US2067178A - Grinding machine - Google Patents

Description

7 Sheets-Sheet l INVENTOR John Edgar BY' ATTORNEYS Jan. 12, 1937. J EDGAR.

GRINDING MACHINE Filed Oct. 24, 1932 7 Sheets-Sheet .2

ATTO RN EY5 Jan. 12, 1937. J. EDGAR 2,067,178

GRINDING MACHINE Filed Oct. '24, 1932 7 Sheets-Sheet 5 Jan. 12, 1937. J. EDGAR GRINDING MACHJINE Filed Oct. 24, 1932 7 Sheets-Sheet 4 INVENTOR John Edga r BY ATTORNEYS Jan. 12, 1937. J. EDGAR GRINDING MACHINE Fil ed Oct. 24, 1932 '7 Sheets-Sheet 5 1 I I l l I I I l I l HEW INVENTOR' Jo hn E cigar. W 1: MW

ATTORNEYS Us Mm g 8 3 mm a Km vm .M i mm wo in I 4 I w U aw \m vh QM nh v AA/ 7 Jan. '12, 1937. J. EDGAR 2,067,178

GRINDING MACHINE Filed 0ct.,24, 1932 7 Sheets-Sheet 6 I r W .5 a ZY .7 Q U 5 E r I 4 E n w w 6m MM A 6 0 w d 1 AX M M L w w E BY I 63 Jan. 12, 1937. .1. EDGAR GRINDING MACHINE 7 Sheets-Sheet '7 Filed 00L 24, 1932 Ill INVENTOR Job n Edgar BY tfi my! MW ATTORNEYS Patented Jan. 12, 1937 GRINDING MACHNE John Edgar, Rockford, 111., assignor to Barber- Colman (Jompany, Rockford, 111., a corporation of Illinois Application October 24,1932, Serial No. 639,262

it) Claims.

The present invention relates to improvements in grinding machines, and has particular refer ence to a new and improved machine of the type disclosedin my copending application Serial No. 466,764, filed July 9, 1930.

One of the primary objects of the present invention resides in the provision of a novel grinding machine which will correctly grind the teeth of rotary cutters having either straight or in.- clined gashes, and being either cylindrical or tapered axially in form.

Another important object resides in the provision in a machine of the foregoing character of a novel traversing mechanism which is selectively available to provide either a continuous or a stepby-step axial feeding movement of the work blank relative to the grinding wheel, thereby adapting the machine at will for the grinding of rotary cutters having either annular rows of teeth, as in thread mills, or helically arranged teeth, as in hobs.

Further objects and advantages will become apparent as the description proceeds.

In the'accompanying drawings, Figure 1 is a front elevational view, partially broken away, of a grinding machine embodying the features of my invention.

Fig. 2 is a plan view of the machine.

Fig. 3 is a fragmentary left end view.

Fig. 4 is a fragmentary right end view.

Fig. 5 is a fragmentary rear elevational view.

Fig. 6 is a fragmentary vertical transverse sectional view taken along line 5-5 of Fig. 2.

Fig. 7 is a fragmentary detailed sectional view taken along line 7-1 of Fig. 5.

Fig. 8 is a fragmentary vertical longitudinal sectional View taken along line tL-B of Fig. 4.

Fig. 9 is a fragmentary perspective view of the traversing mechanism.

Fig. 10 is a fragmentary sectional view on an enlarged scale of the mechanism shown in Fig. 9. Fig. 11 is a fragmentary perspective view of means for controlling the longitudinal contour of the work blank.

Fig. 11 is a detailed view taken substantially along line li -l l of Fig. 6.

Fig. 12 is a fragmentary vertical sectional view taken along line 52-42 of Fig. 2.

Fig. 13 is a side elevational view of the dressing device for the grinding element.

Fig. 14 is a horizontal sectional view along line l t-4d of Fig. 13.

Fig. 15 is a rear elevational view, partially in section, of the dressing device. I I

Fig. 16 is a fragmentary vertical sectional view taken along line lfi-l8 of Fig. 15.

While the invention is susceptible of various modifications and alternative constructions, I have shown in the drawingsand will herein describe in detail the preferred embodiment, but it is to be understood that I do not thereby intend to limit the invention to the specific form disclosed, but intend to cover all modifications and alternative constructionsfalling within the spirit and scope of the invention as expressed in the appended claims.

Referring more particularly to the drawings,, the machine constituting the exemplary embodiment of the invention although adapted for grinding. various types of cutters, is illustrated in connection with a thread mill cutter A of the ring type. The cutter comprises a plurality of radially relieved, substantially V-shaped teeth which are arranged in parallel peripheral rows alternating with annular grooves, and which are separated by longitudinal flutes or gashes. In the present instance, the cutter A has straight gashes parallel to theaxis of rotation.

The grinding element preferably comprises an abrasive disk wheel B, the periphery of which is adapted to grind the annular cutter grooves and thereby form the cutter teeth, and the cutting contour of which is V-shaped in form when taking the final cut.

Work support and drive The machine comprises a suitable elongated horizontal bed or frame I! formed on the top with longitudinal guides E8 on which a work carriage I9 is mounted for translation. The right end of the carriage I9 is formed on the top with longitudinal guides'2ll on which a suitable tailstock 2! is mounted for adjustment. On the left end of the carriage i9 and preferably integral therewith is a headstock 22 formed with a tubular bearing 23. A cutter spindle 25 is rotatably journaled in the bearing 23 for endwise movement with the carriage E9. The cutter blank A is removably mounted on an arbor 25 held between the tailstcck 2i and headstock 22, and rotatable with the spindle 24. i

The power inlet comprises a cone pulley 26 which is secured to a short drive shaft 27 journaled in the upper left front corner of the frame 97, and which is adapted to be connected by a belt (not shown) to an external countershaft (not shown) adapted to be connected through a reversible clutch (not shown) to a suitable source of power. A drive pinion 28 on the shaft 21 meshes with a large drive gear as connected through a planetary transmission 3G to a shaft 3i into one end of which the spindle 24 is splined for axial movement.

The transmission 38 preferably is like that disclosed in said copending application, and comprises two sets of cluster gears 52 and 33 rotatably mounted at diametrically opposed points on the drive gear 29, and adjustable thereon to permit the proper angular setting of the work blank A relative to the grinding wheel B. The outer gears 32 mesh. with a terminal gear 34 rotatable on the shaft 3i, and normally held in fixed position, and the inner gears 33 mesh with a terminal gear 35 keyed to the shaft 3i.

Traverse mechanism The means for efiecting a relative traverse between the work carriage l9 and the grinding element B, in either a feeding movement in one direction or a rapid free-return movement in the other direction, along the axis of rotation of the work blank,comprises a driving element 36 having an operative connection with the work carciage l9, and adjustable means available at will for automatically modifying the action of said element to obtain the desired resultant movement.

The driving element 36 preferably is in the form of a feed screw (see Fig. 8) which is in threaded engagement with a nut 31 mounted in a depending lug 38 on the underside of the carriage IS. The nut31 is normally fixed against rotation so that the carriage l9 will travel along the screw 36 upon operating the latter. However, provision is made for rotating the nut 31 in' the lug 38 to adjust the phase relation of the carriage l9 to the screw 36 and the work spindle 24. Thus, the nut 31 is rigid with a worm gear 39 meshing into a worm 40 on a vertical shaft 4! journaled in the headstock 22 and adapted for manual actuation at will.

The screw 36 is driven constantly in timed relation to the work spindle 24, and preferably the drive (see Figs. 2, 3 and 8) is taken from the main gear 29. Thus, a gear 42'rigid with the gear 29 meshes with a gear 43 fixed on one end of a stub shaft 44 journaled in the frame H. A pinion 45 on "the other end of the shaft 44 is connected through change- speed gears 46 and 41 to a gear 48 fixed on the outer end of a short shaft 49 journaled in a bearing 50 on the left end wall of the frame IT. The change-speed gears-46 and 41 are removably mounted on an arm 5| mounted for angular adjustment on the'outerend of thebearing 50. The inner end of the shaft 69 is formed with an axial bore 52into which the ad" jaoent end of the screw 35 is splined for a rotative drive and relative axial movement.

} Secured n the opposed end of the screw 36 between a fixed end thrust collar 53 and two lock nuts 54 is a sleeve 55 which is rotatably anchored in a tubular bearing 55 on the right end of the machine frame 57. The sleeve 55 is held in position by means of a peripheral flange 51 on its outer end seating in a groove 58 in the .outer end of the bearing 55, and the collar 53 which engages the inner end of the bearing. Back lash between the feed screw 35 and the nut 3'? is taken up by a weight 59 (see Fig. 1 which is operati'vely connected to the carriage l9 to urge the latter to the right. The weight 59 is connected-to a cable to aces/317s 6% is anchored at one end to the carriage l and at the other end to a sheave 55 fixed on the rear end of the shaft 52 to complete the operative connection from the carriage to the weight 5t. Sincethe screw 35 is free to move axially in the shaft 49, the weight 5% acts to urge the carriage ill and the screw as a unit against the end of the bearing 56. p v

The drive for the feed screw 36 is automatically reversible to. effect reciprocation of the work carriage W. More specifically, the carriage i3 is movable repeatedly first in one direction, for example to the right, ,in a grinding stroke, and then in the reverse direction, for example to the left, in a return stroke in order to traverse the grinding element B recurrently in a series of cuts 1 along the work blank A until the latter is ground the desired depth or form. The

versible in rotation simultaneously with each reversal of the feed screw 36.

In the present instance, the means for reversing the drive for the work spindle 24 and the feed screw 36 comprises apiston and cylinder unit 66 (see Figs. 2, 4, 5 and 11) mounted on the rear of the frame IT. The unit 66 has a projecting piston rod 61 which is formed on its outer end with a yoke 63. A roller 69 mounted on the free end of a lever Iii secured to a vertical shaft H operatively engages in the yoke 68 The upper end of the shaft H is connected. to suitable actuating means (not shown) for the reversing clutch (not shown) in the countershaft (not shown) adapted for driving connection with the cone pulley 25. A hand actuator 12' on the shaft H provides means for manual actuation.

The supply of pressure fluid, such for example as compressed air, alternately to opposite ends of the unit 66 to effect reciprocation of the piston rod 61 as desired, is under the control of an osci1-' latory valve 13. The details of the unit and the valve 13 per se form no part of the present to one arm of the lever 14 and tends to oscillate the valve 13 into a position to effect movement of the carriage !9 to the left. The other arm of the lever 14 constitutes a pawl 16 adapted to be swung against the action of the spring I5 into interlocking engagement with the notched end of a latch Tl. A lever arm 18 is pivotal with the latchl'l, and is connected at its free end to a coiled tension spring 19 anchored to the frame I! and serving to hold the latch against the pawl H6 at all times- When the pawl i6 is seated in the latch ll, the valve i3 is positioned to effect movement of the carriage I9 to the right.

A trip dog 83 mounted on the carriage 9 for movement therewith has an inclined surface adapted to ride against a pin 8! extending upwardly from the free end of the lever arm 13, and to gradually swing the latter rearwardly until, at the end of the carriage movement to the right during the grinding stroke, the latch ll suddenly releases the pawl it. Thereupon, the

lever i4 is moved under the influence of the spring to eiiect reversal of the valve 83, and consequently to institute the return' movement of the carriage. A reversing dog 82 mounted on a position in which the cam face 94 is parallel the carriage I9 is positioned to engage a pin 83 on one arm of the lever 14 at the end of the return movement to reinstitute movement in the original direction preparatory to taking a new depth cut on the Work.

Since the screw 36 is rotated continuously, it will, if held against endwise movement, cause the carriage l9 to travel uninterruptedly in either direction in timed relation to the rotation of the work blank A. Such movement is required where the grinding element B is to describe a helical cut, as for example in the grinding of gear cutting hobs or of screw threads. However, where the grinding element B is not to describe a continuous cut, the carriage l9 must be fed in a.

step-by-step movement during the grinding stroke. Thus, in the case of thread mills having a series of uniformly spaced annular grooves as illustrated herein, the carriage must be advanced in a series of timed steps, each equal inextent to the space between adjacent grooves, and must be at rest during the grinding of each groove.

To adapt the machine for the grinding of these various types of work blanks, adjustable means is provided available at will for modifying the re sultant action of the feed screw 36 to the extent desired. In its preferred form, this means (see Figs. 9 and 10) acts periodically duringthe grinding stroke first to shift the carriage l9 and the screw 36 as a unityagainst the action of the "weight 59 in a direction opposite. the relative movement of the carriage alongthe screw, thereby completely or partially counteracting the normal action of the screw, and then to release said unit for a return movement into initial position, thus utilizing the accumulated feed to advance the carriage sharply in a retarded'step. Obviously, the distance through which the unit I9, 36 is shifted determines the extent of each step through which the carriage is indexed. Where the shifting movement completely counteracts the action of the screw 36, the carriage I9 is stationary during the interval between successive steps.

The aforesaid shifting means in its detailed form comprises a slide 86 which supports the end bearing 55, and which is mounted between two opposed guides for movement in a direction parallel to the screw 36. The guides 85 are mounted in ahousing 86 rigidly secured on the right end of the frame I! beneath the work car riage l9. Anti-friction bearings 87 are suitably interposed between the slide 84 and the guides 85.

Mounted in the housing 86 on the underside of v the slide 8 for pivotal movement is a cam 'follower 88 having a flat face 88a. Preferably, the follower 88 is in the form of a block having a pivot pin 89 extending upwardly into the slide 8 5.

A cross slide 90 is mounted between opposed guides 9! on the underside of the housing 86 for reciprocation transversely of the slide M and the screw 36. Preferably, anti-friction bearings 92 are interposed between the slide 90 and the guides 9i. Mounted on the slide 90 for angular adjustment about a vertical pivot 93 is a fixed cam 9 3 in theforrn of an elongated'plate having a fiat face 94311 on one end constantly in engagement with the follower face 88a. The other end of the cam 94 extends out of the housing 85 into to the line of movement of the slide 90.

One end of the slide 90 carries a hardened plate Q9, constituting a follower, which engages a rotary cam I Bil enclosed in a housing it?! on the rear of the frame IT. The follower 99 is held constantly against the cam l0!) by a compression spring 102 acting through the arm 95 (see Fig. 4). The cam I00 has a true peripheral spiral face lllfia terminating in an abrupt drop lDilb which determines the range of movement of the slide Q0.

The cam if!!! is driven in timed phase relation to the work spindle 24 so as to move the drop I001) across the follower 99 to institute each step of the indexing movement during the grinding stroke at the precise moment that the current cut on the corresponding groove of the work blank A is completed. Thus, the cam I89 is fixed on a shaft H13 which extends along the rear of the frame 51, and which is journaled at one end in a bearing I04 in the housing NH and at the other end in a bearing H35 on the left end of the frame. A gear H35 (see Figs. 2, 3 and 5) rotatable on the left end of the shaft 103 is connected through two speed-change gears l0! and IE8 tothe gear 43. The gears l0! and I98 are mounted on a bracket I09 integral with the bearing 5 (15. Fixed on the shaft I03 within a hub I IE! on the gear I96 is a collar H I (see Fig. 7) formed with a peripheral notch H2. A pivotal detent H3 in the gear hub H0 is pressed into the notch H2 by a leaf spring H4 to drive-the shaft I03 and hence the cam I00 in a clockwise direction as viewed in Fig. 9, but not in the reverse direction.

It will be evident that when the cam face 94a is not'inclined, reciprocation of the slide 90 will not effect any movement of the slide 84, and hence the feed screw 36 will move the carriage l9 without interruption in either direction. However, when the cam face 95a is inclined to the direction in which the slide 98 is reciprocated, the screw 36 will be moved gradually to the left and then suddenly released for a quick return movement once for each revolution of the cam 100 to produce a step-by-step indexing movement of the carriage 19 during the grinding stroke. If the carriage i9 is to remain stationary during each cut,.the cam 94 should be inclined at such an angle that the screw 36 will be shifted to the left at the same speed as the carriage is fed along the screw to the right. Thus, the inclination of the cam 96 is related to the lead and speed of rotation of the feed screw 36. The extent to which the carriage 36 is indexed in each step may be varied by adjusting the speed of the screw 36 relative to the work spindle 2G, and making a corresponding adjustment in the angle of the cam 9d.

To return the carriage l9 after each grinding stroke into initial position for a repetition of the cycle, the rotation of the screw 36 is reversed. By reason of the one-way drive .for the shaft I03, the cam H39 cannot be driven in a reverse direction, and must remain stationary. Hence, the return stroke of the carriage i9 is uninterrupted regardless of the character of the indexing movement during the grinding stroke.

When the blank A is formed with inclined gashes, the Work spindle 24 is angularly adjusted proportionately with each step in the indexing movement so as to compensate for the inclination of-the gashes. This adjustment may be positive or negative depending on whether the blank A has right-hand or left-hand gashes. The means for this purpose (see Figs. 1, 2 and 12) comprises a gear 555 rotatable with the terminal gear 3 5 of the planetary spindle drive. The gear H5 is connected through an idler gear M5 to a gear rack Ill formed on the lower end of a bar H8 vertically reciprocable in a g'uideway I89. The upper end of the bar Mil carries a pin I29 which is slidably disposed in a longitudinal guideway ill in a horizontal bar I22. The bar 822 is pivotally adjustable at I23 on a horizontal arm I24 rigidly secured at one end to an upstanding bracket I25 on the work carriage 59 for movement therewith. The other end of the arm I2 1 is slidably disposed in *a horizontal guide I26 formed on the upper end of an upstanding bracket in on the machine frame I1. The'free end of the pivotal bar I22 constitutes a pointer movable along an arcuatescale I28 formed transversely on the horizontal arm I24, and carries a clamp bolt I29 adjustable in an arcuate slot I39 extending along the scale. When the pivotal bar I22 is secured in a horizontal position at the zero point on the scale I28, no movement will be imparted to carriage I9 in either direction, and hence the terminal gear 34 will be stationary. However, if the pivotal bar I22 is adjusted above or below the zero point of the scale I28 at an angle corresponding to that of the cutter gashes, translation of the carriage I 9 will impart a reciprocatory movement to the rack II1, thereby effecting a compensatory drive through the terminal gear 34. In the present instance,-the blank A is shown with straight gashes. and hence no compensatory adjustment is required.

Grinding wheel support The grinding wheel B is mounted on one end of a drive spindle I3I (see Fig. 2) which is rotatably mounted in a spindle head I32 slidably adjustable on ways I33 formed on the end of a suitable bracket I34. An adjusting screw I35 rotatably anchored on the bracket I34 is in threaded engagement with the spindle head I32. The spindle I3I has an operative drive connection (not shown) with a sheave I36 connected through a belt. I31 to a suitable source of power (not shown).

The bracket I34 is fixed on a horizontal feed slide I38 (see Figs. 2. and 6) mounted for adjustment transversely of the blank A on a horizontal relief slide I39. A feed screw I49 in threaded engagement with a nut I4I on the underside of the slide I38 is journaled in a bearing bracket I42 on the front end of the slide I39. The outer end of the feed screw I49 is provided with an enlarged head I43 rotatable in a seat I44 in the front face of the bracket I92. A cylindrical block I45 is rigidly secured to the outer end of the head I43 by means of bolts M6. A cam abutment I41 is seated in a recess in the front end of the block I95 and projects forwardly therefrom. Extending slidably through the screw M9, the block M5 and the abutment M1, is an elongated axial draw bolt M9. Of the bolt M8, the rear end is in fixed threaded engagement with a lug M9 on the relief slide I39, and the front end is formed with a bearing ring or eye I159. A bifurcated rotary cam I5! provided with a hand lever I52 is pivotally mounted on opposite ends of a pin E53 extending through the eye we in bearing engagement with the cam abutment Mil, and. serves as -means for anchoring the feed screw M9 rigidly to the slide l39. A coiled compression spring I59 disposed on the draw bolt I93 in end; abutment between the screw M8 and the lug M9 serves upon the rack II1 upon translation of the aoeaivs releasing the cam 956 to shift the screw forwardly in the hearing it, and thereby retract the grinding wheel B from the blank a into inopera= tive position.

The cross feed screw Hill may be adjusted by any suitable means, for example to advance the grinding wheel B further toward the work blank Relieving mechanism Means is provided for effecting a relative relieving reciprocation between the blank A and the grinding wheel 3 transversely of the blank once for each tooth as it passes through the grinding zone, and for separating the blank and the grinding wheel during each indexing movement and during the free-retum stroke (see Figs. 6 and 11) To this end, the relief slide I39 carrying the grinding wheel B is mounted for reciprocation on horizontal transverse ways Won the machine frame I1. nected to the slide I39 through a cable I62 leading over two sheaves I63 mounted in brackets I64 on the front of the frame I1, tends to urge the grinding wheel B yieldingly away from the blank A. v

Pivotally connected at its upper end to the rear end of the slide I39 is a depending cam lever I65 normally fulcrumed about its lower end. A cam follower block I66 is secured to the lever I65 intermediate its ends, and rides on a rotary relieving cam I61 having a spiral face I61a terminating in an abrupt drop I61b. The cam I61 is secured to a longitudinal shaft I68 joumaled at its ends on the machine frame I1 and connected at its left end through a; train of speedchange gears I69, I10 and HI (see Figs. 1 to 3) A weight I6l, which is conto the main drive shaft 21'. The rotation of the cam I61 is so timed to .the blank A that the grinding 'wheel B will be fed rearwardly during the grinding of each tooth so as to generate a suitable radial relief, and will then be'returned' quickly to initial position for the succeeding tooth.

To maintain the cam follower I66 always in the same horizontal plane as the axis of the cam I61, one side of the follower is extended to form a pivot I12 (see Fig. 11) rotatably mounted and slidable in a horizontal guideway I14 in a block I13 for supporting the lever I65. The upper end of the lever, I 65 is journaled in two blocks I15.

slidable vertically in a guide I16 in the slide I39. Likewise, the lower end of the lever I 65 is journaled in two blocks I11 ,slidable vertically in a guide H8. Thus, each endof the lever I65 has.

a floating connection.

The drop I672; of the cam I61 is of such depth example, while the blank A and the wheel B are apart.

are held. in spaced relation, independently of the action of the relieving cam I 81, during the con tinuous free-returnstroke of the carriage I9 after each grinding stroke. This is accomplished by automatically adjusting the fulcrum of the lever I95, i. e. the guide I78, rearwardly upon movement of the carriage I9 into its extreme right end position at the end of the grinding v stroke. To this end. the guide II8 is rigidly secured on the forward end of a plunger I19 which ismounted for reciprocation transversely of the frame IT. The plunger extends through a brack-' ed on the rear end of the plunger I19, and is in peripheral bearing engagement with a bore I82 in the bracket I89. The pinion I9I is normally held against endwise movement, and is formed on its inner end with a forwardly projecting cam I83. Fixed on the plunger I79 is a sleeve I89 which is formed with a rearwardly projecting cam I85 adapted for movement into and out of engagement with the cam I83, A gear rack I86 extends slidably through the bracket I89 in mesh with the pinion I8I, and is provided on one end with a rod I81 slidably supported in a bracket I88 on the rear of the ,frame II. Two spaced collars I89, constituting abutments, are adjustably secured on the rod I8'I for engagement respectively with opposite sides of an arm I99 on the yoke 68. I 9

Upon operation of the piston and cylinder unit 66 to institute movement of the carriage I9 to the left, the arm I99 will move into engagement with one of the collars I89 to effect rotation of the cam I83 out of engagement with the cam I89, thus effecting a substantial separation of the work blank A and the grinding wheel B. At. the end of the free-return stroke, the piston and cylinder unit 89 will move the arm I99 into engagement with the other of the collars Hi! to engage the cams I83 and I85, thereby causing the relief slide I39 to advance the grinding wheel B into operative position.

Taper grinding formed on one end with an annular groove Nil in which two shifter shoes I92 are slidably disposed. The shoes I92 are pivotally mounted in the arms of a yoke I93 fixed on a vertical rock shaft I98 journaled in an upstanding tubular bearing I95 on the bracket I89. A lever I 97 is fixed on the upper end of shaft I94, and on its free endcarries a pivotal follower block I98.

.Pivotally mountedfor angular adjustment on a 209 on the underside.

movement of the carriage I9, .thus adapting the machine for the grinding of tapered work blanks.

It will be understood that the taper may be varied by adjusting the bar I99 into different angular positions.

Dressing mechanism Means is provided for dressing the grinding wheel B from time to time to maintain the desired form and to remove glaze from the grinding surface. This means (see Figs. 13 to l6)' comprises a base slide 299 mounted on a guide 29I on the feed'slide I38 for adjustment transversely of the grinding spindle I 3!. Since 'the grinding spindle is inclined to the work spindle 24, the slide 299 is inclined on the slide I38. Fulcrumed intermediate its ends on a knife edge pivot 292 against a bearing lug 293 on the slide I38 is an adjusting lever 299. One end of the lever 294 is pivotally connected to a block 295 slidable along a guide An adjusting screw 291 rotatably anchored in the guide 296 is in threaded engagement with the block 295. The other end of the lever 294 has a knife edge pivot 298engaging a bearing block 299 on the forward end of the slide 299. A coiled tension spring 2I9 anchored to the slide i38 acts to hold the slide 299 against the pivot 298.

Rigidly mounted on the slide 299 for adiustment along a longitudinal guide 2 is a bracket 2I2 having a vertical standard 2I3 on one end.

The rear of the standard 2I3 has an arcuate face I 2M and is formed with a horizontal shelf 2| 5 having an arcuate guide groove M8 and an elongated slot 2II along the groove. Mounted for angular adjustment on the shelf 2I5, with an arcuate tongue 2I8 fitting into the groove 2I6, is

a support 2I9 having a straight transverse guide The support 2I9 may be secured in adjusted position by means of a bolt 22I extending through the slot 2H. A slide 222 is reciprocably mounted on the guide 299, and carries a dressing tool 223 adapted to act on the peripheral face of the grinding wheel B.

Rigidly mounted on the standard 2 I 3 is a rearwardly extending bracket 224 formed on its free end with an upstanding tubular bearing 225, and in its underside with an arcuate guide groove 226 concentric to the bearing. Two supports 22? and 228, with arcuate tongues 229 fitting into the groove 226, are mounted for angular adjustment on the underside of the bracket 224 generally at opposite sides of the tool 223. Bolts 239 extending through spaced arcuate slots 23I in the bracket 224 are provided for securing the supports 221 and 228 in adjusted position. Secured on the underside of the supports 22'! and 228 are two rectilinear guides 232 and 233 in which two slides 234 and 235 are respectively mounted for horizontal reciprocation. The slides 234 and 235 respectively are formed with depending arms 236 and 231 in which suitable tools 238 and 239 for dressing the opposite sides of the grinding wheel B are mounted. The tools 223, 239 and 239 are located in the horizontal axial plane of the grinding wheel B and hence of the grinding spindle 28. Since the grinding wheel B has a-V- shaped contour, the supports 22! and 228 are so adjusted that the tools 238 and 239 describe the correct'angular paths.

To afford means for simultaneously adjusting 234 and 235 are provided respectively with longitudinal gear racks 249, 2 and 242. These racks 'the dressing tools 223, 238 and 239, the slides 222,

mesh respectively with gearsectors 243, 244 and 20 298 secured along one side of therelief slide I39.

. ceive the grinding wheel B and avoid interference with the dressing tools 233, 238 and 239. The

gear sectors 244 and 245 bear against the underside of the bracket 224, and the outer shaft 241 is cut away to permit the gear sector 244 to project outwardly into operative engagement with the rack Threaded respectively onto the upper ends of the shafts 24B, 247 and 248 and disposed in closely superimposed relation are three adjusting disks 25I, 252 and 253 of which the second rests against the upper end of the bearing 225. The disks 25I,

-252 and 253 are adapted to be adjustably secured for rotation as a unit by means of two clamp screws 254 extending through tvvo diametrically opposed sets of arcuate slots 255 adapted to be moved into various degrees of registration.- A hand lever 256 is integral with the lower disk 253.

It will be evident that the shafts 246, 241 and 248 positions so as to vary the order of movementof' may. be adjusted into different relative angular the dressing tools 223, 238 and 239. Preferably, the shafts are so adjusted that .upon unitary movement thereof, the dressing tools will be moved in clockwise or counter-clockwise order so as toavoid interference. By adjusting the various/supports 2I9, 221 and 228, the contour of the grinding wheel B may be varied as necessitated for different types and forms of work blanks. Upon feeding the slide I38 rearwardly to advance the grinding wheel B toward the work, the lever 204 will automatically advance the dressing device proportionately toward the grinding wheel so as to position same for dressing- Rsum of operation The operation of the machine will be clear from the foregoing description. Briefly sumnext groove.

marized, the cutter blank A is rotated slowly in a counter-clockwise direction as viewed in Fig. 6, and the grinding wheel B is driven at a relatively high speed. At the start of the operation, the blank and the wheel are positioned longitudinally of the blank to grind the first annular groove, and are relatively adjusted laterally of the blank through the cross feed screw I40 to effect a light initial out. A relieving reciprocation transversely of the blank A is imparted to the grinding wheel B once for each tooth. During the rotation of the blank A through onecomplete revolution, the

work carriage I9 is held stationary while the feed screw 36 is shifted to the left: by the index cam I00. When all of the teeth in the initial row have been ground, the index cam I 00 releases the screw 36 to'index the carriage I9 through' one step so as to advance the blank into position to grind the The indexing movement is timed to occur while the blank A and the wheel B are separated at the start of a relieving reciprocation.

The foregoing operation is repeated until a I of the rows of teeth have been ground with an step-by-step grinding stroke.

initial cut, if e. until the blank A has been com pletely traversed across the grinding wheel B in a Thereupon, the dog institutes operation of the piston and cylinder-unit 66 to effect movement of the grinding wheel '3 into inoperative position spaced from the blank A, and to'reverse the drive for the feed screw 36, and incidentally the work spindle 24, so as to traverse the blank in a free return stroke to initial position. The index and relieving earns I00 and I61 are not rotated, and hence the return stroke is continuous and the relief slide I39 is-not reciprocated. At the end of the return stroke, the dog 82 institutes operation of the unit 66 to effect return of the grinding wheel B into operative position and reversal of the drive for the feed screw .36 preparatory for the next out along the blank A. During the free return stroke, an incremental feed toward the blank A is imparted to the grinding wheel. On occasion, the grinding wheel B may be dressed 15 by actuating the hand lever 256, the dressing device being automatically advanced toward the grinding wheel in proportion to the feed to compensate'for wear. Successive cuts of increasing depth along the blank A are taken until the teeth are ground to the desired depth.

For cylindrical cutters with straight gashes, the bars l22 and I99 are adjusted into zero position. It will be understood, however, that for cutters withinclined gashes, the bar I22 is angularly adjusted to impart a compensatory rotation to the spindle 24, and for cutters with a'tapered contour the bar I99 is angularly adjusted to advance the grinding wheel toward the work automatically in response to indexing movement of the carriage I9. Obviously, the bar I99 may be shaped to adapt the machine for grinding contour cutters having other than a straight taper.

I claim as my invention:

1. In a machine tool, in combination, a base, 35 a carriage mounted for rectilinear movement on said base, a depending lug on the underside of said carriage, a nut fixed in said lug, a feed screw in threaded engagement with said nut, said nut being rotatably adjustable in said lug, drive means for rotating said feed screw continously to advance said carriage relatively along said screw in one direction, and means for adjusting said sc'rew axially in the other direction to modify the resultant movement of said carriage.

2. In a machine tool, in combination, a base, a machine element mounted 'for movement on. said base, a nut on said element, afeed screw inthreaded engagement with said nut, drive means for effecting relative continuous rotation between 50 said feed screw and said nut to advance said element relatively along said screw in one direction and means automatically operable during said 'said element relatively along said screw in one direction and. means for reciprocatingi said screw axially through a predetermined range, each re ciprocation consisting of a slow movement at the same rate as but opposite in direction-to the advancement of said element along saidscrew during 70 which said element is stationary relative to said base and'a quick return movement in said one direction, whereby said element is given a step by-step movement on said base. r

4.. In a machine tool, in combination, a base, a 75 machine element mounted for rectilinear movement on said base, drive means for said element and including a continuously movable adjustable member in operative engagement with said element for translating said element continuously in one direction of said movement relatively to said member, and means automatically operable during the operation of said drive means in said one direction for periodically moving said element and said member bodily as a unit reversibly first to oifset said translation of said element and then quickly in said one direction so as to obtainla step-by-step movement of said element relative to said base.

5. In a machine tool, in combination, a base, a carriage mounted for rectilinear reciprocation on said base, a nut on said carriage, a feed screw in threaded engagement with said nut, drive means having axial spline connection with one end of said screw for rotating said screw to advance said carriage-in a continuous movement along said screw in one direction, said cam in operative engagement with one end of said slide, yieldable means for holding said slide against said rotary cam, and means for rotating said cam in timed relation to said screw.

.6. In a. machine tool, in combination, a support, a machine element movable on said support,- drive means for moving said element relatively in one direction, said drive means being reversible to return said element in the opposite direction, and means operable in timed relation to said drive means upon movement of said element in said one direction for periodically reciprocating said element and said drive means as a unit, each reciprocation having a slow stroke in said opposite direction ata rate substantially equal to the movement of said element along said drive means in said one direction, and a quick return movement in said one direction, whereby a stepby-step movement in said one direction relative tion, said drive means being reversible to return said carriage in the opposite direction, yieldable -means tending constantly 'to move said screwaxiall'y in said one direction, control means acting on said screw in opposition to said yieldable means and defining a normal position 'for said screw, said control means being automatically'operable periodically to move" said screw againstthe action of said yieldable means from said normal position in said opposite direction gradually through a predetermined distance and then to release said screw for a quick return'movement into said-normal position, and drive means for said control means, said last mentioned drive means being timed to said first mentioned drive means and being inoperable duringmovement of said carriage in said opposite direction.

8. In a machine tool, in combination, a base, a carriage mounted for rectilinear reciprocation on said base, a slide mounted for reciprqcation transversely of said'carriage, drive means for reciprocating said slide, a nut on said carriage, a feed screw in threaded engagement with said nut, said screw being mounted for axial adjustment, drive means for efiecting relative rotation between said nut and said screw to advance said carriage in a continuous movement along said screw in one direction, yieldable means tending constantly to move said screw axially in said one direction, control means acting on said screw in opposition to said yieldable means and defining a normal position for said screw, said control means being automatically operable periodically to move said screw against the action of said yieldable means from said normal position in the opposite direction gradually through a predetermined distance and then to release said screw for a quick return movement into said normal position, drive means for; said control means, said last mentioned means being timed to said two first mentioned drive means so that said carriage will be moved along said'base in said one direction step-by-step, with each step occurring while said slide is remote from said carriage.

9. In a machine tool, in combination, a base, a carriage mounted for movement on said base, a nut on said carriage, a feed screw'in threaded engagement with said nut, said screw being mounted for axial adjustment, drive means for to said yieldable means and defining a normal po sition for said screw, said control means in one position of adjustment acting to maintain said screw in said normal position, and in other selective positions of adjustment being automatically operable periodically to move said carriage against the action of said yieldable means from' said normal position in the opposite direction gradually through a predetermined distance and then to release said screw-for a quick return movement into said normal position, and drive means for said control means, said drive means being'timed to said first mentioned drive means.

10. In a machine tool, in combination, a base,

a carriage mounted for rectilinear reciprocation on said base, a nut on said carriage, a feed screw in threaded engagement with said nut, said screw being mounted for axialadjustment, drive means for effecting relative rotation between said nut and said screw to advance said carriage in a con tinuous movement along said screw in one direction, said drive means beingreversible to retum' said carriage in the opposite direction, a bearing ,for rotatably anchoring said screw, a cam slide movable transversely of said screw, an adjustable cam member on said'slide, a cam follower on said bearing in operative engagement withsaid cam member, yieldable means tending to move said screw axially in said one direction to hold said follower against said cam member, and means for reciprocating said slide in timed relationto the rotation of said screw.

11. In a machine tool, in combination, a base, a carriage mounted for rectilinear reciprocation on said base, a rotary spindle journaled on said carriage, across slide mounted on said base for movement transversely of said spindle, a rotary relieving cam for reciprocating said cross slide in a-gradual approaching movement and a quick separating movement, a nut and feed screw drive for reciprocating said carriage axially of said spindle first in one direction and then in a return direction, nieans operable in timed relation to said drive for separating said cross slide from said spindle during the return movement, and means operable during movement of said carriage in said one direction periodically to shift said carriage and said feed screw drive as a unit in the opposite direction to effect a step-by-step movement of said carriage in said one direction, with each step being timed to occurwhile said slide is remote from said spindle.

12. In a machine tool, in combination, a base, a carriage movable on said base, a slide movable on said base transversely of said carriage, an adjustable stop, means coacting with said stop for determining the position of said slide relative to said spindle, an axially shiftable non-rotatable rod supporting said stop, a cam abutment on said rod, an elongated pinion rotatably and slidably mounted on said rod, said pinion having a cam on one end coacting with said abutment, gear,

means for rotating said' pinion in any axial position to adjust said stop, a templet movable with said carriage, and means coacting with said templetv in the progressive movement of said carriage to control the axial position of said pinion and therethrough the position of said stop in accordance with the pattern of said templet.'

13. Ina machine tool, in combination, a base, a carriagemovableon said base,'a slide movable on said base transversely of said carriage, yieldabIe means tending to urge said slide from said 65 5 a carriage reciprocable on said base between two carriage, an adjustable stop, a lever fulcrumed intermediate its ends and coacting at one end with said stop and at the other end with said slide for determining the position of said slide relative to said carriage, an axially shiftable rod for supporting said stop, a templet mounted on' saidcarriage and having a face of predetermined form, said templet being adjustable relative to the direction of movement, and means. coacting I slide relative to said carriage, means acting as a.

fulcrum for said lever, atemplet movable with said carriage, said templet having a face with a contour extending generally along said base, and means mounted on said base and coacting with.

said face for controlling the position of said stop asdetermined by said contour during the progressive movement of said carriage. 1 1

15. In a machine tool, in combination, a base,

opposed predetermined end positions, a spindle on said carriage, a slide movable on said base transversely of said spindle, a stop, means cot g;.v'vith said stop for determining the posisaid slide relative to said spindle, means p Siva to the movement of said carriage into either' of said end positions to adjust said stop into either of two relative corresponding positions, and means for independently adjusting 2,067,178 said stop automatically in-res'ponse' to the pro gressive movement of said carriage.

16'. In a machine tool, in combination, a base, a carriage slidable .on said base, a slide movable on said base transversely of said carriage, yieldable means tending. to move said slide from said carriage, a stop, means coacting with said stop 5' for determining the position of said slide under the influence of said yieldable means, a bearing on said base, an elongated pinion rotatable in said bearing, said pinion having an annular end face cam on one end, a non-rotatable rod supporting said stop, a follower on said rodcoacting with said cam face, a gear rack meshing with said pinion, and means responsive to the movement of said carriage for actuating said rack to rotate said ca m toadjust said stop selectively into different positions.

17. In a machine tool, in combination, a base, a member movable on said base, a tool slide adjustably mounted on said member, screw means for adjusting said slide ina feeding movement on said member, yieldable means tending to move said member in one direction, a stop abutment adjustably mounted ,on said base and independent of said member and said screw means, means coacting with and interposed between said abutment and said member for determining the position of said member under the influence of said yieldable means, and two means independently available for translatably adjusting theposition of said stop abutment to control the position of 3 said member, each of said last two means being automatically operable in timed relation to the movement of said member.

18. In a'machine tool, in combination, a base,

a slide movable onsaid base, yieldable means said base, a rotary relieving cam, a cam lever in 1 operative engagement intermediate its'ends with said cam, one end of said lever having an operative engagement with saidslide, .a fulcrum-coacting with the other end .of said lever, yieldable means for holding said'lever against said cam, a non-rotatable rod.supporting said fulcrum, said rod being axially shiftable, a cam follower on said rod, a rotary cam having an annular end face in operative engagement with said follower, means for rotating said last mentioned cam to adjust said fulcrum, and independent means for shifting said last' mentioned cam to ad ust said fulcrum. 20. In a machine tool, in combination, a support, a member-reciprocable on said support, ,a lever'having a floating connection with said member, a fulcrum, said lever having a floating connection'with said fulcrum; yieldable'means tending tomove said member in one direction,

,means coacting with an intermediate portion of saidlever for oscillating said lever about said fulcrum against the action of said yieldable means, and means for constraining said portion "of said lever to move in arectilinear path parallel to the movement of said member.

21. In a machine tool, in combination, a support, a member movable horizontally on said support, a rotary cam, a vertical lever having a cam follower intermediate its ends coacting with said cam, slide means reciprocable in a horizontal rectilinear direction transversely of the axis of said cam, said follower being pivotally mounted on said slide means, the upper end of said lever having a floating connection with said member, a fulcrum mounted in said support, the other end of said lever having a floating engagement with said fulcrum, and yieldable means acting to hold said cam and said lever in operative engagement.

22. In a machine tool, in combination, a support, a member movable on said support, a rotary cam having a gradual throw terminating in an abrupt drop, a lever pivotally mounted intermediate its ends for rectilinear shifting movement and coacting with said cam in the plane of said movement, one end of said lever having an operative floating connection with said member, a fulcrum mounted in said support, the other end of said lever having a floating engagement with said fulcrum, and yieldable means acting to hold said cam and said lever in operative engagement.

23. In a machine tool, in combination, a base, a carriage mounted on said base, a work spindle rotatably mounted on said carriage, means for driving said carriage axially of said spindle in a step-by-step indexing movement in one direction, a tool slide mounted on said base for reciprocation transversely of said spindle, a rotary relieving cam on a horizontal axis in said base, a

with said slide, a fulcrum for said levenyieldable means acting to hold said lever against said cam and tending to retract said} slide from said spindle, and means for driving said cam in timed relation to said spindle and said carriage to effect a relieving reciprocation of said slide during said indexing movement and to cause each step of said indexing movement to occur when said slide is retracted from said spindle.

24. In a machine tool, in combination, a base, a carriage mounted on said base, a work spindle rotatably mounted on said carriage, means for reciprocating said carriage axially of said spindle, a'tool slide mounted on said base for reciprocati'on transversely of said spindle, a rotary relieving cam, a lever pivotally supported intermediate its ends for rectilinear shifting movement and coacting with said cam in the plane of said movement, one end of said lever having a floating connection with said slide, afulcrum, the other end of said lever having a floating connection with said fulcrum, yieldable means acting to hold said lever against said cam and tending to retract said slide from said spindle, and means operable upon movement of said carriage in one direction for driving said cam in timed relation to said spindle to effect a relieving reciprocation of said slide.

25. In a machine tool, in combination, a base. a-carriage mounted on said base, a work spindle rotatably mounted on said carriage, means for reciprocating said carriage axially of said spindle in a step-by-step indexing movement in one direction and then in a continuous return movement in the opposite direction, a tool slide mounted on'said base for reciprocation transversely' of said spindle, a rotary relieving cam, a cam lever pivotally supported intermediate its ends for rectilinear shifting movement and co acting with said cam inthe plane of said movesupported in said base, the other end of said lever having a floating connection with said fulcrum, yieldable means acting to hold said lever against said cam and tending to retract said-slide from said spindle, means for driving said cam in timed relation to said spindle and said carriage to effect a relieving reciprocation of said slide during said indexing movement and to cause each step of said indexing movement to occur when said slide is retractedfromsaid spindle, and means automatically operable in response to each reversal of movement of said carriage to shift said fulcrum to locate said slide in operative position during said indexing movement and in retracted inoperative position during said return movement.

26. In a machine tool, in combination, a base, a carriage mounted on said base, a work-spindle rotatably mounted on said carriage, means for reciprocating said carriage axially of said spindle in a step-by-step indexing movement in one direction and then in a continuous return movement in the opposite direction, a tool slide mounted on said base for reciprocation transversely of said spindle, a rotary relieving cam on a horizontal axis in said base, a vertical lever coacting intermediate its ends with said cam, said lever being pivotally supported for horizontal v rectilinear shifting movement transverselyfof said axis, the upper end of said lever having a floating connection with said slide, a fulcrum adjustably supported in said base, the lower end of said lever having a floating connection with said fulcrum, yieldable means acting to hold said lever against said cam and tending to retract said slide from said spindle, means for driving said cam in timed relation to said spindle and said carriage to effect a relieving reciprocation of said slide'during said indexing movement and to cause each step of said indexing movement to occur when said slide is retracted from said spindle, means for automatically adjusting said fulcrum in timed relation tosaid indexing movement to vary the relative position of said slide and said spindle, and means automatically operable in response to each reversal of movement of said carriage to shift said fulcrum to locate said slide in operative position during said indexing movement and in retracted inoperative position-during said return movement.

2'7. In a machinetool, in combination, a base member, a work spindle, a support slidable on said base member transversely of said spindle, a grinding wheel mounted on said support, means for adjusting said support to advance said Wheel toward said spindle, a dressing device adjustably mounted on said support in operative relation to said wheel, and means interconnecting said base member, said supportand said device and being automatically operable by the relative movement of said support and base member in the adjustment of said support on said base member toward said spindle to adjust said device on said support proportionately but at a slower rate toward said grinding wheel.

28. An index mechanism comprising, in combination, a lead screw, an index cam, a work holder, a cutting tool, a relief cam periodically rotatable out of an initial position to advance said tool relatively toward said holder in a relief movement, means for continuously rotating said relative longitudinal axial movement between said cutting tool and the work is arrested during one or more-revolutions of work and a quick indexing movement of the cutting tool relatively longitudinally of the work is made at a time when said relief cam is in said initial position.

29. In a machine tool, in combination, a base, a work spindle operatively mounted on said base, a-support slidable on said base. transversely of said spindle, agrinding wheel mounted on said support, means for adjusting saidsupport'ato advance said wheel toward said spindle, a slide mounted on said support for adjustment toward said wheel, a dressing device supported on said slide in operative relationto said wheel, spring means tending to' retract said slide from said wheel, and means automatically operable upon adjustment of said support on said base toward said spindle for adjusting said slide against the action of said spring means proportionately but at a lower rate toward said grinding wheel.

30. In a machine tool, in combination, a base, a work spindle operatively mounted on'said base, asupport slidableon saidbase transversely of said spindle, a grinding wheel mounted on'said support, means for adjusting said support to advance said wheel towardv said spindle, a slide mounted on said support for adjustment toward said wheel, a dressing device supported on said slidein operative relation to said wheel, spring means tending to retract said slide from said wheel, a guide rigid with said base and extending perpendicularly of saidqspin'dle, a block secured for adjustment along said guide, and a lever pivoted to said block andhaving a pivotal bearing engagement with said slide and a second bearing engagement with said support to adjust said slide automatically against said spring means toward said wheel upon adjustment of said support toward said spindle.

31. In a"; machine tool, in combination, a stationary support, relatively rotatable screw elements, an axial thrust anchor on said support for one of said elements, power drive means for effecting relative rotation of said elements in one direction, and means automatically operable during said rotation in one direction for adjusting said anchor axially of said elements first inone direction and then in the reverse direction whereby to effect a variable speed movement of the other of said elements relative to said support.

32. In a machine tool, in combination, a stationary support, two relatively,rotatable screw elements, an anchor on said support for limiting the axial position of one of said elements,'reversible power drive means for effecting relative rotation of said elements in opposite directions, and means automatically operable during rotation in one direction for adjusting said anchor axially of tion of the other of said elements relative to said support other than the relative .axial translation between said elements, said last mentioned means being'inoperative upon relative rotation of .said elements in. the opposite direction.

33. In a machine tool, in combination, a base, a member movable on said base, yieldable means tending to move said member in one direction, a lever coacting with said member, a relieving cam engaging one side of said lever, a stop engagingthe other side ofsaid lever and adjustable to pivot said lever about said cam as a fulcrum said yieldable means, said 'ward said wheel said lever tosaid base portion of said lever having a pivotal bearing crum" on said support said elements to obtain a tra'nslameans, and two means independently available for adjusting the position of said stop, one of said last mentioned means being operable upon mbvement of said member into a predetermined position, the other of said last mentioned means being operable progressively during the movement,of said member.

34. In a machine tool, in combination, a base ,member, a work spindle, a support slidable on ably. mounted on said support in operative relation to said wheel for adjustment transversely of the axis of said wheel, and means independent of said first mentioned means and responsive to themovement of said support on said member for adjusting said dressing device, said last mentioned means comprising a lever extending generally transversely of said. support, a pivot connecting one end portion of said lever to said base member, the other end portion of said lever having a pivotal bearing connection with said dressing'device, and a fulcrum on said support engaging an intermediate portion of said lever and operable to oscillate said lever about said pivot to adjust said device on said support toupon adjustment of said sup port on said base by said first mentioned means toward said spindle.

35. In a machine tool, in combination, a base member, a work spindle, a support slidable on said base member transversely of said spindle, a grinding wheel mounted on said support, screw her, and for adjusting said support to advance said wheel toward said spindle in a feed'adjustment, a dressing device slidably mounted on said support in operative relation to said wheel for adjustment transversely of the axis of said wheel, a lever independent of said screw means and extending generally transversely of said support, a pivot connecting one end-portion of member, the other end connection with said dressing device, and a fu1- engaging an intermediate portion of said lever and operable to oscillate said lever about said pivot to adjust said device toward said wheel in a dressing adjustment upon adjustment of said support toward said spindle, said. fulcrum being located at from said pivot than from said bearing connection so that feed adjustment will be greater than said dressing adjustment.

36. In a machine tool, in combination, a base,

a greater distance means anchoring said support to said base mema carriage movable on said base, a member movable on said base, yield'able means tending to move said member in one direction relative to said carriage, a stop abutment separatefrom said member, means connected to said member and anchoring against said stop abutment for limiting the position of said member under the influence of saidyieldable means, saidmeans including a member operable recurrently to reciprocate' said first mentioned member relative. to said stop-abutment, and two means independently operable for adjusting the position of said abutment and thereby to control the position of said first mentioned member, each of said twomeans being automatically operable in response tov predetermined movements of said carriage.

'37. In a machine tool, in tombination, a base,

a work spindle mounted on said base, a slide reciprocable on said base transversely of said spindle, a support mounted on said slide for movement transversely of said spindle, a nut and screw device directly connecting said slide and support for adjusting said support, a grinding wheel mounted on said support, a dressing device slidably mounted on said support in operative relation to said wheel for adjustment transversely of the axis of said wheel, a horizontal lever extending generally transversely of said support, a pivot connecting one end portion of said lever to said slide at one side of said support, means for adjusting said pivot on said slide along said support, the other end portion of said lever having a pivotal connection with said dressing device, and a fulcrum on said support for an intermediate portion of said lever and operable to oscillate said lever about said pivot so as to adjust said device on said support toward said wheel upon adjustment of said support by said screw device toward said spindle.

38. In a machine tool, in combination, a base, a carriage mounted for rectilinear reciprocation on said base, drive means for reciprocating said carriage and including two coacting parts relatively movable in the direction of reciprocation, one part being connected to said carriage, an anchor in said base for the other of said parts, means for efiecting a continuous relative movement of said one part along said other part in one direction, a cam slide movable transversely of said carriage, an adjustable cam member on said slide, a cam follower on said anchor in operative engagement with said cam member, yieldable means tending to hold said follower against said cam=member. and means for reciprocating said slide in timed relation to the relative movement between said parts whereby; to reciprocate said parts as a unit in a direction opposite said one direction at a rate substantially equal to the relative movement between said parts and then at a fast rate in said one direction, whereby a step-by-step movement in said one direction is imparted to said carriage.

39. In a machine tool, in combination, a base, a carriage mounted for rectilinear reciprocation on said base, two coacting parts relatively movable in the direction of reciprocation, one of said parts being connected to said carriage, and the other of said parts being mounted for adjustment in the direction ofsaid reciprocation, drive means for effecting relative continuous movement of said parts in one direction, yieldable means tending constantly to move said parts as a unit in said one direction, control means acting on said other part in opposition to said yieldable means and 'defining a. normal position for said other part, said control means being automatically operable periodically to move said parts as a unit against the action of said yieldable means from said normal position in a direction opposite said one direction gradually through a predetermined distance and then to release said parts for a quick return movement into said normal posi tion, and drive means for said control means, said last mentioned drive means being timed to said first mentioned drive means so that said carriage will be moved along said base in said one direction in a step-by-step movement.

40. In a machine tool, in combination, a base, a carriage reciprocable on said base, reversible drive means normally operable to translate said carriage continuously in either direction, and means operable only during translatory movement of said carriage in one direction for reciprocating said drive means and said carriage as a unit to superimpose a reciprocatory movement on said translatory movement, said reciprocatory 'movement serving alternately to ofiset and augment said translatory movement.

' JOHN EDGAR.

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