US2576201A

US2576201A - Grinding method and machine

Info

Publication number: US2576201A
Application number: US602275A
Authority: US
Inventors: John C Wilson
Original assignee: Thompson Grinder Co
Current assignee: Thompson Grinder Co
Priority date: 1945-06-29
Filing date: 1945-06-29
Publication date: 1951-11-27
Anticipated expiration: 1968-11-27

Description

Nov. 27, 1951 .1. c. WILSON 2,575,201

GRINDING METHOD AND MACHINE Filed June 29, 1945 5 Sheets-Sheet 1 XNVENTOR .J GEN CJMSLQON.

ATTORNEYS Nov. 27, 1951 1 J. c. WILSON 2,576,201

GRINDING ,METHOD AND MACHINE Filed June 29, 1945 5 Sheets-Sheet 2 us g 32- INVENTOR A'TTORNEY'S JOHN C-UQ1LEDN I Nov. 27, 1951 .J. c. WILSON 2,576,201

GRINDING METHOD AND MACHINE Filed June 29, 1945 5 Sheets-Sheet 3 6 r I70 'ecs 0 N 9o 93 INVENTOR ATTORNEY 'S Nov. 27, 1951 J. (3. WILSON 2,576,201

GRINDING METHOD AND MACHINE Filed June 29, 1945 y 5 Sheets-Sheet 4 v I I INVENTOR 20 Jm-m Lwusm ATTORNEY s Nov. 27, 1951 .J. c. WILSON 2,575,201

' GRINDING METHOD AND MACHINE Filed June 29, 1945 1 5 Sheets-Sheet 5 A1 WHEEL MOTOR 154 \Aav V I 3 I64- lz" I66 /TIMING MQTOR 322 B 38 LS 3 Q0 RODUCTION I :RIVE MOTOR 7 I69 4 f INVENTOR JUHN C.UJ1LEDN MASTER ROLL BY DRIVE MOTOR 5 WCQM ATTORNEYS Patented Nov. 27, 1951 GRINDING METHOD AND MACHINE John C. Wilson, Springfield, Ohio, assignor to The Thompson Grinder Company, Springfield, Ohio, a corporation of Ohio Application June 29, 1945, Serial No. 602,275

24 Claims. 1

This invention relates to a method and apparatus for grinding workpieces and is particularly directed to a grinding method employing a crushing type dresser.

In the grinding of workpieces having complex contours or contours Which must be reproduced to a high degree of precision, it has been found that a most satisfactory way of forming the grinding wheel is by crushing it against a formed steel roller which has a cross-sectional configura- A tion identical with that desired to reproduce in the workpieces.

As the wheel is crushed against the dressing roll, the latter gradually wears off until, when the wear exceeds the tolerance limits, it must be replaced with a properly shaped roll. Heretofore, it has been customary for the manufacturer of the grinding machine to supply the rolls with which the purchaser of the machine is to dress the grinding wheel. This involves the shipping of many rolls with its appended hazards and time delays and the necessity of maintaining equivalent standards in two shops, which may be quite remote.

Should the user of the grinding machine desire to shape the rolls in his own plant, it has been necessary heretofore for him to have a cylindrical grinder or its equivalent in order properly to perform this job. Such equipment is very expensive to purchase and maintain.

In either case, it is necessary that the dressing roll be removed from the machine and a new one installed involving a delay period when the grinding machine is out of production.

The principal object of the present invention is to provide a means for overcoming the aforementioned objections so that the grinding machine remains in production substantially continuously. Y

Another object is to provide a method for truing up a crush dressing roll without removing a it from the grinding machine.

Still another object is to provide a grinding machine having a crush dressing roll with a master roll so that the dressing roll may be trued up by the same wheel which it dresses.

Still another object is to provide control means for feeding the wheel and rolls together in order to obtain the best possible dressing result.

The objects of this invention are attained by mounting on a grinder table a master roll of the same configuration as the dressing roll. In operation the wheel is dressed against the dressing roll as often as is desired to maintain the wheel in good condition until the dressing roll has been worn down to one of the tolerance limits. Thereafter, a grinding wheel is dressed by presenting it to the master roll in order to restore the true configuration thereto. Then, the wheel is brought into grinding engagement with the crushing roll while the latter is rotated so that the said configuration is transferred to the dressing roll thus restoring it'to its original condition. With the crushing roll trued up it is possible to use it again for dressing the wheel.

The intermittent use of the master roll gives it long life so that a setup including a master roll and a crushing roll will maintain a grinding machine in operation over a period of time which is several times that which could be obtained if the machine were supplied only with a dressing r011. Furthermore, the limits of accuracy may be maintained at a much higher degree than is possible with a single dressing roll.

The above objects and further objects and advantages of this invention will be more apparent upon reference to the attached drawings, in

which Figure 1 is a perspective view of a grinding machine having a production dressing roll and a master dressing roll;

Figures 2 to 10, inclusive, are diagrammatic views illustrating a typical work cycle involving both of the dressing rolls;

Figure 11 is a sectional view taken substantially along the line of l|--H in Figure 1 illustrating a portion of the mechanism for automatically elevating and lowering the grinding wheel;

Figure 12 is a view taken along the line l2-l2 of Figure 11;

Figure 13 is a plan view showing one arrangement of adjustable stop and limit switch for controlling the down-feed of the grinding wheel;

Figure 14 is a plan view over a typical arrangement for supporting and driving a dressing roll Figure 15 is a side elevation of a somewhat modified arrangement for adjustably supporting a dressing roll;

Figure 16 is a diagrammatic perspective View illustrating a modified arrangement for dressing the grinding wheel and crushing roll during dressing;

Figure 17 is a sectional view taken on the line 11-17 of Figure 16 illustrating an over-running clutch associated therewith; and

Figure 18 is a wirin diagram adapted for controlling the dressing cycle in any one of the modifications.

Referring to the drawings, there is illustrated in Figure 1 a grinding machine which has a 2% bed ID on which is reciprocable a table I2 by motor means which are not shown but which are preferably fluid operable. Suitable controls may be supplied with the motor means for regulatin the speed and direction of travel of the table on the bed.

Secured to the bed or fixedly mounted adjacent thereto is a column I l which slidablysupports a saddle It on ways which precisely guide said saddle in a vertical direction. Horizontally slidable in the saddle IE on the ways I8 is a wheel support structure 20 which. carries; the grinding wheel 22 and its driving motor. The drive shaft of the wheel 22' ismounted in-pr'ecision bearings for accurately controlling the re"-' tation of the said wheel.

Mounted on the bed I2 is a workpiece holding fixture 24 which may comprise a magnetic plate or any other suitable means for rigidlyand accurately securing a workpiece 26 for being D- erated by the'wheel" 22.

Mountedat the right endof the table I2 is-a unit, generally designated 28 which comprises a drive motor 33 and suitable meansfor rotatably supporting a production dressing roll' 32'. The unit 28) is more; particularly shown in Figure 14 wherein it will be seen to comprise a bed 3:: which supports a motor 30 at one end thereof and the roll 32 at" the other endthereof; The

.roll; 32 is journalled in heavy duty, precision antifrictio'ni hearings such as the ballbearings indicated at 36'. Driving means such as the pulleys. 38i anjd belts 40' interconnect the output 7 Shaft of. the drive motcirv 30' with the shaft 42 which supports the, roll 32.

Mounted at the left end'of' the table i2 is a similar unit. which is generally designated i l and which comprises a master dressing'roll indicated at 46. The units 28"and 4 3 are precisely alighedb v any suitable means such as keys or dowels SOI that each will engage the Wheel 22in exactly the same manner;

The saddle I6v is provided with a nut 48, which is} engaged by. a lead v screw 50" which. is joinhalled iii the column I4 Rotation of the lead screw 50.. is. operable, through the .nut 48, to raise andIloWerthe saddle I6.. The lower end of the lead screw 56 has a bevel, gear thereon which meshes with a bevel gear on the end of a horizontalj shaft 52. which extends through the bed m and into the housing 54.

The arrangement within the housing 54 is more particularly shown in Figures 11', and

wherein it will be seen that the shaft 52 has keyed thereto a clutch member tthavihg teeth adapted for engagementwith' similar teeth on the end or asleeve B which-is rot'atably mounted onthe said Shaft. The clutch 55 is adapted for actuation by a pivoted lever 58. which, in 7 turn; is connected to be actuated'by the'hand lever 59'.

tion, the latter being adapted for engagement with the toothed'sector l0 and the gear "I2, re-= spectively; The toothed sector it carries the pawls I4 which engage teeth around'the periphery of the ratchet wheel 62. The gear'lz has attached thereto, a gearit which meshes with a gear T8atta'ched to anarmwhich carries the" turn, actuates the valve I69 which is connected pawls for engagement with teeth around the periphery of the ratchet wheel 60. Reciprocation of the plunger 66 brings about the counterclockwise rotation of the shaft 52 for downieeding the wheel 22 while reciprocation of the plunger 68 rotates the shaft 52 in the opposite direction for upfeeding the wheel.

In order to control: the amount of downfeed obtained with each reciprocation of the plunger there ma be provided an adjustable stop screw 82 which abuts the toothed sector 13 at any desired point.

The plungers ct and 68 have fluid directed to the opposite ends thereof from a fluid source a valve arrangement, not shown, but which is preferably solenoid operated.

Thehand wheel 64 may be actuated by the knob 84 or a vernier setting of the same may be had by means of the knob 86 which drives through a pinion 81 into a circular rack 89 carried by the housing 54. The periphery of'the hand wheel is preferably graduated. for indicating the exact amount of up and down'feed of the wheel. 7 a

The hand wheel fiealso mounts-an adjustable cam member 88 which is adapted for contacting a plunger 90* which is carried ona bracket 92. The bracket 92 is pivoted-at 94" and has at'its inner end a. projection 93 adapted for actuating the movable portion 95* of the limit switch-LS1 when thebracket is tilted-bythe engagement of the plunger 99 by the cam 38 asthe wheel-6 1 is indexed in the downfeed direction. The stop member or camet may beadjusted'around the periphery of the handwheel by-a toothed'shoe 96 which is engagedby a--pinion 98= rotated by the lever I08, the latter-being stopped in various-portions of adjustment by suitableplunger means at I02.

In Figure 18 there is illustrated an electrical circuit for controllingthe operation of the grinding-machine" during its crushing and roll grinding cycles; Between the-power lines LI and L2 there is connected a contactor A through the normally closed limit switch LS2, the normally open start button' I50- andthe normally closed stop button I52: ThesWitch-I'Bll-isbypassed-by the blades A-I- of the contactor A which provide a holding circuit for the coil A;

A second pair of blades-A2 of the-contactor-A are serially connected with the wheel driving motor I54 which is bypassed by the normally closed blades A3 and-the adjustable resistor I56.

Also connectedbetween the power lines is acontactor B in series with the normally-closed limit switch LS I", the'normally closed stop switch I58 and the normally open start-switch Itilthe latter of which isbypassed by the blades BI a A second pair of blades B2 of the contactor B are serially connected-with the motor I62 which is adjustable-in speed by. means of a variable. resistor I64. Other means-of adjusting the speed of the motor willoccur to those skilled inthe art but, for the sake-of simplicity, there has been shown the resistor I64. shaft which carr'ies a'ca'm I66 adapted for closing the switch LSB' which is in series withthe blades B3 and the solenoid-I68; The'sw-itch LS3 is intermittently closed bythe cam I65 for intermittently energizing the solenoid I68 which, in

to control the supply of pressure fluid to theopposite ends of the downfeed plunger 66.

The contactor 13 also has th'e blades 134 which are in" series with-thedrive motor -3'0"of the dress- The motor I62 has a ing attachment between the power lines LI and L2.

Also between the lines LI and L2 is a solenoid I which is in series with a pair of normally open contacts on the limit switch LSI and the selector switch III. When the selector switch III is closed actuation of LSI energizes the solenoid I'I0 toactuate the valve I13 to bring about a supply of pressure fluid to the upfeed plunger 68 to actuate the ratchet wheel 60 and to elevate the wheel.

Operation of preferred embodiment A complete cycle of operations include truing of the wheel by the master roll 46 and truing of the roll 32 by the wheel 22 is shown in Figures 2 to 10, inclusive.

In Figure 2 the Wheel is being driven at grinding speed and is traversing the workpiece 26 carried on the table I2 by the fixture 24. When it is desired to true the wheel for dressing the production dressing roll, the wheel is elevated and the wheel and rolls are moved relatively to their Figure 3 position. At this time, the limit switch LS2 is opened by the cam I53 on the tableso that the motor I54 is deenergized by the de-energization of the contactor A. Contactor A has the blades A3 which close when the contactor is deenergized and which, when closed complete a circuit across the motor I54 through the resistor I56. The motor I54 is thus dynamically braked to its halted position. Thereafter, the wheel is moved downwardly to its Figure 4 position until it touches the roll 46. A predetermined pressure between the wheel and roll is established by turning the hand wheel 64 a predetermined amount and the dressing cycle is commenced by closing the switch I60.

When the switch I60 is closed, the contactor B is energized and the motors I62, 30 and 3I are also energized. The motor I62 drives the cam I66 thereby intermittently. to close the limit switch LS3 to energize the solenoid I68 to feed the wheel 22 into the roll 46. As the wheel and roll are fed together the pressure of the roll on the wheel breaks or crushes the bonding agent which holds the abrasive particles of the wheel. The result is a sharp wheel which will grind a workpiece to the exact configuration of the roll.

When the wheel has been fed down until the limit switch LSI opens, the contactor B and the motors I62, 30 and 3I are deenergized bringing the wheel and roll to a halt. The switch I II being open at this time the wheel does not feed upwardly but remains in contact with the roll 46 under pressure.

Thereafter, the operator elevates the wheel from the roll as shown in Figure 6 either by manually actuating the wheel 64, or by actuating the lever 59 to disengage the clutch member 55 and to energize the motor to drive the shafting 52 in the proper direction. The operator thus moves the wheel and table relatively to their Figure 7 position to place the wheel under the roll 32.

The wheel motor I54 is now energized by closing the switch I50 so that the wheel 22 rotates at grinding speed. The operator then closes switch III, and also closes switch I60 to energize the upfeed the wheel from the roll. The iipfeeding of the wheel occurs substantially instantaneously so that it precedes the stopping of the roll 32 thereby preventing a flat spot from being ground contactor B to again energize the motors I62, 30

on the latter.

A new cycle of grinding operations may now be commenced with the wheel being dressed by the production dressing roll 32 until the latter is worn down to the tolerance limits.

There is illustrated in Figure .15 a modified form of support for the rolls which permits the said roll to be. vertically positioned in order to bring it to the level of the workpiece being ground so that during ordinary dressing of the wheel the same may be moved directly from the dressing roll to the workpiece with the adjustment of the downfeed stop. In Figure 15 there is a bed 200 and a sub-bed 202 which supports the crusher drive motor 204 and the crusher roll 206. Aneccentric shaft 208 may be actuated to adjust the table 262 about its pivot 2I0 thereby the elevate or lower the roll 206.

The roll 206 may be automatically fed into the wheel instead of the wheel being fed into the roll by connecting with the shaft 208 a worm and wheel reduction unit as at 2I2 which is actuated by the ratchet 2 I4 and the solenoid and pawl arrangement at 2I'6. By mounting a limit switch LSIa on one of the beds and an adjustable plunger 2I5 on the other of the beds, the crusher roll 206 may be automatically and intermittently fed into the wheel by the circuit of Figure 18, the solenoid 2I6 in this case replacing the solenoid I68, and the switch LSIa replacing the switch LSI.

In the case of very large and heavy wheels it is necessary to drive the wheel directly at crushing speed rather than by the crushing roll. An arrangement of this type is illustrated in Figure 16 wherein the wheel 300 is adapted for being driven at grinding speeds by the motor 302 and at dressing speeds by the motor 304 which is connected through reduction gearing at 306 and an over-running clutch at 308 with the drive shaft of the motor 302. The dressing roll 3I0 is rotatably mounted in a frame 3I2 on the bed 3I4 of the machine and is driven by the wheel when the latter is in engagement therewith. It will be obvious that this mounting applies only to the master dressing roll while the production dressing roll would be provided with means for driving it in rotation when it was being trued by the grinding wheel.

The over-running clutch at 306 is illustrated in Figure 17 wherein it will be seen to comprise a shell 3I6 which is secured to the drive shaft of the motor 302 and an inner clutch member 3I'3 which is secured to the output shaft of the motor 304. The clutch member 3I8 comprises the inclined surfaces 320 between which and the shell 3I6 the rollers 322 wedge when the clutch is driven counterclockwise at a greater speed than the shell. When the shell is driven at greater speed than the clutch the rollers are separated from the surfaces 320 and no driving action takes place between the clutch and shell.

It will be understood that various modifications and arrangements in structure could be made without departing from the spirit of my invention and, accordingly, I desire to comprehend such modifications and substitutions of equivalents as may be considered to come within the scope of the appended claims.

I claim:

1. A method of dressing the working surface ofiasigrinding'; wheel-.1 and a.-.crushing-* roll" opera'e ttvelv: associated; therewith.- which. comprises. the steps; of,. ..engaging-c. a:..crushinge rollagainst. the. Working surface; of: a. grinding. wheel. to crushform the grinding wheel working surfaceth'ereby; complementary;torthat of the. surface of. crushing roll, establishing,- a..surface.-truing;.roll imposition font engagement; by the. working: surface. of the grinding wheel with thesurfaceformofi-the 'truing. rolliimradiali. alignment.withtheisurface formiof thea-crushingroll, andLintermittentlycausing :the working: surface of; thegrindingwheel to engage. the: truing rolltozcrush'form the: grinding wheel: surface thereby. complementary to; that v of the surface of: the; truing :rolland .thence causingithe. grinding wheel. to engage: the crushing: rolllto.

V grind :form'the. surface-f. the crushingrollstherebyt'toi'that-zof thesurfacecfxthe.truing" roll.

2... 'llhe method of. dressing the working. surface ofi;a;l .grinding wheel and of a crushing. roll. in operative association therewith which comprises the steps of, engaging a crushing rollw-ith theworking surface. of. a grinding. wheel. with. the

surface form of. the crushingsrolkin. radial alignmentzwith complementary surface parts'on the grinding WheeLto crushformtheigrinding wheel complementary to that. of. the. surface of the crushing. ro1l,. establishing-a surface-truing roll in: positiorn for:engagementabyv the: working surface :of ithecg-rinding Wheel with the surface. form of. the;tr.uing.. roll in. radial: alignment. with. the surface form of thecrushing rolland' withthe complementary. surface: parts. onthe grinding wheel; and intermittently. causing the grinding wheel surface to engage the truing roll to crush form the grinding wheel surface thereby to, that of the. truing roll. and .1. thence. contacting: the crushing roll; grinding. engagement togrind form; the. surfaceiof the crushingrolL thereby. to thatiiofi.the .-surface of the truing roll.

3;. A methodofidressing the: working-surface; of algrinding wheel and a crushing troll operatively associated; therewith which comprises: the steps of;.engaging: a crushingnroll against; the working surface of. a .grinding. wheel and crush: forming the grinding. wheel :working-surfacethereby com, plementaryto. that of the surface of the crushing roll, establishing. a surfaceetruing crushing roll imposition for engagement. by the. workingisur faceiofithe grinding wheeliwit h the surface; form ofithe truingroll in radial alignment with the surface form ofithe-crushing roll, and intermits tently causing the working surface of the grin'd ing'wheel to. engage the truing roll and'crush formuthe.grindingiwheel surface thereby complementary to that of the surface of thetrui-ng roll and thence causing the 'grindingwheel' to engage the: crushing roll and grind form the surface of the crushing. roll thereby to that of the surface of the truing roll.

7 41A method of dressing the working-surface of a= grinding wheel and a crushing rolloperativel-y associated therewith which comprises the steps of; engaging a crushing roll against the working surface of aigrinding wheelandcrush form the grinding wheel Working surface thereby' complee mentary to that of the surfaceofthe crushing roll,.establishing a surface truing roll' in position for. engagement by the workingisurface of the grinding wheel with the surface form ofi-the truingroll in radial'alignmentwiththesurface form of? thecrushing roll, intermittently causingtthe working surface of the grindinggwheeltoenga e the truing roll and crush form the grinding .wheebsurfacethereby; complementary; to that of the surfaceiof' the struingirollland thencecausing the grinding wheel to engage the crushing roll and;-.grind form the; surface of the; crushing 11011 thereby to. that. ofjthesurface of thetruingroll', andcausing .allcrelative movements between saidwheeliandrsaid rolls. to xbecarried out in coplanar relationship 7 5. The method of maintaining accuratethe working configuration of' a, grinding; Wheel: which comprises;. establishing .first and; second) crush dressing rolls having like configurations complementary to. thgponfiguration, they place on a grinding wheel" in position for engagement with the workin surface of a grindingiwheeliby Irelativemovement therebetween and. in a fixeds. co planar position Witheach 'othen andwith corresponding parts of said'wheel, crush formingthe wheel-.byone :of' said rollssto: crush dress the surface of the'wheel to within predeterminewlimits; intermittently crush dressing the wheel by the second roll :to crush dress the surface of thewheel to w ithin other predeterminedilimits, and thereafter grinding the said-one roll by the wheeli as crush-dressed by said second roll to re formthe surface of thesaid one roll to that of the surface former the secondlroll'.

6. The method of maintaining accurate the working I configuration of a grinding wheel which comprises-, establishing first and second. crush dressing rollshaving like configurations comple= mentary to the configuration: they. place on a crush dressing the wheel by the-second rolli to crush diessthe surface of the wheelthereby-to restore'the wheel'to within-limits of original ac curacy; and thereafter grinding said: one roll: by the wheel'as crush dressed by said second roll to restore the surface of thelsaid one roll to. with in li'mits of accuracy of the-said second roll;

'7. A.method ofdressing the working'surface of a grinding wheel'and of a'crushing roll in opera-'- tive association. therewith" which comprises the.

steps :of engaging" a crushing roll. with therw'orks ing: surface-of aigrindin wheel with the surface of the crushing rol-l'.iniradialialignmentwithrcom plementaryjjsurface partson the grinding. wheel and" causing rotati'oni ofxthe grinding wheel; and of the crushing roll at substantially thesa'me pe' ripheralzispeedrwhi'le retaining crushinglpressure therebetweento. surface form. the-grinding, wheel complementary to that of the surface of .the crushingsrolL; establishing a surface-truingiroll in position: for. engagement by, the workin surface ofthe grinding wheel with the surfaceform of thetruing roll'in radial alignment with the surface. form of the crushing; roll and'with the complementary surface form v of the grinding Whefih. and intermittently causing the grinding wheel to. engage: the. truing; roll' with rotation thereof. at; substantially; the same peripheral speed? as; the truing roll. with crushingpressure therebetween to: surface; form .the grinding wheel to. that: off. the: surface of the truin roll',-. and thereafter causing, the grinding wheel to engage the::crushingrolllat grindingspeed relative tothe crushing rolLto reform the surface of. the: crush- 7 rings roll Oizthevsurface of the tru-ing .roll.

8. The method of maintaining accurate the working configuration of a grinding wheel which comprises, establishing first and second crush dressing rolls having like configurations complementary to the configuration they place on a grinding wheel in position for engagement with the working surface of a grinding wheel by relative movement therebetween and in a fixed coplanar position with each other and with corresponding parts of said wheel, crush forming the wheel by one of said rolls to crush dress the surface of the wheel thereby so long as the surface of the said one roll remains within predetermined limits of original accuracy, crush dressing the wheel by the second roll after said one roll has been worn beyond predetermined limits of original accuracy while crush dressing the wheel to crush dress the surface of the wheel thereby to within limits of original accuracy of said second roll, and thereafter grinding said one roll by the wheel as crush dressed by said second roll to restore the surface of the said one roll to within limits accuracy of the said second roll.

9. The method of maintaining accurate the working configuration of a grinding wheel which comprises, establishing first and second crush dressing rolls having like configurations complementary to the configuration they place on a grinding wheel in position for engagement with the working surface of a grinding wheel by relative movement therebetween and in a fixed coplanar position with each other and with corresponding parts of said wheel, crush forming the wheel by one of said rolls to crush dress the surface of the wheel thereby so long as the surface of the said one roll remains within predetermined limits of original accuracy, intermittently crush dressing the wheel by the second roll of crush dress the surface of the wheel thereby to restore the wheel to within limits of original accuracy, thereafter grinding said one roll by the wheel as crush dressed by said second roll to restore the surface of the said one roll to within limits of accuracy of the said second roll, and carrying out all relative movements between said wheel and said rolls in coplanar relationship.

10. The method of maintaining accurate the working configuration of a grinding wheel which comprises, establishing first and second crush dressing rolls having like configurations complementary to the configuration they place on a grinding wheel in position for engagement with the working surface of a grinding wheel by relative movement therebetween and in a fixed coplanar position with each other and with corresponding parts of said wheel, crush forming the wheel by one of said rolls to crush dress the surface of the wheel thereby so long as the surface of the said one roll remains within predetermined limits of original accuracy, crush dressing the wheel by the second roll after said one roll has been worn beyond predetermined limits of original accuracy while crush'dressing the wheel to crush dress the surface of the wheel thereby to within limits of original accuracy of said second roll, thereafter grinding said one roll by the wheel as crush dressed by said second roll to restore the surface of the said one roll to within limits of accuracy of the said second roll, and repeating the engagement of said wheel with said second roll periodically so long as the second roll remains within predetermined limits of accuracy.

11. The method of maintaining accurate the working configurationof a grinding wheel which comprises, establishing first and second crush 10 dressing rolls having like configurations complementary to the configuration they place on a grinding wheel in position for engagement with the working surface of a grinding wheel by relative movement therebetween and in a fixed coplanar position with each other and with corresponding parts of said wheel, crush forming the wheel by one of said rolls to crush dress the surface of the wheel to within predetermined limits, intermittently crush dressing the wheel by the second roll to crush dress the surface of the wheel to within other predetermined limits, thereafter grinding the said one roll by the wheel as crush dressed by said second roll to re-form the surface of the said one roll to that of the surface form of the second roll, and separating the wheel and said one roll during grinding thereof by said wheel while said wheel and said one roll are rotating.

12. In grinding machine, in combination, a

work station adapted to receive a workpiece for grinding, a grinding wheel operably associated with said work station and mounted onthe machine for relative movement between said wheel and the work station, drive means connected with said wheel to drive the same at grinding speed, first and second crush forming rolls including mechanism mounting the same on the machine in a fixed coplanar relationship with said grinding wheel, said mounting for said wheel and the mounting means for said rolls providing for relative movement between said rolls and said wheel for engagement of said wheel with either of said rolls selectively and forv movement of said wheel into operable association with said work station, and drive means connected with at least one of said rolls to drive the same at a speed substan tially less than grinding speed. i

13. In a grinding, machine, in combination, a work station adapted to receive a workpiece for grinding, a grinding wheel operably associated with said work station and mounted on the machine for relative movement between said wheel and the work station, drive means connected with said wheel to drive the same at grinding speed, first and secondcrush forming rolls including mechanism mounting the same on the machine in a fixed relationship with said grinding wheel with the form surface of said rolls coplanar with each other and coplanar with the corresponding work surface of the grinding wheel, said. mounting for said wheel and the mounting means for said rolls providing for relative movement between said rolls and said wheel for engagement of said wheel with either of said rolls selectively and for movement of said wheel into operable association with said work station, drive means connected with at least one of said rolls to drive the same at a speed substantially less than grinding speed, and control means operably connected with said wheel drive means selectively rendering said wheel drive means operative or inoperative at grinding speed when said wheel is in engagement with the driven roll.

14. In a grinding machine, in combination, a work station adapted to receive a workpiece for grinding, a grinding wheel operably associated with said work station and mounted on the machine for relative movement between said wheel and the work station, drive means connected with said wheel to drive the same at grinding speed, first and second crush forming rolls including mechanism mounting the same on the machine in a fixed relationship with said grinding wheel with the form surface of said rolls coplanar with arage;

all each.- other; and cpoplanar with 'the corr spondin :work surface :ofitheegrindingewheel, saidmoun ringfor :said wheeliandithdmounting'g'means fior -said rolls providing ator-relative,:.movement be- "tween said.ro1ls;andxsaid1whee1 for-engagement of said :wheel with ieithersofxsaid. rollszselectively and .for movementwof :said wwheel "into operable association with saidwork station, drive means connected with atleashone of said-rolls to drive the same :at'a speedisubsta-ntiallyless than grind- .minedslimits and also mountedaonasaid ::tab1e.iln-

dependently from said production roll S'etidjlQHS ,and wheel having their correspondingpants-coplanar in oneplane, and the workingssurfaces .ofsaid rolls being co-planarlinea gplane-parallel to andv above said tableya first motor for-drivin the wheel at grinding speed for grinding a work- ,piece on said table or forgrindingsaid production ,roll; a second motor for :drivingsaid wheel ,10 fat dressing speeds for dressing the wheel by ing speed,- control means :operably connected with said wheel drive means a selectively rendering said 'wheel drive-means operative or inoperative at grind-ingspeed when said wheel is inengagement -with-thedriven roll, and includingcontrol means tive associationwithsaid wheel on axes parallel withithe axis of said wheelw-ith their-surface *formsin fixed coplanar rela-tionship with each other and in fixed coplanar relationship with the corresponding worksnrface ofsaid wheel, mounting mechanism supporting said wheel'and said rolls on the machineiforrelative1movement bertween thewheel. andthe rolls selectively and for relative ,movement'between'isaid wheel and the work-stationdrive mechanism connected with said ,mounting mechanism "for said "wheel and rolls ,for relatively moving said wheel and said rolls into and out of crush'iforming engagement selectivelylbetween said-wheeland-saidrolls, drive imeans Ionrotating; said wheel and "either -roll engaged thereby at a "speed substantiallvless than grinding speed whileiin crushiformingengagement whereby'to crushform-theworking surface ,oi' the grinding wheel, and drive --mechanism connected with said wheelrand 1atleast fOI'lBfOf said ,rolls to drive said wheel at "grinding speed and'the said rollat substantially"lessthangrin'dr g d with engagement "betweensaid grinding .Wheelanjd the said one roll-"to grind form the saidflroll ,16. in combination .in :a :grindingmachine; -a .grinding wheel; a pro'duction'crushing roll operable tojdress thew'heel between'first predetermined limits;',,a master crushing roll operable toildress the wheel between second and, closer predetermined limits; independent supporting ,means mounting said grollsgfor rotation ;on axes parallel with the axis of rotation :of said wheel, said supporting means also holding said rolls with their corresponding ..parts co planar "with each Tether .andalso with the same-parts of said wheel; .a ,ifirst motor jfor driving -the wheel at grinding, speed ,for operating a workpiece .or for grinding said productionroll; asecond motor for driving said wheel at dressing speeds "for dressing the wheel iiby either of saidrolls; and i ontr 1 means connected with saidwheel; and rolls. .operable antqmaticallytoieed the wheel andrtharoll Joy which it is being dressed, or which it is grindin together a predetermined distance.

17. In combination in ao grinding jmachine a grinding, wheel; av table; -a production crushing 'rolli operable to "dress said wheel between jfirst predetermined limits and mounted onsaid table; a .master crushing roll operable to dress said wheel'between'limits closer than said-predetereither ofsaid rolls; andzcontrolimeansgconnected with said "wheel and rolls operable-automatically to feed the wheeland the ,roll-cby which itliszbeing dressed, or which itvis ,grindin rtegethert-a predetermined distance.

71-8. In-Ta: grinding machine, the'combinationnf, a work station adaptedto receive -a workpiecerfor grinding, a-grinding wheel voperal'ily associated with said -:work station, first -.and second ;-cr-ush forming rolls positioned onthe machine inopera- :tive association withsaid wheel on axes-parallel with the-axis of said wheel with their surface forms in fixed coplanar relationship with each other and in fixed coplanar relationship with :the

corresponding work surface ofisaidnwheel meunt-' ling mechanism supporting said wheel. and; said .rollson the machine for :relative movement vhe- ,tween'the wheel and the rollsselectively andnfor relative movement between said wheel .andwthe work station, drive -mechanism -connected with said ,mounting mechanism vfor said wheel and .rolls' forrelatively-nmving said wheel andv. said rolls into and out of crushstorming engagement selectively between saidrwheel andsaid rolls,drive means for rotating' said (wheel and either roller-1- gaged-thereby at a speed substantially less than grinding speed while ,in -crush Yforming engagement whereby to crush form the working-surfaceof the grinding wheel, 'drivemechanism connected withsaid wheel and at leastone -of said rolls te -drive said wheelat grinding speed and the said r011 :atsubstantially less than grinding speed with engagement between said grinding wheel and the said oneroll to grind form the. said roll, *and control mechanism operatively connected with said drivegmechanism ionsaid wheel :to render the same :inoper-ative to drive =said wheel at-grinding speed when 'inengagement-with ithe'gother'of said rolls.

19. In a grinding machine, the combination-of,

a work station adapted to receive arworkpieceffor grinding, a grinding wheel "operably "associated with said work station,jfirst rand rsecond'crus'h formingzrolls positioned .on the machine in operativeassociation with said'wheel on=axesparallel with the axis of said wheel with'theirsurface forms in fixed coplanar relationship with :each other and in fixed coplanarrelationship with the corresponding work surface of said wheel, mounting mechanism supporting said wheel and said rolls on the machine 'for relative movementbetween the wheel and the rolls selectively and for relative movement between said'wheeland "the work station, drive mechanism connected with said mounting mechanism for said wheel and rolls for relatively moving said wheel and said rolls into and out of crushform-ing engagement selectively between said wheel and said rolls, drive means for rotating said wheel and either roll engaged thereby at a speed substantially less than grinding speed while in crush 'forming engagement whereby to crush form "the working surface of the grinding wheel, drive mechanism connected with said wheel andatleast oneio'f'said rollsto drive said wheel at grinding speed andthe said roll at substantially less than grinding speed with engagement between said grinding wheel and the said one roll to grind form the said roll, and control mechanism operatively connected with said drive mechanisms to render said lastmentioned mechanism inactive and concurrently render said first mechanism active for disengagement of said wheel and rolls.

20. In a grinding machine, the combination of, a work station adapted to receive a workpiece for grinding, a grinding wheel operably associated with said work station, first and second crush forming rolls positioned on the machine in operative association with said wheel on axes parallel with the axis of said wheel with their surface forms in fixed coplanar relationship with each other and in fixed coplanar relationship with the corresponding work surface of said wheel, mounting mechanism supporting said wheel and said rolls on the machine for relative movement between the wheel and the rolls selectively and for relative movement between said wheel and the work station, drive mechanism connected with said mounting mechanism for said wheel and rolls for relatively moving said wheel and said rolls into and out of crush forming engagement selectively between said wheel and said rolls, drive means for rotating said wheel and either roll engaged thereby at a speed substantially less than grinding speed while in crush forming engagement whereby to crush form the working surface of the grinding wheel, drive mechanism connected with said wheel and at least one of said rolls to drive said wheel at grinding speed and the said roll at substantially less than grinding speed with engagement between said grinding wheel and the said one roll to grind form the said roll, and control mechanism actuated by a predetermined movement of said first drive mechanism in moving said wheel into said rolls to render the said mechanism inactive for moving said wheel into the roll engaged thereby.

21. In a grinding machine, the combination of, a work station adapted to receive a workpiece for grinding, a grinding wheel operably associated with said work station, first and second crush forming rolls positioned on the machine in operative association with said wheel on axes parallel with the axis of said wheel with their surface forms in fixed coplanar relationship with each other and in fixed coplanar relationship with the corresponding work surface of said wheel, mounting mechanism supporting said wheel and said rolls on the machine for relative movement between the wheel and the rolls selectively and for relative movement between said wheel and the Work station, drive mechanism connected with said mounting mechanism for said wheel and rolls for relatively moving said wheel and said rolls into and out of crush forming engagement selectively between said wheel and said rolls, drive means for rotating said wheel and either roll engaged thereby at a speed substantially less than grinding speed while in crush forming engagement whereby to crush form the working surface of the grinding wheel, drive mechanism connected with said wheel and at least one of said rolls to drive said wheel at grinding speed and the said roll at substantially less than grinding speed with engagement between said grinding wheel and the said one roll to grind form the said roll, means for bringing said wheel against either of said rolls under pressure while the wheel and roll are not rotating; control means selectively operable thereafter for driving the wheel and roll at the same peripheral speed while automatically feeding the two together a predetermined distance, and for halting the rotation of the two while still together under pressure, and other control means operable to bring the wheel and one of the rolls together while their surfaces move relatively at grinding speed, automatically to feed the wheel and said one roll together a predetermined amount, and to separate the wheel from the said one roll while both are rotating.

22. In a grinding machine, in combination, a grinding wheel mounted for rotation on a horizontal axis, a work receiving table having a work station thereon, means mounting said grinding wheel and said table on said machine for relative movement therebetween, a crush dressing roll at each end of said table beyond opposite ends of the work station, each of said crush dressing rolls including means mounting the same on an axis parallel with the axis of said Wheel and in fixed relationship thereto with the surface forms of said rolls coplanar with said wheel in a plane perpendicular to the axis of rotation of said wheel, means for causing relative movement between said wheel and said table whereby to bring said wheel into engagement with either of saidrolls selectively in a straight line movement and including means to apply crushing pressure between said wheel and either of said rolls, and driving means operatively connected with said wheel and at least one of said rolls selectively operable for driving said wheel and either of said rolls at less than grinding speed whereby to crush form said wheel by either of said rolls or driving said wheel at grinding speed while concurrently driving one of said rolls at less than grinding speed whereby to grind-form the said roll by said wheel.

23. In a grinding machine, in combination, a grinding wheel mounted for rotation on a horizontal axis, a work receiving table having a work station thereon, means mounting said grinding wheel and said table on said machine -for relative movement therebetween, a crush dressing roll at each end of said table beyond opposite ends of the work station, each of said crush dressing rolls including means mounting the same on an axis parallel with the axis of said wheel and in fixed relationship thereto with the surface forms of said rolls coplanar with said wheel in a plane perpendicular to the axis of rotation of said wheel, means for causing relative movement between said wheel and said table whereby to bring said wheel into engagement with either of said rolls selectively and including means to apply crushing pressure between said wheel and either of said rolls, driving means operatively connected with said wheel and at least one of said rolls selectively operable for driving said wheel and either of said rolls at less than grinding speed whereby to crush form said wheel by either of said rolls or driving said wheel at grinding speed while concurrently driving one of said rolls at less than grinding speed whereby to grind-form the said roll by said wheel, and means for adjusting the vertical position of the said last-mentioned ground roll relative to said table to maintain the working surface of the said roll at the same horizontal level as the other of said rolls relative to the work table.

24. In a grinding machine, in combination, a grinding wheel mounted for rotation on a horizontal axis, a work receiving table having a work station thereon, means mounting said grinding wheel and said table on said machine for relative movement therebetweemh a; crush'dressing; roll. at. each; "end.- of said; .t'abie beyond" opposite? ends: of:

the: workstation, eachof said crush dressingrolisinciuding: meansi mounting, thersame on an axis paraHeLwith-the axis: of; said wheeiand in fixed relationship: thereto with the-surface forms of saidzrolis coplanar'with' said Wheel in a plane perpendicular to the: axis; of rotation of. said wheel; means fonca-using: relative movement betWeen-said wheela and: saidv tablewhereby to bring said wheel into engagement with either of said rollsselectiveiy andincludingmeans-i315) apply crushing'pressurebetween said Wheel and either of. said r'oi-l's; andidriving; means operativeiy connected-with saidwheeland at least one of said rolls!selectively-operablefor driving said. wheel andieitheraf said-Trolls at less than grinding speed whelieby to. crush'rform said: wheel by either saidaroHs-or' driving. sa-idwheei at grinding speed While: concurrently driving: one of saidrolls at less tha'ni grinding spfeed whereby to grind-form the-said: r011 by said wheel.

JOHN C; WILSON.

BEEERENGES- CITED file of this patent:

UNITED STATES PATENTS Number Name Date" 957,201 Gail- --r. May 10; 1910' 1,513 '758 Hanson Nov. 4, I924 1,865,067 Warsaw June 2819-32 1,899,654 Ward-z V 1 Feb; 8;?19'33 2,002,938 Du-mser May 28', 11935- 2 135202 Scrivener Nov.- 1'; 1938- 2,385,644 Pol-k Sept; 25; 1945 2 ,477,418 Paik July- 26; 194:9

FOREIGN PATENTS r n Number Country Date 465,869 GreatvBritain i May-18;.Ifi7 492,591 Great; Britain Sept; 1933'