US2567589A - Grinding machine - Google Patents

Description

2 Sheets-Sheet 1 8 INVENTOR.

AT TURNE Y BY Mm.edxam D R U V L Av E 5 E L R. A H E C. C. ALVORD GRINDING MACHINE Sept. 11, 1951 Filed March 5, 1949 w hw WK Qm P 11, 1951 c. c. ALVORD 2,567,589

GRINDING MACHINE Filed March 5, 1949 A 2 Sheets-Sheet 2 PRESSURE REEL/LATER \[0/ 92 F SEPARATE I03 RSV INVENTOR.

CHARLES C. ALVURIU MU.W-

ATTDRNEY Patented Sept. 11, 1951 UNITED STATES PATENT OFFlCE GRINDING MACHINE Charles C. Alvord,: Worcester, Mass, assignor to Norton Company, Worcester, Mass., a corporation of Massachusetts Application March 5, 1949; Serial N0.'79,.7.40

dissipating heat from the work-generated by the grlnding; ;action. In either case more or less of theygrindingliquid and swarf remains on the surface of the workpiece after the grinding operatiornhasbeencompleted. Itis desirable to remover-thiscoating, of grinding, liquid and swarf from. .thersurface of the work before removing it from the machinenot only tofacilitate handling ofithe groundwork piece but also to. prevent. loss ofsgrinding, liquid from the system.

One object of the invention is to. provide a simpleand thoroughly practical automatic work cleaning or Washing apparatus for removing the residualfluid and swarf from the groundwork piece. before it is removed from the grinding machine. Another object is to automatically stop theflow of grinding liquid and to start the flowof washing or cleaning liquid when the grinding operation has been completed. Another object of the invention is automatically to stop the flow of grinding liquid and'tostart the flow of washing or cleaning liquid in timed relation with movement of the wheel slide to an inoperative position after a'grinding operation has been completed.

Another object is to provide a washing or cleaning fluid nozzle adjacent to the work piece being ground and to provide an independent fluid pump to convey' cleaning fluid to said nozzle under sufficient pressure to clean residual liquid and swarf from the rotating work piece after a grinding operation has been completed) Another objectis to provide an electrical control means actuated by and in timed relation-with movement of the grinding'wheel to an inoperative posi-. tion automatically to start the cleaning fluid pump. Anoth'er'object of the invention is to provide an electrical timer for controlling the duration of the grinding operation in which the timer serves after a predetermined time interval" to reverse the feeding movement of the; grinding wheel and:to*stop the: fiow 'of grinding;

liquid. and: cooling liquid and to energize a sec ondelectric timer whichserves automatically to start the washer pump and ,to control the =duration of the washing or cleaning operation.v Other objects will be .in part obvious or in part pointed out hereinafter.

The invention accordingly consists. in" the features of construction,combinations, of elements, and arrangements-of parts,- as=will be exemplified in, the structure to be hereinafter described;

and the scope of the applicationzofwhichawill:

be indicated. in the followingplaims.

Inv the, accompanyingdrawings in. which 1 is shown done of "various possible. embodiments: of the mechanical ,featuresxof this invention,

Fig.- 1 ,isxacross sectionalview through a'grinding machine embodying; the invention, showing the headstock andgiwheel slide in end:v elevation;

Fig.1 2 is:a fragmentary: end elevatiomon an enlarged scale, .of the *valveszfor:controlling-the grindingifiuid;

Fig? 3 is' a fragmentarytcross =zsectional f view; on) an zenlargedisoale; through the work-wash ing nozzle; and 1 Fig. 4 is a combinedtfluid'piping' and'electrical diagram.

A grinding machine. has been illustrated in the drawings comprising a base .1 In which supports: a transversely movable-wheel slideil l. The wheelslide H is supported on transversely sextending ways (not shown) on the base 10. slide ll supports-a rotatable grinding wheel l2 on one end of arotatable wheel spindle l3. The wheel spindle l3 may be driven-by-any of the well known mech'anisms;-such as; an electric motor I 4 mounted 'on the wheel slide 1 I. As illus-' trated, the motor I4 is provided with an arma-eture shaft l5 which supports aamultiple V-groove pulley l6 which is connected by multiple V-belts' I 1 with amultiple -V-groove pulley- I 8 mounted on the end of thewheelspindle l3.

The base Ill also supportsa longitudinally movable work tab1e=2il on a -fi'at way- 2! and aV- way 22 formed onthe'base H]. The table 20'is provided with a rotatable work support including a headstock 23 and a footstock (notshownl each of which are provided with" work supporting centers rotatably to support'a'work piece.

in operative relationwith.the-grinding wheelv l2. The table '20 :may be :traversed longitudinally by" a manually operable: traverse mechanism which,may comprise asrack :bar.:.25 depending The -rack fIOmTJthB underside of'the table 20. barzs25 meshes with r a; gear 26 mounted ,onthe right-hand endpf-airotatable ishaft .21.. Aman The "wheel ually operable traverse wheel 28 is mounted on the outer end of the shaft 21 and is arranged to be manually rotated in either direction to traverse the table longitudinally relative to the base In to facilitate positioning the work piece 24 relative to the grinding wheel |2. If desired, a power operated table traversing or reciprocating mechanism may be provided, such as for example a mechanism of the type shown in the expired United States patent to C. H. Norton, No. 762,838 dated June 14, 1904.

A wheel feeding mechanism is provided for manually feeding the grinding wheel |2 toward and from the work piece 24, which comprises a half nut depending from the underside of the wheel slide H. The half nut meshes with a rotatable cross feed screw 3|. A forwardly extending portion of the feed screw 3| is slidably keyed within a rotatable sleeve 32. The rotatable sleeve 32 is journalled in a bearing 33 which is fixed relative to the base If}. A gear 34 is keyed on the sleeve 32 and meshes with a pinion 35 formed on the right hand end of a rotatable shaft 36. A manually operable feed wheel 31 is mounted on the front of the machine base. The feed wheel 3'5 is arranged to rotate a gear 38 which meshes with a gear 39 supported on a stud 49. A gear 4| preferably formed integral with the gear 39, meshes with a gear 42 which is keyed on the outer end of the shaft 36. It will be readily apparent from the foregoing disclosure that rotation of the feed wheel 3'! will be imparted through the gear mechanism above described to rotate the feed screw 3| and thereby transmit a transverse feeding movement to the grinding wheel slide I and the grinding wheel l2. The direction of rotation of the feed wheel 3'1 will determine the direction of movement of the wheel slide In the preferred construction, the wheel slide II is arranged so that it may be moved toward and from the work piece 24 to grind the same to a predetermined size by means of a fluid pressure actuated wheel feeding mechanism. As illustrated in the drawings, the rear end of the feed screw 3| is rotatably supported in a slidably keyed bearing sleeve 45. The sleeve 45 is slidably keyed within an aperture formed in the casing 46. A fluid pressure cylinder 4'! is arranged in axial alignment with the feed screw 3|. The cylinder 4! contains a slidably mounted piston 48 which is fixedly mounted on a double end piston rod 49. The left hand end of the piston rod 49 is rotatably connected with the bearing sleeve 45.

A piston type control valve 50 is provided for controlling the admission to and exhaust of fluid from the cylinder 41. The control valve 58 may comprise a valve stem 5| having a plurality of valve pistons 52, 53, 54, and formed integrally therewith. A compression spring 56 serves normally to hold the valve stem 5| in its right hand end position as illustrated in Fig. 1. An electric solenoid 51 is operatively connected to the left hand end of the valve stem 5| and is arranged sothat when energized, it serves to shift the valve stem 5| toward the left to shift the valve parts into a reverse position.

A fluid pressure system is provided for conveying fluid under pressure to the cylinder 4'5. This system may comprise a motor driven fluid pump 60 which draws fluid through a pipe 6! from a reservoir 62. The reservoir 62 may be formed within the base N3 of the machine or may be formed as a separate unit if desired. The pump 60 forces fluid under pressure through a pipe 63 and a pipe 64 to the control valve 50. An adjust able relief valve 65 is provided in the pipe line 63 to facilitate maintaining the desired operating pressure within the system. The relief valve 65 is arranged so that excess fluid under pressure will be by-passed directly to the reservoir 6-2.

In the position of the parts as illustrated in Fig. l, fluid under pressure within the pipe 64 enters a valve chamber located between the valve pistons 53 and 54 and passes through a passage 65 into a cylinder chamber 67 to move the piston 43 together with the wheel slide and grinding wheel |2 toward the right (Fig. 1) into an operative position. During this movement of the piston 43, fluid within a cylinder chamber 68 passes through a passage 59, through a valve chamber located between the valve pistons 52 and 53 and through an exhaust pipe 10 into the reservoir 62. In order to facilitate controlling the speed of movement of the piston 48, a throttle valve 1| is provided in the pipe line 10 to facilitate controlling the exhaust of fluid from the cylinder 10.

The cylinder 47 and piston 48 above described serve to provide a rapid approaching movement for the wheel slide H and grinding wheel |2 rapidly to move the grinding wheel |2 into an operative position adjacent to the work piece to be ground. To facilitate slowing down the rapid approaching movement to a slow predetermined grinding feed, a dash pot feed regulator 14 is provided. This dash pot feed regulator will not be described in detail since it is an old and well known feed control means such as for example that shown in the prior United States patent to B. H. Goehring, No. 2,151,660 dated March 2 1939, to which reference may be had for details of disclosure not contained herein. The rapid approaching movement of the grinding wheel |2 continues until an adjustable sleeve 15 carried on .the right hand end of the piston rod 49 engages the dash pot pistons, after which continued movement of the piston 43 toward the left is controlled by a needle valve 16 which serves to regu late the exhaust of fluid from the dash pot cylinders so as to provide a predetermined slow feeding movement of the wheel slide II and grinding wheel 2. The grinding feed continues as controlled by the needle valve 16 until a positive stop sleeve 11 engages a stop surface formed on the right hand end face of the dash pot feed regulator 14. This positive stop sleeve 11 serves positively to stop the forward advancing movement of the grinding wheel l2.

In the preferred construction, a time delay relay (Fig. e) is provided for controlling the shifting movement of the feed control valve 50 so as to control the entire infeed movement of the grinding wheel I2, namely to control the overall cycle including the rapid approaching movement of the grinding wheel l2, the slower grinding infeed of the wheel and the dwell which occurs thereafter before the grinding wheel is moved to a rearward or inoperative posiiton.

A pair of push button switches 8| and 82 are mounted on the front of the machine base If]. The push button switches 8| and 82 are arranged to be actuated by a control lever 83 which is pivotally supported by a stud 84 which is fixedly supported on the base ID of the machine. The push button switch 8|, when actuated, is arranged to cause a rearward feeding movement of the grinding wheel I 2 and the wheel slide H and the push button switch 82, when actuated, serves to start the grinding cycle. The control lever 83 .5 moved in a counter-clockwise direction to actu 5. ate *the. pusn'button switch 82 rwhemit is; desired to start agrinding cycle:

Aa time i delay relay 8 mayrbezonaofi thetstand ardlelectrically operated adjustable. time de1ay-relays, such asuthat known asthe Microfiexf. instantaneous: reset. timer manufactured by the EagleSignalscorporation of Moline, Illinois." The Microfiex timer 80 is a synchronous motor -operatedtime delayrelay and consists of aclutch operated-.mechanismand a motor and gear trainassembly, with: an.- electromagnetically operated clutch. for; coupling them. together. It is entirely automatic in action and requires 'only the closing or opening'of thetimer control circuit to initiate a'cycleof operation.

The time relay relay-80 may be adjusted to control 1 the entire approaching and infeeding movement of the grinding wheel that is the rapid approach, grinding feed and dwell. A. grinding cycle may be initiated by actuation of the lever 83 to momentarily-close the. push. button switch82 which in turn servesto set. thetimer 80 in motion. andsimultaneously toenergize the solenoid.51.to shiftthe-Valve stem toward the .left. so. as... toainitiate. a. forward movement of the wheel slide II .andgrindingwheel I2.. The

infeeding movement. continues. first as .a rapid.

approaching movement,. then a slow grinding feed and -.thereaf.ter a .dwell until. a. predetermined time interval has elapsed, after which the. time delay. rela'yservesto'. deenergize the solenoid 51 thus releasingtl'le compression of. thespringfifi to shift the. valve stem 5| .into the positionillustrated in Fig. 1 to cause arearwardrnovemcnt of the wheel'slideII andfthegrindi'ng. wheel vI2 to an inoperative position.

Closing. of the pushiibutton switch..82lat the start of. a grinding cycle also serves through the timer 8!] "to start a work drive motor "I I5 so as to rotate the work piece 24 for a grinding operation;

As illustrated in the. drawings, a; two-fluid system is provided such as. that shown in the prior United States PatentNo. 2,434,679 in which agrinding liquid is employed to facilitate the grinding operation and a coolant fluid is supplied for dissipating heat from the work piece. generated by the grinding action. A wheelfguard 9B is adjustably'mounted on'the Wheel slide II and surrounds aportionof the grinding Wheel I2. The wheel guard 99 serves as a'support fora fluid r manifold 9! to be hereinafterldescribed. A pipe 92 (Fig. 1) conveys fluid through a shut-off valve 93 throughthe manifold!!! to the coolant nozzle 94 -which supplies" coolant fluid, such as for BX- ample water, to the'work piece being ground tov dissipate heat generated due ,to the grinding op,- eration. Coolant fluid is supplied ina' relatively largevolume at a comparatively lowpressure from a pump" mechanism to be hereinafter. described. Grinding fluid, such as "for example an oil compound, is pumped througha pipe 95 (Fig;

1) to a shut-off valve 95 and from the shut-off valve 96 to a distributor manifold 91. v The grinding fluid is then: conveyed fromthe manifold 91 to'a'plurality of nozzles 98, only one of which has been indicated in Fig." 1 to supplygrinding fluid in a'relatively small volumeat a'comparatively high pressure to'theplace of contact between the grinding wheel I2 and the work piece 24 so as to lubricate thegrinding operation and thereby to facilitate the grinding operation. The'pressure of thegrinding liquid is such that it keeps the coolant fluid away from the pointer grinding contact so that the grinding liquid; lubricates 'the grinding-action and the coolant liquid dissipates heat from the work caused by grinding: The-dea, tails of itlie co'olant and igrindingf-liqui'd nozzles have not-:be'en illustrated Zin their present... case since they are not consideredia part of.the:present' These: 'nozzlesrz-may' be identicaluwith. that shown in. thewpriorU. S. .Patent. No.:2,434,6'79

invention;

referred 'to above, to which reference .:may. be-

had for details of disclosure notcontained herein:

As shown in Fig. 4,: a tanklonsump- Illflrispro-r vided. to" contain coolant. and grinding: liquid: draining from the machine'after .use.: Fluidfriom the tank I00 flows through apipe ;I DI: into a sepa:-.-

rator I 82 which. hasbeerrillustrated ..diagrammati-. cally in. Figs. 4; The'separator; I82 servesto separate .thercoolantxfluid from :the grinding-fluid.-

soL. that .theye-mayrbecindependently: circulated to thenozzlesfor ar grindingoperation;,

A;.pipe 1103 ZdIaWS'iCOOIaIIt fluid from. the sepa-:

rator I 92.. Aappmp I :24 pumps .fluid- .from .the-

pineal-B3 ;thro1.igliza-. pipe I 85. :to .thepipe 92 so as; torconveycoolant:fluidto.thewvork piece 24'. A motor: I05is provided for driving.;,, the coolant. pumpvl 04::

arator. I02. A pump- II! draws fiuidfrom the p pe sired pressure through; a :pipe I H which is.con-,- nectedato thepipe (Fig; l) torsupp-lygrinding fluid under, pressure to the point wof contact .be:

tween thesgrindingpwheel 1'2 .andthe .work piece:

lie-regulated as..desired.. An electric-motor II Lis.

provided for driving the grindingfiuid-pumpl I I.

In a grinding "machine where grindingliquid such as oil or oil compoundsvareused, the:workpiece becomes coated With.,a, film of grinding. fluid and: swarf frommhe, grinding operation. If.

the work piece is removed from thermachinein this-condition, acertain amountofi grinding liquid is lost from the system-and also the Work is quiteemessy for the operator to handle. To attain-the main object in this invention, it isdesirable to provide a suitable washing or clean.- ingapparatus so that-the rotatingwork piecemay be Washed :or. cleaned after a grindingoperation and before it is removed from the machine; This mechanism. may-comprise a. washer. or cleaningnozzle I20 which as .illustratedis,adjustably supportedeby a bracket IZI on the table Zdbelow the workpiecei24c. The nozzle I20 .has a plurality of small perforations. which.;are. arranged .to. directa plura1ity;0f streams of washingor cleaningfluidpsuch as Water, onto the periphery of the rotating workpiece 24 soas toremove anyg-rinding,- .-.f1uid and .swarf therefrom before theawork piece is'removeddrom the machine.- Washingfluidsuch as for example wateris drawn fromlthe separator I02 bymeans of i a pipe-I22. A washer pump" I23 pumps'fluidirom the pipe I22 and forcesfluid under. pressure through a pipe I24-to the-nozzle I20. A -controlivalveI25 is placed in thex'pipe-line- I24 to facilitate regulation of the amount of fluid passing. through the pipe." I24 to the nozzle I 20:

Electric power I is supplied as' il1ustrated 'dia-- grammatically in Fig. 4 by means 'of a main control switch I30from power lines ISI When the push-button start switch efa is closed to energizethe timer 80, a relay switch I 32 is closed to startthe work drive motor I I5 at thestart of a'grind lug-cycle. At the same time thesolenoid 51 is energized-to shift the control 'valve 50 to start a:

I Ill and passesgrindingrfiuid unden the 018-1 7, forward feeding movement of the grinding wheel I2. At the start of the grinding cycle, the motors I06 and IE4 are started to start the flow of grinding liquid and cooling liquid to lubricate the grinding cut and to dissipate heat generated in the work piece 24. After the grinding cycle has continued for a predetermined time interval, as governed by the electric timer 80, the solenoid 51 is deenergized so that the control valve 50 returns to the position illustrated in Fig. 1 to cause a rearward movement of the grinding Wheel I2. At the same time, the motors I06 and H4 and the work drive motor I I5 are stopped so as to stop the flow of grinding liquid and cooling liquid. When the timer 80 is actuated to terminate the grinding cycle, it also serves to energize a second time delay relay I34 which is arranged to again make a circuit to rotate the work drive motor H5 and at the same time to start the washer pump motor I26 to convey washing or cleaning fluid under sufi'icient pressure to the nozzle I20 which forces fluid under pressure onto the peripheral surface of the rotating ground work piece 24 to wash off any grinding fluid or swarf remaining thereon. The washing or cleaning cycle continues for a predetermined time interval as governed by the timer I34. After a predetermined time interval has elapsed, the timer I34 serves to break a circuit so as to stop the work drive motor I I5 and to stop the washer pump motor I26.

It may be desirable in setting up the machine to jog the work piece. This may be accomplished by means of a jog switch I35 which is arranged to close a circuit so as to start the work drive motor I I5. The jog switch I35 is a momentary contact switch so that the work may be jogged manually as desired. A similar jog switch I36 is provided for jogging both the washer pump drive motor I26 and the work drive motor H5 in case it is desired to wash the work piece 24 for a further interval.

The operation of this improved grinding machine will be readily apparent from the foregoing disclosure. Assuming all of the parts to have been previously adjusted, a work piece 24 is placed in the machine. The control lever 83 is rocked in a counter-clockwise direction (Figs. 1 and 4) to actuate the push button start switch 82 which serves to set the timer 8!] in motion.

The closing of the switch 82 also serves through the timer to energize the solenoid 5'! to start a' forward'movement of the grinding wheel I2 and also serves to start the work drive motor II5 to rotate the work piece 24, and to start the pump motors I 06 and I I4 so as to start the flow of grinding liquid and cooling liquid. The grinding operation continues for a predetermined time interval as governed by the timer 80. After a predetermined time interval has elapsed, the timer 86 operates to deenergize the solenoid 51 to cause a rearward movement of the grinding wheel I2, also serves to stop the work drive motor H5 and to stop the pump motors I06 and I I4 so as to stop the flow of the grinding liquid and the cooling liquid. When the timer 8D is actuated after a predetermined time interval, it serves to energize the time I34. Energizing of the timer I34 serves to make a circuit so as to start the work drive motor I I5 so that the work piece '24 remains in continuous rotation. The energization of the timer I34 also serve to start the washer pump motor I26 automatically to convey washing or cleaning fluid through the nozzle I20 onto the peripheral surface of a ground work piece 24 to wash or clean the surface thereof as soon as the grinding operation has been terminated. The

time interval as governed by the timer I34 after which a circuit is opened to stop the work drive motor and the washer pump motor I26. The ground work piece may then be removed from the machine and replaced with a new piece of work to be ground.

It will thus be seen that there has been provided by this invention apparatus in which the various objects hereinabove set forth together with many thoroughly practical advantages are successfully achieved. As many possible embodiments may be made of the above invention and as many changes might be made in the embodiment above set forth, it is to be understood that all matter hereinbefore set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

I claim:

1'. In a grinding machine of the type having a longitudinally movable table, a work wpporting means thereon, a transversely movable wheel slide, a rotatable grinding wheel thereon, means including a pump for supplying grinding fluid to the place of contact of the grinding wheel and the work piece for promoting grinding action, the combination of a work washing apparatus therefor including a nozzle located adjacent to the workpiece for removing residual liquid film from the work piece after a grinding operation, means including an independent motor driven pump for supplying fluid under sufficient pressure to said nozzle for cleaning a. ground work piece before removing from the machine, and electrical means including a switch actuated automatically in timed relation with movement of the wheel slide to an inoperative position to start said latter pump.

2. In a grinding machine of the type having a longitudinally movable table, a work supporting means therefor, a transversely movable wheel slide, a rotatable grinding wheel thereon, means including a pump for supplying a grinding fluid to the place of contact of the grinding wheel and the work piece for promoting grinding action, the combination of a work washing apparatus therefor including a nozzle to remove residual liquid fllm from the work after a grinding operation, means including an independent motor driven pump to supply liquid under sufficient pressure to'said nozzle for cleaning a ground work piece before removal from th machine, and means including an electric timer automatically actuated in timed relation with movement of the wheel slide to an inoperative position to start and stop the pump motor after a grinding operation has been completed to supply washing fluid to said nozzle and work piece for a predetermined time interval.

3. In a grinding machine of the type having a longitudinally movable table, a work supporting means thereon, a transversely movable wheel slide, a rotatable grinding wheel thereon, means including independent fluid pumps for supplying separately to the place of grinding contact of the wheel with the work and to the work piece a grinding liquid and a cooling liquid respectively for promotin grinding action by the grinding wheel and for abstracting heat produced by the grinding operation, the combination of a work washing apparatus therefor including means to remove residual liquid film from the work after a grinding operation including a nozzle on said table, means including an independent motor driven pump to supply fluid under pressure to said nozzle under suflicient pressure for cleaning a ground Work piece, electric control means for the work drive motor to maintain rotation of the work piece being ground during the grind ing and washing operations, and means including an electric time relay to facilitate starting said pump motor automatically at the termination of the grinding operation, said relay serving after a predetermined time interval to stop said pump after a predetermined washing operation has been completed.

4. In a grinding machine of the type having a longitudinally movable table, a Work supporting means thereon, means including a motor to rotate the work piece, a transversely movable wheel slide, a rotatable grinding Wheel thereon, means including independent fluid pump for supplying separately to the place of grinding contact of the wheel with the work and to the work piece a grinding liquid and a cooling liquid respectively for promoting grinding action by the grinding wheel and for abstracting heat produced by the grinding operation, the combination of a work washing apparatus therefor including means to remove residual liquid film from the work after a grinding operation including a nozzle on said table, means including an independent motor driven pump to supply fluid under pressure to said nozzle under sufficient pressure for cleaning a ground Work piece, and means including an electric time relay to facilitate starting said pump motor automatically at the termination of the grinding operation, said relay serving after a predetermined time interval to stop said pump after a predetermined washing operation has been completed, electric control means for the work drive motor to maintain rotation of the work piece being ground during the grinding and Washing operations.

5. In a grinding machine of the type having a longitudinally movable rotatable work support, means including a motor to rotate a Work piece to be ground, a transversely movable wheel slide, a rotatable grinding wheel thereon, a, hydraulic piston and cylinder to move said slide, a solenoid actuated control valve therefor, means including independent motor driven pumps for supplying separately to the place of grinding contact of the grinding wheel with the work and to the work piece a grinding liquid and a cooling liquid respectively for promoting grinding action by the wheel and for abstracting heat produced by the grinding operation, an electric timer, a manually operable switch simultaneously to energize said timer to initiate an infeeding movement of the grinding wheel, to start the work drive motor and to start the pump drive motors, said timer serving after a predetermined time interval simultaneously to cause a rearward movement of the grinding wheel, to stop the pump motors and to energize a second electric timer, the combination of a work washing apparatus therefor including a nozzle adjacent to the work piece, and means including a motor driven pump to supply fluid under pressure to clean residual liquid from the surface of the ground work piece, the timeout of the first timer serving to start said latter pump motor and to maintain rotation of the work drive motor during a Work cleaning operation, said second timer serving after a predetermined time interval simultaneously to stop the work drive motor and to stop the Washer pump motor.

CHARLES C. ALVORD.

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

UNITED STATES PATENTS Number Name Date 762,838 Norton June 14, 1904 1,814,454 Penn July 14, 1931 2,102,140 Ungar Dec. 14, 1937 2,434,679 Wagner et a1 Jan. 20, 1948 2,434,771 Mueller et al Jan. 20, 1948

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