US2449372A - Compensating abrasive wheel dressing machine - Google Patents

Description

Sept. 1948. e. F. EGLINTON .ETAL 4 2,449,372

COMPENSATING ABRASIVE WHEEL DRESSING MACHINE Filed .Nov. 15, 1944 4 Sheets-Sheet 1 INV NTO .GEORGE E EGIENTO I J DONALD J. WOODWORTH ATTORNEYS Se t. 14, 1948. I e. F. EGLINTON ETAL 2,449,372

' COMPENSATING ABRASIVE WHEEL DRESSING MACHINE Filed NOV. 15, 1944 4 SheebS-Sheet Z O INVENTORS I O GEORGE E EGLINT ON 0 By DONALD J. woo WORTH ATTORNEYS COMPENSATING ABRASIVE WHEEL DRESSING MACHINE Filed Nov. 15, 1944 Sept. 14, 1948.- e. F.IEGLINTON ETAL' 4 Sheets-Sheet 3 TON NALD J. WOODWORTH INVENTORS GEORGE F EGLIN DO ATTORN EYS Sept. 14, 1948, e. F. EGLINTON ETAL 2,449,372

COMPENSATING ABRASIVE WHEEL DRESSING MACHINE Filed NOV. 15, 1944 4 Sheets-Sheet 4 1 E: 4. JNVENmRs GEORGE E EGLINTON D ONALD J; WOODWOR'ITH ATTORN EYS Patented Sept. 14, 1948 i COMPENSATING ABRASIVE WHEEL DRESSING MACHINE n George F. Egli nton LincolnPark and Donald J. 7 Woodworth, Detroit, Mich., assignors to Lincoln Park Industries, Inc., Lincoln Park; Mich., acorporation of Michigan 1 a 3 g a Application November 15, 1944;seria1 No. 563.474 1 UNITED TA ES T NT OFFICE 13 Claims. 1

The present invention relates to a compensating abrasive wheel dressing machine for forming, dressing or truingthe operative faces of grinding wheels used in form grinding. More particularly,the present invention provides a compensating Wheel-dressing machine adapted for the grinding ortruing within close precision limits of abrasive wheels, such for example as diamond impregnated wheels, utilized 'in grinding high precision forms in a work piece.

In the particular embodiment herein disclosed the machineof the present invention is designed to dress the grinding edge of an abrasive wheel utilized in the precision grinding British standard threads on a high precision thread gauge. In 'suchuse, it is essential thatthe shape and dimensions of the grinding wheel be maintained to the desired shape within close precision limits. Thisis accomplished by first dressing the grinding surface of the grinding wheel to the desired shape and thereafter by performing truin operations thereon to maintain the desired working form within the desired limits. In the instance just mentioned, a diamond impregnated abrasive wheel is employed as the grinding wheel to grind the desiredthread form into the body of the gauge member which is formed of a hard wear resisting material, such for example as tungsten carbide. The grinding wheel edge is dressedto provide angularly inclined cutting faces thereon which J'oin each other in a small radius to forman arcuate circumferential edge on said wheel. When such a wheel is employed for grinding the body of the gauge, the thread form which results from its use has inclined side portions joined in an arcuate bottom portion corre-' sponding to the shape of the dressed or trued grinding surfaces of the grinding wheel. It is to be understood however, that th machine of the present invention is a universal type machine'and angle relative diameter of the said dressing wheel as a result of may be utilized either to dress or true the grind ing'form surface of any type of abrasive grinding wheel.

The'present application is related to Patent No. 2,373,882 in the name of George F. Eglinton, owned by our common assignee.

It is an object of the present invention to provide a compensating abrasive wheel dressing machine characterized particularly by its accuracy in operation,its relative simplicity of structure and design and its ready adaptability to the grinding or truing of abrasive wheels having different shaped grinding edges, and by means of which the? shaped grinding edge is uniformly dressed or' trued to a desired form within close precision limits, M

A further object of the present invention is to provide a compensating Wheel dressing machine in which the dressing wheel is moved through a, fixed dressing cycle at a uniform wheel dressing pressureand, if desired, at an adjustably fixed berm, which is provided said turning operations.

i Other objects of this invention will appear in the following description and appended claims, referencebeing had to the accompanyingdrawings forming a part of this specification where in likereference characters ponding parts in the several views.

In the drawings: y

Fig. 1 is atop plan view of a compensating wheel dressing machine embodying the present invention showing the wheel truing tool and carrier in a removed position.

Fig. 2 is aside view partially inelevation and partially in vertical section takensubstantially on the line 2-2, Fig. 1,in the direction of the arrows butshowing the Wheel truing tool in its wheel truing position. y

Fig. 3 is an elevation of the right hand end of the machine as shown in Fig. 1 but showing the Wheel truing tool in its wheel truing position,

Fig. 4 is an elevation of the left handend of the machine as shown in Fig. 1. t

Before explaining in detail the present invention,-itls to be understood that the invention is not limited in its application to the details of construction and arrangementoi parts illustrat ed in the accompanying drawingssince the invention is capable of other embodiments and of being practiced or carried out in various ways. Also itis to be understood that the phraseology or terminologyemployed herein is for the purpose iof description and not of limitation.

A compensating wheel dressing machine of the present invention may be constructed for operation either as a single independent wheel dressing unit or it may be mountedand used as a permanent sub-assembly on a grinding. machine. either instance it will bemounted on a base memwith arcuate guideways II. A hollow subbase, i2 is carriedgon arcuate slides 13, which areseated in the arcuate guide ways I I for movement therein. A fixed table I 4 is secured to the top of the sub-base l2, and is provided with guideways l5. A transversely movable table It is mounted on the slides 17,

which are carried by ball bearingsjld'and the guidewaysliofthe fixed table [4. The tran'sversely movable table i6 is provided with guide- Ways l9 whose axes extend at right angles to the designate corresaxes of the. slides i7: 1 The guideways' l9 aredoi the same construction as the guideways I5.

A longitudinally movable table is mounted ways 15, slides i1, and ball :bearingsJB, The: longitudinally movable tableifl is provided: with;

a flanged end 22 on which is mounted-a fixedtvertical guideway 23, in which is mounted a reciprocating slide 24, to which is secured the housing. 25 of a high speed grinding spindle 2b. The high speed grinding spindle 26 is lubricatedh' any suitable type of lubricating device as for example an (pileup-39;

The guideway 23 and reciprocating slidefdii'z are of the same ball bearingsuspensiom type previously described connection; with the ways 1-?! and slide iii. The slide-24:15.reciprocated inthe guideway 23 by a; connecting rod. 2 which is pivotally connected ;as+at 28; with-a walkingbeam 29: having acentral pivot 30:- on' a. bracket: 31. mounted on the flangezz.

The walking beam 29- isdriven by an. electric" motor 32 which is mounted-one motor mounting bracket 33 secured to the topic-f. the-table -28. Theimotor 32 is connected. through-reduct on gearsin a gear housing 34 with a cam shaft 35 having-aneccentric cam 36 thereon; A connecting rod '31- is connected with the eccentric cam 36. and-is .pivotally connected at the .p oint. 3'8rwith the end of the walking beamfifi; Theconnectingrod 31 causes the walking beam zfi to-irock about its centralpivot 3 fiasit isrecipnocated by-the action of the eccentric-camsh- The rocking motion of the walking boame it causes. the slide 24 and spindle housing 25 and spindle.lfix-to-berreciproe cated vertically in the g-uideways 23.

.Adressing wheel iaismoun-ted on the lower end of the-high speed: grinding spindleJZii. At the upper end of the high speed grinding spindle. 28 a drive pulley M is provided. Thedrivegpul ley dl is power driven through. acflexiblezbeitm bye-motor 43 havin a motor. drive .pulley ld.

The motor 13 is mounted on a motor mounting bracket -45 (see-Fig. '1 which is pivotally. mounted at one end on a motor bracket. super-ting, rod 46. carried by the longitudinally movable table 29'; IA belt. tensioning screw 41. .is provided, in; the opposite end of the bracket 115 and-engages the end of the bracket liaand-the endrofz a. second motor bracket supporting rod 48 carried by the. longitudinally movable table iilr This permits: an. adjustable support-of the'end of the-said. bracket 45 while permitting a pivotal. adjustment. thereoflto. maintain proper tensionon-thebelt -42.

"Fromthe "foregoing it will be seen that the dressing wheel Gbjiss'imultaneoufly .rpower driven by the motor 2 3 to effect its rotation about a.

verticalfaxi's and at the same time isbodily r'ecipr'oca'ted'vertically'by the'motor32. The dress,- ing "wheel 40 'is so "operated at all times during the wheel dressing'operation in order that "the dressing or truin'g action of the dressing wheel dil -will be; uniform at all points on the edge to be .trued. or dressed on thegrindingwheel 5B.- The vertical reciprocation of :theirh'tating wheel 40 against the edgeof.theirotating grindingwvfneel 50 permits the generation, dressing or truing' thereof within much closer precisionslimitsnthan is possible by the use of a. dressing. wheel. "which. rotates without a bodily vertical reciprocation. The form which is to'lbe generated dressed or true'd' on the edge of the grinding, wheel 50. is determined by ithe .loiigi'tudinal and transverse movement of the dressing wheel #01 This is offected by coordinating the longitudinal movement of the table 2i) and the transverse movement of the transversely movable table IE to produce the desired direction and amount of longitudinal and transverse movement of the dressing wheel All, Thisis accomplished by the table guide and feed mechanism now to be described.

On one end of the fixed table i4 there is secured-a guide cam 5! whose contour is developed to. produce movement of the tables l6 and 20 and to move the dressing wheel 40 in a path to correspond to the desired shape of theworking edge of the grinding wheel 350. A fixed bracket 52 having vertical guidew-aysv (not shown), issecured to a flange 53 on theend.of-"thelongitudbnally movable'table 28. A moyable-bracketziAi-s. mounted on the fixedbr-acket 52-. by meahstot a. slide portion 55 which is engaged in therventicali guideways of the fixedbracket52. The-movable: bracket 54 is adjustably moved relative. to the. fixedbrack-et. 52 by an adjusting. screw 55, which. is nested in a portion of thefixed .braeketand has a screw threaded engagement with or screw. threaded recess 51 in the movable bracket-54. Adjustmentof the bracket 54 isr-accomplishedi by rotating the screw 56 by means of. a knurled? calibrated adjusting knob'58.

The movable bracket 54. .is provided. a. forkiednendfiii in; which :a frusto-corricali, cam .fiol lowerfl isrotatably mountedonashaztt 62. The: upper end of the shaft 62 is. secured thebodt of the movable bracket 5 and 'itslower endds mounted in the lower .arm of. the iorkedend 510i and extends downwardly therefrom to a. point. below the saidforked end-50 of the bracketsfll.

As shown in Fig. 2, the surfaces of. the follower 6] have a-rolling contact.with 'theiswfaces of the cam 51., which as here-shown are. preferably inclined to match the. inclination of. the surfaces of the cam .follower .61.. The-largest. diameter of the cam follower Si in the present.- embodiment corresponds tot-he initial diameter .of the dressing wheel ea, .or thelargestdiameter dressing wheel at which will-be used with: the machine. Thesmalles-t diameter of the oamiollower 6;! corresponds to the smalllestd-i-ameteriof. the dressing wheel. lib, or. the diameter of: the smallest dressing wheelv Iii] which. will;he.-ut1-li-Zed. with the machine.

As shown inFigs. 2 and Y3, thedress'ingwhell 4.0 is trued by a .diamondset wheelltruing tool 65., which .is. mounted in .a .s'lidable carrier 65,, mounted on. .the lower .face .0: therfixed vertical. guideway '23. The carrier 55 permits bodily movement of the wheel trui'ng tool .fi-5..substan tially at right angles to the axis of the spindle. Zfi-in order to bring. the. tool 65. intoandout of wheeltruing contact with the grinding edgeot the dressing wheel till. .Asshown iniFigr 1,. the. wheel truing tool 6.5. andthe carrier BB isisholwn as r'emovedtfrom the lower face .01 Lthe..v.erltical. guideway 23 in order that .the paiits, thereof may be more clearly shown. As there a.

knurled calibrated adjusting knob "61 .is connected with a screw .68 toimovea-wedge member 69 against an inclinedisurface 69A of the carrier 66'. Any other type .of'suitablemechanismmay be employed to advance or. retract the. sliilable. carrier 68 and the diamond set twine-00135 with respect to the dressing wheel dfl'. Thisaconstruction is. suchthat the dressing wheel may be either trued intermittentlyr'from t'imeto by the manual. advancement orretractionioithe. truing .tool 65. If desired, thetruing .61 the.

dressing wheel 40 may be effected simultaneously with the dressing of the grinding wheel 50 but the intermittent truing of the dressing wheel 40 is to be preferred.

The calibrations of the knob 51 and the knob 58 are preferably coordinated in such a manner that when the wheel truing operation is completed, a reading of the calibrations of the knob 61 may be taken and provide the basis for the adjustment of the knob 58 to correspond thereto. The adjustment of the knob 58 rotates the bracket adjusting screw 56 and moves the movable bracket 54 to bring into contact with the cam 5| a surface of the cam follower 6| having approximately the same diameter as thediameter of the trued dressing wheel 40. Thus any change in the diameter of the dressing'wheel 40 may be compensated for by adjustment of the cam follower 6| relative to the cam 5|. This same adjustment may be madeto accommodate either larger or smaller dressing wheels on the high speed spindle 26.

Movement of the cam follower '6| relative to the cam 5| effects longitudinal movement of the table 20 and transverse movement of the table Hi. In the embodiment here shown, the cam follower BI is moved by manually actuated means but it is to be understood that any other suitable means may be employed. A satisfactory manually actuated mechanism is here shown and includes a crank Wheel 1|! secured to a rotatable shaft II which is journaled in a gear housing 12 secured to the hollow sub-base I2. A reversible worm gear" is secured to the rotatable shaft II and meshes with a p nion gear 14 fixed to a vertical shaft 15 journaled at one end in gear housing 12, and at the other end in a vertically spaced flange 16 secured to the gear housing 12. The vertical shaft 1'5 is rotatably driven by the worm 13' and pinion 14 in either direction by corresponding rotation of the shaft A cross-head bracket I1 is secured to the shaft II by a key 18. Parallel guiderods 19 and 80 are secured to the cross-head bracket 11 and extend outwardly therefrom substantially at right angles thereto. The parallel guide rods I9 and 80 are connected at their opposite ends by a cross-arm 8|. A slide bracket 82 is slidably mounted on the guide rods 19 and 80, and is connected with the depending lower end of the shaft 62. Suitable spring tensioning members 83 are provided to hold the slide bracket 82 in a suitable position and prevent its unintended movement on the guide rods 19 and 80. i

The guide rods 19 and 80 and the slide bracket 82 are moved as a unit in an arcuate path upon rotation of the shaft 15 in response to rotation of the crank wheel 10. This causes the shaft 62 to travel also through an arcuate path carrying with it the bracket 54 and the cam follower 6|.

The cam contacting surfaces of the cam follower 6| are maintained in surface contact with the cam BI and are prevented by the spring tensioning members 83 from moving out of contact therewith. As the cam follower 6| is moved by the arcuate movement of the guide rods 19 and table It to effect its transverse movement it required by the shape of the cam 5|. Thus the cam follower BI and the cam 5| determines the direction and extent of movement of the tables 20 and I6 and consequently the direction and extent of the path traveled by the rotatingand reciprocating dressing wheel 40 during the wheel dressing operation, this path corresponding in shape and size to the contour of the surface to be dressed or trued by the dressing wheel 40.

In certain instances it is desirable to dress a grinding wheel surface having a helix angle formed therein. This is a common occurrence when dressing grinding wheels which are employed in, thread grinding operations. In order to dress such a grinding surface the entire wheel dressing assembly is tilted by movement of the arcuate slides l3 in the arcuate guideways H which movement may be adjusted and controlled in any desired manner. A fixed indicator 84 (Fig. 3) is provided adjacent a segment 85 of a protractor scale which is mounted on the tilting sub-base l2. As here shown, the wheeldressing machine is set at zero to provide for dressing an edge on a grinding wheel without a helix angle thereon. The parts are held in this position by an adjusting screw and clamp member 86.

In dressing the grinding edge of a grinding wheel utilizing the machine of the present invention, the grinding wheel 5|! is rotated on its spindle and the dressing wheel 48 is brought: into contact therewith. While the grinding wheel 50 is rotated, the dressing wheel 40 is, rotated about its vertical axis and is bodily reciprocated in a vertical plane against the surface thereof at the sametime the dressing wheel 40 is moved in a predetermined path either to dress or true the desired contour on the edge of the grinding wheel. The movement of the dressing wheel 40 in a predetermined path is accomplished, as previously described, by the operator manually rotating the crank wheel 10. 'When the crank wheel 10 has been rotated in one; direction to complete the travel of the dressing wheel to throughout its full predetermined path in, one direction, the crank wheel 10 is rotated in the opposite direction and the cycle is reversed.

It is to be understoodthat while a machine of the present invention is particularly suited for the uses herein described, it is not expressly limited thereto as it may be readily adapted for numerous uses of a similar orrelated nature by slight modifications and adjustments which may be readily effected by any mechanic skilled in the mounted on said table for vertical reciprocation relative thereto, and power means for simultane ously rotating and reciprocating said spindleand dressing wheel vertically relative to-the grinding wheel to be dressed, and means for moving said table longitudinally and transverselyof said base in a predetermined path and including a fixed cam on said base, a cam follower secured to said table, and means for movingsaid camfollower relative to said cam.

:52. A:compensatinagrinclingiwheelgdresseraoomprisingeaibase; aiita'lole mounted rforrlongitudinal iandztransverse reciprooatiomnelative.zto saidbase,

a rotatal'nle dressing dwlieel earriedaon a :spindle mounted-on said tablefor" vertical :reciprocation --relative thereto,'land:powerimeans for simultaneously rotating and: reciprocating sai'd--spind1e= and :olres'singwvheelwerticailly relative'nto the' grinding-vvheel to be dressed, and-means for moving said 'tablelongitudinally: and transversely. of s'aid base in: a predetermined path and incliJd-ing t a fixe'ol -cam on ssaidabase, i a cam follower secured to said ta-ble, and means for moving said -cam follower relativeito saifd oam, said fixed :cam having a contour corresponding to the contour of the working surface of a grinding wheel to be comprisingi a:base;:-a stable mountedfforilongitu- "clinal a-ndtran'sverse reciprocation relative tolsai'd base, a:rotatablew dressing .wheelvcarried on a spindle-mountedon-zs'ai'd tablei foralvertical. reciprocation relative ithereto, .-and power pmeans :for

simultaneously rotating zxarrd' reciprocating :sa'id spindle andrdressingr Wheel, and: means for mov- 'ingsaid table longitudinally andv transversely 10f said base in a predetermined path and including :a "fixed cam :on. said'loase, a cam f.o'llower'"secured to-sai'd -:tab1e,' means forz-movingsaidrcam followerr relative" to; said:cam, said: cam follower icomprising ma .rfrusto-conieal ".EIOHBI -rotat-ably 'mou'nteda innaibracket :monntedronssai-d -tablej-for vertical :rmovem'ent: relativestheneto, --,:a nd;; adj ustable-:means *forrmoyin-g 1*.said :braoket vertically relativemto sai'd "table into ompensate for variations; in :thev diameten dzxd essing :wheel.

.ffiilsAcompensating r ding;

m Lint-e 'pr sin saaxrbasecai a l or; .fii i lidinal -and:tra=nsvers e: reciprocationrela vet tosaicl base, i;

rrotatableaklressingowlieel carried on, a fsl pinidle mountedeon. -said rtable; tro wertita reciprocation relative:tneretompower; means for simultaneously rotating and reoiprooatlngtsaidspindle and clr essing wheel, and means for moving said table longitudinally and transversely of saidmbase in a .predeterm-inedpath andiincluding ,a flxed cam on said basal-a cam. follower secured to ,said ,talole,

means for movingtsaid 90am; follower, relative ,to-

said: cam, said fixed cam having Ha contour..developed; ,in relatio-nnto the contour v of thenworlging surface ofia grinding-wheeltolbe dressed. a dsaid icam follovveri (comprising ;a itrusto coniml roller rotatablv-um unted 'nia loracketmoun-te'dsonsaid table for =vertical neoiprocation.relative, thereto.

6. Aloompensating grindingwheeldresser comprising a rbase,=.;a table mounted Z for dongitudinal and transverse reciprocation relative gto-said base, a rotatable: dressingr wlieel'acarried ona a. -spindle mounted on said table for vertiealireqiprooation 275 relatiyeatneretownewer meansior simultaneously rotatin sand ireiei-prooatin said pindl dressing"whee1;iand.1mean :fommow lasai a e develope'dain: relation torthe contour-or the -.worl I line I surface 1, 01; a :sgrind-ing r :wheel to be :dressed, :said ;;cam:'follower.rcomnrising 3a.: frustoeconical roller tICtata/bLyi mounted: in; a braoket rmounted on said table lf-or :vertioal' movement -:relative thereto; and t-adjustable 1 meansfor -moving :said bracket irve'rticallyrelative ::to said table :to 100mpensateifor variations j in :the diameter z of i said dressing Wheel.

'27. A compensatinggrintlingwhee1 (dresser comprising :a base, azt'able mountedzfonzlongitudinal and: transversesreciprocation:rel'ativeiltozsaidibase, a rotatab1e::.--dressingitvvheelzz carried on "a: spindle mounted on said table for. vertical-reciprocation relative thereto; power meanslfor:simultaneously rotating :and meciprocating. said "spindle.- and 'dressing'tvheel; means f or: movingisaidctable; longitudinallylandxtransverselyj of said-la ase ima predetermined :path and;z-inoluding zarifixedcam "on said base, i a :cam:ifollowerzsebuned etc; :5 aiid stable. means for :moving saircli:czam'ifollower relative .gto .sai'd acam, and :meansjfor: adiustablvriturningxsaid table ;.about .1 its, longitudinal :axis T170 p,ermit ;:s;ai;d e sin wheelie;dres z elielixaneie; orrthe Worki'n' rrsurface of ithegnmdmg wheel o b dressed- E418. :Aocomnensatinac indinsnwheel res mom n s xaibasas :itableim -untedf nlone tud nal and; transverse: 'rec-iprocationrelative oi saidi base, a' rotatable siresfiingiw arr ied:.0n a pindl mountedgonzsaid"ta le for;1verticalareciproca i n relativerythereto;(power grneans i-f or simnltaneously rotating rand re ipro in sai :spin le and dressing wheel, l ans f rmovi es sai t ble, 101 igitudinally; and ansversely;-;of, said-.base-dn a predetermined; pathyandjincluding a fixed scam QmSaiJd: base,-; aucam FfOHOWBIrSBGLIITQdjtQ said: table, means -for movin saida- ;cam -i o llower -relative to :said cam, 11821511 ifixed camwl a-ying 3%..6011130111 -cleveloped: r.e1ation:to-;th r on u of th work n surface of a:-grinding-;:whee1. to be .clressedesaid cam :fioiiower; comprising i a frnsto-iconioals rroller rotatably mounted-in ajaracket-mounte isaid stable ifor: vertical movement r l iva ther o, a means ion adinstahlytumme said .tab-l ra o t itswlen itzud-l xisutonermi r aid-l essins wh l to dress a hel J 11 81: .qn the WQIkiQEiSHIfBfiEnOf thee-findin wh l; .iheidress d- 19.; A comnensa inesgrindine W e l. dress comnrisin -iarase .aa l in ed -l n itu ina l-andiztran verserre pr a iont elativ rtozsaidl ase, a otatabl :dressi ve rw e l-rear ied' on a spind .mountedionssai-dltal le o v ic l r ci roc t on relative theret powenmeans iforwsimul n us- 'lyirritatin .rand:v re p o atin -:s id.- $n n nd workin zwrfaee, ofiagrindin iwheel tolbe dress'ed,

"said Ucam: follower .v comprising lea frosts-conical roller. rotataolyl, mounted r. in. a bracket, mounted onsaid table. for vertical movementrelative, there,- to and adjustable, meansfor movin said-bracket .yertically relative itolrsaid table .ito. compensate for variations in the diameter of said dressing wheel, and means for adjustably turning said table about its longitudinal axis to permit said dressing wheel to dress a helix angle on the working surface of the grinding wheel to be dressed.

10. A compensating grindin wheel dresser comprising a base, a table mounted for longitudinal and transverse reciprocation relative to said base, a rotatable dressing wheel carried on a spindle mounted on said table for vertical reciprocation relative thereto, power means for simultaneously rotating and reciprocating said spindle and dressing wheel, means for moving said table longitudinally and transversely of said base in a predetermined path and including a fixed cam on said base, a cam follower secured to said table, and means for moving said cam follower relative to said cam, and an adjustably mounted wheel truing tool for truing said dressing wheel and including a calibrated adjustment means for adjustably feeding the said truing tool to said dressing wheel during the truing operation'.

11. A compensating grinding wheel dresser comprising a base, a table mounted for longitudinal and transverse reciprocation relative to said base, a rotatable dressing wheel carried on a spindle mounted on said table for vertical reciprocation relative thereto, power means for simultaneously rotating and reciprocating said spindle and dressing wheel, and means for moving said table longitudinally and transversely of said base in a, predetermined path and including a fixed cam on said base, a cam follower secured to said table, and means for moving said cam follower relative to said cam, said cam follower comprising a frusto-conical, roller rotatably mounted in a bracket mounted on said table for vertical movement relative thereto, adjustable means for moving said bracket vertically relative to said table to compensate for variations in the diameter of said dressingwheel, and an adjustably mounted wheel truing tool for truing said dressing wheel and including a calibrated adjustment means for adjustably feeding the said truing tool to said dressing wheel during the truing operation, said adjustable means for moving said bracket and said tool dressing adjustment means having coordinating calibrations whereby adjustment of said bracket adjusting means may be made by reference to the calibrations of the adjusting means for said truing tool adjustment means, thereby to permit adjustment of said sam follower to compensate directly for changes in the diameter of said dressing wheel due to the truing action of said tru ng tool.

12. A compensating grinding wheel dresser comprising a base, a table mounted for longitudinal and transverse reciprocat on relative to said base, a rotatable dressing wheel carried on a spindle mounted on said table for vertical reciprocation relative thereto, power means for simultaneously rotating and reciprocating said spindle and dressing wheel. means for moving said table longitudinally and transversely of said base in a predetermined path and including a fixed cam on said base, a cam follower secured to said table, means for moving said cam follower relative to said cam, said cam follower comprising a frusto-conical roller rotatably mounted in a bracket mounted on said table for vertical movement relative thereto, and adjustable means for moving said bracket vertically relative to said table to compensate for variations in the diameter of said dressing wheel, means for adjustably turing said table about its longitudinal axis to permit said dressing wheel to dress a helix angle on the Working surface of the grin-ding wheel to be dressed, an adjustably mounted wheel truing tool for truing said dressing wheel and including a calibrated adjustment means for adjustably feeding the said truing tool to said dressing wheel during the truing operation, said adjusting means on said bracket and said tool dressing adjustment means being coordinated in their calibrations whereby adjustment of said bracket adjusting means may be made by direct reference to the adjusting means of said truing tool adjustment means to permit movement of said cam follower to compensate directly for changes in the diameter of said dressing wheel due to the truing thereof by said truing tool.

13. A compensating grinding wheel. dresser comprising a base, a table mounted for longitudinal and transverse reciprocation relative to said base, a rotatable dressing wheel carried on a spindle mounted on said table for vertical reciprocation relative thereto, power means for simultaneously rotating and reciprocating said spindle and dressing wheel and comprising an electric motor for rotating said spindle and dressing wheel, and a separate electric motor for reciprocating said spindle and rotating the dressing wheel in a vertical plane, means for moving said table longitudinally and transversely of said base in a predetermined path, and including a fixed cam on said base, a cam follower secured to said table, means for moving said cam follower relative to said cam. said fixed cam having a contour developed with relation to the contour of the working surface of a grinding wheel to be dressed, said cam follower comprising a frustoconical roller rotatably mounted in a bracket mounted on said table for vertical movement relative thereto, adjustable means for moving said bracket vertically relative to said table to compensate for variations in the diameter of saidv dressing wheel, means for adjustably turning said table about its longitudinal axis to permit said dressing wheel to dress a helix angle on the working surface of the grinding wheel to be dressed, an adjustably mounted wheel truing tool for truing said dressing wheel and including a calibrated adjustment means for adjustably feeding the said truing tool to said dressing wheel during the truing operation. said adjusting means on said bracket and the said adjusting means on said truing tool being calibrated in coordination whereby adjustment of said adjusting means on said bracket may be made by reference to the adjusting means of said wheel truing tool adjustment means, thereby to permit movement of said cam follower relat ve to said cam to compensate directly for changes in the diameter of said dressing wheel due to the action of said truing tool.

GE RGE F. E LINT'ONT. DONALD J. WOODWORTH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,182.362 Fischer May 9, 1916 1,896,533 Vuilleumier Feb. 7, 1933 2,115,908 Fox May :3, 1938 2,331,189 Flygare et al Oct. 5, 1943 numbered patent requiring correction as follows:

; aridethat the said Letters Patent should be read with these corrections therein that Certificate of Correction Patent N 0. 2,449,372. September 14, 1948.

GEORGE F. EGLINTON ET AL.

It is hereby certified that errors appear in the printed specification of the above f Column 2, line 12, for the word turning read trmlng; column 9, line 54, for sam read cam;

thesame may confornfi to the record of the case in the Patent Oflice.

Signed and sealedthis 7th day of December, A. D. 1948.

THOMAS F. MURPHY,

Assistant Commissioner of Patents.

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