US1627090A - Metal-working machine - Google Patents

Description

May 3 1927? B. M. w. HANsoN METAL WORKING MACHINE Filed Oct. l0. 1922 11 Sheets-Sheet l gnvenfoz z3 Mayv 3 y 1,627,090 B. M. w. HANsoN v METAL WORKING MACHINE Filed Oct. 10, 1922 11 sheets-sheet 2 1,627,090 May 3 1927' B, M. w. HANsoN METAL WORKING MACHI NE Filed Oct. lO. 1922 11 Sheets-Sheet 3 ay 7 B. M, w. HANsoN METAL WORKING MACHINE l1 Sheets-Shet 4 1,627,090 B. M. w. HANsoN METAL WORKING MACHINE Filed Oct. 1o, 1922 11 Sheets-Sheet 5 Mammm 61H01' ula-14 3 1 2 1,627,090 May 9 7 B. M. w. HANsoN l METAL WORKING .MACHINE Filed oct. 1o. 1922 11 sheets-sheet 6 May 3 B. M. w. HANsoN METAL WORKING MACHINE ,1

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. 1,627,090 May 3 1927 B. M. w. HANsoN ETAL WOR ING MAC Fil-ed 00%. 0. 19 h S-She Ufff/'2M 31 Patented May 3, 19127.

UNirEo srArEs PATENT OFFICE.

IBENGT M. W. HANSGN, F HARTFORD, CONNECTICUT; EINAR A. HANSON AND CLAB- ENCE E. WHITNEY EXECUTORS 0F SAID BENGT M. W. HANSON, DECEASED.

IETALWORKING MACHINE.

Application led October 10, v1922. Serial No. 593,487.

This invention relates to metalworking machines of the type set forth in my copendin application Serial No. 334,952 filed Novem er 1st, `1919. In that application, I

have described the machine `forming the subject matter of the invention in connection with its use for shaping, contouring, or otherwise machining or linishing curved members, and more particularly with reference l0 to the final inishing or grinding operation on a thread for the purpose of giving to that thread extreme accuracyl in its shape, size and finish. a

The aim of the present invention is to le provide certain features of novelty and advantage in machines of this type wherebytheir range of usefulness and effectiveness is increased; and more particularly to provide a machine of such construction and ar- !0 rangement that it may operate upon members having spiral flutes, such as spirally flutedv taps, and upon members varying 1n diameter, such as tapered taps. These and other objects of the invention will be pointed 35 out more in detail in the following specification.l In the accompanying drawings, wherein I have shown for illustrative purposes one embodiment which the present invention may :0 take, l

Fig. 1 is a front view of the entire machine with the grinding wheel in section;

Fig. 2 is a top plan view thereof;

Fig. 3 is the right hand end view;

15 Fig. 4 is a vieT looking at the left hand -end of the upper portionof the machine with certa-in parts in section or broken away;

Fig. 5 is a sectional view taken vertically on substantially line 5-5 of Fig. 2 and lool;-

.0 ing in the direction of the arrows;

Fig. 6 is a detail view, showing the' truing 'device in section;

Fig. 7 is a top View of the lefthand end of the machine, the lcover of the gear box L5 being removed and certain parts being in section for the purpose of clearness;

Fig. 8 is the rear view of one end of the rocking bed, the-'variable connection constituting a portion of the feed mechanism forI i0 rocking the bed being shown in longitudinal vertical section;

Fig. 9 is a vertical sectional view taken substantially. on line 9'9 of Fig. 7;

F-ig. 10 is a diagrammatic layout showing the driving connections for the lead screw, the head stock spindle, and the several instrumentalities for rocking the rocking bed on its fulcrums;

Fig. 11 is a view in side elevation of a ratchet mechanism through which feeding of the work relative to the tool is effected;

Fig. 12 is a detailed view of an escapement ratchet clutch mechanism;

Fig. 13 is a View taken through the truing device-on substantially line 13-13 of Fig. 6;

Fig. 14 is a view of a special thread;

Fig. 15 is an elevational view of one form of tap-which may be finished by the use of the present machine; A Fig. 16 is an enlarged partial view thereof 1n section,

Fig. 17 is a cam which may be employed to obtain the desired longitudinal contour on the tap shown in Figs. 15 and 16;

Fig. 18 is a developed view of the cam shown in Fig. 17; y

Fig. 19 is a View showing the manner in which ythe teeth on the tap cut a groove on thlwork. y

The general larrangement and organization of the principal parts of the machine are as follows: a 1s a pedestal or fixed bed of convenient size and shape upon which is mounted a movable bed b carrying the Work holder c.' In the present illustrative disclosure of the invention the movable bed b is supported for rocking movement on fulcrums d, 'which are in the formof knife edges as most clearly shown in Fi .1, 3, 5 and 9. The rocking bed isprefera ly in the form of an L, it having a longitudinally extending portion on which the work holder c is mounted for sliding movement and a rearwardly extending arm e, which carries the various instrumentalities through which therocking bed is rocked soas to move the Work relative to the tool, the latter being here shown in the form of a grinding wheel f. The work holder comprises a main slide or carriage g adapted to be moved longitudinally by a lead screw h, a supplemental slide z' mounted thereon and adapted to be adjusted by turning the screw c, and head and tail stocks Z and m res ectively supported on the sup lemental sli e. The tail stock m is adjusta le to accommodate pieces of to the. tool when a new cut or chip is to be taken; second, means, includin an intermittent] rotated eccentric g, or moving the wor from the tool durin the reverse stroke of the work because bac lash or lost motion in the driving connections will not permit accurate cutting of the work on its reverse stroke; third, means, including a pattern cam r, for rocking the bed c in accordance with the circumferential contour of the Work operated upon, as in the case of a tap which is to be relieved back of its cut"- ting edges; and' fourth, means (which, in

:the present instance, includes, in part, a cam s resting on the to of the variable connection p) for swinglng the work toward the tool during the cutting operation, in accordance with the longitudinal contour of the work, as in case where the piece of work varies in diameter, for instance, in the case a tapered tap is to be ground. These various instrumentalities, together with the lead screw and work spindle, are driven and controlled by theV mechanism within the gear box e' mounted on the arm e of the rocking bed.

Mounted on the ixed pedestal a rearwardly of the longitudinally extending portionof the rocking bed b is a slide t which is adjustable transversely of the axis of the head and tail stock spindles and this slide carries a bearing box u in which is rotatably mounted a spindle driven by the belt and carrying the grinding wheel f.l The bearing u, together with the grinding wheel shaft carried thereby, is angularly adjustable, as hereinafter described more in detail, to permit the inding wheel to be brought into incline position corresponding to the lead of the thread to be ground. The letter e designates generally a truing device so arranged and constructed as to give to the grinding wheel an edge correspondin exactly in size to the groove of the threa to be operated upon.

From the foregoing brief description, it will be understood that the rocking bed b has no movement relative to the xed bed a except a rocking movement on its fulcrums comprisin the knife edges d, and that the work hol er, with the work rotatably supported between the head and tail stocks, is moved longitudinally bn the rocking bedfby the lead screw It and on aline parallel to the axis on whichthe rocking bed swings. The grinding wheel, during the grinding operation, is solidly xed on the rigid pedestal a. and, the various instrumentalities above recited are on the rocking bed so as to move the work up to and away from the grinding wheel at the proper times to effect the desired shape on the work. When it is desired to true or resurface the grinding edge of the wheel, this may be done by moving the wheel into proper relation to the truing device without alecting the set or adjusted relation between the grinding wheel and the work, thus assuring, that after the grinding wheel has been trued, it may be brought again up to the work and the cutting operation proceeded with without introduction of any inaccuracies or errors.

It will be noted that the grinding wheel is solidly and rigidly supported on a fixed bed, while the work is carried by a rocking bed mounted on knife edges. This arrangement is of the utmost importance in that it assures the greatest nicety in adjustment and maximum smoothness in operation, which means that very delicate rinding operations may be carried out with accuracy and precision; vibrations, friction, and other disturbing influences being reduced to a minimum or entirely eliminated. More particularly, the grinding wheel being mounted on a relatively heavy wheel slide, and the latter being securely clamped to and rigidly held at rest on the solid bed or pedestal a, vibration of the wheel is practically eliminated. The grinding wheel is rotated at relatively high speeds which necessitates the use of a belt.y Owing to unevenness and irregularities in the belt, it has a tendency to set up vibrations in the grinding wheel shaft, but with the resent arrangement these vibrations are a sorbed by the solid slide t and bed a and thus the grinding wheel is held steady7 and will rotate smoothly" and evenly; which would not bethe case were the grinding wheel mounted for movement (other than rotary) during the rinding operation. The work s indle n is driven at a relatively slow speed t rough a mechanical train of gears and therefore is not subjected to any excessive strains or stresses such as are exerted by a belt passing about a pulley. This means that the work holder maybe mounted for movement on the rocking bed and the latter fulcrumed on knife edges with the result that there is little or no friction at the fulcrumed point of the rocking bed, this bed may be rmoved with great nicety permitting very delicate grinding operations as where a fine relief is to bg had on a threaded member, and smoothness in operation and accuracy in the finished product are obtained.

Reference will now be had to the detail construction -o the machine and, more particularly, to the various instrumentalitiesis so connected u or associated with the for rocking the bed on its fulcrums. The variable connection for feedin thework to the tool when a new cut is toe taken will irst be described.

Referring particularly to Figs. 5 and 8,

on the rear end ofthe arm e of the rocking bed is a housing 25 within which is mounted for sliding movement a nut 26 to the lower Aend of which is keyed a worm wheel 27 in mesh with a worm 28. In threaded engagement with the nut 26 and keyed against rotation to the housing, as at 29,1is a screw 31 having a bearing at its lower end on a block carried b the short end of the rocking beamA moving the rocking bed a Slig t 30 arising from the base a'. Supported in the upper end of the nut 26 is a pin 33 which is preferably non-rotatable and on which theshort end of the rocking lever o rests. The pin -33 carries, at its upper end, an anti-friction roller 34 on which the cam s o rests. he worm 28 is carried by the shaft 35 which may be manually rotated by turning the hand wheel 36 to reliminarily adjust the work, radially otP the tool. This shaft is intermittently rotated (through suitable automatically o rated mechanism hereinafter described) or the ur ose of istance toward the tool each time a new cut or chip is to be taken. It is to be understood that when the shaft 35 is rotated', the nut 26 is also rotated so that it will move up or down, as the case may be, on the screw 31` and thereby vary the distance between the anti-friction roller 34 and the block 30,

In order that the tool shall be free of the work during the reverse stroke of the latter, means which in the present instance includes the eccentric g is provided for raising the rocking bed away from the work on the completion of the operative stroke of the latter and moving it again toward the work when the new out is to be taken. In the present instance, as lshown most clearly in Fig. 5, the eccentric g is connected to the long end of the rocking beam o by a link 40 and an adjustable screw 41, there being a loose connection between these parts to permit of proper operation. This eccentric q is intermittently rotated 180 through' instance where the thread of' m tap is to beA relieved, the cam 1- is provided. This pattern or shaping cam acts upon (through suitable adjustable means) the long end of the rocking beam o (see Fig. 5). "In the present instance, t-his cam has a single rise or lobe' and beam which means', of course, that the extent to which the rocking bed and the work carried thereby are rocked will be varied. vAs shown in Fig. 5, there is carried by and pivoted to the rocking bed, as at 43, a piece 44 carrying a roller 45 resting on the cam 11. Journa'lled in the long end of the rocking beam o is a. screw 45 on which works a nut 46. provided with a finger 47 the lower end of which rests on the upper edge of the piece 44. The screw 45 may be rotated in any suitable manner as by turning the hand wheel 48 which acts through the bevel gears 49. It will be. understood that when the finger 47 rests on the forward end of the piece 44, as shown in Fig. 5, the rocking beam and bed b will be rocked by the cam 1' a minimum distance. To increase the extent to which the rocking beam is rocked, as when a greater relief is desired, the nut 46 is run back on the screw'45 so as to move the finger 47 toward the free or rear end of the piece 44. The piece 44 is normally urged by a spring 50 in a direction to maintain the anti-friction roller 45 in engagement with the cam 1". In order to raise the piece 44 out of engagement with the cam fr, and thus eliminate the annoyance and jars resulting from the anti-friction roller 45 riding on this cam during the reverse stroke of the work (and during which time the finger 47 is raised out ofl engagement with the piece 44 by the eccentric g) I provide on the link 40 a projection 52 which is adapted to engage and lift an extension 53 on the piece producing the desired relief on the work.

The rocking beam' o may be disassociated from the pattern cam 1l by turning down the screw 55 carried b the rocking beam, onto a stop 56 on the roc ing bed to such an extent that the finger 47 is raised out of engagement with the piece 44. This is done where the piece of work is concentric and relief is not desired. As hereinafter described more, in' detail, the pattern cam 1' mary be automatically controlled and driven in such shown most clearly-in Figs. 4, 5, and 8, thisv cam rests upon the anti-friction roller 34 of the variable feed connection. The cam s is ixed to a shaft 60 journalled in the short end of the rockin beam o and driven, as hereinafter described, through suitable change gears at the desired s eed depending upon the extent of longitudinal contour or taper of the work. Wherethe work is cylindrical, as distinguished from tapering, the taper cam s may not be used, and is, therefore, thrown out of operation. To this end I provide, on the shaft' 60, a loose plate 62 having a high point 63 of greater radius than that of the cam s- Connected to this plate, as at 64, is a rod 65 which is moved ongitudinally by turning the screw 66. When it is desired to disengage the cam a from the anti-friction roller 34 the screw 66 is turned by means of a hand wheel to a position where the high point 63 of the plate rests upon the anti-friction roller 34, as shown most clearly in' Figs. 4 and 5. The manner in which the variable feed connection p, the reversing eccentric lq, the lead screw h, and the work s ind e are driven and controlled is quite simi ar to that shown in my said co-pending application and will now be briefiy described. As hereinafter pointed out in detail, the drive for the taper cam is connected up to the drive for the lead screw, and the attern or relief cam r is driven throu h di erential arin associated with the ead screw ande wor spindle. Thisdrivin and contrfilling mechanism is mounte for the most part within the gear box z and in turn is,controlled b the reciproating movement of the work ho der c. Y

The arran ement of the various shafts and-gears wil be readil understood upon reference to Fig. 10. ounted within the gear box z is a main sha-ft (so termed for convenience) driven by a belt 71 passing about a drive ulley 72 carried by a. shaft ,journaled in t e base a and also about a driven pulley 73 fixed to the main shaft.

The shaft 70 drives an intermediate shaft,

75 through suitable gears 74. Fixed on thel shaft 75 is a pair of ears 76 and 77, which respectively mesh wit gears 78 and 79 norma 1y loose on a shaft 80. Keyed for sliding movement on this shaft 80 is a clutch sleeve 81 which is adapted to be moved, as by means of la. handle 83, into clutching engagement with the gears 78 and 79 for respectively fixing the same to the shaft 80. The drive for the Work spindle may be either through the gears 76, 78, or the gears 77, 79. Adjacent the shaft 80 is a. clutch shaft 85 on which is a pair of normally loose gears 86, 87, which are adapted to be fixed to, so as to rotate with, the shaft 85 by means of a clutch mechanism including the slidable sleeve 88. This clutch mechanism is not shown in detail as the specific construction thereof forms no art o f the present invention, it being su cient to say that when the sleeve is moved into engagement with the clutch teeth on gear 86,'this gear will be fixed to the shaft 85 and the other gear 87 will run loose, and when the sleeve is mo'ved in the other direction the is fixed and the gear 86 is loose. ear 86 is continuously driven in one direction from shaft 80 through change gears 89, stub shaft 90, and gear 91. The gear 87 is .continuously driven in the opposite direction gear 92 fixed on the main shaft 70. work spindle n is driven from the shaft 85 through change gears 96,8. gear 98 fixed on shaft 97, and a gear 99 meshing with the ear 98 and keyed to the work spindle n.

he lead screw` h is driven from the shaft 85 through the gears 105, shaft 106, Achange gears 107, shaft 108, and intermeshin gears 109, 110, when a right hand threade member is to be ground. When a left hand threaded member is to ound, the drive from the shaft 108 to t e. lead screw is through the ear 109, gear 111 meshing therewith, an gears 112, 110. It may be here stated that the gears 76, 78; the change gears 77, 79; and change gears 88, have been added in the present machine so as to permit the work spindle 'to be driven at any desired speed and to attain the selected speed in a very ready and economical man-4 ner.

The control of the driving mechanism just described is, as stated, very similar to that illustrated in my said co-pending application and operates briefly, as follows; when the work holder c has reached the end of its operative stroke, a dog 115 carried by ear 87 bih i this holder (see Fig. 1) engages a dog 116 on a rod 117 whereupon this rod is moved to the left and a shaft 118 is rocked through the link and lever arran ement 119 in a direction ,to raise a vertica rod 120 (see 8 and- 9) which causes a bell crank 121 connected to the rod 120 to swin counter-clockwise, referring to Fig. 9. ne arm of the crank lever is provided with a slot 122. in which engages a pin 123 carried by'a rod 124 on which is mounted an esca ement yoke v 125. 4 When the bell crank 121 is swung, as stated, the yoke 125, through the pin and slot connection 122, 123, is raised so that the upper stop 126 thereon is disengaged from a paw1 127 (see Figs. 7, 9 and 12) which is stroke.

plvoted to a cam sleeve 128 fast on a'shaft 129 carrying the eccentric g. The pawl 127 thereupon engages the ratchet wheel 132 which is fixed to a gear 133 normally loose on the shaft 129 and in mesh with a constantly driven gear 134 fast on the shaft 75. The pawl 127 now being in engagement with the constantly driven ratchet wheel 132, cam sleeve 128 and shaft 129 will be rotated 180o and then the lower stop 126 on the .escapement yoke 125 will disengage the pawl from the ratchet wheel 132. When the cam sleeve and shaft are thus rotated 1800, the eccentric g will be brought into a position where the long end of the rocking beam o is raised, and this rocking beam now being fulcrumed on the variable feed con` nection p the work bed will be moved in a direction to carry the work out of engagement with the grinding wheel; and the cam sleeve 128 will throw a shipper lever 135 connected to clutch sleeve 88 in a direction .a to disengage the gear 86 and iix the reverse gear 87 to .the shaft 85 whereupon the lead screw is driven in a direction to quickly move the workv holder on its inoperative When the work holder has reached the end of its inoperative stroke, the dog engages a-second dog 136 on the rod 117 (see Fig. 1) whereupon this rod is moved to the right and through the connections described the bell crank 121 is swun in such a direction that the escapement yo e 125 is lowered thus releasing the lower stop 126 ofthe yoke 125 from the pawl 127 whereupon this pawl will engage the constantly driven ratchet wheel 132 and the cam sleeve 128 and shaft 129 will be rotated another 180O to effect the following: The eccentric g will be brought to a position Where the rocking bed b lis swung downwardly and backwardly thus moving the work towards the tool; the cam sleeve 128 will swing the shipper lever 135 in a direction to ix the clutchigear 86 to the shaft 85 and disengage the clutch gear 87 whereupon the work spindle will be driven at the proper cutting speed and the lead screwh will be rotated in a direction to feed the work on its operative stroke at a speedcorresponding to the lead of the thread being ground. Further, a feed cam 137 fixed to the shaft 129 will rock a lever 138 (see Figs. .7, 8 and 9) which acts through a link 139, an arm 140 fixed on a rock shaft 141, the rock shaft 141, an arm 142 (see Fig. 1) fixed on the forward end of that shaft, and a link 143 to operate the ratchet mechanism shown in Fig. 11 for automatically turning the worm shaft 35 whiclnfas stated, is associated with the variable feed connection p., `The spring 147 (see Fig. 8) resiliently holds the lever 138 in engagement with the feed cam 137. This lratchet mechanism may be of any suitable construction, in the present instance it being conventionally shown as having a ratchet wheel 144 xed to the shaft 35 and a lever 145 pivoted on the shaft and carrying a pivoted pawl 146 cooperating with the 70 teeth of the ratchet wheel. When this ratchet mechanism is thus operated, the shaft 35 is turned causing the worm 28 to` run the nut 26 of the variable connection p down the screw 31, the result being that 75 the work is fed towards the tool to the extent that a new -cut is to be taken.

The work will now be moved on its operative stroke with the grinding wheel in engagement therewith, and the sequence of 80 operations repeated.

The shipper lever 135 is fixed to a vertical shaft 148 on the upper end of which is a handle 149 whereby movement of the' work may be instantly stopped when desired, by 85 throwing the clutch sleeve 88 into neutral position, the cam groove in the cam sleeve 128 being of increased width or offset as at 150 (see Fig. 7) so as to permit of this movement. The operator of the machine 90 may, by merely pushing in on a rod 152 (see Fig.- 9) so set the machine that the work holder will stop when it has reached the end of one of its strokes. When this rod is pushed in,` it moves (through a pivoted 95 l lever 153) a. slide 154 into the path of movement of the pawl 127 of the ratchet clutch mechanism. When this pawl `hits the slide 154, the cam sleeve 128 will be stopped in such position that the shipper will lhave moved the sleeve 88 of the reverse lclutch mechanism into neutral position, that is, where both of the gears n86 -and 87 will, be running loose on the shaft 85.

Reference will now Vbe had to the manner .105 in which the taper cam s is driven. As most clearly shown in the diagrammatic view of' Fig. 10, this cam is connected up to the drive mechanism leading to the lead screw so that the cam and lead screw are driven a't a prelio determined ratio. Extending along the left hand end of the gear box z is a shaft 156 driven by shaft 108 through bevel gears 157. This-shaft 156 drives. through gears 158, a vertical shaft 159 which is connected by bevel gears 160 to a shaft 161 journalled in ,a bearing-located at the pivotal point of the rocking beam o. J ournalled in the short j end of the rocking beam o is a shaft 162'connectedto the shaft 161 by gears 163. Also, 120 journalled in the short end of the rocking beam o is a worm shaft 164 carry/ing a worm in mesh with a worm gear on the shaft 60 on which the taper cam s is fixed. On the rear ends of the shaft 162 and the worm 125 shaft 164 are change gears 166 housed within a removable casing 167. It will be noted that the drive for the taper cam extends throughl the axis or pivot of the rocking beam thus permitting the taper cam to be mounted on this beam and coopt rate withl course, that where the piece of work tapers but slightly the cam s will be driven at such speed that while the lead screw is moving the work the length of the tapered portion of the work, the taper cam 8 will be rotated through a small angle. Where a piece of work having a large taper is to be ground, change gears 166 of such ratio will be selected that thetaper cam s will be driven through a large angle while the lead screw is moving the work the distance of its tapered portion. It will be seen that since the taper cam is connected up with the drive for the leadV screw, it is controlled in its movement in the same manner asis the lead screw through the ratchet clutch mechanism, as above described.

The manner in which the pattern or re. lief cam r is driven will now be described. When a tap is provided with spiral flutes making spirally arranged rows or lands of teeth, the distance between the forward or cutting edges of successive teeth will be different from the distance between the cutting edges of a tap having straight flutes of the same number, that is to say, ina tap having four straight antes there win be four teeth to each convolution of thread, but where the flutes are s iral in a direction opposite to the lead of t read there will be slightly more than four teeth to each convolution. The angular distance between the cutting edges of successive teeth of spirally fluted taps will depend, in part, on the lead of the thread and the lead of the flutes. In each convolution of the thread of a spirall fluted tap, 4there are a given number of teet plus a` fraction of a tooth. When a straight fluted tap, for instance, is to .be ground. the shaping or pattern cam 1- (when provided with but a single rise as shown)` will be driven as many times faster than the work spindles as there are reliefs to be ground, that is to say in a four fluted tap, the ratio of the cam and work spindle will be 4 to 1. In the event that a spirallv lluted tap is to be ground, the drive of the relieving cam from the work spindle is modified, through differential mechanism, by the lead screw change gears 107 and b other suitable change gears which are se ected in accord ance with the lead of spiral flutes, so that the relieving cam is driven at a sli htly greater speed than where a straight uted tap is beingground. A

Referring now to the drawings, it will'be seen that the relieving cam r is lixedto a shaft 170mounted within the gear box z. This shaft 170 is driven (throu h chan e ears 171, stub shaft 172, ears 17 3 and t e ierential mechanism in icated generally by the numeral 174) from the shaft 97, which, as previously stated, is connected up to the work spindle by gears 98, 99. This differential mechanism or speed compensating device comprises` a bevel gear 175 fixed to shaft 97 and meshing with idlers 176 which turn a differential gear 177 meshing with the gear 173. When a straight fiuted tap is to be ground, the shaft 179 (through which the axis of theidlers 176 is rot-ated) is disconnected by removing the change gear 180 on shaft 179 and securing the shaft against rotation by means of the set screw 180 and thus the reversin cam r is driven solely through the mec anism which drives the work spindle n.

When a spirally fluted tap is to be ground, the axis or shaft 178 on which the idlers 176 of the differential mechanism are mounted is driven, as follows, from a point to the driven side of the interchangeable gears 107 'which determine the rate of rotation of the lead screw. As stated, the shaft 156 is driven from a shaft 108 through the gears 157. 179 is a shaft driven from the shaft 156 throu h the change gears 180. On the forward en of the shaft 17 9 is a worm 181 meshing with a worm wheel 182 fixed on a shaft 183 on whichv is fixed at ri ht angles the axis or shaft 178 of the iferential mechanism. When the differential mechanism is thus driven, the rate of rotation of the relieving cam r is slightly` increased so as to bring the speed of rotation of this cam into accordance with. the disposition of the teeth on the piece of work being ground. It will be noted that the axis of the gears 178 isfixed to the inner end of the worm wheelshaft 183 which shaft is slowly rotated. Gear 177 is driven in the same direction as the rotating axis from the work spindle driving mechanism through the gears 17 8 which revolve about their rotating axis. Thus it will be seen that, as said axis is rotated in thesame direction as gear 177, it will increase the speed imparted by the work spindle driving mechanism to said gear 177 and the cam r.

It will be understood that the speed at which the relieving cam is driven in case a spirally iluted ta is to be`ground will 'depend on the fo lowing considerations:

'rst, the speed of the work spindle; second, the lead of the thread; third, the lead of the flutes, and, fourth, the number of flutes on the piece of work. In setting up the machine, theV operator will, of course, (Whether the relieving cam is used or not) select the proper change gears for driving the work spindle and lead screw at the proper ratio of speed. It will be noted that the relieving Vcam is driven through the change gears 96, which determine the speed of rotation of the work spindle, and through the lead screw change gears 107, and thus the operator is relieved from making any calculations, adjustments or change ofl gears to particularly take care of the first two considerations. To take care of the third consideration, namely the lead of the spiral flutes, it is merely necessary for the operator to select the proper change gears 180 for the connection between the shafts 156, 179. The set of gears from which these change gears are selected will bear suitable indicia and may be selected without the necessity of the operator making any calculations, thus eliminating the chance of any errors and Vgreatly facilitating the setting up of the machine. In order to take care of the fourth consideration, namely the number of flutes, the proper change gears 171 will be selected.

It is to be noted that all of the means for moving the work rotatably, longitudinally, and transversely relative to-the tool or grinding wheel are connected up and driven so as to be properly co-ordinated to effect the desired conto-ur on the work. More especially, the various instrumentalities for rocking the rocking bed have such relation one to the other and are so co-related in the purpose of exemplification. More their operation that finished threaded members of variouskinds and shapes may be very accurately and economically produced. By preference, these instrumentalities rock the bed carrying the work through the means of a rocking beam pivoted tothe rocking bed, as by such arrangement these instrumentalities may operate simultaneously or in such sequence that each may properly perform its function without, where required, interfering with the functioning of another instrumentalit or, Where desired, modifying the operatlonof other nstrumentalities in order to effect the desired results. This arrangement, however, is by `way of preference only, it being understood that the `preferred embodiment of the invention is here illustrated only for particularly, it will be noted that the means for effecting a circumferential contour on the Work, in the present instance, the relieving cam 7', and the means for effecting a longitudinal contour on the work, 1n the 'present instance the cam s, may operate simultaneouslyV so that relief, for example,

may be effected on a thread varying in di' ameter, and, further, the means for modifying the rotation of the relieving cam, where the work has a spiral flute, may be employed in conjunction with the cam s so as to accurately and completely lfinish threaded members havin a taper or other longitudinal contour. A so, the means for varying the throw of the relieving cam in order to thereby change the extent or depth of relief on threaded members may be used simultaneously with either or both the cams.

which maybe accurately ground by the use of this machine,.reference may be had to thel tap shown in Figs. 15 and 16. This tap is shown as having a right lia-nd thread interrupted by .left hand spiral flutes, four in number. The thread at the forward section A of the tap is tapered at its top; the thread on the middle section B is tapered at its root but cylindrical at its top; While the thread on the third section C is straight or cylindrical both at its root and top. The teeth of the first section gradually increase in height and decrease in Width at their tops. The teeth of the second or middle section B- gradually increase in width,while those of the third section C are uniform. The first or lowest tooth of section A (as shown in Fig. 19) will make a wide but very shallow cut as it is fed into the work; the second tooth will take a little deeper cut; the third tooth a still deeper one, and so on. Each of the teeth of section A for vthe most part will cut along its -top but little or nothing along its sides, so that they will rough out, so to speak, a thread groove to the proper depth. The teethbf the middle section are for the purpose of cutting the groove to the proper width, each tooth taking out, as it comes into play, line chips (as at 10, 11, etc.) out ofthe sides of the thread. Finally `the teeth 20 of' the third section will take finishedv cuts on the side faces and root of the thread. The extent of relief on the .teeth of the several sections may be, for one reason or another, of different extents; for instance, inthe case of the teeth of the middle section which, -for the most part, cut on their side edges, the best results are obtained ifthese teeth are given a very substantial relief.

To grind, by the use of the present machine, a tap such as just described, a taper cam having a true involute or a taper cam such as shown in Fig. 17, may be employed. In either event, the selected cam is coupled up to the lead screw and thus be driven in snchronism therewith. The speed at which t is ca m is driven relative tothe lead screw will be determined by selecting the proper change gears 1 66. In case-a taper cam having a true'involuteI surface, `-such as shown in Fig. 4, is employed, this cam will be rendred inoperative y the disk62 while the lllll lao ` an involute portion B corresponding to the ing bed b middle section of the tap, and th'en a `con lcenti-ic portion C corresponding to the third section of the tap. In the event that the middle section B is not a straight taper, but is slightl curved longitudinal y (as shown by 'dotted lines in Fig. 16), the portion B of the cam will be curved relative to the axis of the cam corresponding to the curved taper of the work. During operation of the machine on the tap shown in Figs. 15 and 16, the cam, shown in Fig. 17, will be driven in synchronism with the lead screw through the proper change gears, and the relieving cam will be driven at the proper speed in order to take care of the lead of the spiral flute of the tap by its connection with the work spindle and lead screw through the differential mechanism. The means for varying the throw of the relieving cani will be properly adjusted by turning the hand wheel. The machine will then be started and the work will' be moved from end toend while in engagement with the grinding wheel. The work during its operative strokes will be moved transversely relative to `the tool by the relieving and longitudinal contouring cams in such manner that the work is pro rl contoured circumferentiall and longitudinally. The relieving cam, t rough its described drivin connections, will be driven at such speed relative to the lead screw and work spindle that relief is effected along the spiral flutes, that is to say, the relief is spirally distributed both on the straight and tapered portions of the'tap, while at the same time the taper cam is operative to effect the desired longitudinal contour on the work. The means for var ing the throw of the relieving cam may be adjusted so that a greater relief, for instance, may be had on the central portion of the tap than on the end ortions. This adjustment of the throw o the y relieving cam may be effected without adjusting the relieving cam or taper cam or in any way disturbing the relation of these instrumentalities relative to other. operative parts of the machine.

For the urpose of preventing the rockom being swung to such an extenty that Ithe nut 26 of the variable feed connection n jams against either the head of the screw 31 or the collar on'the bottom end thereof, a suitable tell-tale device is provided. This device (see Fig. 8) includes a rod 184 resting on the base a and slidably either of the extreme lines'184, the operator is warned that the nut 26 is in danger of jamming against the screw 31.

The machine is provided with a work gauge by means of which the work can be very quickly adjusted with the greatest accuracy and precision relative to the grinding wheel.' Because of the large size ofthe v rinding wheel, its rough and uneven surace, and the relatively small size of the threads to be ground, it is very difficult, if not practically impossible, to accurately position the tool by merely observing its contact with respect to the .work. This gauge is similar to that illustrated in my co-pending application and includes, briefly, a racket 186 mounted for lon itudinal movement axially of the work spindles in the T-slots 187 on the forward face of the rocking bed. On the upper end of this arm is a slide block 188 adapted to be adjusted longitudinally by the screw 189. Pivoted to this block, as at 190, is a gauge arm 191 .carr ing a pointer 192. TheA forward end oft e pointer is shaped correspondingly to the groove of the thread to be ground. This pginter is carried by a slide 193y adapted to adjusted radially of the work by turning the screw 194. As stated in my co-pending application, in practice to set the gauge relatively to the work, a test piece, preferably unhardened and of any diameter and having the same number of threads to the inch as the parts to be finished, is positioned between the head and tail stocks and the threads thereon are ground. Then the work gauge is thrown Aover into the operative position shown in Fi s. 1l and 2, and the gauge is accurate] adjusted to the test piece until the forwar end of the pointer accurately lits into the thread. After the gaugeA is so adjusted, it is locked into position so that its relation to the grinding wheel will remain fixed, but it may then -be thrown back into the position shown in Fig. 3 when not in use. The test piece is taken out and the piece to be finished is substituted therefor. The gauge is then thrown forward and by adjusting the slide z' of the work holder by means of the screw c, the work is adjusted longitudinally until the pointer accurately fits the thread thereof. As the lll) work is now properly set to the gauge, the operator knows that it is in correct position relative to the grinding wheel, for the gauge has already been set to the wheel by'usin'g the test piece. As the gauge is carried by the rocking bed 7) which has no rectilinear movement on the base a and the tool or grinding wheel is fixed to the base against movement longitudinally of the axis of the work, the relative positions ofthe work and gauge remain fixed. After the work is properly adjusted to the gauge, the gauge is thrown back into inoperative positlon and the grinding operation proceeded with.

AS previously stated the bearing box u in which the grinding wheel spindle 196 is journalled, 1s angularly adjustable on the lslide t topermit the grinding wheel t-o be brought into inclined position corresponding to the lead of the thread to be ground. The slide t (see Figs. 1, 2 and 3) is mounted on suitable ways and may be moved up to and away from the work by rotating the screw 197 havin on its forward end a Wheel 198 with which 1s associated indexing means 199 for indicating the extent of adjustment of the slide. The screw 197 passes through an opening in the rocking bed which is of suiiicient size to avoid interference with the movement of this bed. In the present instance, the bearing box u is mounted in a way 201 (see Fig. 1) the center of curvature of which is in the center of the wheel f by which is meant a point at the axis of the wheel which isincluded in aplane bisecting the cutting edge of the wheel so that thev axis about which the wheel may be angularly adjusted is on a line a-b (see Fig. 6) substantially perpendicular to the axis of rotation ofthe work. The drive belt passes about a. pulley 203 carried by a shaft journalled in the base a and also about a pulley 4204 secured to the grinding wheelspindle 196. This belt also passes about intern'iediate idlers 205, 206 which are vertically and horizontally adjustable so as to permit of extreme inclination of the grinding wheel spindle. In the present lnstance, as shown more clearly in Fig. 3, rising from the slide t is a standard 207 onwhich is vertically adjustable, by means of a screw 208, a slide 209. Horizontally adjustable on suitable ways in this slide 209 is a second slide 210 which carries the idlers 205, 206. This slide 210 may be adjusted by a screw 211. In order to take up the slack in the belt 202, the idler 205 is carried by a bell crank 212 pivoted to the slide 210 as at 2 13, and urged in a direction to normally mamtain the belt 202 taut by a spring 214.

The truing device lu. by means of which the edgek of the grindingjwheel may be shaped in accordance with the cpnfiguration and size of the groove of the thread operated upon, is generally similar in its operation and in its relation to other parts of the machine to the truing device shown in my said co-pending application, but has certain additional features of construction which are novel and advantageous. This truing device is carried by a slide or bearing member 220 adapted to be fixed to the bed a by bolts 221, the heads ofwhich engage in T-slots 222. These T-slots are parallel to the ways on which the slide for the'.

grinding wheel is adjustable. Journalled in the bearing member 220 and adapted to be secured in any angular position of adjustment, as by a clamping bolt 223, is a pin 224 to the forward end of which is fixed a post or support 225 having a vertically disposed bearing 226, the axis of which intersects the axis of the pin 224 at right angles. The axis of the pin 224 is coincident with the line a-J), that is to say, it is in a line passing substantially through the point about which the grinding wheel is angularly adjustable and perpendicular Vto the axis of the work. Mounted in the bearing 226 is a hollow shaft 227 having at its lower end a projection 228 which carries a bolt or bearing member 229, the axis of which is substantially at right angles to the axis of the shaft 227 and parallel to the axis of the pin 224. Journalled on this bearing member 229 is an arm 230 in which is mounted for longitudinal adjustment the sharpening or truing tool 231 here shown as a diamond point. When the shaft 227 and the arm 230 are in themid-position shown in Fig. 6, the diamond point lies substantially in the line a-b. The arm or tool carrying part 230 is provided with a segmental gear 232 with which meshes bevel gear 233 carried by a shaft 234 journalled in. the shaft 227 and carrying an operating handle 235 at its upper end. It will be seen that by swinging the handle 235 in opposite directions the tool carrying part 230 will be oscillated through the gears 232 and 233 so as to move the diamond point or tool 231 across the face or edge of the grinding wheel being resurfaced. The shaft 227 and the parts mounted thereon which as a whole may be considered as the carriage, may be turned in the bearing 226 in order to bring the diamond point -into operative relation with any face of the grinding wheel, and for the purpose of indexing it to the proper position, there is keyed to the upper end of the shaft 227, a plate 236 carrying in a suitable T-slot 236 adjustable dogs 237 adapted to abut against the stop 238 on the post 225 For the purpose of holding the truing device in midposition, the plate is provided with a recess 23.9 in'which a spring pressed plunger 239 is adaptedto engage. The plate carries, on its edge, a scale 240 which cooperates with a zero mark 240 on the stop 238 so that

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