US2641873A - Automatic truing mechanism - Google Patents

Description

June 16, 1953 I s. H s 2,641,873

AUTOMATIC TRUING MECHANISM Filed March 5, 1949 9 Sheets-Sheet 1 June 16, 1953 F. s. HAAS 2,641,873

AUTOMATIC TRUING MECHANISM Filed March 5. 1949 9 Sheets-Sheet 2 INVEN TOR. Q11 flPar/P/c/rs #448 N BY N )7, 2463mm: *3? flTTOAA/EYS June 16, 1953 F. s. HAAS AUTOMATIC TRUING MECHANISM 9 Sheets-Sheet 3 INVENTOR. 1" F505 F/C'K 6: H1445 BY Filed March 5, 1949 June 16, 1953 F. s. HAAS AUTOMATIQ TRUING MECHANISM 9 Sheets-Sheet 4 Filed March 5, 1949 s 4 M 3 s 4 s 7 e 1/ mu 8. m 2 we 1 h 6 ix W N w. a mmfi 2 m m vb m 2 m M 9 a x, w m o T MW m M Z L l m i m am T m m MV 7 2 9 4 B 2 a a z I June 16, 1953 Filed March 5, 1949 June 16, 1953 F. s. HAAS 2,641,873

AUTOMATIC mums mcmxsu Filed March 5, 1949 9 Sheets-Sheet 7 VEN TOR.

B Y xMMrziX W Ayn/Mfrs June 16, 1953 F. s. HAAS 2,641,873

' AUTOMATIC TRUING MECHANISM Filed March 5,1949 9 Sheets-Sheet 8 June 16, 1953 F. HAAs AUTOMATIC TRUING MECHANISM Filed March 5. 1949 9 Sheets-Sheet 9 INVENTOR.

m WW W 01 CM 5 0 mm Y fl B m M a r r A Patented June 16, 1953 UNITED STATES PATENT OFFICE 2,641,873 Q AUTOMATIC TRUING MECHANISM Frederick S. Haas, Orgonia, Ohio, assignor to The Cincinnati Milling Machine Co., Cincinnati, Ohio, a corporation of Ohio Application March 5, 1949, Serial No. 7 9,892

This invention relates to automatic grinding planes on the periphery of the same grinding wheel.

A still further object of this invention is toprovide an improved control mechanism including work counting means for automatically determining the frequency of truing operations in an automatic machine by controlling the number of work pieces ground for each truing operation.

An additional object of this invention is to provide an improved automatic controlmechanism for effectin truing operations at some predetermined frequency and each time autOmati-L callyeffecting compensation in the position of parts resulting from the truing operation. Another object of this invention is to provide a truing mechanism with relative control means such that the truing operation may be performed with the grinding cycle progressing or alternatively with the cycle interrupted and in either case at some, regular frequency predetermined,

Claims.

for instance, by the number of work pieces 7 ground.

Other objects and advantages of the present invention should be readily apparent by reference to the following specification considered in conjunction with the accompanying drawings forming a part thereof, and it is to be understood that any modifications may be made in the ex Referring to the drawings in which like refer- 1 ence numerals indicate like or similar parts:

Figure 1 is a plan view of a grinding machine.

to which this invention has been applied.

Figure 2 is a vertical section through the grinding wheel support and actuating mechanism therefor as viewed on the line 22 of Figure l.

Figure 3 is a sectional view in elevation as viewed on the line 33 of Figure 1.

Figure 4 is a detail section on the line 4-'4 of V truing slide adjusting mechanism as viewed on the line 8-8 of Figure 3. V

Figure 9 is a sectional View on the line 99 of Figure 8. A

Figure 10 is a sectional view through the Work support adjusting mechanism as viewed on they hide Iii-l El of Figure 1.

Figure 11 is an end View partly in section of; the work support compensating mechanism asviewed on the line Illl of Figure 10.

Figure 12 is a detail sectional view as viewed on the line l2- -l 2 of Figure 11.

Figure 13 is a diagram of the solenoid control circuit.

Figure 14. is a chart to accompany the circuit shown in Figure'13.

Figure 15 Ba diagram of the electricalcon trol circuit.

Figure 16 is a chart to accompany thecontrol circuit shown in Figure 15.

Figure 17 is a diagrammatic view of the hydraulic control circuit.

Automatic grinding machines have a continuj cusly repeating grinding cycle and in order to' obtain maximum production are usually. provided with'automatic work" loading means. Due to the high productive rate of such machines it will beobvious that the wear of the grindingwheel will be at a corresponding high rate. It nevertheless is necessary to maintain the grinding wheel in good grinding condition, that is, its cutting quality, itsshape, and its position with respect to the work, if precision or accuracy'of work size is to be maintained.

, In the more highly developed machines, the

V grinding wheel face is altered to grind some othershape on the surface of thework, than a plain cylindrical surface. For example, in the roller bearing industry the raceways have a dihedral angular surface and the demand of the industry requires that these surfaces be ground in one operation. This obviously requires a corresponding shape on the periphery of the grinding wheel, which in this case constitutes two intersecting as viewed on surfaces which must be dressed or trued with accuracy.

The truing mechanism of this invention is particularly adaptable for use in this type of automatic machine and is adapted to automatically true two angularly intersecting surfaces on the periphery of the grinding wheel in coordinated relation to the continuously repeating automatic grinding cycle. This invention is so contrived that it will periodically interrupt the cyclic action after a predetermined number of work pieces have been ground, and true the two angular surfaces on the wheel automatically in succession and then reinstate the grinding cycle. In addition, the control mechanism of this invention.

may be adjusted at will to cause the truing operation to be performed simultaneously with the grinding operation, in those cases where the amount of stock to be removed is sufficient to permit the truing operation to be completed before the grinding operation is completed.

A counting mechanism has also been provided that may be manually-set to select the number of 7 work pieces to be ground between truing operations and-thus determine the frequency of the truing operations.

It will be obviousthat after each truing operation that the grinding wheel has been reduced india-meter, and this requires readjustment between the wheel and the work as well as readjustment of the truing elements with respect to the wheel, and mechanism has been provided by means of this invention for automatically effecting these readjustments.

A grinding machine shown in copending application,.serial No- 734,080, filed March 12, 1947, now Patent 2,478,562, issued August 9, 1949, has been selected as an example ofan automatic grindingv machine to which this invention is particularly adaptable.

In this machine,-the general structure of which is shown inFigures .1 and 2 of the drawings, the reference numeral In indicates the bed of the machine-upon which is slidably mounted a work supporting structure indicated generally by the reference numeral H and which may be moved or adjusted along the top of thebed by-means of a lead screw I2 which, as shown inFigure 10, is'threaded in a nut member I3 fixed with the bed Ill-of the machine.

The work piece is indicated by the reference numeral !4 in Figure .1 and is held against the driving member I5 by means more fully disclosed in the co-pending application, and further .description thereof is not believed to be necessary since it forms no part of this invention.

Thegrinding wheel is indicated by the reference numeral H5, and it will be noted that it has two angular faces I! and [8 formed on its periphery for grinding an angular surface on the workpiece. The grinding wheel I8 is secured to the end of a. rotatable spindle [9 which is journaled in suitable bearings 2a mounted in an oscillatable support 2i as shown in Figure 2. The support '2! constitutes, in effect, a grinding wheel head, which is supported for oscillation about a trunnion 22 to move the center of the grinding wheel through an arcuate path, indicated by the dotted line 23 in Figure 2, to cause enga ement of the periphery of the grinding wheel with the work.

The grinding head 2! is oscillated in .an automatic grinding cycle consisting of a rapid traverse movement to take up the work loading clearance between the work and the wheel, a

feeding movement during which the grinding operation is performed, followed by a rapid traverse movement back to starting position.

Briefly, the mechanism for eifecting these movements consists of a hydraulic J'ack, indicated generally by the reference numeral 24, which effects the rapid traverse movement, and a feed piston indicated by the reference numeral 25, which effects the feedmovement. The grinding head has a bore 25', in which is slidably mounted a sleeve 26 and a piston member 2'! whichhas, a reduced piston rod portion 28 that passes through the cylinder end 29 and is in constant engagement with a bell crank 30 pivoted in the bedat 31'.

The other arm 32 of the bell crank engages the end of the piston rod 33 formed integral with the end of the piston 25.

In Figure 2 it will be noted that most of the weight of the grinding head 2| is to the right of the trunnion .22, whereby eravl yoauses t hea 21 to normally rotate a clockwise direction,-

The par srare shown in Figure 2 after they have completed the rapid traverse movement and are-readyto; startthe feed movement. The chamber 34 above the'piston 21 is filled withfiuid under pressure. nd it sho ld b v u th t i there were no fluid under pressure in the cham.-. ber a l that the head 2 I would rotate in a clockwise direction and c lapse he ch mb r .34 due to the fact that the piston 2'! would be held the positi -sh w The p otub rance .35 on th cylinder head 36 whiohcloses the end of the sleeve 26 w uld thus ter the es ion 3 f rmed ihthe nd f the piston 21. This ou limit, the ext nt of ,olo kw e m men of h head 2| andwould correspond .to the extreme return position of the grinding wheel.

Thus, a he. beginning f a cy le, f uid p essur is admitted to the cha ber .34 wh ch wo l r t e the head?! in -a counterclockwise direction until the shoulder 38. formed on the piston rod 2.! enga ed he t om .39 o a dash t p sion so. formed on the inner ve o the lin rho d 29.. When this occurs, the forces would be bala oed a d furth r m v m ld s p duo to the fact that the-pressur n he am r 4 s attempting to. push the gr nding h ad u While its ngagem nt with the hO llder 38 is p eventi h movement.- n ot er r s, th pr sure .ihthe c amber th h s mom is i p y holdng .th c li d r head 3. i a s pa at d relation WithreSpeot t the endof the p st n v od 21. .This upward movem nt o th e nt i t rapid trave s movement,

The fe d m ment is sta ted by ad i h e pressur ifluid th ough the port 4| behind h piston 25, causing the same to advance toward he...right, as viewed in Fi u e 2, n ther y e fec counterclockwise o at on of t b ll crankhis will cause. upward movement of thep to 2'1, and the pressure in the ch mber 34 w l transmi this mov ment to th head 2|, e y

aus ns he head 21 to m ve in un n h h pi tonahd boll drank Th s d m m n i l clent pressure therein to hold the cam 42 solidly against the positive stop 43.

During this advancing movement the bell crank arm 32 is at all times held against the piston rod 33 by a spring pressed plunger 44, which is continuously acted upon by a. spring interposed between a shoulder 46 integral with the plunger 44 and a positive abutment: or

shoulder 41 formed on the member 48 which is J securedto the bed Ill. A secondv positive stop 49 is threaded inthe end of the hollow member 48 to act as a final limit to the movement of the rod I cycle of operation may be effected automatically 7 This machine is usually is shown in Figure 1'7. provided with an automatic loading fixture, the

. details of which form no part of the present invencommunication with the chamber 34. As pre-.

viously stated, the parts are in the position at the completion of the rapid traverse movement and therefore the chamber is under presusre; The shiftingof the valve .12 is controlled auto- I matically by a solenoidBt.

A third valve 8!, which may be termed'the feed control valve, has a pressure port 82 and an exhaust port 83. This valve, it will be noted, has not yet been shifted to establish the feed movement and is held in its right hand position by a spring 84. A solenoid 85 when energized will shift the valve plunger 88 to the left and thereby connect'the pressure port 82 to channel 81, and the fluid pressure will flow. through a reducing valve 88. and throttle valve 89 to channel 90.

It will be noted that the channel 99 has a branch line SI leading back to the port 92 of valve Bl. When the valve 85 is shifted to the left it will close the port 83, thereby isolating the channel 5H so that the fluid pressure in line 90 will not be lost. The fluid pressure in channel 96 will flow to the feed cylinder, thereby actuating the feed piston to effect the feed rate.

When thegrintling operation is completed all of the solenoids will be deenergized, whereby the tion, but it is necessary to know when a new work 7 piecehas been loaded in the machine and to have some means for detecting this fact in order "to start the grinding cycle. For this reason the piston 50 and cylinder 5| which causes actuation of the work loading mechanism, indicated generally by the reference numeral 52, is shown in- Figure 1'7. In other words, the work pieces are loaded in a chute 53 and the member 54 in moving up receives a work piece and upon downward movement carries it down to the grindingpositionindicated by the dotted circle 55. The. cyl inder 5| is connected by channels 55 and 51 to ports 58 and 59 of a workloading reversing valve indicated generally by the refernce numeral Ell.

This valve has a pressure port 6| connected to the main pressure supply line 62 which receives fluid under pressure from a pump 63 having an intake 64 through which fluid'is withdrawn from a reservoir 65. A suitable relief valve 66 is connected to the line 62 to control the pressure therein. It will be noted that the valve s is in position to connect the pressure port 6| to port 59 whereby the work loading fixture has moved down to position a new work piece in the machine. The port 58 is connected at this time to exhaust port B'L'the returning fluid flowing.

through the exhaust line 68 and the low pressure relief valve 89 back to the reservoir 65.

When the work loading control valve is shifted to the right it will be obvious that the pressure port 6| will be connected tothe port 58, and that port 59 will be connected to a second exhaust port I the rap-id traverse control valve has a pressure port 13 which it will be noted, is connected by the valve plunger '14 to port 75. Fluid pressure will thus flow through line it to port 11 in the rapid traverse jack, the port communicating with a wide annular groove '38 formed in the periphery thereof.

A port 19 is drilled in the sleeve to establish feed valve 8! will return to the position in which it is shown in Figure 17, and the fluid in the feed cylinder willv pass directly to reservoir through interconnected . ports 92 and 83 without passing through the rate vvalve. This allows the oil to drain from the feed cylinder so that the piston 25 will return freely under the action of spring 55.: The return of the rapid traverse valve I will eifect connection of port 75 with the reservoir portet, thereby permitting the fluid in chamber 34 to return to reservoir whereby the part 35 will eventually move down into the cup 3;! formed in the end of cylinder 2! which will act asla dashpot to prevent shock to the mecha nism. 1

The solenoid H is the last one to be released to insure that the grinding 'wheel is out'of en gagement with the work before the work is'lifted out of its grinding position. .lVhen this occurs, port 6! will be connected to port 58 which will thereby lift the work loading mechanism, which will immediately return to load a new work piece and start-a new automatic grinding cycle.

The truing mechanism which-will be described in detail later is illustrated diagrammatically in Figure 1'? and comprises a first reciprocable member 94 which isattached tothe reciprocating rod fit that is'slidably mounted in the guide-block 96 for movement parallel to the face 3? of the grinding wheel. The member 54, in turn, has guided in it a second slidable member 98 that is guided for movement parallel to the other face '99 of the grinding wheel. The member 98 has a diamond holder :00 integrally secured to the end thereof in which is mounteda diamond iili for truing the face 99, and a second diamond 182 for truing the face 97 of the grinding wheel. The rod 98 has an operating piston Hi3 slidably mounted in a, cylinder {64 which has ports H65 and H36 in opposite ends thereof. These ports are-connected bychannels Hi1 and let to ports its and H0 of a reversing valve HI. This valve has a pressure port H2 and a valve plunger H3 which .is normally held in the position shown by a spring l [4. In this position the port H2 is connected to port I99 which holds the piston [t3 in the position shown during the grinding operation. Upon actuation of thesolenoid. H5, which is operatively connected to the valve plunger H3, the

7 port: I I2 will ibelconnectedto the port; I I; wheree by diamond Ifl'iiwill be caused to traverse across the face 99. of. thegrinding wheel.

In actual:operation,.the.face 911- oisthe-grinding wheel is trued first,-. andthis is accomplished by providing two piston .members 6- and II1, which are. slidable in bores. formed in the guide block 96, the piston H6 being integrally C011".

nected-by the member H8 to the rod 95and; the

piston H1 being integrally connected to: "the member 94. It will thus be seen that the parts I I6, i I8, 95,9 hand. I I1 are all connected together to form a unit which is capable of reciprocation relative to thesupport 9S and, in addition, the member supports the member 98 and therefore this member and its actuating piston and.

cylinder also move with the member 94-. By acl mitting pressure behind thepiston .I H the en-z' tire assembly is moved relative to: the support 96 to cause the diamond I92 to reciprocate -across theface 31 of the grinding wheel.

Fluid pressure is admitted to the piston H1 through channel I I9 which; is connected to port I26 of a reversingvvalve, indicated generally by the'reference numeral I2i. This valve also has a port I22 which is connected by channel I23 to v the piston H6. This valve has a pressure port I24 which is shown connected by the valve plunger I25ywhen in its normal position, to port I22, while port I20 is connected to. an exhaust port I26. In this position of the parts it will be noted that fluid pressure is continuously acting on the piston I I6 to hold the diamond support in retracted position with respect to the grinding wheel and during the grinding operations.

When the time comes to true the face 91 of the grinding wheel a solenoid I'21,'which is operatively connected to the valve piston I25, is

energized, thereby shifting the valve plunger to,

the right against the resistance of a spring I28, and the port I24 is connected to the port I20,-and the port I22 is connected to exhaust port I29. The two exhaust ports I26 and I29 are connected by a channel I30 to a throttle valve I3I which regulates the rate of traverse of the diamond across the face of the grinding wheel.

After the face 91 of the grinding wheel is trued, the other solenoid I I is energized to cause traverse of the diamond IIII by interconnecting pressure port I I2 to port II 0, and port 109 to port I32. When the solenoid H5 is deenergized the valve returns to the position shown, and port I I2 is connected to port I09-and port-I I0 is connected to exhaust port I33. Both of the exhaust ports I32and I33 are connected to throttle valve 134 which regulates the rate of traverse of diamond IOI The sequence of operation of solenoids -I I5 and I21 will be explained in connection with the electrical circuit.

The actual construction of the truing slides is shown in Figures 3 to 9 inclusive.

Referring to Figure 3, it will be noted that the support 96 which contains the pistons H6 and H1, and the slidable member 95, is secured by clamping bolts I35, as shown in Figure 6, to another slidable member I36 which is movable in a radial plane of the grinding wheel. The slidable member 95 has an angular bracket I31 formed on the end thereof as shown in Figure '7, and the support 94 is secured to this bracket by stud bolts I38. Referring to Figure 3 the member 94 has an enlargement I39 to which is bolted the cylinder casting I04 containing the piston I03 and piston rod I4l which is connected atone end by a T slot connection I42 to the end oivthe. sliding member 98 11161 061161 end of the piston rod .is'zthreaded at I43 to receivean adjustable stop :member I44? which may. be

rotatably adjusted on the :endxof the piston rod to vary; the clearance with respect to a shoulder I45 formed in a fixed bushing I46.- A look screw- I412 is alsoxthreaded in the member I44 to-clamp the stop member I44against rotation. The bushing I46 is fixed in the end of a housing I48 which is bolted to. the end of'the cylinder casting 140 and within this housing-are certain reversing limit switches, one-of which is'operated by a collar I49? which may be adjustably positioned on the piston rod, and another of which is actuated by the stop member I44. The relationship of these parts is more particularly shown in Figure5.

Since the position of thedi-amond with respect tort-he grinding wheel may need some adjustment the support 96; is made adjustable with respectto-the slide 136 by: providing a pair of adjusting screws I50 and [5.111, which, as shown in Figure 7,

are threaded in bosses I52 and I53 formed integrally on the side of the member 96, and the slide" I36is'provided with a fixed stop member I54 against which the adjusting screws may be operatedtoshift the position of the member 96=witl 1 respect to its supportin slide I36 and also used for locking in position .in conjunction with the T bolts I35.

The member 96 hasa housing I55 formed on the top thereof in which are mounted a pair of limit switches which are adapted to be operated by plungers I56 and I51 which are alternately engageable by'a projection I58 formed on the bracket I31, and the adjustable screw I59 carried by the connecting member H3. The operation of these limit switches will be explained in con.-

nection with the operation of the electrical circuit.

It will be obvious that after the-truing diamonds have reciprocatedacross the face of the grinding wheel that it is necessary to feed the diamonds toward the wheel in preparation for the next op eration. This is accomplished automatically in the following manner. As previously described, it will be noted that the entire diamond supporting structure shown in Figure 3 is carried by the slide I36 and, as shown in Figure 44, the slide I36 is provided with a dovetailed guideway and adjustable gib I60 for movement relative to the wheel housing support, indicated enerally by the reference numeral 2 I. As shown in Figure 8,,the slide I36 has a ratchet mechanism housing I6I formed on the top thereof. A ieed screw, I62, which isthreaded in a nut I63, secured in the wheel head 2.I passes through the housing and is anchored therein. bythe shoulder I64 integral withv the screw I62 and an indicating dial I65 which is secured to the screw bya clamping screw I66. A hand wheel I61 is secured to the upper end of the-screw I62 for effecting manual rotation thereof.

Within the housing and mounted on the unthreaded portion -I68-of thescrew is an adjustable stop member I 69, a ratchet wheel I10 and a pawl carrier I1I; Referring to. Figure 9, the pawl carrier IN is connected by a pin' I12 and a link I13 to the armature I14 of an operating solenoid I15; On the opposite side of the shaft I68, the pawl carrier I1I has a spring I16 connected to it for effecting counterclockwise rotation of the pawl carrier upon deenergization of the solenoid. The pawl I11 is pivotally connected to the pawl carrier by a pin I18, and the heel I19 of the pawl upon-its return 'bythe sprin engages the stop between the work and the grinding wheel.

I89 which is upstanding from the member I69 as shown in Figure 8.

The opposite sides of the member I69 are adapted to be engaged by stop screws IBI and I92 for determining the rotatable position of the stop I88, thereby determining the amount of rotation that will be effected by the ratchet mechanism upon actuation of the solenoid. To assist the operator in determining this amount, the stop member I59 has an upstanding lip I83 upon which appears certain indicia as indicated by the reference numeral I84 in Figure 3 of the drawings. The housing has an opening I35 adjacent the periphery of the lip I83 whereby the indicia may be observed by the operator. It should now be obvious that each time the solenoid is energized that the feed screw I62 will be rotated some predetermined amount and the diamonds fed toward the grinding wheel.

It will be obvious that, after a truing operation, the grinding wheel has become smaller in diameter, and since the wheel head always stops in .the same final position at the end of a feeding movement, the work would be ground large, and, therefore, it is necessary to effect a readjustment This is accomplished by adjusting the work support toward the grinding wheel a sufficient amount to compensate for the truing operation.

As previously described, the work support slide II, as shown in Figure 10, carries a feed screw I2 which meshes with a nut I9 fixed with the. bed I0.- A backlash eliminating nut I86 is threaded on the screw and held against rotation by a bolt I87 which is threaded in the bed and interfits a slot I88 formed in the periphery of the nut IBIS. A spring I39 is interposed between the head of theh nut I86 and a sleeve I90, which is pushed against the end of the nut I3 whereby the spring tends to separate the nuts and thereby take out the-backlash. I

The slide II has an end plate I9I which depends from the end of the slide, and this plate has a bore I92 which forms a bearing for the shaft portion I93 of the screw. A flanged sleeve I94 is keyed at I95 to the screw and held in position by a nut I96 threaded on the end of the screw. The flange portion I97 of the sleeve has a cup-shaped cover plate I99 secured thereto,

which has formed integrally thereon an internal gear I99. This gear intermeshes with a pinion 299, as shown in Figures 1 and 11, the pinion being keyed to the end of a long shaft 20I which extends to the other end of the machine where it isprovided with a hand wheel 202 having micrometer graduations 203 formed on the hub thereof. The cover plate I98 has a handle. 284 secured thereto, and it should now be obvious that by means of the handle 264 the screw I2 may be rotated directly, or by means of the hand wheel 292. The screw maybe rotated through a reduction means so as to eifect fine adjustments of the work support;

Mechanism has been provided on the end plate I9I, Figure 10, to also effect fine adjustments automatically to compensate for the truing operation. This mechanism. comprises a flange sleeve 295 which is supported for free rotation on the periphery of the sleeve I94, and an electric magnet 206 is secured to the sleeve 295, the magnet forming part of an electric clutch. The clutch plate assembly 207 is attached to the flange I91 of the sleeve I94 and held in position by a series of studs 298 on which are slidably mounted a series of headed buttons 299 which are contin- OR! to line 223.

energized and that better operating conditions can be obtained during energization of the magnet if the plate 291 would move into contact with the magnet. By means of this construction it is possible because the springs 2 It will yield suffici'ently to make it so.

The member32i5 has an operating lever ZII'I' formed integral therewith, and this lever is operatively connected by a link 2 to an operating solenoid 267, Figure 11. A spring pressed plunger 2 I2 located in the bottom of the housing 2 I3 normally urges the lever 2) in a clockwise direction against a stop screw 2 It. In operation the clutch is first energized, and then the operating solenoid is energized to rotate the lever 2 It in a counterclockwise direction, and while so held theclutch is deenergized whereby upon release of the solenoid the lever 2 III may move back without causing counterrotation of the screw. This performs the same function as an index mechanism with the added advantage that the operator. maymake slight manual adjustments at any time without disturbing the length of the next indexing because there is no ratchet mechanism.

In order to prevent shocks to the mechanism by the sudden operation of the solenoid, a dashpot has been arranged in conjunction with the plunger 2 I2 in the form of a chamber 2I5, which is connected by, a'throttle valve 2I6 to a reservoir space 2H, which is maintained full of oil. A check" valve 2H3 is also connected between the space 2 I5 and the reservoir whereby upon move ment of the plunger 2I2 to the left, oil will be admitted to the space 2I5 by automatic opening of the check valve 218; and upon return of the plunger 2I2 to the right, the check valve will close, and the oil will be throttled through the valve 2I6. This will prevent hammering of the parts and insure smooth operation.

The electrical control circuit which governs the complete automatic operation of the machine will now be explained in connection with Figures 13, 14, 15, and 16.

In general, one part of the electrical-control circuit controls the automatic operation of the grinding cycle. Most of the remaining part of the circuit controls the automatic operation of the truing mechanism, and this portion of the circuit is interconnected with the first part of the circuit by a counting mechanism which may be preset to determine the number of work pieces that are to be ground between each truing operation. In addition, a selector switch is provided whereby the truing operation may be effected while the grinding cycle is interrupted, that is,

with the wheel head stationary, or it may be performed simultaneously during a grinding cycle.

The automatic grinding cycle is initiated by closing the start button 2I9, Figure 15, which establishes a circuit from the power line 220 through a stop button 22I, line 222, and relay Relay CRI will close its contacts CRIA and CRIB, thereby establishing a holding circuit around the start button 2I9 as,

well as connecting line 228 to main line 220 which can only be broken by the stop button 22L In addition, the operation of the push button will establish a circuit through line 224 to relay CRI2 which will close its contact CRI 2A in line 225 and thus complete the following circuit from line 220 through stop button 22I line 226; closed contacts 11 CRIA and CRIB, line 225, normally closed switch 226', line 221, normally closed contacts CRBA to relay CR2. CR2 establishes its own holding circuit by closing contact CR2A, thereby completing a circuit from line .228 through normally closed limit switch LS3A and line 229 to line 221. In addition, relay CR2 closes a second contact -CR2B completing a circuit from line 228, through line 230 to relay CR3. As shown in Figures 13 and 14, energization of relay CR3 closes contact CR3A, energizing solenoid ll, thereby lowering the work fixture.

Attention is invited to the fact that while the work fixture is up in a loading position, it holds a limit switch LS1 closed as shown in Figure 13 of Patent 2,478,562, supra. This switch is in line 23l,which interconnetcts line 228 with line 225 and also contains. the normally closed selector switch 232. It will be noted that the line 23l is connected-in parallel with the contact CRIZA, and this contact is only. momentarily closed while thestart button 2l9 is held depressed. In other wordsr as soon as the start button is released, the circuit through line 225 is broken, andas soon as the work fixture moves down to a grinding position the limit switch LSl is opened. The

obj ect of the limit switch LSI isto automatically close the circuit to line 221 after each grinding operationto start the next cycle, thus avoiding the necessity of operating the push button to close contact CRI2A.

Relay CR3 also closes contact CR-BB in line 233 whichis connected by branch line 234 to line 230.

When the work fixture has completed its down- Ward movement it closes a limit switch LS2 as shown in said patent supra by a suitable operator such as lug 54, thereby establishing a circuit from line 228 through lines 235, normally closed contact TRIA and line 236 to rapid traverse relay CR4. This relay latches itself in by closing contact CR4A, thus completing acircuit from line 228 through closed contact CR2B, line 234, line 233, closed contacts CR3B and- CR4A, normally closed contact TRIA and line 236 to line 223.

"Referring to Figures '13 and 14, rapid traverse relay CR4 closes contact CR4B, thus energizing the rapid traverse solenoid 80. In addition, re-

lay CR4 closes contact CR4C which, it will be noted, is located in line 231, paralleling the lnmt switch LS2 so that when the limit switch is opened by the rising of the work fixture, the circuit may still be maintained to relay CR4.

It will now be seen that the automatic operation of solenoid 80 started the rapid traverse movement of the wheel head and upon completion of this movement the wheel head automatically operates limit switch LS3 as shown in said patent supra and indicated diagrammatically in Figure 2 as actuated by lug 24 which has a pair of normally closed contacts LS3A and a pair of normally open contacts LS3B. As previously explained, the normally closed contact LS3A was in line 229 which constituted the holding circuit for relay CR2 so that upon opening of contact LS3A the holding circuit to relay CR2 is now broken and the relay .is deenergized, which thus opens contact CR2B. The circuit to CR3 is, however, maintained, it now extending from 228 through line 231, closed contact CR4C, line 235, line 233, closed contact CR4A, closed contact CR3B, lines 234 and 230 to CR3. Switch LS3B is simultaneously closed in time with the opening of LS3A to establish a circuit in line 238 to feed through line 229 to the relay CR2.

12 control relay CR5 which closes contact CRSA in line 239.

Referring to Figures 13 and 14, feed control relay CR5 closes contact CR5B, thus energizing the feed solenoid 85, thereby causing the grinding wheel to advance at a feed rate to efiect grinding of the work.

. Line 238 leading to relay CR5 has a branch connection 239' in which is a normallyv closed selector switch 240 which leads to timer relay TRI. This relay is set to time the grinding operation including the time to execute the feed movement and the tarry of the grinding wheel after the .wheel head has engaged the positive stop 43. When the time has run out, the relay opens its normally closed contact TREA, thereby releasing the rapid traverse control relay CR4. This opens the con- .tact CR4B in Figure 13, deenergizing the rapid traverse solenoid 80, so that valve 14 immediately .shifts to effect rapid retraction of the grinding wheel. This also breaks contacts CR4A and CR4C .in lines 233 and 231- respectively, but the circuit to line 230 through contact CRSA is maintained to prevent elevation of the work fixture until the grinding wheel has disengaged the work. When the grinding wheel head has retracted to the point where it started the feeding movement, it will again operate limit switch LS3, thereby opening contact 1.533 and closing contact LS3A. The opening of contact LS3B will release the relay CR5, reversing the feed: control valve to efiect .feed return and opening the contact CREA which will. deenergize the work-loading control relay CR3 and through the opening-of contact CR3A in Figure 13 will cause the control valve 60 to shift and cause elevation of the work fixture. Thus, the rapid traverse .return separates the wheel from the work and then the feed return and elevation of work fixture follows. a

The closing of. contact LS3A in line 229 reestablishes the circuit in line 229 to-contact CR2A which is open. at this time. Elevation ofthe work fixture closesxlimit switch. LSI to energize relay CR2yand initiatea new grinding cycle and close contact CR2A to establish again aholding circuit It will thus be seen. that this part of the electrical circuit controls the continuously repeating automatic grinding cycle of the machine.

The automatic counter which determines how many work pieces shall be ground before the grinding wheel is trued is indicated generally by the reference numeral 24Iin=Figure 10. This device is mounted onthe bed ill of the machine, and

since this is a commercial device its particular constructionforms no part of the present invention. However, this. device is known as a No. HZlGrv counter manufactured by the Eagle Signal Corporation and is. more particularly described in Patents Nos. 2,175,864 and 2,175,865.

.As shown in Figure 10, it has an operating knob 242 which may be rotated to any selected position, the knob having a first pointer -243.which is movable over an inner scale 244, and one rotation of the knob will. cause indexing of a second pointer 245, one graduation mark ofanouter scale 246. For illustrative purposes the device has been set for 22. This means that 22 work pieces will be ground. between truing operations. This is an electrical device and referring to Figure 15 it has a clutch operating coil 24'! and a counting coil 248. In general, the device is a ratchet operated mechanismand the clutch connects the ratchet mechanism to a control cam, and each time the counting coil is energized and released the indexin'g mechanism is operated, and after a selected number of indexing operations, the cam closes a control switch. This device is connected in the I machine control circuit of Figure in the following manner.

The coil 241 is connected to main 220 through closed contact 249 of a selector switch indicated generally by the reference numeral 250, line 25I, contact CR4D, and normally closed contact -CRI IA. The selector switch 250 determines Whether the truing operation shall be performed during the grinding cycle or the grinding cycle shall be interrupted during the truing operation so that the wheel head is stationary. Switch 258 is shown in the drawing as set for the latter type of operation. It should now be obvious that upon the first of a series of grinding cycles that the operation of the rapid traverse control relay CR4 will close contact GRAD and thus energize the clutch coil 241. In so doing, the clutch coil will automatically close contact 252 and thus latch itself in through line 253 leading from the main 220, line 256, line 255, and parallel lines 256 and 251, the former containing the normally closed 1 contact CRI IA and the latter containing the normally closed limit switch LS4. It will now be seen that on the first cycle of a series of grinding cycles that the clutch in the counting device is engaged and will be maintained engaged throughout'the required number of cycles regardless of- I the subsequent opening and closing of contact CR ID.

The operation of rapid traverse control relay CR4 also closes a contact CR4E and this completes a circuit from line 254 through line 258 to the counting coil 248. Thus, each time that the rapid traverse control relay is energized to cause advance of the grinding wheel, the counting coil is energized, and upon release of the rapid traverse control relay to cause return of -the grinding wheel, the counting coil is released and effects a count on the counting mechanism. When the necessary number of counts have been made, the counting coil upon its release at the start of a rapid traverse return, closes contact 259 and completes a circuit through closed switch 26I to the truing cycle start relay CR6.

' The actuation of relay CR6 closes contact CREB and thereby latches itself in through line 264. The relay CR6 is the one that interrupts or halts the grinding cycle and initiates the truing operation.

This is accomplished as follows. The relay CR6 opens the normally closed contact CRBA in line 22?, thereby opening the circuit to relay- 'CR2, so that upon closing of limit switch LS-I at the end of a cycle, a new grinding cycle will not be started. Y

Relay CR6 starts the truing cycle by closing contact CRBC. This interconnects mainline 223 of the machine control circuit to the main line and I15, the first of which is shown in Figure 17 and the other of which is shown in Figure 9.

.The solenoid IZTactuates the valve I2I to start the first truing operation by the diamond I62 while the solenoid I15 indexes the diamond supporting slide I36. Relay ;CR6 ,also closes a contact CRBD to energize work support feed clutch energizing relays CR1 and CR8 to effect return of truing diamond and close the latching contact CRSB in'line 218. In addition, relay CR9 will close contact CRQC in line 2' so that upon return of the truing diamond caused by deenergization of solenoid I2! due to'the release of contact CR'IA, limit switch LS6 will be closed and a circuit established to the timer relay TR2.

This relay will eventually time close contact TR2A, establishing a circuit from line 2l2 through normally closed contact CRIIB and closed contact 'IRZA to relay CRIil. This relay will close contact CRIBA shown in Figures 13 and 14 and energizes solenoid H5 which will operate the valve to start the movement of the second truing diamond. Relay CRIU will also close contact CRIUB in line 213 so that-upon the finish of the truing operation and the closing of limit switch LS1 a circuit will be established from line 264 through closed limit switch LS'I, line 213 and closed contact CRIGB to timer relay TRSV relay will time close, thereby allowing dwell for the diamond at the end of its truing stroke, eventually closing contact TRSA, thereby completing a circuit to relay CRII which will latch itself in by closing contact CRI IC.

Relay CRII Will open its normally closed concontact CRIIA in line 256 to clutch coil' 24? so that upon completion of return of the second truing diamond and operation of LS4 the circuit to the clutch will be broken. This will result in "contact 252.

the counter mechanism automatically returning to its starting position and simultaneously open This will break the circuit to relay CR6 and open contact CRBC, which will break circuit to the entire truing circuit releasing relays CR9 and CRI l.

The work support clutch 296 has to be operated by direct current and, therefore, is connected by a rectifier 21-4 across lines 264 and223.

As previously mentioned, the truing operation may be performed during the grinding operation and the circuit is set for this purpose by selector switch 250. In other words, switch 25I is opened and switch 215 is closed. Thus, upon completion of a count by counter coil 248 upon release of contact CR iE at the start of a rapid traverse return of the grinding wheel, contact 259 will be closed as previously explained. Since switch 26I is open the circuit to relay CR6 must be completed through contacts CR5C and CR lF, but CR4F opened simultaneously with CR4E. The return movement of the grinding wheel will, therefore, continue, feed relay CR5 dropping out to open contact CR5C to complete the feed return movement.

Upon reversal of the grinding wheel, and start vof the next cycle, the rapid traverse relay CR4 will close CR IE; and then the feed relay CR5 This,

"gear-31c will close 'CRSC, thus completing the circuit through 259 to relay CR6 just at the beginning of the feed movement. Thus, the truing. cycle will progress simultaneously with the feeding movement of the grinding wheel.

When it is desired not to use the automatic truing mechanism at all, the switches 249, 275 and 26! are all opened.

The function of the various manually operated 1 selector switches will now be explained.

The switch 232 is a selector switch for choosing between a continuous cycle and a single cycle and by opening this switch, the'machine willperform a single grinding cycle and then stop.

The manual selector switch 225 is operated,

when an automatic work fixture is not used, to

open the circuit to line 22! and close the circuit from lines 225 and 23! direct to line 236.

The grinding wheel truing may be controlled at will by the operator by opening switch 250 and using the manual start button 216 in line 253 which will operate relay CR6 direct and start the cycle.

It should now be apparent that an improved truing mechanism has been provided in conjunction with an automatic machine in such a manner that the truing may be done with the grinding cycle stopped or during a grinding cycle and the necessary compensations in the relative position of wheel and work resulting from the truing operation are effected automatically as well as infeeding of the diamonds in preparation for the next truing operation.

What is claimed is:

1. In a grinding machine having a bed, a grinding wheel support and a work support mounted thereon, the combinattion of a feed screw supported by the bed and operatively connected to one of said supports, manually operable means connected to the feed screw for imparting rotation thereto including a plate fixed with said screw, a power oscillatable member supported for free rotation on the screw and having a definite stroke for imparting an indexing movement to said screw, and electro-magnetic means carried by said member and energizable for coupling the member to the plate in any rotatable position thereof upon connection of power to said oscillatable member.

2. In an automatic grinding machine. having an automatic work loader movable between a leading position and. a grinding position, and an oscillatable grinding wheel support carrying a I grinding wheel, the combination of a power operable cycle actuating mechanism connected to said grinding wheel support for efiecting cyclic movement thereof to and from said grinding position,

and having a starting control circuit energized by a limit switch connected to a source of power trip operable by the work loader during movement to a grinding position to start a grinding cycle, a counting mechanism operatively connected with said grinding wheel support for counting the grinding cycles including a switching means operable by the mechanism to demergize said starting circuit, and a power operable truing mechanism mounted on the grinding Wheel support for truing the grinding wheel including starting switch means operable by said counting 'g'rinding two surfaces on a vs'rorkfpiece and. is

automatically movable through recurring. cycles, the combination with a support for said grinding wheel, of individual dressing tools for the respective faces, superimposed slides supporting said tools on the grinding wheel support including an indexible slide mounted on said wheel support,

power operable indexing means connected to the indexible slide, a second slide mounted on the first slide, power operable means carried by the indexible slide and operatively connected to the second slide for moving the same in a direction parallel to one face of the wheel, a third slide mounted on the second slide, and supporting the truing tools-, power operable means connected for moving the third slide parallel to the other face of the wheel, a source of power, a grinding cycle counting mechanism having means connecting the source of power to the first two power operable means simultaneously, and trip operable means eiiective upon actuation. by the second slide upon completion of its cycle of movement to connect the source of power to the third-named power operable means.

4.. In a grinding machine havingv a grinding wheel support carrying a grinding wheel, said support being movable toward and from a work support in recurring automatic cycles, and a wheel truing mechanism mounted on said wheel support, the combination with a power operable cycle actuating mechanism 7 connected to the grinding wheel support to move the same through its grinding cycles, of a counting mechanism operatively connected to the grinding wheel support for counting the cycles of operation thereof, a source of power, electrically operable means connecting said source of power to said cycle actuating mechanism, electrically operable means for connecting said truing mechanism to the source of power, a control circuit operatively connected to said counting mechanism andincluding switch means operable by the counting mechanism to deenergize said first-named electrical means and energize said second-named electrical means, whereby the grinding cycle will stop during the truing operation.

5. In an automatic grinding machine having an indexible work support including an automatic work loader movable to and from a grinding position and an oscillatable grinding wheel support having a grinding wheel, the combination with a power operating cycle actuating mechanism connected to said grinding wheel support including a starting control circuit energizable by a starting switch operable by the work loader upon movement to grinding position, of a cycle counting mechanism .operatively connected to said grinding wheel support having switch control means responsive to a predetermined count to deenergize said. starting control circuit, andstop the grinding cycle, atruing mechanism comprising an indexible slide mounted on the grinding wheel support and carrying two power operable truing slides each having a power operable cycle actuating mechanism connected thereto including a starting control circuit having a starting solenoid connected thereto, switch means in one truing starting circuit operable by the counting mechanism to energize one solenoid and effect actuation of one truing slide, switch means in the other truing starting circuit operable by the actuated truing slide to energize the other solenoid, means operable by the second truing slide to actuate the switch control means of the counting mechanism to reenergize the starting con- 17 trol circuit of the grinding wheel support and Number other switch means operable by the counting 2,292,947 mechanism to effect indexing of the indexible 2,311,213 supports at the beginning of the truing operation. 2,314,019 FREDERICK S. HAAS. 5 2,320,235 2,323,401 References Cited in the file of this patent ,4 3

2,418,14 UNITED STATES PATENTS 2,447,478 I Number Name Date 10 2,450,336

1,150,535 Reinecker Aug. 17, 1915 1,997,551 Romaine Apr. 9, 1935 2,025,885 Nonninger Dec. 31, 1935 Number 2,187,227 Flanders Jan. 16, 1940 4,849A

Name Date Kasparson Aug. 11, 1942 Cramer Feb. 16, 1943 Shaw Mar. 16, 1943 Hjarpe May 25, 1943 Johnson July 6,, 1943 Seyferth Mar. 18, 1947 Addicks- Apr. 1, 1947 Rundt Aug. 17, 1948 Hillquist Feb. 1, 1949 FOREIGN PATENTS Country Date Great Britain Feb. 27, 1906'

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