US2596814A - Helical spline grinding machine - Google Patents

Description

May 13, 1952 J. l.. JEssuP 2,596,814

HELICAL SPLINE GRINDING MACHINE Filed Feb. 24, 1949 l5 Sheets-Sheet 1 l l 1 l i F l l I I L t\ m, 1 N l l l 1 l i 1 l #W77 il SEF l I z w q MV Q OQO m l Q 1! #l y d 5 t L x H WH l N35 l A: f *m l H N i fl 2Q l Nk R N w N INVENTOR. /Yef Jszz/v. BY

May 13, 1952 J. L. JEssUP HELICAI.. SPLINE GRINDING MACHINE 15 Sheets-Sheet 2 Filed Feb. 24, 1949 May 13, 1952 J. L. JEssUP 2,596,814

HELICAL SPLINE GRINDING MACHINE Filed Feb. 24, 1949 l5 Sheets-Sheet 5 INVENTOR.

BY EEL. Myw

J. JEssUP 2,596,814

HELICAL. SPLINE GRINDING MACHINE Filed Feb. 24, 1949 l5 Sheets-Sheet 4 5 E W M 2, N/ MNw. ffm manu... wwn t im MNM. www WI WMON Wm m w ,www ,f MM.. @L N vMay 13, 1952 May 13, 1952 J. l.. JEssuP 2,596,814

HELICAL SPLINE GRINDING MACHINE Filed Feb. 24, 1949 15 sheets-sheet 5 May 13, 1952 J. l.. JEssUP 2,596,814

HELICAL SPLINE GRINDING MACHINE Filed Feb. 24, 1949 15. SheeS-Slleel'l 6 May 13, 1952 J. l.. JEssuP 2,596,814

HELICAL SPLINE GRINDING MACHINE Filed Feb. 24, 1949 15 Sheets-Sheet 7 May 13, 1952 J. L.. JEssuP n 2,595,814 HELICAL sPLINE GRINDING MACHINE Filed Feb. 24, 1949 15 sheets-sheet s [I] vs May 13, 1952 J. 1 JEssuP HELICAL. SPLINE GRINDING MACHINE l5 Sheets-Sheet 9 Filed Feb. 24, 1949 xwm,

May 13, 1952 J. L. JEssuP 2,596,814

HELICAL SPLINE GRINDING MACHINE Filed Feb. 24, 1949 15 Sheets-Sheet 10 IN V EN TOR.

479 @.LE. BY

| Afew .3%9//4 vMaly 13, 1952 JESSUP 2,596,814

HELICAL SPLINE GRINDING MACHINE Filed Feb. 24, 1949 15 Sheets-Sheet 1l I l l Eli I N VEN TOR.

May 13, 1952 J. JEssUP HELICAL SPLINE GRINDING MACHINE 15 Sheets-Sheet 12 Filed Feb. 24, 1949 INVENTOR. Jfea' @5yd/y.

May 13, 1952 J. JEssUP HELICAL SPLINE GRINDING MACHINE 15 Sheets-Sheet 15 Filed Feb. 24, 1949 INVENTOR.

BY Mwzm- Am .MM

May 13, 1952 .1. L. JEssuP 2,596,814

HELICAL SPLINE GRINDING MACHINE Fued Feb. 24, 1949 15 sheets-sheet 14 FTTJiV/VEKS May 13, 1952 1 JESSUP 42,596,814

HELICAL SPLINE GRINDING MACHINE Filed Feb. 24, 1949 l5 Sheets-Sheet l5 Q JNVENTOR.

BMQA'Q/fm Patented May 13, 1952 Eo fsf-re regs er j "19 -('Jlaims. (Cl. 51-95) l ,invention .re1ates. genernny .to .grinding machines-.and thelike, ,and v more particularly to faQ-,helical- :spline grinding' machine.

.flt -is-:anoo-j ecttof. 'this `invention tov provide ,a grinding-machined the aforementioned -type in which the lead vbar-.is .connected to and disposed belowa reciprocating worktable so that the overall l'length A-,of the l:machine is materially reduced, as`. co'rxipa red to machines `wherein the lead .bar

is-disposed-:abovethe-work table, and --so' that '1 the lead-,barisi protected against metalchips fromthe wor-k- Tpiece, Y or otherV foreign particles which citen adheretov leadlhars disposed .above the wor-letame.

@It-,is aFfurther-objectof Qthisinventior to pro- 1 generate iinvolute hclicalfsplines von .a work zpiece.

- Its-is a-fsltill further object of this invention to prfwide'zin fa'fg-rinding-machine- .of the-aforemen- .'tioned iltypef la 1 Ldouille .-acting .hack-lash device ,which isfoperably-.connected AtoV the machine 4 lead :bar-isoixas to :remove backlash in the lead har, change ispeedggearingfandwor-k index head, Afor pbotlfridirections v-of -table `reoiprocation.

EIMS-:a still furtherlooject `of this `invention 'to f ,providein-fa grinding amachine of fthe `aforementioneditypefmeansforsynchronizing,the'recipro- :cation-off'rfthefmarketable `with the operation-of the'eaforementionedbacklash device, so that when `'-.tlie-table,reaclfiesffthe end-of each reciprocating vstroke-fthednacklashy devicewillv` be operated :to atake .thel backlash out -of fthemachine -in ythe .prQper'- direction gprior to the reciprocation .f fthecwork-tablein theopposite direction.

nas alstiufrnnther @bientot ltnisiinvention' ktn provide, in a grinding'machine offtheafore'men- .tioned typefagrinding wheel spindle quill', which is-reciprocable -inf-twodire'c'tions on--ar'iti-f-i'iction .bearingsgandf-feed- .screws kfor feeding -the quill .in :both (directions,` -each o f which Yengages and meshes with-lso :as to'rfee'd 'the quillrgrooved #anti-friction rollers Awhich .are connected with dzheifquill, =.wheeby -zto eliminate lorY at -l east .Ina- :terialflyfreduce friction ,arid-lza'clrlashV -i-nthe `.quill operating mechanismsothatthe voperatiomand i' contrer nf the" reaingpf fine"V grinding when is enhanced vlto provide *,an'litiemely accurateand tudient' machine.

-It :is afstill frtherbbject-,fthis invention to provide an improved hydraulic circuitY and ysystem -for .operating the :movable elements ofl the grinding machine.

It `is a still' further object of .this-.invention to provide a grinding machine of' 'the aforementioned v.type which is efficient in operation, exrem'ely accurate in use, and'durable infcon'strucion.

These and other objects of this `invention will ,become Aapparent from the ,following detailddescription takenA in-conju'n'ction .withthe accompam'ing drawings, inV which:

Figures 1 -A and 1-B,- when'placed endto end, ,are longitudinal sectional -views..f the vmachine of this invention, with parts lor'oken away in eiffivaism.-

L.lighl-.zfisfan Venlarged fragmentary sectional .view-of the-structure"illustrated ,in` Fig. l-B, taken along -theflinel 2 2 thereof.

-.Eig.3.-is ranfenlarged fragmentary View, .partly in section vandpar'tly inelevation, -of the strucvture illustrated in Eig. 1"-Bgl taken .along the lline 3T-3 thereof. EigQ 4 isgase-ctinal .View of the'structure illustrated in,1ig'.3, .taken 'along' the linedthereof, with parts .broken away` fr purposes .of clarity. Fig. 5 A is a'fragrnentary 'sectinal'viewof'fthe structilre illustratedin` Fig. '3, Vtaken alongV Mthe line theiei".v

Fig` 6 .iNs-asectional view of the structureillusvtraten@ Fig.:s tnkenniong-the,lin s-ls thereof.

V.7 is'la sectional'view-of `the-"structure illus- Ivtrated .in Fig.=.6 ,takenalong the line .1-:1 thereof.

is a sectional view of the structure illustrated ln -Fig..6, 1tal en along the line 8--8 thereof.

l'gig .-9-isan' enlarged v iew partly-in section vand fpartly in# elevation;v of` the f structure illustrated .-in--Eig'- 1-B ,-ftaken along -theline 9-9- thereof,

with certain parts of the machine illustrated diagrammatically in elevation for purposes of clarity.

Fig. 10 is an enlarged sectional view of the structure illustrated in Fig. 9, taken along the line Ill-I thereof.

Fig. 11 is an enlarged fragmentary sectional view of the structure illustrated in Fig. 9, taken along the line thereof.

Fig. 12 is an enlarged fragmentary elevational .f

view of the structure illustrated in Fig. 11, taken along the line |2|2 thereof.

Fig. 13 is a fragmentary sectional View of the structure illustrated in Fig. 11, taken along the line |3|3 thereof.

Fig. 14 is an enlarged fragmentary sectional view of the structure illustrated in Fig. 9, taken along the line |4|4 thereof.

Fig. l is an enlarged fragmentary sectional view of the structure illustrated in Fig. 1l, taken along the line |5|5 thereof.

Fig. 16 is a View partly in section and partly in elevation of the structure illustrated in Fig. 15, taken along the line |6-I6 thereof.

Fig. 17 is an enlarged fragmentary sectional view of the structure illustrated in Fig. 9, taken Fig. 18 is an enlarged fragmentary side elevational view of the structure illustrated in Fig. l-B, taken within the circle I8 thereon, with parts broken away in section for purposes of clarity.

Fig. 19 is an enlarged sectional view of the structure illustrated in Fig. l-A, taken along the line |9|9 thereof.

Fig. 20 is a sectional view of the structure illustrated in Fig. 19, taken along the line 20-20 thereof.

Fig. 21 is an enlarged sectional view of the structure illustrated in Fig. l-B, taken along the line 2|-,-2I thereof.

Fig. 22is an enlarged sectional view of the structure illustrated in Fig. 9, taken along the line 22-22 thereof.

Fig. 23 is a vertical section through the Work index head shown in Fig. 1-A.

Fig. 24 is a fragmentary sectional view of the structure illustrated in Fig. 23, taken along the line 24--24 thereof.

Fig.'25 is a diagrammatical view of the hydraulic circuit and operating mechanism of the machine of this invention.

Referring now to the drawings, it will be seen that thergrinding machine of this invention includesl a base or supporting structure 21,V which is enclosed by a housing, including side walls 29. A reciprocable work table 3| is slidably supported on the top of the base 21 in ways 33 and 35. A vertical column 31, in which is housed the operating and supporting mechanism forY a grinding wheel 38, extendsupwardly above the base 21, rearwardly of the reciprocating work table 3|, and is supported on Athe base in any suitable manner. A tail stock 39 for supporting one end of a work piece 40, is adjustably mounted in an inverted T slot 42, on the reciprocable work table 3|, in a conventional manner, and includes (Fig. 18) .a housing 4|, having an axially movable center 44. A shaft 43 is journalled in the housing 4| and carries a worm 41 on ythe inner end thereof, which meshes with a rack 49, formed on the underside of the center 4|. A hand wheel 48 is connected to the outer end of the shaft 43 for operating the latter, and the pointed end of the center engages and supports one end'of the work piece 40, as shown in Figs. 1-A and 1-B. A coolant pump 5| and tank 52 are mounted in the base 21 for supplying coolant to the work piece during the grinding operation in a conventional manner, and a coolant drain trough 53 and passageways 54 are provided in the base for returning used coolant to its reservoir tank.

A work indexing head 55 is rigidly mounted on the work table 3| adjacent one end thereof and in spaced relation to the tail stock 39. The work indexing head is described in detail in the applicants Patent No. 2,528,753 relating to Improvements in Index Head for Rotary spindles, and includes generally a housing or base 51 having a sleeve 59 journalled in the rear portion thereof (Figs. 23 and 24). A drive shaft 6| is rotatably supported in the sleeve 59 and the rear end thereof projects outwardly through one end of the housing for connection to suitable gearing, as will be hereinafter described. A second sleeve 63 is supported in the front portion of the housing, in coaxial relationship with respect to the sleeve 59, and a spindle 65 is rotatably supported in the'sleeve 63 and has a center 61 detachably connected thereto. An indexing mechanism 68, which includes an 'indexing plate 69 and a plunger 10 carried on worm gear shaft 1I, is supported in the housing 5'1 for indexing the spindle 65 relative to the drive shaft 6|. 'Ihe spindle drive shaft BI, indexing mechanism 99 and spindle 65 are inter-connected by means of differential gearing 12, so that the spindle 65 can be driven by the drive shaft 6| independently of the indexingmechanism and so that the spindle can be indexed relative to the drive shaft ylil by the indexing mechanism 68, even while the spindle is being driven by the drive shaft. The spindle center 61 is adapted to engage the opposite end of the work piece 40 from that engaged by the tail stock center and a dog type clamp 13 is provided, in a conventional manner, for driving the work between the spindle and tailstock centers, as will be hereinafter described.

In order to reciprocate the work table 3 I, a hydraulic piston and cylinder unit 15 is provided, which includes a movable cylinder 11 and a pair of stationary adjacent pistons 19 and 8|, which have outwardly extending hollow piston rods 83 and 85, respectively, connected thereto. The rods 83 and 85 have openings 86 in the walls thereof, adjacent their respective pistons, for a reason which will appear. The outer ends of the piston rods 83 and 85 are threadably connected in blocklike plates 81, which -in turn are supported in vertical ribs Yor bulkheads 89 of the base 21. Fluid conduits 9| and 93 are threadably connected to the block-like plates 81 so as to communicate with the outer ends of the piston rods 8| and 83 respectively. The conduits 9| and 93 are connected to a work table reversing valve 95, in a manner which will be hereinafter described. A hydraulic iiuid reservoir or tank 99 is built into the bottom of the base 21 and a hydraulic pump |0| is supported above the tank 99 and has a suitable intake pipe or conduit 03 extending into the tank.

The right hand end of the cylinder 15, as viewed in Fig. l-B, extends through an angle bracket |05 and has an annular shoulder |99 on the end thereof, which is connected to the vertical leg of the bracket |85, by any suitable means. The upper horizontal portion of the bracket |05 is connected to the under side of the reciprocating work table 3| by suitable means such as key |1 and cap screws |01; 'The piston'rod extends outwardly throughasuitable -s'e'al"-an'd'end"cap in the cylinder, 'for cor'n'iez'ztion nto" the 'plateiSI "The opposite fend f Lthe "cylin- "der I 5 44is s'lidably "supported in fthe Vertical `por- `vti'o'nv of an angle"bracket I I I., 'Which is` similar fto thebracket r`Hl 5; 'and the "piston rodvll 8% extends 'outwardly' through' af suitable's'eal v'l I3 v-andiend cap I I5 `in the" cylinder end'for -c'onnexcticn to lits plate 81. The upper horizontal-portion of the angle' bracket' II I `"is A'connected to the -under-side IVof the recipro'oable-work "table 31 A"by any suit able m'eans' such as "capl 'screws AIii-'I and a` key 'I'I`I. v"I'herefore, when -hydra'ulicfluid -fis Iforced vunder pressure into, for example," 'the piston Arod lfiigitovvs through the rod 135 and into 'the-cylinder through the" opening""8-5; adjacentlitsinner `end,Wliile"^any *fluid'iin' the opposite-'endof the cylinder '15 flows .out "or" :the cylinder through `the `vopeningt adjacentlthe"innerl'endof the -piston rod 83,'through'the piston rodi-'Baandback 'to the"control'valve-"$5= through ithe conduit "S, thenceto thepil reservoirg. Theinduction Aof 'pressurizedliquidiinto'onepiston 'rod'or theA other causes the movement of lthe cylinder' =in lone vcli- "rec'tion' or'the "'oth'en and vwhen i the vcylinder `and"`work' tablehave reached oneend Yof' `'their stroke; rtheir direction -ofr'n'ovemen't uis' reversed, in amanner whichvvill be' here'ina'fter described., so that'reciprocationof the'^wo1l "table 4is 'obtained. Thus, "by "hydraulically 4operating' the cylinder ''the work'table is recipro'cated and "the Work piece:ltlj'the'y indexing headset `and 'tailstoclos'g are moved'ba'ck and "forth lacross the "base In order'to` control theileng'th of Athe'reciprocating strokes" of the' Work' table-3Iyafrack |23 is mounted lonlthe front 'Taceof` the Work ltable and has 'a .pair Yofstop 'members' 1'25 movably positioned thereon. l'The stops 125 carry pau/ls I2'| which `are 'adapted lto engage 'the rack 'teeth in any"predeterminedposition. The stops '|25 'also Acarry 'dogsiI'ZB thereon-'f and ythe lposition 'of the dogs can Ybe "adjusted by lmeans oiadjusting 'screws ISI. lThe dogs IZQ-arevadapted to engage a'lever 'element I'33 on the `reversing valve-S5 'so -as' to causeV ashifting of the mechanism Vin *the* valve 'Whichywill in turn vreverse the' `-iow "of 'hydraulic uid from one piston rod 83 -or #to the other, in-amanner which AWilljbe herein- "after described. UAn''additionalfstopv 1131 is -carried `on the rack YI-23 -and 4is-fadaptedto 'engage the upperend -ofla'lever or 'fnger Imember its, -which-isconnected to a shaftcIHv I(Figl 2'). The I'shaft 11H-is rotatably supported in-the basegand has a depending nger for lever -I4-3Jconnected 'to the-'opposite Yend thereof. 'The finger-for'flever I 43 vis :adapted to engage la :plunger i fl rof the -valve 95, so as-tostop lthe moveinentoi thework Itable-'When it is-moving -frcm left to right as fviewediin Fig. 18. 'This.arrangementpermits the tablefwhenlit has va'grindingWheel dresser -.there- Aon, to be fmoved to a `predetermined position, beyond the end Aofthe reciprocating stroke, so as to bring the dresser Yup. to Lthe. wheel. I This Scan 'be accomplished by manuallyraisingfdog =l2i so that'the'table Willlnotreverse,!but will bestopped fwhen the stop I`3'I` engages thelleverelement'ls.

vAfter the dressing operation .ithesreciprocation can 'again be lstartedlrlziyactuating .the valve manuali-control handle M6 and vother .mecha- 'ni-sms. vas vvill be *hereinafterl described.

' As -the grinding "machine of this :invention vis primarily designed-'to grind helical splinesvitfis V-pro`i`1ided-with means for rotating `the spindle in synchronism with jthe reciprocations of thework e Atable. The preferred- Inechanismf `for this pur- 'pose is a helical :lead-bar elementfand acooperatting nut-j-element, either lone ofmwhichirnay ibe mounted on the base of* the "machine-andthe other rotatably journalled on the table-endop- Ieratively connected -to vthe Aindexing `head spindle.

Work table 3i. Theright lhand end of the -lead `barlll'l, AasI besti`seenin^Fig."leB, `is rotatably 'supported intheangle member' "m5 by meansof bearings* II and Abearing supporting means 'The opposite-end V'of' the lead 'bar =I @il -is rotatably supported'in the angle memberill Vby means 'of bearings' 157, andprojects therethrough, vrse Vas to oarrya gear I S'on the-extreme end thereo'f; 'beyondthe anglewrneniber Hl. The leadbar I'l'there'fore recipro'eates with `the cylinder Ve i and 'the work tableSI. In'order tri-impart 'rota- 'and thrust bearings T83.

tion to the leadbar vduring itsreciprocatioir'a pair "of longitudinallyspaced -nutstl -and itil are' "provided, which engage 'the "leadbar 'fi and are rigidly connectedV to the 'opposite 'ends "or van annular 'sleeve "''by means'oic cap 'screws (Figi 5'). Theisleeve'ldhas argear lformed on one 'endthere'o' and "thegear `Iiuneshes vWith the teeth of a rack' Ill, which `isl settued 'to a rnernb'c-:r H5; for reasons which will hereinafterappear. The sleeve M33 is'rotatably'supportedinahousing I'Iby means oranti-friction bearings I i9. The sleeve is secured against long'itudinalmovementin the housing I'IS by 'means 'of the gear portion JIE5? of the s1'eeve,'a"nut 81 Therefore, While" 'the lead bar nuts |59 and 161 "are rotatable and adljustable 'for 'certain purposes, 'as"wi1l behereinafter 'brought' out, they are stationaryY during the longitudinal 'movement' of the Vlead bar and 'thereby' impartrota'tion .to 'the lead bar vduring l 'its movement.

"Theleft hand end of theieadbar es?, asvievve in lFig.' l-A, 'is connectedV to' the Work Aindexing "head drive shaft and'i'o't'ating spindle 6l 'and 65,

"[91.' 'Gears vIS'I and I9? are rotatably connected t9 an adjustable arm or .bracket Issey suitable internally disposed bearings. The arm or bracket ISB isjjournalled at its lowerend on a hub member IBD, vvhi'oh is secured to the angle member Hl,

and'is adjustably connected to a vertical end Wall I9 I" o'fthe Work table 3l by means of a cap screw H33," which extends through'an elongated 'slet I 95111 the arm. This assembly forms a reversing device"whih`may`be used to loharnge the hand of apait'being'ground, that is,` to produce a' right or 'left"hand-helixv as desired regardle's tot `the number"of"gears in the change gear system or the hand'of the master lead bar. 'It shouldbe noted thatthe gearslld |81 and |91 all have 1/1 and thus does not enter into the calculations of the change gearing to produce a desired lead on the part being produced. By loosening cap screw |93, the arm |89 can be pivoted to permit meshing either gear |81 or |91 with the interchangeable gearing represented by gears |99, 20|, 203, and other gears to be hereinafter described. One of an infinite variety of gearing is represented in Fig. 19, in which gear |99 meshes with the small gear 20| of a gear cluster 203, and the large gear 205 of the cluster meshes with the small gear 201 of a gear cluster 209. The large gear 2|| of the cluster 209 meshes with a gear 2|3, which is carried on the end of the indexing head drive shaft 6|. The gear clusters 203 and 209 are journalled on a fan shaped supporting bracket or arm 2 I9, and the arm or bracket 2 9 is pivotally supported on the drive shaft supporting hub portion 22| of indexing head housing. The mounting shafts or bolts 2 I4 for the gear clusters 203 and 209 extend through elongated slots 2|5 and 2|1 respectively in the bracket 2|9, so that various sized gears may be-employed when de. sired. The arm or bracket 2|9 is provided With additional slots so that the size and number of the change speed gears can be changed. It will thus be seen that the lead bar is connected to .the drive shaft and rotating spindle of the informed on a work piece through a variance of the change speed gearing arrangement.

In order to protect the lead bar and the other operating mechanisms of the machine, which are disposed beneath the work table from dust, dirt, chips, or other foreign particles, a canvas strip 225 is provided. One end of the strip 225 is connected to a sheet metal housing 221 which is disposed over the change speed gearing |85 and extends outwardly and over a roller 228 which is supported on the base adjacent one end thereof by means of a bracket 229. The opposite end of the canvas strip is wound around a drum 23| which is supported on the bracket 229 by a pair of narrow canvas belts 233. The drum 23| is composed of a shaft 232, an outer AShell and two end plates. plates far enough to allow the canvas straps 233 to be attached to it. If the canvas strip 225 is rolled up on the large diameter of the drum before the canvas straps are attached to the l central shaft 232, the entire drum can be supported by the two canvas straps. When the table moves to the right (as shown in Fig. l-A) the canvas strip will be unrolled from drum 23| and in so doing will cause the canvas straps 233 to be rolled up on the shaft 232. As the table moves to the left the weight of the drum will cause it to unroll the canvas straps from around the shaft and reroll the canvas strip on the drum.

Thus the strip is always under a tension propor- Shaft 232 etxends beyond the end tend to cause wear or damage thereto. Likewise, it will be appreciated that as the lead bar is disposed beneath the Work table, rather than above the base and longitudinally outwardly of the work table, as in most conventional machines, the length of the machine is materially reduced and is approximately forty percent shorter than machines which have the lead bar mounted above the base, and on the work table.

In the event that there is any leakage of the hydraulic fluid from the reciprocating cylinders 'l5 or any drippage from the lead bar |41, the base is provided with a Ipair of longitudinally spaced and longitudinally extending, inwardly and downwardly inclined plates 231 and 239, which direct such fluid into a trap or sump 24|, which surrounds and is adjacent to the reservoir tank 99. The side Walls 29 of the base are provided with plugged apertures 243 at the bottom thereof, adjacent to the sump or trap 24| so that any sediment in the leaked uid can be easily removed. In the event that there is a considerable amount of leakage in the hydraulic system, there is no danger of the fluid overowing and spilling onto the floor, due to the fact that when the level of the liquid in the sump or trap rises to the level of the top of the reservoir tank 99, it will flow into the reservoir tank and will be recirculated through the hydraulic system. Any sediment in the leaked fluid Will have had a chance to settle to the bottom of the sump 0r trap before the fluid overflows into the tank. In this way a neat and eflicient manner of handling any fluid which may leak is provided, without the danger of any foreign particles or sediment getting back into the hydraulic system.

One of the most prevalent diilculties in grinding machines has been that of inaccuracies due to backlash which is set up in the lead bar, the work indexing head and the connections therebetween. It will be appreciated that with the machine of this invention, due to the change speed gearing connection between the lead bar and the spindle of the indexing head, a great amount of backlash would ordinarily be present.

rIhis machine is therefore provided with a double acting backlash device 245, which removes all of the backlash between the lead bar nuts and the rotating spindle 55 of the work indexing head. This machine is, therefore, extremely accurate and the work piece will be properly indexed, by an exact predetermined amount, during the reciprocation of the work table. This machine thus grinds work pieces much more accurately than has been lheretofore possible.

The double acting backlash device 245 is shown in detail in Figs. V3 through 8, and comprises a housing 241, which includes a cylinder 249, having polygonally shaped members 25| sleeved on and vwelded to each endthereof. End caps 253 are connected to each end of the housing 241, by means of cap screws 255, which extend through and are threadably connected to the sleeved members 25|. The housing 241 is connected to a slide 251 by means of cap screws 259. The slide 251 is slidably mounted in a dovetail way 26| of a plate member 263. The plate member 263 in turn is connected to a slide 265 by means of Vcap screws 261, and the slide 265 is slidably mounted in a dovetail way 269 in a plate member 21| forming a part of the base of the machine. The slides 251 and 255 may move relative to each other for purposes which will hereinafter appear. The slide 251 is a part of the rack supporting member |15, which is connected to the rack |1|.

messia In. this way when the housing# 4.1 and ,the Slide.

25.11 move.. the rack |1|` will likewise.be..move.d so-.as to. rotate the gear|61 formedon theend of, the .sleeve member |63,.which in turnw-ill. lio:y

tate.the .lead bar nuts. |59 and l-GI.. in 0r.der.. to eliminate backlash, as will ,hereinafter appear.`

DisposedI within the. cylinder 2.49,. are.. a.. pair, ofV end toend piston rods. 2].5wand 2.1.1. Theinnll end ofthe piston rod'. 2.15,' formed wth .a threaded .end portion 2.1.9 which iits.intlc` .v a.A

threaded. aperture'28| inthe.. innerendj ofthe.

rod 2.1.1.y and thev two rods .are immovably .cnnnected together. in an endV to. end.relationship,by`

meansoi taper pin 283-, sothatin effectasingle.

pistonrodis provided.. The. adjacent. inner .ends

offtherods 215 and 2,11. are externallyllhreadedtontothe threaded .portion 28,1",of1the rodjy 2111.'

The pistons 29| and 293 arel bore ttingpistons within the.cylinder 249 andare provided with* a.. plurality. of .pistonrings or seals, 39|', inv a conventimial manner.

The piston. rods 2 15 .and 211.'extend outwardlythrough their respective pistons and through bores 3.93' which are. provided' in inwardly extending, shank portions. 335 Aofi ,the end caps I253; as well vas through seals3.01""and' seal' retainers 309, which are carried in theouter ends ofi-the` end caps 253. 'I'he inner ends vof the shank'pgntions 305 of the endcaps253extendf inwardly.

through apertures 309'v in .the rear-or outer-wall'- ofthe pistons 29|Y and 293,- so 'that` the-cylinder- 249 and shank portions. 30.5 vare free to slide 1011- gitudinally. with respectto the pistons-f The .outer periphery of each .end cap Hshank 305-is formedj with a pluralityA of circumferentially spaced spline spaces 3|'01for-:a reason-thatwillvv hereinafter appear, and the wall ,of-` each .piston which denes `apertures 309' 'has apair- -of'opposed splines 3`|2 which slidably*engagea pair-of' the spline spaces 310 for retaining lthe pistons against rotation, but permitting-relative -axialj movement `between the end vcaps v and pistons.- Themovement of the cylinder relative to the pistons 29| and .293- is lmitedfbytheshank portions- 305 ofthe end-caps. For eXample-when-t-he cylinder moves to the left; the extent-,ofits movement is limited by the yengagement of the shoulder of the piston 293, adjacentthe threadedaperture 291,1 with the shank portion-305 of the end cap-253. The same piston -andshank abutment will occur when the pistons moveto the rightand the piston 29| will engage the adjacent shank portion 305.v

The outer end of the piston rod- 211,-outward-ly of the housing- 241, is journalledl in an aperture 3|`|, in-a rib or plate 3|3 of the base (Fig. 3)-, and aknurled handle or knob -3-|-5 is--secured to the outer end of; the rod for turning-the same.V The outerend of, the rod ,215 extends-,outwardly -beyond the opposite vend of the housing 241,and is rotatably supported in a` journal block or bracket 3 1. The block 3 |1, in turn, is supported on, and rigidly connected to,` the plate 263 bymeans yoi capscrews 3|9. The plate 263 is, of course, ind turnrigidly connected to the second slide 255.

valve 95 or to the tank side thereof, in accordance is. held. against axial, movement with respect thereto bamcans. `of; collar members 32| and nutsv 32.3... Therefore, whenthe knurled handle 3|5, ontheendof. the. r.0d 21.1, isrotated, pistons 2 9 I and 293 will" be rotated and will` move axiallywithin., the cylinder 249.. As the threaded por-- tions on the. inner ends ofthe. piston rods-are ofthe opposite hand, the pistonswi-llx be eithermovedtaward or away from each other-so that the. extentof relativemovement between the cylinder and pistonscan be adjustably controlled;

The..backlash.device is. connected in` the hydraulicsystemoithemachine in a manner which; willbehereinafter described, so that it will operate only at. the endofeach reciprocating stroke ofthe table. Avhydraulic passageway head-or block 325.. isattached von, one end of the cylinder 249eanda similar block 325" is secured to the opposite endof the cylinder 249. The |block 325 andcylinder end member 25| are provided with` afluid passageway 321-, which. has va conduitV 329` connected to the outer endfthereof', and whichcommunicates .at its inner. endrwith'an .aperture 33|. in the wallolicylinder 249. The conduit- 329- is Y connectedto .either .the pressure side `,ofy the with the positioningof certain yalve means which will be hereinafterk described.. The wall aperture 33|. is .disposed .adjacent to but forwardly ofthe rear portion. of-lthe endjcap shank` 39.5 so 4that when. the, piston293 moves rearwardly or -outwardly, thatistoward the left` as viewed in Fig.V 6;- theaperture 33| will be closedv by the. piston. outwardlyv or .rearwardly of the passageway 321-,

` thel block, 325 and. .cylinder endmember. .25 v.are

provided with a. passageway .333," which extends parallel toy the .passageway 321 andwhich khas its4 outer end .normally closedby acheck valve which includes a ball 335 and a spring 331, anditsinner end-communicating with, an aperture 338i in the wall otcylinden 2.4.9.. The free end of the spring 331 extends through. the cylinder wall andaouts a-portion ofthe .ends cap 253, outwardly or rearwardlyof thepshankportion 305.l The. passageway 32-1v isV connected. with the. passageway 333,

' outwardly-ofenbeyondthe .bal1.33.5,'by means of apassageway 339.` The passageways 321 and.333 are connected.l inwardlyof thecheckvalve by means ofy a passageway 34|, which communicates with and-extends at right angles tothe passageway.v 321, a passageway 343- which communicates withand extends at right anglesto passageway 333, and a passageway 345. which connects pas.- sageways 34| and 343..

A-meteringpin 341l is` threadably connectedn to the block 325: andsecuredby-a lock .nut 349. The

The outer endv of the pistonrod2'|5, while being inner endof the-.pin extendsinto the passageway 34-5.- The outer end of the pin 341 is provided with -a k-nu-rled handle-.350 to-permit the pin to .be threaded into 01' outA of the block-3325 so as..to. adjust -thef--posi-tion of-theinner end-of the pin` in the passageway-,345 and-therebycontrol-the flow ofv i-ud, through the passageway 345. The block 325' onfthe opposite end of the cylinder ,is constructed inthe` same manner as the vblock 3.25 previously descrbcdand corresponding parts of the lblock 32 5f: are` indicated by primednumbers. corresponding to thenumbers employed ,in connectionwith the description ofthe block 325.

Invoperation, when it isdesired to actuate the backlash device, theA piston rod 'handle 3 I5 isA turned so as topoosition the pistons 29| and 293V ina desiredrelatipnship withrespect to the cylinder anl gthe"shankportion 395 ofA the cylinder end caps;- that ie,- the pistons are positioned 'so that

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