dd.

In order to avoid the errors which would occur, as shown in Fig. 18, I vary the relationship between the relieving movements of the tool and the rotative movement of the blank in such a way that the tool, as concerns its relieving movements, is always in the same position when engaged by the front edge of the tooth. This will be" clear from an inspection of F igs, 19 and'20. Fig. 19 shows the tool at the same radius?" from the blank axis as was shown in Fig. 18, but the relation of the relieving movement has been so changed that the blank is in position to be engaged by. the point of the tool The when the relieving movement starts. tooth is therefore cut with the correct relief line d-ol. Similarly, in Fig. 20, the tool is shown at the same distance 1" from the blank axis as was shown in F ig. 18 but the relation of the relieving movement has been so'changed that the blank is in position to be engaged by the point of the tool when the effective relieving movement starts. The tooth is therefore cut with the correct relief line 'd-d. .It will be seen that the operation, as illustrated in Figs. 18 to 20, is in no way effected by or dependent on the longitudinal inclination of the cutting faces. In other words, -it is immaterial lUl) whether the cutting faces be helical orstraight.

The required variations in the relationship between the relieving movements of the tool and the rotative movement of the blank radial cutting faces on the blank will bedescribed. The former pin 27 is'preferably I have found it simpler, to-

dove-tailed to a sliding bar 107 and is firmly connected thereto by means of a bolt 108. The bar 107 is slidably mounted in an upstanding portion 109 exten ing from the slide 24 and an arm 110 which is attached to the. portion 109. The arm 110 is shown attached to the extension 109 by means of bolts 111', but if so desired, such arm may be made an integral part of the slide 24. The bar 107, which slides in a slot formed in the extension 109 and the arm 110, is provided with shoulder portions 112 which are engaged by plates 113. The plates 113 are attached to the arm 110, inany suitable manner, as by means of screws 114 and hold the bar 107 in position. v I

Casings 115 each carrying a roller 116 are mounted on the extension 109 adjacent to the bar 107; The rollers 116 engage guideways on projecting portions 117 from thecarri-age 21. A detaildescription of the casings 115 will be given when. reference is made to Figs. 21 and 23. I

A bracket 118 is mounted on one of the projecting portions 117 of the carriage 21 and is connected thereto by bolts 119. .The bracket 118 carries a supporting arm 120 which in turn pivotally supports an L- shaped guide lever or member 121. The supporting arm 120 is provided with a block portion 122 which slides in a'suitable guideway formed in the bracket 118. A screw 123, which is attached to the blockportion .122, is provided for adjusting the position of the bar 107 and the former pin '27 in accordance with the maximum diameter of the blank for .a purpose to be hereinafter set forth. A gib member 124, which is held in position by set screws 125, is provided for holding thearm 120 in any set position. The screw 123 is rotatablymounted in a plate 126 which is attached to the bracket 118 nected to the connecting lever 131, serves to eliect relative movement between the guide member 121 and the arm 120 which supports the guide member. The screw 138 is rotatably mounted in a lug 139 projecting from the lever 121. A fixed collar on the screw is disposed on one side of the lug] and a removable collar is mounted on the screw on the opposite side thereof in order to 'pre-' vent longitudinal movement of the screw. 'A set screw 140 is provided for holding the screw 138 in any adjusted position. A pin 141, having acenter point marked therein, is mounted in the lug 139 and together with the portion 137 of the lever 131 serve as reference points for adjusting thelever 121.

.A second slot 142, which is preferably disposed perpendicularly to the slot 133, is formed in the lever 121. Av correcting lever 143 is provided with an elongated portion 144 which is fitted to the slot 142. A pin 145, which is attached to the bar 107. ex-

. tends through the portion 144 of the-lever 143 and is provided with a center point marked therein to serve as a reference point when adjusting the screw 123. The lever 143 is connected by a pin 146 to a block 147 which slides in a slot formed in the arm 110.

In the-mechanism disclosed in! Figs. 24, 25, 26, 29, 30,- 31 and 32, the center marks on the pin 145 and the connecting lever 131 are adjusted. by the screw 123. a distance apart which is equal to the maximum radius of the blank. The pin 145 and the correction lever 143, which are mounted upon the slide 24, efiect no translatory movement during such operation. The connecting lelow ver 131, which carries theguide lever 121,

is moved relatively to the slide 24. The

center marks on the pin 141 and on the? connecting lever 131 are moved a distance apart by the screw 138 in accordance with by means of screws 127. A collar 128, which the undercut on the teeth of the blank and is an integral part of the screw 123,;is disposed on one sideof the plate 126 and a removable collar 129 is attached to the screw 123 by a pin 130 on the opposite side of the plate 126. i

The arm 120 is attached to the guide member 121 by means of a connecting lever 131. The lever 131 is provided with an elongated portion, 132 which fits within a slot 133 for-med in the guide member 121. Shoulder portions 134 are provided which fit within grooves formed in the sides of the slot 133. A cylindrical portion 135 of the lever 131 is fitted to an opening in the arm 120 and a nut 136 is provided forholding the arm 120 and the lever 121 together. A portion 137, having a center point marked thereon, ex-

tends through the nut 136 to serve as a reference point when settingrthe former pin 27 for different blanks provided with difierent undercut.

5 A screw 138, which: threadedly conthe angle of relief for the teerth.- When adjusting the relative position of the pin 141 and the connecting lever 131, it should be noted that the lever 131 is held against transverse movement by the arm 120 which is supported on the carriage 21. Consequently, the guide lever .121 is given a movement of rotation. Thus, the slot 142 is placed at an angle to the center line of the bar 107 and such angle is varied in accordance withjthe undercut and the angle of relief. Preferably the screw member 138 reference to the center line of the bar 107,

Consequently,

the correction lever 143 effects an angular movement, and, in so doing not only moves the block 147 in the slot formed in the 121 is given a movement of rotation, the only point on the center line ofv theslot. 142, which coincides with the center line of the bar 107, is the center of the pin 145. Con: sequently, when the slide 24 is moved forward to cut smaller'diameters on the blank, the correction lever 143 is moved forward to increase the angular position of the slot 142 relative to the center line of the bar 107. The Mm 120, which supports the guide lever 121, is, as before stated, mounted on the carriage 21 and consequently prevents the guide lever 121 from efi'ecting any movement of translation during the forward movement of the slide 24. Thus, the forward -movement of the correction lever 143 in the slide 142 compels the-guide lever 121 to effect a movement of rotation about the part 135 of the connecting lever 131. The correction. lever 143 is compelled to effect an angular movement in accordance with the angular movement of the guide lever.

Such angular movement of the correction lever 143 effects a small translatory movement of the bar 107 and the former pin 27 relative to the slide 24.

In the above manner, the distance between the tool andthe former pin is varied to compensate at different blank diameters for the non-radial cutting faces on the teeth.

. The means for determining the distance apart to set the center marks on the pin 141 and the connecting lever 131 will be disclosed more fully when reference is made to Figs. 27 and'28 of the drawings.

The adjusting mechanism disclosed in Figs; 24, 25, 26, 27, 2s, 29, 30, 31 and 32 for" varying the relation between the cutting tool and the former pin is set in accordance with the maximum diameter of the cutter blank, the amount of relief and the amount of undercut on r the teeth of the blank. The screw'123 is adjusted to make the distance between thecenter marks on the pin 145 and the, connecting lever 131 equal to the maximum radius of the cutter blank. The distance between the center marks on the pins 145 and 146 is made equal to on'eumt of length, preferably one inoh. The distance between the center marks on the pin 141 and connecting lever 131 is obtained mathematically by aformula to be explained in dg'esc'ribin -Figs; 27 and 28. The distance between she center marks on the pin- 141 and the connecting lever131, when the slot 142 is parallel to the bar 107, is varied a. distanceto compensate the relieving operation at different blank diameters in accordance with the undercut or the-non-radial cutting faces on the teeth of. the blank.

Referring to Figs. 27 and 28, it is assumed: w:The change indistance between the former pin and the cutting tool.

ezLength of the correction lever 143 (one unit of length)..

F"=The correction factor for setting the compensating mechanism (Fig. 27).

yiRequired change in position of relieving movement. a

rzRwd'ius of the cutter blank at any int.

F=Total relief including all teeth.

- F'=The total undercut.

r=The maximum radius of cutter blank. Referring to Fig. 28, the distance y that it is necessary to change the position of the relieving movement for non-radially ar-- ranged cutting faces is mathematically de termined as follows: In 28 it is assumed 7c is the center of the cutter blank,

the line 2k is the cutting face of a tooth if the cutting faces were radially arranged, and the line 2k is the cutting face of a tooth if the cutting faces were non-radially arranged. The undercut is assumed to'equal F and accordingly the line 2h is drawn tangent to the circle having a radius equal to F. The line gk is drawn parallel to, and at a distance F, from the line 2k.

At any point on the cutter having a radius r which is less than the maximum radius r, the angles pic and gkl are constructed with the lines 72 and qlc equal to the radius 1'. Comparing a cutter blank having radially arranged cutting faces with a cutter blank' having undercut cutting faces, it is apparent that in thecase of undercut teeth, the cuttin tool would approach too near the centera of the cutter blank before the cutting faces werereached by reason of the relieving movement. Thus, for a radius r, the cutting tool would approach the center is of the cutter by a distance equal to relief eflected through the angle Zkq. Inasmuch as the total relief is F, the relieving distance for which compensating must be effected is aequal to (angle qkl') 360 F In other words, the position of the relieving movement must be changed or retarded a (angle qlce)v 360 4 on the cutter-blank having a radius '1'.

Referring to Fig-'28. The angle gkl=angle pkZ-angle pkg.

The angle pkq==angle gkz.

distance F when cutting a point It is apparen that the angle pkg equals about the center k. U on being turned through. such anangle t e line cg takes a Angle-Y pkl=arcsin position coinciding with the line gp. In ike manner the line zl assumes a position coinciding with the line 9]? when rotated through an angle glaz about the center. 7c.

Therefore angle gklzangle plot-angle gkz and y (angle pkl angle pkg) F (angle pklangle gkq) F Inasmuch as the value of y, the relieving distance for which compensation must be efi'ected, is given in terms of the' angle, vilues must be obtained for angles pkl and g z.

The angle pkl is equal'to the are which COIIQSPOIldS-tflthfi known sine of such angle.

The angle gkz is equal to the are which corresponds to the- F a sine Angle g7cz= arcsm Therefore (angle plcl-angle gkz) F i F i1 (arcsm 7 arcs1n The above value of yis the amount the tool mustbe retarded at any radius r of the cutter blank, when compared with the The position beyond r is larger, and the re tardingamount is largest when the position compared with is-considered to extend to infinity. If we consider r to equal infinity,

, then arcsin c swimw- Therefore, ifwe consider r to equal infinity the retarding amount e uals E (arcsin 3/ q 2H 1 .In the case of very small angles, such as are being considered, the arcsin may' be taken equal to sine.

arcsin does not produce an exact mathematical result but an approximation is obtained which is very much closer to thecorrect result than can be worked to by The solving-of the above equation by substituting the sine for the modern tools. Accordingly we may use an approximation formula cutter blank. In other words the relieving movement must be retarded an amount -which"varies inversely with the radius of the cutter blank. Referring to Fig. 27, itis shown that the compensating mechanism disclosed in Figs. 24 to 32, inclusive, satisfies the above requirement and changes the position of the relieving movement. inversely in accordance with the radius of the cutter blank.

The levers, which are shown in Figs-24 to 32, inclusive, are diagrammatically 1llus trated in Fig. 27 in order to more clearly set forth their 0 erative relation to each other.

The line af' in Fig. 27 is equal to the radius 7" of the cutter blank at any point and is the distance between the center markson th e'fpin 145 and connecting lever 131. The line a is equal in length to e and is'placed in the position assumed by thecorrection lever 143 for any desired compensation of the relieving operation. The lines ab and fb are respectively drawn perpendicularly and parallelly' to the line af'. The line fb equals the distance m, whlch represents the variation in distance between the cutting tool and the former pin that must be made for certain values of the relief, the undercut. and the diameter of the cutter blank. The line b';' isdrawn perpendicularly to the line ab and has a length F which is to be determined. The line ab is drawn in the angular position necessary to place the slot 142 when a a correctionmis made in the distance between the cutting tool and the former pin. Inasmuch triangles, it is apparent obtained for setting the compensating mech- 1 '.The above formula although not absolute I 1y mathematically correct will determine the 130 correction factor F" much closer than can be worked to .on modern machines.

By means of the equation II a F 0211 the correction factor F' may be determined I center-punch marks on the pin 145 andon' ual to the maxiinasmuch as e is a constant andthe relief F and the undercut Ff are known. lJpon determination-the value of F" for a given cutter blank, the screw 138 is operated to adjust the distance between the center-punch marks on the pin 144 and the connecting lever 131 in accordance therewith. The normal distance between the two center-punch marks is diminished in'- accordance with the value of F". After setting the screw 138, the screw 123 is adjusted in accordance with the maximum radius of the cutter. The screw 123 is 'so adjusted that the distance between the the connection lever 131 is mum radius of the cutter blank. The cutting tool is finally set to cut the maximum radius on the cutter blank. Upon movement of the tool to cut a different radius, the position of the relieving movement is varied inversely with the value of r.

When the compensating mechanism is set for the maximum radius of the cutter a value of a: is indicated on the compensating mechanism inasmuch as the correction is referred to an infinite radius as above set forth. The value of w thus indicated is v i The difference in the correction between points at radius r and radius r or the cor; rection at r when compared with the radius r is v 2H 1 7 i It will be seen that two independent variations are effected in the relation between the scribed, the first said variation is effected by:

changing the rotativemovement of theblank and the second variation is effected' by changing the relieving movements of the tool. It will be understood, however, that the invention isnot limited to this exact construction, as any mechanism for effecting the re uired variations in the relationship i would within the scope of the invention. A screw 150, which engages a nut 151 carried by a bracket 152 depending from the carriage, is provided for moving the carriage 21 longitudinally along the bed 1. The screw 150 is supported at itsleft-hand. end in a bearing .153 formed in a bracket 154 secured to the bed. 155, which is connected with the screw 150 by means of bevel gearing 156, is mounted in the bracket 154. At the front end of the shaft 155 is a hand wheel 157. by means of A transverse shaft which the screw may be turned manually to move the carriage 21. In order thatthe carriage may be moved automatically to feed the tool from onecu tting position to another, a suitable mechanism is provided. This mechanism is preferably adapted to feed the carriage intermittently, but it will be understood that as concerns certain phases of the invention I do not so limit myself inasmuch as the carriage may be moved continuously if desired. Mounted inthe bracket 154 is a transverse bearing pin 158 upon which is rotatably mounted a sleeve 159. A gear wheel 160,- which meshes with a'gear 161 on the shaft 155, is loosely nected to the gear wheel 160. --Gear teeth 3163, which mesh with a gear. wheel 164 secured to the shaft 150, are formed on the sleeve 159 near the'outer end thereof. A

ratchet wheel 165, which is similar to the- I ratchet wheel 162, is keyed to the sleeve 159.

A swinging arm 166 is loosely mounted on the hubof the ratchet wheel 165. A link 167, which is adjustably connected at its deft-hand end with an oscillating crank arm 168,- is pivotally connected with the arm 166 near'the lower end thereof.

The crank arm 168 is secured to a transverse rock shaft 169 which is mounted in a bearing 170 and which carries at its rear end a lever 171. A roller 172, which is positioned tobe engaged by a cam member 173 on a longitudinalrotatable shaft 174, is carried by the lever 171 near the upper end thereof. -A transver se pin 175, which carries two similar pawls 176 and 177 adapted respectively to engage theratchet wheels 162 and 165, is mounted on the swinging arm 166. Either pawl can be thrown into or-out of engagement with the correspondingwheel. The 'shaft 174 is rotated, in the manner to be presently described, and it will be seen that at'. each rotation thereof the arm171 and the crank arm 168 are oscillated. Theoscillation of the crank arm 168 A A is by means of the link 167 to the plate 166, the extent of oscillation of

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