US2347283A - Means for dressing grinding wheels - Google Patents

Description

April 25, 1944. w. F. ROSS 2,347,283

MEANS FOR DRESSING GRINDING WHEELS Original Filed Oct. 30, 1939 6 Sheets-Sheet l A ORNEY.

April 25, 1944. w. F. ROSS MEANS FOR DRESSING GRINDING WHEELS 6 Sheets-Sheet 2' Original Filed Oct. 30, 1959 J Y O E 5 m m w m m T Y W 3 Q a K m @Q LR Y B Qfi 0 Q J 3 O Q G 9% 5 E lam & R

April 25,- 1944. w, E oss 2,347,283

MEANS FOR DRESSING GRINDING WHEELS Original Filed Oct. 50, 1959 6 Sheets-Sheet 3 Fig. 4.

' M ATTORNEY.

April 25, 1944. w. F. ROSS MEANS FOR DRESSING GRINDING WHEELS Original Filed Oct. 30, 1939 6 Sheets-Sheet 4 lm wwrliii 11-1! Ill V V ||1||1| 1 I: .h....u...|......... llll 1 W V M April 25, 1944. w. E oss 2,347,283

MEANS FOR DRESSING GRINDING WHEELS Original. Filed Oct. 50, 1939 6 Sheets-Sheet 5 Mwm.

April 25, 1944. w.'F. ROSS 2,347,283

MEANS FOR DRESSING GRINDING WHEELS Original Filed Oct. 30, 1939 6 Sheets-Sheet 6 Patented Apr. 25,

1 STATES PATENT OFFICE t actress f i Walter FL Ross, Detroit, Mich.

Original application October 30,1939, Serial No. 301,918, now Patent No. 2,307,238, dated Janu; aryB, 1943. Divided andth-is application June 3, 1940, Serial No. 338,492

2 Claims. (o 12,5-11) This invention relates to apparatus for the 7 dressing of grindingwheels ior the finish forming of gear teeth, lobes or similar forms,- and to the method of producing the form of abrasive wheel; this application being a division of my copending application, Serial No. 301,918, filed Octo'ber 30, 1939, which matured as Patent N 0. 2,307,- 238, January 3, 1943. The said invention has for its object to provide for the'production of a form.

of grinding wheel which-will lend itself to the finish forming of gear teeth, and so forth; in such manner that gears or forms of great perfection and tooth or formed surface fidelity, both as to contour and spacing, may be produced, such gears and forms as a result having a correspondingly higher degree of practicalstrength with noiseless operation, and being capable of production practically without restriction as to tooth or other form.

An .important object of the Said invention is to provide a main grinding wheel having a thread formed thereon in such amanner that the section of the wheel face taken normal to the helix is-the conjugate of the normal pitch-of the gear being ground and which is accurate and specifically adaptedto the contour of each specific size, style, and space of tooth; and which is further adapted to progressively grind the full .form of a dresser wheel, and the recessing of such form bysaid dresser wheel in the surface of the grind ing wheel as a helix having the normal pitch of the normal pitch of the teeth to be ground in the work. The invention also contemplates formation of such helical grinding wheel with a face width of some whole multiple ,of the helix lead as a means of insuring running balance,

Still further objects or advantages subsidiary to result from the aforesaid objects, or from -the construction or operation of the invention as it may be carried into effect, will become apparent as the said invention is hereinafter further dis-' closed.

In carrying the said invention into efiect, I may provide a gear or form grinding machine comprising, in general, a large rectangular base structure having mounted-on the center portion a main,

grinding wheel characterized by its being provided .55 Figure 4.

135 form of tooth section, by pantograph control with a helical thread of a cross section at right anglestto the lead thereof which is the conjugate rack of the normal pitch of the gear to .be ground; and in advance'of said grinding .wheel a dresser wheel driven by a small motor mounted for adjustment toangular positions about a horizontal axis at right angles through the axis of rotation of the dresser wheel, whereby said dresser wheel may be set at an angle equivalent to the helix angle to be dressed on the main grinding wheel.

Suitable mechanismis provided to effect the movement of the dressing wheel in a direction parallel to the axis of the main grinding wheel to adjustable limits in either direction, and to efiect its movement into and out of working position relative to thesaid main grinding wheel at opposite ends of its working travel, much in the manner of the action of a threading tool when used in a lathe. Means for progressively feeding the dresser wheel into the grinding wheel to promote the dressing out are also provided.

For the formation of the required contour of the margin of the dressing wheel in order that it may produce the proper helix section on the main grinding wheel, I may provide on the forward end of the machine a pantograph mechanism adapted to translate the template-controlled motion of a tracer disc into reduced motion of a. dressin diamond which-may he-moved up to the aforementioned dresser wheel -to efiect its dressing, the diamond-being accurately lapped and polished, in so fara's its-active edge is concerned, to a circular cross section whose diameter is a'fraction (say, one-tenth) of that of the'tracer disc.

A- template having the form of the rack tooth space to be ground by the main grinding wheel, and in the same proportion as the tracer disc is to the diamond (say, 10 times the section) is suitably mounted on the machine for guidance of the dresser wheel by the said diamond.

In carrying the said invention into effect, I,

' ,may utilize the novel construction and arrangement of parts hereinafter described, by way of example, having reference to the accompanying embodying the said invention.

Figure 2 is a plan of the same. Figur 3 is a side elevation of the same.- Figure 4 is 'a vertical 'section of the same taken on a plane indicated by the line 4-4 in Figure 2.

Figure 5 is a horizontal section of the same taken on a plane indicated by the line 55 in j ments shown in Figure 9.

- and of the feed'screw 36. the previously described elements mounted thereon 'is movable tail hereinaften. I I

' From the foregoing arrangementoi slides, it

Figure 6 is a detail sectional view illustrating the adjustable mounting of the dresser wheel feed screw.

Figure 7 is a horizontal "section of the machine taken on a plane indicated by the line 1-1 in Figure 4.

Figure 8- is a diagram illustrating the pantograph linkage associated with the form templet.

- Figure 9 illustrates in larger scale detail and in plan the abrading wheel shown in. association with the dressing wheel and also in association 'withagear to befinishformed; and

' Figure 10 is a detail -front elevation of Similar characters of reference indicate similar parts in the several figures of the drawings.

"Certain supporting structure which would interfere with a. clear illustration of the mechanism and whichis. not necessary to an understanding 1 thereof is eliminated from some of the sectional illustrations of thedrawings.

The machine, as illustrated, is'part of a comthe eleplete machine for the finish forming of gears and,

so forth, more extensively described in my 00'- pending application, Serial No. 301,918, filed October 30, 1939, the description andillustration inthis application bein confined to that mechalel thereto 'and adjustable transversely of the machine in ways 24 by a manual feed screw 25.

Positioned, on the machine in advance of the ,main'grinding wheel 2| is a dresser wheel 26 mounted on thespindle 21 of a motor 28, which motor is carried by an arcuate. member 29 for swinging movement about-the center of the dresser wheel 26 by virtue of its being rotatable marcuate ways 30 of a quadrant support 3|.

' Also carried bythe motor support member 29 is a pantograph table 32, movabl'e on the said mem-' ber 29 towards andirom the dresser wheel 26 by means of the manually operable adjustin shaft 33 through the -medium of gears 34 and 35 The quadrant support 3| and longitudinally and transverselyof the machine by reason of its being in turn provided with a saddle :3], adjustable lengthwise of the machine example, all of these adjustments and movements are for convenience associated with' the said dresser wheel 26, the main grinding wheel 2| in this case beingnon-adjustably mounted on the machine, except insofar as the manual cross feed by the said screw 25 is concerned. Thi cross feed of the main grinding wheel 2|.- doesnot,

however, have'any bearing on the relationship with the dresser wheel 26. and is simply used on occasion in connection with the the grinding of work in the machine by the said main abrasive grinding wheel. a

The said main grinding wheel 2] is intended to'be driven at a-high speed in onedirectionwhen performing-its ear grinding operation and receiving its power from the main motor '41, but

'when the thread is being formed on the main grinding wheel 2| by the dresser wheel 26 it is driven in alternately changing directions at low* speed receiving its power from a smaller auxil-- iary motor 48 which isshown in this case as being situated exterior to the base structure of the-ma chine; the selection of the drive to the,main.

grinding wheel being controlled by a manually operable clutch according to requirements.

When the said main grinding wl'i e1 2| is being driven for the grinding of work, it receives its ,power, from the main motor 41 through the medium of Reeves gear 49, main pulley 50, belt 5|, pul- I ley 52 and clutch member 53 which rotates with the shaft 54 and is moved into engagement with the said pulley 52 by means of a clutch operating rod55lunder the influence of the clutch handle 56 by suitable belt crank linkage "(not shown).

Said shaft 54 in turn transmits the power through v the pulley-51 and belt 58 to the large pulley 59 of the main grinding wheel spindle'22."

. 6D is the Reeves gear control and wheel which,

2 through the shafts 6|, Hand 63, suitably geared togetherfcontrols the regulation of the said Reevesgear, in the manner well known, tofin- 7' crease or diminish the speed ofthe main grind on the 'slide 39 by means of the manual adjusting screw 38. The said slide member.39 is also car- 'ried by a saddle 46 transversely movable of'the machine on a cross slide 4| undertheinfiuence of a feed screw 42 engaging in a nut '43 on the -underside of the said saddle 40, which mean of operating the saidfeed screw 42 being later referred to; v

. The cross slide 4| is also capable of reciprocation in the direction-of the length of the ma chine by virtue of-its being mounted 'onthe longi- 3 tudinally slidable'member '44 which receives its motion from a pinion 45 engaging a rack 46 on the underside or the said slidable member 44, as

' best seen in Figure 5, the source'of operationof' the said pinion 45 being also referred to in de will .be seen that provision is made whereby the dresser wheel 25 and the main abrasive grinding ,wheel 2|, are movable relative to each-other in practically all directionaand in .the illustrated ing wheel within reasonable limitations to suit varying degrees of wheelhardness or abrasive 'quality, or to meet variable grinding conditions,

such as differing gear'hardness, andso forth.

' Nominally it is proposed to proportion the pulleys and the motor speed of 3600 R. P. M. and a grinding wheel spindle speed oi -1800 R. P. M. al-

though, of course, grinding wheel spindle speed, beyond that permitted by regulation of the Reeves gear, may be simply effected by varying relative sizes ofthe pulleys 51 and 59'.

The main grinding wheel 2| which it is proposed to use in the finish forming of gear teeth through the agency of suitably timed'mechanism' (nbt shown) operating the work 64,'is intended to have a characteristic helical thread formed there- ,on which in section transverse of the lead angle is the conjugate rack for the gear or'work to be ground considered relation to the normal pitch of such gear; and in producing the said form on the said main grinding wheel 2 it is preferably first rough chased on.an enginelathe, in relation to certain key ways-(not shown) in the wheel hub in order to save time in the dressing operation about to be described.

The dressing operation is effected-by the dresser wheel 26 'in the form of a'; disk of emery or the like, having its marginal'portion'formedin cross section as the, reverseor counterpart of the space ing of the conjugate rack of the gear to be ground.

This cross'sectional form of the margin of the dressing wheel 26 it is proposed toproduce bythe pantograph mechanism which'will be later described. v

After the rough chased grinding wheel 2i has been mounted on the grinding'wheel spindle 22,

' shaft 82 bar is directed through, gears 93 and shaft 94 to such mechanism as may be pro- .vided for controlling the operation ofthe work 64) and connects the shaft 95 through its bevel gears with the shaft 96 operated from the grinding wheel spindle 22, which shaft 95 through gears 91 and 98, shaft 99 and change gears I00, IOI, I02, and I03, operates the dresser travel feed shaft I05 to the inner socket end I06 of which the squared extension I01 of the dresser travel feed screw '42 reciprocally engages. This feed screw 42 is manually adjustable axially. of the feed I5 and obtains its rotation from one or other of bevel pinions I6 and lL'either of which pinions may be coupled to a drive shaft I8 by a sliding dog clutch 19 keyed to the said shaft I8.

The clutch I9 is actuated by a clutch shifting member 80 located-between compression springs 8| and 82 and is slidable onthe rod 83, in one or other direction as one or other of the said compression springs is loaded beyond a determined degree, a system common in load and trip mechanisms. 84 is a spring loading fork the arms of which travel on the said rod 83 and are intended to alternately depress the said springs BI and 82 under the influence of a reciprocating bar 85 connected to the lower end of a lever 86 pivoted The shaft I8, operating the forward and reverse pinions I6 and I1, receives its power from the auxiliary motor 48 through the shaft 88 and -worm and worm wheel 89 and 90, Thus, during wheel 26 is driven independently by its own high speed motor 28. By adjusting the angle of the arcuate member 29 of the dresser wheel motor mounting, the plane of the dresser wheel 26 may be set to the helix angle which it is desired to form on the main grinding wheel 2 I, which is governed by the normal pitch as related to the diameter of the wheel 2 I, and which has preferably been already roughed out on an engine lathe as stated; and by mea'nsof the manual dresser wheel feed screw 38, the said dresser wheel 26 is moved up into dressing position in the roughed-out groove of the grinding wheel 2|. The dresser wheel 26 and the grinding whee1'2I being then rotated by the motor- 28 and 48, respectively, in the accepted relative directions for efllcient dressing of the grinding wheel 2|, the said dresser wheel 26 is given a motion similar to that of a threading tool when used in a lathe, the dresser wheel 26 traversing the main grinding wheel face at a controlled rate of travel to generate in the walls of the roughed-out groove the desired threadformation, dropping back at the end of the travel to clear the grinding wheel face, then returning to its starting point'and being advanced to its pre-determined dressing position, following which the dresser wheel 26 again traverses the wheel face, and so on, until the cycle is stopped by the operator. It will be understood that as the cycle is repeated, the dresser wheel 26 is progressively advanced into the work, as required, by operation of the said dresser wheel feed screw 38.

This lath like action of the dresser wheel 26 is secured by throwing the clutch 9| into position where it isdisconnected from the shaft 92 (which shaft I05 by means of an adjusting screw I08 independently rotatable on an extension spindle I09 of the said feed screw 42 and threaded into one end of the slide 4|, whereby rotation of thesaid adjusting screw I08 will effect longitudinal movement as a whole of the feed screw 42. This effects corresponding adjustment of the dresser wheel 26 crosswise of the machine by virtue of the said wheel 26 being movable with the slide 40 coupled to the said feed screw 42 by the nut 43. Thus the operation of the said manual adjusting screw I08 serves to determine the lateral adjustment of the dresser wheel 26 to the roughed-out groove of the main grinding wheel 2I.with which the said dresser wheel 26 is to match. To effect such matching the main grinding wheel cross feed screw 25 may' also-be utilized, if desired.

When the dresser wheel travel feed screw 42 is rotated in one or other direction. the nut 48 travels along the said feed screw 42 until an extension IIO on the said nut 43 strikes the inner end .of one or. other of stops III or II2 which stops are threaded for adjustment into sleeves II3 and II4 slidably movable in the slide M and connected to the opposite ends of a link H5 attached to the upper end of the pivoted lever 86. Such contact of the nut extensionl I0 with the stop I or I I2, as the dresser wheel 26 completes its forward travel, or its return stroke, causes the said lever 86 to swing in one or other direction about its pivot 81 and, through the connecting rod 85 and fork 84, snap the reverse clutch I9 out of engagement with one of the pinions I6 or IT and into engagement with the other of said pinions. In'this manner the direction of rotation of the main grinding wheel spindle 22 as well as the direction of rotation of the grinding wheel travel feed screw 42 is reversed.

As the lateral working travel of the dresser wheel 26 is completed in grinding the groove in the main grinding wheel 2 I, as described, and the connecting rod is operated to reverse the motions and effect the return'of the dresser wheel 26 to the beginning of its stroke, it is desirable to withdraw the dresser wheel 26 from the work prior to such return stroke. This may be effected by any suitable mechanism and for the purposes of illustration the connecting rod 85 is shown as being provided with an arm I I6 connected by a rod III to a cam plate II8 mounted for longitudinal'movement by the said rod I II. The lobes II9 of the said cam plate II8 are arranged to effect the movement of a plate I20 at right angles to the movement of the said cam plate H8, as will be readily understood, and, as this plate I20 is connected to the end of a swinging arm |2l on the lower end of the shaft I22 carrying the pinion 45, it will be apparent that such movement of the said plate I20 will result in the rotation of the said pinion 45 in one or other direction according to the direction of movement of the said plate I20. The lobes of the cam plate II8 are intended to be so disposed that through the linkeifect the motion of the rack 46 and the dresser wheel carrying lide 44- to withdraw the dresser wheel 26 from the work as required at the end of each working stroke, and also to advance the wheel 26 to the said work prior to the beginningage described and the said pinion 45 they will duction of the diameter of the main grinding wheel 2I is made, the normal pitch of the thread being maintained, the lead angle and the actual lead increases in a definite-proportion which can be readily calculated, so that the change gears lul IIII, I02, and I03 -or their equivalent are intended to be correspondingly selected or operated to produce the required proportional feed of the feed shaft .42. Therefore, this feed will be determined by the normal pitch form of the dresser wheel and the angularity to which it is set.

Figures 9-and 10' howmore particularly, the relationship of the dresser wheel 26, the main grinding wheel2I and the work 64, and it will be noted that the main grinding wheel is characterized by a formed helical thread I40 having a pitch measured at right angles to the lead of the thread, as distinguished from the usual method of measuring the pitch of a screw on a line parallel to its axis. Inthe example, this pitch is that of thenormal pitch of the teeth I4I to be ground on the said gear. 64. (The gear in this case being a spur gear, the normal pitch is also thatof the circularpitch, but in the case of a helical gear, such would not be the case, as is well recognized in the art.)

I am aware that it has been in the past broadly forming to the lead, would not. comply with the thread; form herein described. Myabrasive wheel is thus characterized by a helicoidal rack generated on the surface of an abrasive cylinder; and having a cross section taken normal to the thread which is the conjugate rack section of the gear form in a plane normal to the gear teeth to be produced. v In Figure 10, the line 0. indicate the angle to which the axis of the dresser wheel is tilted relative to the direction of feed indicated by the line b to produce the thread form shown on the abrasive wheel I0, and the line 0 indicates the plane.

at right angles tothe normal pitch of the gear I3 which, in this case being a spur gear, happens also to be the circular pitch of the gear. I Of course, it will be'understood that this abrasive wheel readily lends itself to precise modification a to thread section to meet modifications as to tooth form required in the finished work.,

The described abrasive wheel especially lendsitself to the form finishing after hardening of helical gears which heretofore, due to present methods of work, have involved considerable exand vaguely suggestedthat an abrasive wheel with a helical grinding thread thereon might be used for the purpose of grinding gear teeth and,

where extreme accuracy is of secondary importance, such a wheel might be so employed, but

. ithas been generally assumed that thethread on the'abrasive wheel might be produced or formed ther, 'it'has been suggested to utilize an abrading by a cutter travelling parallel to the axis of the wheel asin the ordinary,screw threading process, or by means of.dressing disks rotating in a plane transverse of that of the abrading wheel. 'Furwheel having its .thread produced by fiat-faced dressing disks extremely limited as to the form ofthread they are able to produce.

The. thread form'of my abrasive wheel 2I is however that produced by the dresser Wheel 26, the marginalportions I42 of which has sides which are the counterpart of the conjugate rack of the tooth to be ground on the work, the said dresser wheel 2I being presented to the abrasive wheel in aplane corresponding to the lead angle of the thread being formed on a dresser wheel. This produces a groove which is the true counterpart of the cross sectional form of the dresser wheel periphery when this contour of the groove said tracer will move ina line directly towards or. from the axis of the dresser wheel 26 but in a i viewed in a plane at right angles to the lead as distinguished from a plane coincident with the axis of the abrasive wheel. Consequently the a resulting form of tooth which such abrasive wheel may produce on the gear or work is directly conjuga'te to the thread form of the periphery of the dresser .wheel, which would not be the case were a conjugate ,ra-ck form tool of any type presented to the abrasive wheel other than at an angle conpense in determining the extent to which such helical teeth tend to straighten out as a result of the hardening process, and it-has been common practice to make such helical gears with'the teeth initially of greater angle than the final angle to be attained, this very often entailing highly expensive cut-and-try operations with simple gears before the satisfactory result for any particular gear could be obtained. The use of applicants improved abrading wheel as the implement for form finishing such gears after hardening, renders unnecessary this expensive and time-consuming preliminary experimental, work.

Means arev provided for dressing the contour of the counterpart of the conjugate rack form dresser wheel 26 to that of the rack to be eventually ground on the main grinding wheel ZI, such a means including the well-known pantograph motion, the principle of which does not need to be -dwelt upon at length; I23 and I24 being the parallel links connecting the "shorter arm I25 to the longer or tracing-arm I26 which 'termi-.

'nates in the dressing disk I21 which is attach- I29 is the fixed able to the terminal pin I28. point (in the form of a pin carried by the pantograph saddle 32 of the machine) relative to which thepantograph system of levers may be manually moved by means of the handle I30. suitably located on the-said tracer arm I26. The link I24 carries an upstanding tracer mount I3I which supports the tracer I32, in this case a wheel dressing diamond, in such' position that upon the operation of the pantograph the relation to the plane 'ofthe .dresser wheel-26 determined'by the movement of the'dressing disk With the pantograph proportions taken forthis example, the amplitude of movement of the tracer I32 is one-tenth cf'that of the tracing disk. Therefore, to produce the desired contour dresser by the tracer I32 on the periphery of the dresser wheel- 26 I mount, in a pre-determined position on a. suitablesupporting extension-I33 of the saddle 32, a template I34 ten times the size of the form to be ground on the dresser wheel 26. .The dressing disk used: in that case is also ten times the diameter of the active portion of the tracer diamond I32, and, the' dressing disk I21 and the tracer I32 being both circular so far as their active edges are concerned, the contour of the template will be faithfully reproduced to the required scale by the tracer I32 in dressing the periphery of the dresser wheel 26. In order that a correct setting of the diamond I32 may be readily determined, a location hole I35 is provided in the template I34 to receive the said pin I28 so that the pivot I29,.

center of diamond I32 and center of the disk I21 may be in alignment when the pantograph elements are set in a neutral relationship as indicated in Figure 8.

The pantograph saddle 32 is adjustable towards and from the dresser wheel 26 by means of the hand screw 33, and is carried by and movable in all directions of adjustment with the dresser wheel motor mounting 29. Thus the tracer I32 may be brought into any desired setting relative to the dresser wheel 26 to properly perform its wheel-dressing function, and readily withdrawn from such setting when its purpose has been accomplished.

As the invention herein described is not limited in its application to the grinding of abrasive wheels for the form finishing of gear teeth forms alone, it is desired that herein and in the claims, the word gear" shall be deemed to broadly include toothed, lobed and splined forms, eventhe finish forming of gear and other lobed forms,

a dresser wheel angularly adjustable and movable relative to the said grinding wheel to form a thread thereon, a pantograph-operated dressing tool for dressing the periphery of said dresser wheel, and a pantograph-guiding template having the enlarged form of the counterpart of the conjugate rack of the work which the grinding wheel is intended to grind, said pantographoperated dressing tool and said template being swingable with said dresser wheel about an axis passing through the center of said dresser wheel.

2. In combination with a grinding wheel for the finish forming of gear and other lobed forms, a dresser wheel movable relative to said grinding wheel to form a thread on said grinding wheel, a pantograph, a cutter operated by said pantograph for dressing the periphery of said dresser wheel, and an' enlarged template formed in counterpart of the conjugate rack of the work to be ground by the grinding wheel, said template guiding said pantograph to efiect.the dressing of the periphery of said dresser wheel to a contour corresponding to said template whereby said dresser wheel may in turn form a thread on said grinding wheel the cross-sectional form of which thread will be the conjugate rack of the work to be ground thereby, said grinding wheel being adjustably tiltable about a line transverse to its axis, said dresser wheel being adjustably tiltable with and to said grinding wheel about such line, and said pantograph and its template being swingable with said dresser wheel about said line.-

WALTER F. R033.

Images