US2388067A - Dresser compensating mechanism for grinding machines - Google Patents

Description

. A. F. MARKUS DRESSER COMPENSATING MECHANISM FOR GRINDING MACHINES Oct. 30, 1945.

Filed Aug. 28, 1944 4 Sheets-Sheet l Magus yam 44s 2 dun, m 7% 44 T (fl-rwoxzms J Oct. 30, 1945.

A. F. MARKUS 2,388,067

DRE SSER GOMPENSATING MECHANISM FOR GRINDING MACHINES I 4 Sheets-Sheet 2 NvEINTok (AT-r0 Oquyusffl /arkaa MW I S 3 kwmm Q K l i -wHHHHHHM.H. .-M-H.wn H u. m. 8 m b Om mm m Q @W y w f mm A. F. MARKUS DRESSER COMPENSATING MECHANISM FOR GRINDINGMACHINES Filed Aug. 28, 1944 4 Sheets$fieet 4 N vbm r'ro p sf f. Wank/s (We! a *Wi W CATTO Patented Oct. 30, 1945 DRESSER COMPEN SATIN G MECHANISM FOR GRINDING MACHIN ES August F. Markus, Detroit, Mich., assignor to Ex- Cell-O Corporation, tion of Michigan Detroit, Mich., a corpora- Application August 28, 1944, Serial No. 551,479

10 Claims.

The present invention is intended for application to grinding machines such, for example, as thread grinders, and has particular reference to grinding machines incorporating that general class of mechanisms known as automatic dressing compensators which serve to modify automatically the relative displacement of grinding wheel and work by an amount requisite to compensate for the diminishment in wheel size necessarily incident to each dressing or truing of the same.

One object of the present invention is to provide a grinding machine arranged to employ movement of a floatingly mounted cylinder for effecting relative movement between wheel and work supports of the machine and in which a piston within the cylinder is rigid with a non-rotatable nut threaded on a screw so that such screw may be revolved for size control purposes andshifted bodily endwise for dresser compensation.

Another object of the present invention is to provide a grinding machine embodying a work support pivoted to be rocked toward and from a grinding wheel by a suitable size control device, together with a novel arrangement for also rocking said work support compensatingly in accordance with the shift of an independently pivoted dresser support toward and from the-wheel.

The invention also resides in various novel relations and combinations of the parts by means of which effective and reliable operation is accomplished with a simple, rugged mechanism.

Further objects and advantages of the invention will become apparent as the following description proceeds, taken in connection with the accompanying drawings, in which: 7

Figure 1 is a front elevation of a thread grinding machine embodying the present invention;

Fig. 2 is a vertical sectional view through the upper portion of the machine and taken substantially along the pivotal axis of the work supp r I Fig. 3 is an end elevation, partially in section along the line 3-3 in Fig. 2 of the upper portionoi the machine;

Fig. 3a is a detail sectional view taken substantially along the line 3a3a in Fig. 3;

Fig. 4 is a view similar to Fig. 3 but somewhat more diagrammatic in character and'showing the dresser support and retract cylinder in section;and

Fig. 5 is a fragmentary detail perspective view of the mount for the wheel support.

While the invention is susceptible of various modifications and alternative constructions, I

have shown in the drawings and will herein de-L scribe in detailthe 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 constructions falling within the spirit and scope of the invention as expressed in the appended claims.

Referring more particularly to the drawings of the exemplary embodiment of the invention herein disclosed, it will be seen upon reference to thedrawings that the same has been illustrated as embodied in a thread grinding machine (Fig. 1). Such machine comprises a base ID on the top of which-is a work support, designated generally as II, and including centers I2 and I4 between which a work piece (indicated at W in Fig. 2) is received and presented to a rotatively driven grinding wheel I5. Truing of the grinding wheel periphery by some suitable form of dresser, various ones of which are available in the art, is requisite from time to time as the wheel periphery becomes misshapen by wear. The present invention is concerned primarily with an arrangement for automatically effecting a relative relocation of work and wheel upon each dressing of the latter in order to compensate for the diminuation in wheel diameter necessarily incident to dressing. Such compensating arrangement is, however, so closely integrated with the related portions of the machine that a description of the latter, including the work support, wheel support, dresser support, etc., is desirable as a preface, even though the details of the same may be widely varied, without departing from the present invention.

In the illustrated machine, the work support I I is of the form disclosed in a grinding machine covered by my copending application Serial No. 542,719, filed June 29, 1944. In this exemplary construction the work support includes a main frame I6 (Figs. 2 and 3) having an integral upstanding headstock end plate I? at one end and longitudinally extending guideways I8 on the opposite end and on which the adjustably clamped tailstock I9 is received. Such frame It is slidable axially along a pair of aligned guide bars 20, 2I and is adapted to be rocked or pivoted about such bars to carry the work toward and from the grinding wheel I5. The guide bars 20, 2| are fixed in respective pairs of upstanding lugs 22, 23 and 24, 25 integral with the base I9. Depending integral feet 26, 21 on the work support frame I6 are bored to receive respective ones of the guide bars, the frame being translatable along such bars to shift the work axially, as well as rockable about such bars for moving the work transaxially with reference to the grinding wheel,

A work supporting spindle 28 (Fig. 2) is journaled in the headstock of the work support II by antifriction bearings 29, 30, the latter bearing being carried by a tubular extension 3| in a gear housing 32 removably fixed to the upright plate l 1.: To efiect translation of the work support frame H in timed relation with the rotation of the spindle 28, the latter is equipped with a replaceable master lead screw 33 threaded in a non-rotatable nut 34 carried by a supplemental or auxiliary head, designated generally as 35. This auxiliary head is mounted for rocking motion in unison with the work support frame I6 but is restrained against translation with the latter. Thus the auxiliary head 35 includes a frame 36 having a dependingfoot 31 journaled on a sleeve 38 within the hollow guide bar 2 6 and located at one side of the upstand-' ing lug 22 on the base 16. On the opposite side of this lug is a block 39 fixed to the frame 36 and journaled on the guide bar 20. The frame 36 is thus mounted to pivot about the axis, of the guide bar 26 but is restrained against movement endwise of the latter by the abutment of the foot 31 and block 39 with opposite sides of the lug 22. Within the upper portion of the frame 36 is a sleeve 46 journaled for rotative adjustment and having the nut 34 removably fixed to its outer end. The tubular extension 31 on the gear case housing 32 is slidably telescoped within this sleeve 40 s that the frames [6 and'36 are compelled to pivot in unison about the axis of the guide bars 26, 2!, irrespective of their relative axial displacement. Rotational adjustment of the sleeve 46 is accomplished by a handwheel 4| fixed to a worm'42 meshed with an annulus of worm gear teeth formed at 43 in the periphery of the sleeve, such rotational adjustment being utilized in determining the lead pick-up. A sheet metal housing 44 encloses the outer end of the auxiliary head 35.

Rotation of the work spindle 28 and its feed screw 33 is accomplished from 'a drive shaft 45- (Fig. 2) disposed concentrically with the axis also Fig. 1) adjustably clamped to the front face of the work support frame it rests in sliding engagement with the upwardly projecting nose of a pin 63 carried on the intermediate support 59,

the overhanging weight of the work support retaining contact between the bar and pin at all times. As described in more detail in my copending application, Serial No. 542,719, referred to above, provision may, if desired, be made for adjusting the angle of the bar 62 longitudinally of the same to impart rocking motion ;to the work support relative to the intermedi- J ate support in timed relation with the translation of the former for use in grinding tapered shapes, and likewise provision may be made for automatically raising and lowering the pin 63 through use of an eccentric cam disk 64 driven in timed relation with the rotation of the spindle 28 in accomplishing relief grinding. Such refinements, however, form no part of the present invention and consequently need not be examined except for the observation that the compensating arrangement hereinafter described does not interfere in any way with their.

function.

Bodily endwise movement of a floatingly mounted cylinder 65 (Figs. 3 and 4) is utilized for'rocking the pivoted intermediate support 59, togetherv with the work support carried by the latter.

-Such cylinder constitutes a portion of a rapidretraction mechanism and has a piston 66 slidable therein, the cylinder itself being slidablymounted in the present instance within a tubu lar extension 61 integral with a bracket 68 fixed to the machine base I0. The cylinder is connected to a pair of laterally spaced depending feet 69-, integral with the underside of the intermediate support, by a pair of links!!! (see also of tilting or pivotal motionrof the work support about the guide rods 26, 2| sothat the drive connections will remain undisturbed during all tilting movement of the latter. This shaft is journaled within the tubular sleeve 38 heretofore mentioned and is driven by a worm gear 46 fixed to its outer end and meshed with a worm 4'1. The latter worm is, in turn, connected by a pulley 68 and a belt ifl with an electric drive motor 56 (Fig. 1) fixed to the lower portion of the machine base [6. A pinion 5i fixed to the drive shaft 45 meshes with a gear 52 carried by a shaft 53 journaled within the block 39. To complete a drive connection for revolving the spindle 28, the shaft 53 has a sliding spline connection 54 with a shaft 55 journaled in the main frame l6 and carrying a gear 56. The latter meshes with a second gear 51 rigid with a sleeve 58 keyed to the spindle 23.

Tilting motion is imparted to they work support frame 16 (and to its connected auxiliary head 35) through the use of an intermediate support or apron 59 which underlies the frame l6 (Figs. 2 and 3). This intermediate support is pivoted by integral upstanding legs 66, 6| on it on the guide bars 26, 2!, so that it may rock coaxially with the work support frame l6 but is restrained against endwise movement with the latter. A taper control bar 62 (Fig. 3 and see right from the position shown in Fig. l, thereby rocking the intermediate support and work supportcounterclockwise to withdraw the work rapidly from the grinding wheel 15. Conversely, ad'- mission of pressure fluid through the port 12 and exhausting of fluid from the other port II will thrust the cylinder 65 to the left, thereby rocking the work back toward the grinding wheel.

A suitable source'of pressure fluid and control valve (not shown) for supplying and exhausting pressure fluid to and from the cylinder 65 may of course be provided. In the present instanceit is intended that the hydraulically effected movement of the cylinder 65 be 'used in effecting rapid retraction of the work at the completion of grinding andrestoration of the work to position for re-institution of grinding. Normally the fluid is locked in the cylinder 65'so that the cylinder is compelled to move in unison withthe piston whenthe latter moves.

Provision is made herein for moving thepiston 66'axially,'while carrying the cylinder 65 with it, in order to rock the intermediate and .work supports both for size control and dresser compensation purposes. With that in view the piston 66 is made rigid with a'nut I3 keyed within the cylinder 65 to restrain such nut against rotation and'threaded on a screw 14. The 'nut 13 and its attached piston 66 may acc OrdingIy,

-Such links are pivoted at their respective opposite ends to such feet and to the cylend through the i p ce axially either by rotating the screw 14 or shifting the latter bodily in an axial direction. In the present machine rotation of the screw is used for size control purposes and bodily endwise movement of the same for dresser compensation.

A sizecontrol mechanism, designated generally as 15, is shown herein as mounted on the base I and arranged to revolve the screw 14, such mechanism being splined to the screw so that the latter may have freedom of axial movement. In the present instance the size control mechanism includes a manually rotatable size control wheel 16 for rotating-the screw. Nor-- nism for automatic power actuation of the screw I4 to turn the same step-by-step in effecting the desired infeed of the work in timed relation with reciprocation of the work support. I

Turning now to the matter of the mounting of the grinding wheel I5 and its associated dresser mechanism, it will be observed upon reference to Figs. 3 and 4 that the grinding wheel is carried by a wheel support designated generally as T1. Such wheel support includes a central rectangular plate-like portion 18 having integraltherewith a pair of upstanding side walls or arms 19 between the upper ends of which the grinding wheel I5 is journaled. The lower portions of these side walls are joined by a web 80 integral therewith as well as with the plate I9. Beneath this web is pivotally mounted a bracket 8I carrying a drivemotor 82 connected by a belt 83 with the grinding Wheel for revolving the latter.

The wheel support 11 is mounted on the machine base I0 for adjustment axially of the work, as well as for limited angular adjustment in accommodating respectively positioning of the wheel for operation on various longitudinally displaced portions of the work and various helix angles for the threads to be ground on the work. For purposes of such adjustments, accurately machined fiat surfaces 84, 85 are provided on the machine base I0 and wheel support 11, respectively, a rectangular block 85 (see also Fig. 5) being sandwiched between these surfaces. This block presents accurately machined parallel opposite side faces and is releasably secured to the base I0 by bolts 81 passing through slots 88 extending longitudinally of the surface 84, the block "being accurately guided for adjustment movement axially of the workpiece by a key 89. The wheel support 11 is, in turn, similarly secured to the block 86 by bolts having their heads received in T-slots 90 which are in this instance arcuate. Adjustment movement of the wheel supportwith reference to the block is accurately The key SI and guided by anarcuate key 9|. slots 90 are centered about a line passing through the axes of the work and grinding wheel. Both lateral and angular adjustment of the grinding wheel l5 can thus be accomplished readily and withprecision. It will be understood that the range of angular adjustment need only be quite small, that is, of the order of about 5..

A dresser mechanism, designated generally as carried on a dresser supliortig frame 93 pivoted at 94 to the wheel support 11 so thatthedresser mechanism moves bodily with the wheel and wheel support during adjustments in position of the latter, thereby obviating any necessity for relocation of the dresser as an incident to such adjustments. Th dresser mechanism as such may take a variety of forms and may, for example, be like that disclosed in some detail in Gilbert Stewart Patent No. 2,311,263, issued February 16, 1943. Inbrief, it comprises one or more diamond dresser points 95 mounted on the dresser frame 93 for movement with reference to the latter in a predetermined cycle of movement in which the point or points approach the grinding wheel, engage its periphery to true the same to predetermined contour, and thereafter withdraw out of contact with the wheel back to their startingl osition. Movement of the dresser supporting frame 93 thus serve to shift the mean location of the path of movement for the dresser points with reference to the grinding wheel and thereby deter mine the dressed diameter of the wheel, the

dresser support being shifted toward the wheel a predetermined increment as a preliminary to each successive dressing operation.

In the construction shown (Figs. 3 and. 4) the dresser supporting frame 93 is of inverted L-shape with depending side walls 96 and is pivotedat 94 between the side walls 19 of the wheel support, the pivotal axis of the dresser support being parallel with the axis of rotation of the grinding wheel. 7

A screw 91 (Fig. 4) is used for rocking the dresser supporting frame 93 about its pivot 94 toward the grinding wheel I5 transaxially of the latter. Such screw is threaded in a tubular projection 98 on an upstanding plate 99 integral with the outer end of the web of the wheel support 11. A tension spring I00 anchored at its opposite ends to the plate 99 and to the dresser supporting frame 93 retains the latter in contact with the nose of th screw 91. .For manual operation of the screw 91 a dresser control wheel MI is fixed to its outer end and may be revolved to advance or retract the dresser supporting frame a desired amount. In some instances it may be desirable to turnthe screw 91 automatically stepby-step in coordination with the cycling of the dresser mechanism. In such case a ratchet wheel I02 is provided which is rigid with the hub of the control wheel IN. A pawl I03 is pivoted on an oscillatable pawl carrier I04 journaled on the cylindrical portion of the plate 99 coaxially with the I screw. A guard plate or shield I05 overlying a portion of the periphery of the ratchet wheel may be locked in adjusted position by a thumb nut I06 to overlie a selected portion of the teeth other-,- wise exposed to the pawl and thus determine the angular distance through which the ratchet wheel is advanced at each stroke of the pawl in correspondingly determining the length of each stepby-stepadvance for the dresser supporting frame 93. plunger I01 reciprocable within a bore I08 in the plate 99. Any suitable means may be provided for actuating this plunger. in timed relation with the cycling of the dresser mechanism 92, the arrangement being in general such that the dresser supporting frame 93 is rocked forward toward the wheel I5 through a predetermined increment of distance preparatory to the execution by the of movement.

:12 (Figs; stand 4) for the grinding wheel I515" The pawl carrier I05 is oscillated by a suitablefor such timed actuation of the plunger 1 I01 .is. disclosed-for example in Ira -J, Snader Patent'No.,2,251-,961, issued August 12,'1941,and ace cordinglyrfurther detailing here is unnecessary.:

In th dresser compensating mechanism here;

in disclosedprovision i made'for shifting'thework support II coincidentally with-eachmove'i ment of the dresser-supporting frame 93 in1a manner such that the work is repositioned relative tojthe wheel I5 by an amount substantially equal, to the diminishmentl in wheel, diameter occasioned by the advanceof the dresserisupporting work support 'II througha distance corresponding t each displacementof thedresser supporting frame93. t I

, In the illustrative :construction the linkage 'between the dresser supporting frame 93 and the screw includes a yoke I09 (see Figs, 2 and-3) pivoted coaxially with the intermediate support 59 and work support I Ion the .guide bar 2 I-. Extending between, the upstandingarms of this yoke is a rod III! which is slidably pivoted one end ofa link I extending rearwardly toward the dresser frame and pivoted to the latter at I I2. By. utilizing a sliding connection (including the rod IIII as shown) between the link III and yoke I09, bodily adjustment of the wheel and dresser supports longitudinally, of the work is accommodated without interruption of the linkage connection. For a similar purpose, a ball and socket type swivel joint I I I a is interposed in the link III intermediate its ends, thus, accommodating the angular adjustment of the wheel support relative to the work.

Depending from the yoke I09 is an integral arm I091; (see Fig. 2) having pivoted thereto a pair of links I I3 which are pivoted at their forward ends to a collar II4'(see Fig. 4) journaled on the end of-the screw I4 and held on the latter to move axially with the same by an abutting shoulder II5 and'an opposed nut I I6. The pivot points for the pairs'of links I0 and I I3 for connectingthe same,

respectively, to the intermediate support 59 and yoke {99 are located equidistantly'from the axis of the guide rod 2 I, in order to minimize the effect of angular displacement between the intermediate support and yoke upon change in wheel diameter. With thedresser supporting frame 93 linked to the floating cylinder 65 as described, it will be: seen that upon each advancev or retreat of the dresser supporting frame the screw 14 will be correspondingly displaced axially, thereby carrying with it the floating cylinder 65 and causing the intermediate and work supports to be rocked through a commensurate distance.

In theoperationof thegrinding machinedisclosed, the operator may turn thedresser control wheel IIlI until the dresser supporting frame 93is rocked forward a'sufiicientdistance for effective engagement of the dresserpoint or points with the grinding wheele Then the dresser-mechanism may be cycled to dress thewheel periphery to a desired shape for the grinding operation to follow. Pressure fluid is'admitted through the righthand port II of the cylinder 65 to thrust the pis tonfBS to the left and thus rock the intermediate and'worksu'pp'orts 59, II clockwise for rapid approach of the work into adjacency with the grinding wheel. ,The'motor' 59 revolves and traverses thlwork in timed relation through the drive connections heretofore described and the size control mechanism-I5 is'utilized to rock thework. step-by-step transaxially toward the wheel intimed relation. with the reciprocations of the,

work, all in the usual manner, until a thread of desired depth has been ground in the work. At such times as may be required, the cylinder 65 is shifted relative to the piston 66 to withdraw the work from the wheel and the dresser mechanism 92 is caused to execute a cycle of movement for dressing the wheel. Preparatory to each such cycling of the dressermechanism, the screw 9! is revolved a predetermined distance to rock the, dresser supporting frame forward fora desired increment of dresser feed. As the dresser supporting frame 93 swings-forward the link. III" thruststhe yoke I09 clockwise about its pivotal axis. Such movement of the yoke in turn thrusts the screw I4 axially to'the left, the latter carrying the piston and cylinder 66, B5 with'it. Accordingly, the intermediate and. work supports are rocked clockwise to advance the work relative to i the wheel, the geometry of the parts being such that the advance of the work thus effected is sub 1 stantially precisely equal to the diminishment of g wheelsize which will result from the coincidentadvance-of the dresser supporting frame 93.

I'claim as my invention: 1. In a grinding machine, the combination of relatively movable work and wheel supports, said wheel support carrying a rotatively driven grinding wheel, a rotatable screw having a nut threaded thereon with the latter restrained;

against rotation, a fluid operated piston rigid with said nut and slidable endwise within a floatingly. mounted cylinder, the admission of pressurefluid to alternate ends of said cylinder servingto displace said cylinder endwise of said screw and travel of said nut axially of said screw as an incident to rotation of the latter serving to carry said cylinder in a direction endwise of said screw, size; control means for revolving said screw, and means mechanically connecting said cylinder to one of said supports for moving the latter rela tive to the other support in accordancewith 2. In a grinding machine, the combination of a base, work and wheel supports, the latter having a rotatively driven grinding wheel thereon,

means -pivotally mounting said worksupport on said base for rocking of the same toward and from said wheel generally transaxially of the latter,. size control mean for rocking said work support, a dresser support pivoted on said wheel support. to rock, toward and from said wheel, means onerable in accordance with changes in position of said dresser support with reference to said wheel support for correspondingly rocking said work.- support, and means for effecting bodily adjustment .as aunit of said wheel supportandethe dresser support pivoted thereon to vary the angle of said wheel with reference to a work piece carried by said work support.

supports mounted thereon, the latter carrying a rotatively driven grinding wheel, a rotatable screw having a nut threaded thereon with the nut restrained against rotation, size control means for revolving said screw to cause said nut to travel axially therealong, connecting means for connecting said nutto one of said supports for moving the latter relative to the other support upon endwisedisplacernent of said nut, said connecting means including a fluid operated piston and cylinder for moving said one support relative to the other support between two alternatively available limit positions independently of movement of said nut, a dresser support movable toward and from said wheel, and means for displacing said screw endwise in accordance with changes in position of said dresser support to thereby shift said nut and the connected one of said first-mentioned supports accordingly.

5. In a grinding machine, the combination of a base having a wheel support thereon carrying a rotatively driven grinding wheel, a work support pivoted on said base for rocking motion generally transaxially of said wheel, a rotatable screw having a nut threaded thereon with the nut restrained against rotation, size control means for revolving said screw to cause said nut to travel axially therealong, connecting means for connecting said nut to said work support for rocking the latter toward and from said wheel in accordance with endwise displacement of said nut, said connecting means including a fluid operated piston and cylinder for moving said work support toward and from said Wheel between two limit positions independently of any movement of said nut, a dresser support movable toward and from said wheel, and means for displacing said screw endwise in accordance with changes in position of said dresser support to thereby shift said nut and the connected work support accordingly.

6. In a grinding machine, the combination of relatively movable work and wheel supports, said wheel support carrying a rotatively driven grinding wheel, a rotatable screw having a nut threaded thereon with the latter restrained against rotation, a fluid operated piston rigid with said nut and slidable endwise within a floatingly mounted cylinder, the admission of pressure fluid to alternate ends of said cylinder serving to displace said cylinder endwise of said screw and travel of said nut axially of said screw as an incident to rotation of the latter serving to carry said cylinder in a direction endwise of said screw, size control means for revolving said screw, means mechanically connecting said cylinder to one of said supports for moving the latter relative to the other support in accordance with movement of said cyl inder in a direction endwise of said screw, a dresser support adjustable toward and from said wheel, and means mechanically connecting said screw to said dresser for endwise displacement of said screw in accordance with adjustment in dresser support position and to restrain said screw against endwise displacement when said dresser support is at rest.

7. In a grinding machine, the combination of a base having a wheel support thereon carrying a rotatively driven grinding wheel, a work support pivoted on said base for rocking motion generally transaxial of said wheel, a rotatable screw having against rotation, a fluid operated piston rigid with said nut, and slidable endwise, within a cylinder floatingly mounted on said base, admission of pressure fluid to alternate ends of said cylinder serving to displace the latter endwise of said screw and travel of said nut axially of said screw as an incident to rotation of the latter serving to carry said cylinder in a direction endwise of said screw, size control means for revolving said screw, and a linkage connecting said cylinder to said work support for rocking of the latter toward and from said wheel in accordance with movement of said cylinder in a direction endwise of said screw.

8. In a grinding machine, the combination of a base "having a wheel support thereon carrying a rotatively drivengrindin'g wheel, a work support pivoted on said base for rocking-motion generally transaxialof said wheel, a rotatable screw having a'nut threaded thereon with the nut rcstrained against-rotation, a fluid operatedp iston rigid with said nut and slidable endwise within a cylinder floatingly mounted on said base, admission of pressure fluid to alternate ends of said cylinders serving to displace the latter endwise of said screw and travel of said nut axially of said screw as an incident to rotation of the latter serving to carry said cylinder in a direction endwise of said screw, size control means for revolving said screw, a linkage connecting said cylinder to said work support for rocking of the latter toward and from said wheel in accordance with movement of said cylinder in a direction endwise of said screw, a dresser support adjustable toward and from said wheel, and means mechanically connecting said screw to said'dresser support for endwise displacement of said screw in accordance with adjustment in dresser support position and to restrain said screw against endwise displacement when said dresser support is at rest.

9. In a grinding machine, the combination of a base having a wheel support thereon carrying a rotatively driven grinding wheel, a work support disposed at one side of said grinding wheel, means mounting said work support on said base for rocking of said work support generally transaxially of said wheel and for translation of said Work support in a path generally paralleling the wheel axis, an intermediate support underlying said work support with the latter resting on the same, means mounting said intermediate support on said base for movement about a pivotal axis coincident with the pivotal axis of said work support but with the intermediate support restrained against translation, a screw extending transversely beneath said intermediate support and having a nut threaded thereon with the nut restrained against rotation, a fluid operated piston rigid with said nut and slidable endwise within a fioatingly mounted cylinder, the admission of pressure fluid to alternate ends of said cylinder serving to displace the latter endwise of said screw, and travel of said nut axially of said screw as an incident to rotation of the latter serving to carry said cylinder in a direction endwise of said screw, size control means for revolving said screw, said intermediate support having a depending leg thereon, linkage pivotally connecting said leg to said cylinder for rocking of said intermediate support about its pivot in accordance with endwise movement of said cylinder, a dresser support adjustable toward and from said wheel, and a second linkage connecting said dresser support to said screw for bodily endwise displacement of the latter in aca nut threaded thereon with the nut restrained 6 coma nee with changes in position of said dresser support.

10, In a grinding machine, the combination of a base having awheel support thereon carrying a rotatively driven grinding wheel, a worksupport disposed at one side of said grinding wheel, means mounting said work support on said base for rocking of said work support generally transaxially of said wheel and for translation of said work support in a path generally paralleling the wheel axis, an intermediate support underlying said I work support with the latter resting on the same,

means mounting said intermediate support on said .hasefor movement about a pivotal axis coincident withthe pivotal axis of said work support but with the intermediate support restrained against translation, a screw extending transversely bei neath said intermediate support and having a nut threaded thereon with the nut restrained against rotation, a fluid operated piston rigid with said nut and slidable endwise within a fioatingly mounted cylinder, the admission of pressure fluid to alternate ends or said cylinder serving to displace the latter endwise of said screw, and travel of said nut axially of said screw 'as'an incident to rotation of the latter serving to carry said cylin- -rder in a direction endwise of said screw, size control means for revolving said screw, said interme- -diate support having a depending leg thereon, linkage pivotally connecting saidleg to saidcylinder for rocking of said intermediate support about its pivot in accordance with endwisefin'ovement of said cylinder, a dresser'support adjustable toward and from said wheel,'a second depending leg of a length equal to the first-mentioned one and pivoted to swing on an axis coincident'with the common pivotal axis of said intermediate and work supports, and linkage means interconnecting said dresser support and said screw through said second leg for bodily displacement of said screw in an endwise direction in accordance with changes in position of said dresser support.

AUGUST F. MARKUS.

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