[1]Patented Feb. 21, 1939 2tl47@891 UNITED STATES PATENT OFFICE 2,147,891 OROP &AnO EMED CENTERLESS GRINDER Andrew J. Graf, Norwood, and Clifford II& Schulte, RossmoynL-, Ohio, assitnors to, OWeinnati Grinders incorporated, Cincinnati, Ohio, a corporation of Ohio tvphcation - July 16, 13 Clabip. 7bis invention relates to grinding machines and more particularly to improvements in automatic centerless grinders., One of the object@ of, this Invention is to proa vide an improved and simplified mechanism for obtaining greater advance and retractive movements between the grinding wheels of a centerless grinder of the inf"d type. Another object of this invention is to provlde 10 an improved hydrgulic operating and control mechanism for governing the,rnovements of the regulating wheel in a centerless grander of the infeed type. A further object of this invention is to pro15 vide a control mechanism for producing a complete automatic cycle in an infeed, type centerless grinder, including loading and ejecting of the work, which may be controlled by a single cam. An additional object of this invention is to 20 provide an improved automatic infeed type centerless grinder for automatic grinding of work pieces which do not lend themselves to through feed grinding principals. Other objects and advantages of the present in25 vention should be readily apparent by reference to the following specification considered in conjunction with the accompanying drawings illus-. trative of one embodiment thereof, but It will be understood that any modifications may be made 30 in the specific structural details within the scope of.the appeiided clainis without departing from or exceeding the spirit of the invention. Referrin'g to the drawings in which like reference numerals lndicate.like or similar parts: 35 Figure I is an elevation of a centerless grinder embodying the principles of this.invention. Mgure 2 is a plan view of the machine shown in Figure 1. Mgure 3 is a section through the cam ecitrolled 40 mechanism as viewed on the line 3-3 of Mgure 2. Mgure 4 is an enlarged detail section taken on the line 4-4 of Mgure 3. Figure 5 is an enlarged section taken on the -45 line 5-5 of Mgure 2. Mgure 6 is gn enlarged detail view of the control cam. Flgure 7 is a section through the work loading mechanism as viewed on the line 7-7 of Fig50 ure 1. . Mgure 8 is a section on the line 8-8 of Figure 7. Flgure 9 is a diagramme'ic view of the hydraulic control circuit. 55 3rir.,ilig operations oii a centerless griiider are 1937, Serial No. 154,046 (CL 51- 103) usuall y carried out by two different methods, one of which Is the through feed method and the other the infeed method. 7he through feed metho d is used for grinding cylindrical woik which passes through the grinding throat in -@ .5 contiii uous stream. The infeed method is utilized for grinding work pieces which either have an obstru ction thereon which is larger in diameter than the portion being ground, or have a contour@ d surface, which necessitates their remain- 10 ing in a fixed a)dal position relative to the wheels. When the latter method is used, the wheels must be retmcted for the purposq of removing and inserti ng work, and then b@r@ought together to for ' m the grinding throat, after wliieh an addi- 15 tional movement or infeed is effected to accomplish the,grinding operation and reduce the work re in deals with an automatiq mechanism which will effect a continuous repetition Of 20 an automatic infeed cycle including automatic Positio ning and ejecting of the work. In prior machi nes of this nature it was only necessary to provid e a relatively smau amount of separation betwe en the wheels to permit withdrawal of the 25 work, but iii the present nmehine the work moves lateral ly from the work rest blade and drops between the wheels into a conveyor chute,,which means that the movable wheel must be retracted a much greater amount than heretofore in order 30 to permit work ejection in this manner. Due to thislarger movement prior mechanisms have been found inade;@@ie and therefore an improve d structure has been provided by the present invention, whereby a large movement may be 35 easily and quickly effected, and one of the features of this invention is to provide a mechanism which will execute the Positioning movements at a rapid rate and the grinding movement @ at a desirable slow rate. 40 Ref erring tG Flgures 1 and 2 of the drawings, the reference nuineral I 0 indicates the bed of a center less grinder having a grinding wheel I 1, and a regulating wheel 12, supported on the top thereo f for relative movement toward and from 45 !Dne another, and with respect to a work rest blade 13 which Is located between the wh@els. On the present macwne the grindirig Wheel I I rotate s in a flxed position, and the regulating wheel 12, which rot9ltes at a much slower speed I than the grinding ivheel, and serves the function of rotating the work, is rotatably j6urnaled on a mova ble slide 14 for relative movement with respect to the grinding wheel to Permit insertion and removal of the work.
[2]2 2,147,891 The slide 14, as more particigarly shown in Flgure 5, rarries a nut 15, in which is threaded a screw 16 having gn axially extending shank 17. The shank 17 has a piston I 8 secured thereto which Is reciprocably supported In a cylinder 19. The cylinder is integral with a brack@t 20 which Is attached to the bed I 0. The shank 17 extends through the rear of the bracket 20 for receiving an operating hand wheel 21 *hich serves 10 to rotate the screw 16 relative to the nut 15. It will jiow be apparent that the slide 15 taay be moved, either by admitting fluid pressure to the cylinder 19, or by rotating the hand wheel 21. The piston 18 has a somewhat limited move15 ment within the cylinder 19, but of sufficient amount to permit the work piece to clear the work rest blade, while the hand wheel is adapted to adjust. the regulating wheol the,full length of its stroke and serves to position the wheel relative to 20 the piston I 8 dependent upon the diameter of the work and the amount of room necessary to clear the work rest biade, and thus acts to deternitne the situs of the power stroke to be effected by the piston. The piston 18 serves to move the regu25 lating wheel toward the grinding wheel, while another piston 22 is provided for effecting the return stroke. The piston 22 is connected by a piston rod 23 to the slide 14. The cylinder 24 wliieh contains this piston is the same length as 30 the total stroke of the slide 14, because a relative adjusting movement between the piston 22 and the slide 14 cannot be effected as in the case of the piston 18. The work piece being ground In this machine is 35 indicated by the reference nilmeral 25 In ingur6 7. and it will b@,- noted that the work piece has a conoidal shaped end 26. 7he work is inwrted between the grinding wheels with this end first, and the grinding wheei I I has a puabolle abilped 40 portion 27 which is complementary to the shape to be ground on the ends of the work piece. It Is due to the converging shapes of the two grinding wheels that prevents work pieees of this nature from being ground by the through feed method. 45 The work pieces are stacked in a hopper 28 and a reciprocable plunger or work pusher 29 is supPorted adjacent to the bottom of the hopper for moving a work piece from thi@ hopper to the grinding throat between the wheels. After the 50 plunger has moved a work piece into the grinding throat, it remains in the -dash and dot position indicated by the reference numeral 30 in P%we 7 during the grinding operation to serve as means for holding the work in proper axial position with 55 respect to the wheel, because due to the converging shapes of the grinding wheels, an axial thrust is developed which would tend to cause the work to move backward. The manner in wbich the work piece 26 Is supmore particularly shown in Mgure 8. It will be noted that the work rest blade 13 has an angular top 3 1, and that the clockwise rotation of the grinding wheel urges the work piece downward 65 against this top and into engagement with the regulating wheel. This insures that the work will be held in sufbeiexit frictional engagement with the regulating wheel whereby the same will cause rotation of the work in a counterclockwise dir@e76 tion due to the clockwise rotation of the regulating wheel. 'Me work rest blade 13 Is supported op lower slide 32 which is slidably mounted upon the bed IO, and in tum has guide surfaces fdrmed on the top thereof for recipzloeably supporting@ the slide 14. By clampft the sude 32 to the slide 14 the work rest blade may.be adjusted to the proper position in front of the grinding wheel. The lower slide may then be clamped to the bed I 0 and the upper ilide moved to vary the position of the regulating wheel. 5 . When the work has been ground to size, It will be apparent from Mgure 8, that the regulating wheel 12 must be retracted a sufficient amount that the work piece 25 may fall off of the angular top work rest blade into the work redelving chute 10 33. It will be apparent that the amount of this movement must be equal to the distance between the side 34 of the work rest blade a:nd a line 35 tangent to the periphery of the griiiding wheel at the point of contact with the work. This distance 15 is indicated by the reference numeral 36, and determines the minimum stroke of the piston 18 which translates the regulating wheel. 'Me work pusher 29 is actuated by a piston 37 contained in the cylinder 38, as shown in Miiue 7, 20 and connected by a piston rod 39 to the pusher 29. This cylinder has a pair of ports 40 and 41 at opposite ends which are connected by channels 42 and 43 respectively to ports 44 and 45 of a reversing valve indicated generally by the, reference 25 numeral 46. This reversing valve has a pressure port 47 which Is supplied wlth fluid from a pump 48 having an intake 49 through which flwd is withdrawn from a reservoir 50. The valve also has a pair of return ports 5 I and 52 which are 30 connected to the, return line 53 leading to the reservoir 50. A plunger 54 is - reciprocably mounted.in this valve and is held by fluid pressure into engagement with an operatin'g arm. 55 which is carried by the shaft 17. The plunger has a pair 35 of annular grooves 56 and 57 formed 'therein which serve to alternately connect the pressure port 47 to ports 44 and 45 to effect alternate advance and retraction of the work-pusher 29. The advancing movenient of piston 18 is con- 40 trolled by a servo-valve indlcated generally by the reference numeral 58 and consisting of movable sleeve 59 and an Independently movable plunger 60. The sleeve has a first wide annulargroove 61 which is in constant comm=ication with a Pas- 45 sage 62 termin I ating in an annular groove 63 which Is in communication with the pressure port 47; a second wide annular groove 64 which is in constant'communication with a channel 65 leading to the right hand end of cylinder 19; and a third 50 annular groove 66 which is In constant comihunication with an exhaust channel 67. Radial holes are drilled In the groove 64 forming a port 68 which Is normally closed by a spool 69 formed on the Plunger 60. 55 The spool 60 is substantially the same width as tbt port 118 so that upon movement of the plunger It@'as to the left, the, pressure will flow from the port 47 through the passage 63, groove 61, and thereby through the passage 65 to the cyllnder il to cause actuation of piston 18. Upon movement of the spool to the right, the port 68 will be connected by the- annular groove 72 in plufiger,66, to the exhaust port 73. The plunger 05 60 is held into engagement with a second plunger 74 which carries a roller 75 bearing on the periphery of a cam 76. The plunger 74 is slidably mounted in the open end of sleeve 59, and a key 77 is provided for holding the plunger 74 against 70 rotation in the sleeve so as to maintain the axis of the roller 75 parallel to the axis of t ' he shaft 77 which supports the cam. The sleeve is fixed with the member 55. It will now -be apparent thatIf elevations are provided on the cam that 70 60 ported in the grinding throat of the mgchine is, - port 71, and annular groove 71 to the port 68, oo
[3]2 147,891 the plunger 60 can be nioved, as to the left, Independently of t'he sleeve to cause fluid pressure to flow to cylinder 19, and that upon actuation of the pigton 18, the member 55 will cause the sleeve 59 to follow up the movement of the plunger 60 and thereby close the port 68 to stop movement of the piston. Thus the piston IS is a servo controlled single acting piston for causing advancing movement of 10 the regulating wheel toward the grinding wheel. Retum movement of the regulating wheel is effected by the second piston 22 slidably mounted In a cylinder 24 and connected by a piston rod 23 to the regulating wheel slide 14. This piston 15 is smaller in diameter than the piston I 8 whereby a constant pressure can act thereon in one direction, the left end of the cylinder, as showri in Mgure.9, having a port 81 which is connected by channel 82 to the output of pump'48. In other 20 words, the same unit pressure of the pump is caused to act on pistons 18 and 22, but when acting on the piston 18 its larger area will produce a total resultant pressure which is greater than the total resultant pressure acting in the 25 OPPOsite direction on piston 22 and the slide will move toward the grinding wheel. The cylinder 24 has a length equal to the total length of possible m6vement of slide 14 because no adjustable connection is provided, whereas the piston I 6 has 30 a screw and nut connection with'the slide 14 whereby the piston iS may have-the same starting.position regardless of the longitudinal position of the slide 14.relative to the bed. . Although the shaft 17, as shown in Flgure 5, 35 carries the piston 18 and member 55 during axial movement thereof, it Is not necessary or desirable that these parts rotate, when the shaft 17 is rotated manually to effect relative adjustment of the regulating wheel slide, and.therefore 40 antifriction bearing means have been provided whereby the shaft 17 may I be rotated relative to these parts. To this end the shaft 17 Is provided with a shoulder 83 and a reduced portion 84 upon which are mounted a pair of antifric45 tion thrust bearings 85, one of which abuts the shoulder 63. The piston 18 has an internal annular rib 86 which projects between these thrust bearings, and a nut 87 is threaded on the rod 17 for clamping all of these parts against the shoulder 83 so that the piston is rigidly con50 nected for axial movement of the shaft 17 while permitt!,ng the shaft to rotate without causing rotation of the piston 18. The shaft 17. is provided @vith a second shoul55 der 88 and reduced portion 89'upon which Is mounted a sleeve 90 having a shoulder at one end which is clamped against the shoulder 88 on the shaft by a locking nut 9 1. The sleeve carries a pair of thrust bearings 92 which antifriction60 ally support the member 55. In the enlarged view in Flgure 4, it wfll be seen that the member 55 has a rectangular slot 93 formed in the end thereof for engaging a complementary shaped portion 94 formed @on the end 65 of sleeve 59 whereby the sleeve is held against rotation. The connecting member 55 also has a depending portiot. 95 which carries a set screw 96 which forms an abutment for -the reversing valve plunger 54, and by adjusting the screw 96 7o relative to the member 55, the point of reversal of the actuating pigton, 37 for the work loader may be accurately timed with respect to the movements of the regulating wheel. As previously, stated, the reversing valve plung7r, er 54, and the sleeve 59 are held by constant pressure In engagement with the connecting member 55. This pressure is hydraulic and is supplied by the pump 48, but is much lower than the pressure of the actuating fluid. This lower pressure is obtained by providing two serially ar- 5 ranged check valves 97 and 98 in a branch line 99 leading to reservoir from the main delivery Iiiie of pump 48, which act as serial hydraulic resistances , whereby a channel 100 connected to the line 99 between these resistances may be pro- 10 vided with any unit pressure between -the pump pressure and atmospheric pressure. In the present case, the check valve 97 is set to have about six times as. niuch resistance as the check valve 98 *hereby the unit pressure in chaniiel 100 %vill 15 be about one-sixth of the unit pressure supplied to the piston 18. The channel 100 is connected to the spaces IO 1 and 102 whereby this unit pressure will act on all of members 54, 59 and 60 to hold plunger 54 and sleeve 59 in engagement 20 with the member 55, and the plunger 60 into engagement with, the periphery of the cam wheel 76. In order to take care of any leak@Lge, the space (43 in cylinder 19, and the space 104 in cylinder 79, are conne.cted to a return line 105 25 whereby any accumulation of fluid which might interfere with proper operation of the parts may be disposed of. In oider that the work loading plunger may move at a smooth, even and controlled rate, an 30 adjustable throttle valve 106 may be interposed in the channel 43 whereby it will coritrol the out@. flow from. cylinder 38 during movement in one direction and the inflow during movement in the other direction and.thereby control the rate Of 35 both directions of movement. The machine has a continuously repeating automatic cycle, and the cycle of operation is controlled by the cam 76. As shown in Figure 3, an electric motor 107 is mounted on the bracket 2 0, and connectecl by a coupling i 08 to shaft 10 9 4.0 journaled within the bracket. A spur gear 110 is keyed to the end of th% shaft for driving gear I I I keyed to the end of shaft i 12. The latter shaft carries a worin 113 intermeshing with a 45 worm gear 114 keyed to the cam driving sliaft 77. It will now be apparent that upon actuation of the motor 107, that the cam shaft will be continuousl y rotated at a uniform rate. The cycle of operation of the machine will be 50 explaine d, reference being had to the enlarged view of the control cam 76, as shown in Mgure 6. The radial line 115 indicates the starting point, and the arrow I i 6 indicates the direction of rotation of the cam. The valve plungers 54 aiid 60 55 are shown in the starting position in Mgure 9, and it will be noted that the port 41 of cylinder 38 Is connected to pressure to cause re I traction of the work pusher. Assuming the retractive movement to begin at the line 115 on the cam, (;o It will be apparent that an appreciable length of time at least vill be necessary to complete this movement, and therefore -the . cam is provided with@ a dwell 117 to insure completion of this moveme ni. Vtrhen completed, the parts will be 65 in the position shown In Figure 7, and a new work piece 25 win drop from the hopper 28 into a position in front of the pusher 29. It is to be understood that the'plunger 60 and sieeve 59 constitute what is comm6nly tetmed a 70 servomotor mechanism in that displacement of the plunger 60 to the left, as viewed in Figure 9, by action of cam,76, introduces prossure by way of groove 61, port 70, groove 71 and port 65 to the right hand side of piston 18, moving meiii- 75
[4]4 2,147,891 ber 17 and associate parts to the left. As sleeve 59 is coupled through member 55 with 17, It is correspondingly shifted to the left, restoring the alignment of port 68 with valve land 69, causing discontinuance of this movement. As the land and port form a variable throttle or resistance, the extent of their displacement determines the rate of actuation of the piston. The sharper the rise on cam 76 which is rolo tated at a uniform rate, the f aster the rate of nlovement of the plunger 60 and consequently the faster the foflow-up of member 17 and sleeve 59. Conversely, on reverse movement of the plunger, land 69 couples port 68 via cannelure la 72 with exhaust conduit. 67, variably throttling the relief of pressure on the right hand side of piston 18, permitting retraction of parts by the pressure in cylinder 24, the reverse follow-up of sleeve 59 correspondingly controllinik the rate and 20 extent of this retracting movement. T'he cam is next @rovided with a. rapidly rising portion 118 which wHI cause movement of the servo-valve -plunger 60 to the left as viewed In Mgure 9, thereby admitting fluid to cylinder 19 2a which will cause movement of piston IS and thereby move the reguiating wheel toward the grinding wheel a sufficient amount to contract the grinding throat, Flgure 8, in readiness for Insertion of the next work piece. I)uring the ad30 vancing movement of piston 18, the connecting member 55 has been fohowing up the movement of the servo-valve plunger 60 and has been moving the reversing valve plunger 54 toward the left so that by the time the.point 119 is reached N on the cam 76, the reversing valve plunger 54 has -been moved a sufficient distance to connect pressure port 47 to port 44. The piston 37 now advances to insert a new work piece into the grinding thlroat and in order to permit this move40 ment to be completed, a dwell 120 is provided on the cam. The work is now ready to be ground and a short sharp rise 121 Is provided on the cam for moving the work Into contact with the grinding wheel. 4&. A slow rising portion 122 is next provided on the cam whereby the regulating wheel slowly advances the work into the grinding wheel to reduce the work th size. In order to permit the grinding wheel tinie to el6an up the work and So spark out after the advancing movement of the regulating wheel has been completed, the dwell 123 is provided. With the work now ground to size, a sudden fall 124 is provided on the cam which permits the servo-valve plunger 60 to move 55 toward the right, and connect port It to exhaust port 73 whereby the constant pressure in cylinder 24 may now retract the regulating wheel through action on the piston 22. By the time the reti-acting movement has completed, and the .60 work has dropped off of the work rest blade Into the chute 33, the reversing valve pluriger 54 has moved to such a position that the pressure port 47 is connected to port 45 to cause retractioii of the work pusher ' and the next cycle of operation 65 Is ready to begin. It will now be apparent that the cam controls the rapid advance and feeding movement of the -regulating wheel as well as the return movement thereof, and also causes insertion of a new work piece by power at the TO proper moment in the cycle. There has thus been provided an Improved power operable automatic meebanism for effecting an infeed cycle on a centerless grinding machine, Including mechanism for automaticai]y 75 loading and ejecting the work. What is
