US2599453A - Cam grinding machine - Google Patents

Description

June 3, 1952 R. P. HOOK ET AL CAM GRINDING MACHINE Z5 Sheets-$heet 1 Filed May 5, 1950 vKm wwfl m m P w [LG m ain w Fig. 1

3 Sheets-Sheet 2 Filed May 5, 1950 Ira/enters EUJZSELL f? HOOK (LARENCEJ GREEN l l :WWWH H H I June 3, 1952 R. P. HOOK ET AL CAM GRINDING MACHINE Fild May 5, 1950 3 Sheets-Sheet 3 Fig. 8

zomza bee/entom- /?L/55ELL P HOOK CLARENCE u. GREEN 3;? W Lu). W

Patented June 3, 1952 orso srAr 5 Claims. (01. 51:101

The invention relates to grinding machines, and mo e particularly to a rock bar a uati meehae sm er a am r ndin machin One object. of the inv n on is to p vide simple.- and thoroughly pra tical actuatin m chasm for the rock, bar-of a cam grin in ma h ne- Anot erobject is to prov d a draul c lly o erted rock. bar actuat n me hani m o o tr lline movem nt of; the rockar u i a in ns; operation and. al o m v ment o th rock.- bar to and from operat ve, p s ion An th o je t s to p ovide a ydraul cal O a d re bar ct atin mechanism hereby a e ce pres ure m y be. m n a n d betwe n h mas e cam and the follower rollerover the nose of; the ca and wh reby a s b t nti ll unif rm re re may e ma ntained betwe n. th master. ca t rollover rol r the r se n a o he eam- Othe biee s w l e n ar ob or n part o nt d o t her inaft r,

T e nvent o aoeereinelr consis s in th te tur-es .1: construct on comb nat on o elemen s and arra gements f part s W lli e exemp fi in. th str cture to be hereinafter desc bed, and the cope. of he ap l qe n f h eh w l be nd eate in t fo low n e imsn the e eqmpany e draw n s, in ch s shown one ef'various possible embodiments of the mechanical. ea ur s o this n entio Fig; 1 is a front elevation of the improved cam r ding. a h ne;

F e 2 s a hor o t l se o l ie on an enlarged scale, taken approximately on the line 2-2 of Fig. 1;

Fig, 3 is a plan view, on an enlarged scale of i the worl; head with the cover removed;

Fig. i is a cross-sectional View, taken approxi mate-1y 011 he line 4--4 of Fig. 3;

g 5 l t f a men y s c ona View, on a nlarged ale o a on of the. reek b r matin cyl nde sho g the l ve position of the por s dp ston l nds;

l a 6 is a r ss se tiem en n en a sc le, ap roximat ly on he l e :6 0f s-v 5, th ough the eylind r and. p stes;

F es e l neitudin l e tion l iew! on an e large scale th oug th ac umu ator n i 8 s a eemb nee hyd. is and e ectri d ag am o e ranted-me h nism f r actuation of the ree s bar- A can gr ndin machine has be n illustrate n he dr ings h w-i s e ba e I which e bp & on u ina l trev reame we able II The ta e H erves as a u p rt for a pi e ellv m unte w s ba :2. T li reek. bar is Pre- 2 vided w th a qtata i maete c m. s n e 13 whi h is su orte in a p ir paced ar ng l4 and. 15. (He. 2) whi h ar fixedly p r e o he. o ar 12- T e m ste rn eP le is sup ere Wi h n were h e r me. 6.- Th master cam spindle l3 provided with a work center I! to support the left-hand end of a cam shaft to be ground. The rock bar IZal so serves as. a suppor o teqt toe e '8 ha in Wo Suppor in center t w ich i rra ed to u port the right-hand end of a cam shaft to be e n The m st r" lm sp n le ppor o o me e. aster sam are eP ti re a ship w th a otata l iellew r l er 1 wh h i l b y k yed t a o at b sha 2- If m r h n o e mast reem. 3.9 s Pre ded n n e ing c ani s pro d d. or inde i the ma m oll leneit d ne l n't s a a a ner we leeewn in e prior art This m ch em m y e mpriee a t r W e l 3. wh is actuated by a dog bar (not, shown) on the base H3. The star wheel 23 is connected-through a re v s a me ni m .4 t d x t e mas e cam ro n t i l n m d re a ion wit the positioning movement of the work table II.

This mechanism is substantially identical with that shown in the expired U. S, Patent No. 1,783,755 to C. G. Trefethen et a1., dated Decembe;- 2, 1930, to which reference. may be had for details of disclosure not, contained herein.

A suitable dri ing mechanism is, provided for positively rotating the master earn spindle I3 during the rocking movement of the'rook bar l2. This mechanism may comprise an electric er 5 mo nted ent r of th w e ead frame H5. The motor 25 is provided with a motor shaft '36 having a multiple V-groove pulley 21 which is connected by multiple v-belts'm with a multiple V-groove pulley 29.} supported on an idler haft eehe ehei is po t d on h W head frame It. A multiple \hgroove pulley M is formed integral with the pulley 2!! and is connected by multiple V=belts32 with a multiple V-groove pulley'33 journalled on antidriction bearings 36 which are in turn supported by a hollow bracket which is fastened to the work head frame 16. The pulley 33 is. Q 1h md by a e s l oi i h a shaft. 3"!- The other en f e shaf 31 is onnected by a uni e sal oi 38 with the master cam spindle 13. It will be readily apparent from the foregoing disclosure that rotation of the motor shaft 25 w ll be parted through the driving mecnaniS R abov described to rotate the master cam spindle l3. Roration of the ma rn sp nd e it and the ter cam 26 in engagement with the master cam roller 2| will impart a rocking or oscillating movement to the rock bar |2 so as to grind a predetermined contour on the cam being ground.

The base In also serves as a support for a transversely movable wheel slide 46 which is slidably supported on the usual and well known V and flat ways (not shown) formed on the upper surface of the base I 0. The wheel slide rotatably supports a wheel spindle (not shown) which is provided at its left-hand end with a grinding wheel 4|. A driving mechanism is provided for the grinding wheel 4| comprising an electric motor 42 mounted on the upper surface of the wheel slide 48. Th motor 42 is connected by means of a belt drive (not shown) contained within a belt guard 43 to rotate the wheel spindle and grinding wheel 4|. A manually operable feed wheel 44 is rotatably supported on the front of the machine base by means of which the wheel slide 40 may be adjusted toward and from the work supporting table A manually operable table traverse wheel 45 is also provided for traversing the work table longitudinally relative to the base H) to facilitate positioning the cam to be ground into operative relation with the grinding wheel 4|.

A hydraulically operated mechanism is provided for actuating the rock bar |2 so as to maintain the master cam 20 in operative engagement with the follower roller 2|. It is desirable that the pressure between the master cam 28 and the follower roller 2| be substantially uniform during rotation of the master cam 2|] in order that a cam may be ground to the desired and predetermined contour. A fluid pressure mechanism is provided comprising a cylinder 58 having a piston 5| slidably mounted therein. The piston 5| is provided with a pair of spaced piston lands v clearance holes in the arm 58 and are screw threaded into the rock bar l2. It will be readily apparent from the foregoing disclosure that by manipulation of the screws 60 and GI, the arm 58 may be rocked relative to the rock bar so as to adjust the position of the arm as desired.

A reservoir 62 is provided within the base of the machine. Fluid is pumped from the reservoir 62 through a pipe 63 by means of a fluid pump 64 which forces fluid under pressure through a pipe 65. A pressure reducing and regulating valve 66 is connected to the pipe 65. A pipe 61 is connected to the upper end of the regulator valve 66 to pass fluid under the desired pressure through a check valve 68 and through a pipe 69 to a control valve 10.

The control valve 19 is preferably a piston type valve comprising a valve stem 1| having a plurality of spaced valve pistons 12, 13 and 14 formed integrally therewith. The valve pistons 12, 13 and 14 form a pair of spaced valve chambars 15 and 16. A compression spring 11 serves normally to urge the valve stem 1| in a direction toward the right (Fig. 8) to maintain the valve stem 1| in its right-hand end position. An electric solenoid 18 is operatively connected to the valve stem 1| so that when energized the solenoid 18 serves to shift the valve stem 1| toward the left into its left-hand end position as illustrated in Fig. 8. Fluid under pressure passing through the pipe 68 enters the valve chamber 16 and passes through a pipe 18 into a cylinder chamber to cause the piston 5| together with the piston rod 54 to move toward the left (Fig. 8) so as to rock the arm 58 and rock bar I2 in a counterclockwise direction (Fig. 4) to move the master cam roller 20 into operative engagement with the follower roller 2| for a grinding operation. A pipe 8| connects with the pipe 19 and is provided at its other end with a fluid accumulator 62 which will be more fully described hereinafter.

During movement of the piston 5| toward the left, fluid within a cylinder chamber 83 may exhaust through a port 84 and also through a port 85 to exhaust fluid through a pair of pipes 86 and 81 respectively. The pipe 86 when the port 84 is open passes fluid directly into the valve chamber 15 and through a passage 90, through a pipe 9|, through a ball check valve 92 and a pipe 93 into the reservoir. At the same time fluid may exhaust through the pipe 81, through a throttle valve 88 into the pipe 86. A ball check valve 89 is provided to by-pass fluid around the throttle valve 88 when the fluid is moved in the opposite direction. When both of the ports 84 and 85 are open, substantially unrestricted exhaust of fluid from the cylinder chamber 83 may be obtained. As the piston land 52 moves toward the left from the extreme right-hand end position 52a (Fig. 4) fluid may exhaust through both of the ports 84 and 85. The piston land 52 covers the port 85 while still allowing fluid to exhaust through the port 84. As the port 84 is completely covered during movement of the piston land 52 toward the left (Fig. 5), the port 85 is again gradually opened so that fluid may still exhaust from the cylinder chamber 83 through the throttle valve 88 which controls the rate of exhaust therefrom. This staggered arrangement of the ports together with the throttle valve 88 serves to slow down the movement of the rock bar |2 to an operative position just before the master cam 29 goes into engagement with the follower roller 2 The accumulator 82 may be of the type manufactured by Greer Hydraulics, Inc., Brooklyn, N. Y., and covered by U. S. Patent No. 2,342,356 to J. Mercier, dated February 22, 1944. The accumlator 82 comprises a metallic shell or casing within which is mounted a flexible bladder 95. A valve 96 is provided at the upper end of the accumulator whereby air under pressure may be supplied to the bladder 95. The lower end of the bladder is provided with a metal collar or seat 91 which is arranged to seat upon a surface 98 fastened to the lower end of the accumulator 82. The bladder 95 may be made of rubber or synthetic rubber and is preferably loaded to about 50 lbs. per sq. in. pressure. It will be readily apparent that when fluid under pressure from the pump 64 is passed through the pipe 19 into the cylinder chamber 80, the piston 5| together with the piston rod 54 will be moved toward the left (Figs. 4 and 8) to rock the rock bar |2 to an operative position with the master cam 20 in operative engagement with the master cam roller 2|. As the master cam shaft I3 rotates during a grinding operation, the rock bar |2 will be caused to oscillate in accordance with the shape of the master cam 20. As the rock bar is 'moved in a clockwise direction by rotation of the master cam 20 in engagement with the follower roller 2.I-, the piston rod 54 and the piston 5I will be moved toward the right (Figs. 4. and 8). Fluid cannot pass back through the pipe 69' since the check valve 63 prevents back-flow of fluid therethrough. As the piston 5I moves toward the right, fluid within the cylinder chamber 80 is forced out through the pipe I9 through the pipe 8| into the accumulator chamber 99 thereby displacing the bladder 95 by compressing the air within the bladder 95. The operating pressure with the cylinder chamber 89 may be 100 lbs. per sq. in. for maintaining the master cam 20 at the desired operative contact with the follower roller 2t. This pressure may be varied as desired by regulation. of the valve 66. The actual applied load between the master cam 29 and the roller 2t, in this case, will be approximately 100.1bs. at the top of the arm 58. As the nose of the master cam 20 rides over the roller 2|, the pressure increases slightly due to the pressure built up within the accumulator 82 so that the pressure be tween the master cam 20 and the follower roller 2| is approximately 150 lbs. per sq. in. If desired this pressure may be further reduced by decreasing the effective area of the piston 5| so that a smaller volume of fluid is required for maintaining the desired pressure between the master cam and the follower roller 2|. With a lesser volume of fluid required, a lesser volume of fluid is displaced from the chamber 80 during normal operation, therefore, the increase in pressure over the nose of the cam will be similarly decreased.

The piston land 52 is provided with a plurality of perforations 52a. which are arranged parallel to the axis of the valve stem 54 so that fluid within the cylinder chamber 83 is free to pass therethrough into the chamber 83a formed between the piston lands 52 and 58.

As a further explanation of the action of the piston 5i, as the rock bar I2 rocks in a counterclockwise direction (Fig. 4) so that the master cam 2 approaches the master cam roller 2|, the piston land 52 closes off the port 84. Since the ports 85 and 85 are not in line, there is an overlap so that up to the point of closing off the port 8 5 fluid within the chambers 83 and 83a. is free to exhaust through both of the ports 84 and 85. When port 8 is closed off fluid can still pass from the chamber 63 through the perforations 52a. and out through the port 85, through the needle valve 88 to the control valve Hi. This action serves to cushion the rapid movement of the rock bar I2 in a counter-clockwise direction just before the master cam 26 moves into engagement with the roller '2 i. This cushioning action takes place only while the port as is closed, but it serves to check the speed of movement of the piston 5I sufiiciently to give a soft action of the movement of the master cam 20 into engagement with the follower roller 2 I.

During the normal rocking movement of the rock bar I2 as caused by the master cam 26, both the port 34 and the port 85 are located between the piston lands 52 and 53.

After a cam has been ground to a predetermined size and contour, it is desirable to rock the rock bar in a clockwise direction so that the arm 58 is moved to position 58a and the piston lands 52 and 53 are moved to broken-line positions 52a and 53a (Fig. 4). It is desirable to automatically control the movement of the rock bar I2 to an inoperative position so that the cam being ground .arated from. the follower roller 2 I.

'is allowed'to remainin contact with the grinding wheel; for a predetermined number of rotations of the cam being ground. This is preferably accomplished by means of an electric counter which are old and well known in the art, such as for example, the Microflex electric counter manufactured by the Signal Electric Corporation of Moline, Illinois. As illustrated in Fig. 8 an electric counter HM is provided. The rock bar I2 is provided with a projecting arm H30 which is arranged during the normal rocking movement of the rock bar I2 to engage an actuating roller IN on an actuating arm I32 of a normally closed limit switch H13. Each time the rock bar I2 oscillatesduring the grinding operation, the arm Isil opens the limit switch I03 to impart an impulse to the counter I84. After a predetermined number of impulses, a circuit is opened to deenergize the solenoid 18 thereby releasing the compression of the spring ll which shifts the valve stem II toward the right (Fig. 8). to shift the valve pistons l2, l3 and it into the reverse position. When the valve '19 is in the reverse position, fluid under pressure within the pipe 59 passes through the valve chamber 15 and, through the pipe 86 and. the pipe 8'5, through the ports 83 and 35 respectively into the chamber 83 to cause the piston'fil to move toward the right thereby rocking the rock bar I2 in a clockwise direction to an inoperative position with the master cam 25] sep- During movement of .the piston 5| toward the right, the piston land 52 first closes'off the port 84 and then as piston EI toward the right to an inoperative position.

The operation of this improved cam grinding apparatus will be readily apparent from the foregoing disclosure. A normally operable switch N35 is closed to start a grinding operation. The closing of the switch I05 serves to energize the solenoid lssc that the control valve 70 is shifted into the position illustrated in Fig. 8 thereby admitting fiuid through the pipe I9 into the cylinder chamber to move the rock bar I2 in a counterclockwise direction so as tomove the master cam 2% into operative engagement with the follower roller 21.

The electric motors 25 and 42 are started to start the rotation of the master cam spindle I3 and the rotation of the grinding wheel Rotation'of the master cam spindle I3 and the master cam 28 serves to oscillate the rock bar I 2 so as to generate a predetermined contour on a cam being ground. During the grinding operation fluid under pressure within the cylinder chamber 88 serves to maintain the master cam 20 in engagement with the follower roller 2I at a predetermined pressure. As the master cam rotates up the left of the cam, the piston 5| moves toward the right so that fluid in the chamber 80 is displaced into the accumulator chamber 99. During the movement of the piston 5I toward the right, the check valve 9I is closed and a partial vacuum formed within the cylinder chamber 83 which assists the pressure within the cylinder chamber 80 in maintaining the master cam 20 in operative engagement with the follower roller 2 I. During each actuation of the rock bar by rotation of the master cam, the limit switch 13 is opened to impart an impulse to the counter 04. After a predetermined number of impulses, the counter breaks a circuit that deenergizes the solenoid 18 thereby shifting the control valve into a reverse position to cause the rock bar to move to an inoperative position thereby separating the master cam 20 from the roller 2|.

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.

We claim:

1. In a cam grinding machine having a pivotally mounted rock bar, a rotatable master cam spindle thereon, a master cam on said spindle, a rotatable master cam follower roller, means to rotate said spindle, and a rock bar actuating mechanism comprising a piston and cylinder operatively connected to move the rock bar to and from an operative position and to maintain the master cam in operative engagement with the follower roller with the desired operating pressure during rotation of the master cam, a control valve to control the admission to and exhaust of fluid from said cylinder, and a fluid accumulator operatively connected to said cylinder to facilitate displacement of fluid from the cylinder caused by the rocking movement of said rock bar due to rotation of the master cam during a grinding operation so as to maintain the master cam in operative engagement with the follower roller with the desired pressure.

2. In a cam grinding machine, as claimed in claim 1, in combination with the parts and features therein specified of a pair of offset exhaust ports in said cylinder to control the exhaust of fluid therefrom when the rock bar is moved to an operative position, both of said ports serving initially to facilitate substantially unrestricted exhaust of fluid from said cylinder, and an adjustable throttle valve to regulate fluid exhausting from the one of said ports, said piston having a land which closes the second port prior to engagement of the master cam with the follower roller to cushion engagement therebetween.

3. In a cam grinding machine, as claimed in claim 1, in combination with the parts and features therein specified in which the piston is formed with two spaced lands, a pair of offset exhaust ports in said cylinder to control the exhaust of fluid therefrom when the rock bar is moved to an operative position, both of said ports serving initially to facilitate a substantially unrestricted exhaust of fluid from said cylinder, and an adjustable throttle valve to regulate fluid exhausting from one of said ports when one of the piston lands closes the other port prior to engagement of the master cam with the follower roller to cushion engagement therebetween, said piston lands being arranged so that both of the exhaust ports remain open during the normal oscillation of the rock bar during grinding.

4. In a cam grinding machine, as claimed in claim 1, in combination with the parts and features therein specified of a solenoid to actuate saidcontrol valve, a switch to energize said solenoid to shift the control valve to admit fluid under pressure to the rock bar cylinder to cause the rock bar to move to an operative position with the master cam in engagement with the follower roller, an electric counter, and a switch actuated by each normal rocking movement of the rock bar during a grinding operation to actuate said counter, said counter serving after a predetermined number of oscillations of the rock bar to deenergize said solenoid so as to shift the control valve into a reverse position to shift the rock bar to an inoperative position.

5. In a cam grinding machine having a pivotally mounted rock bar, a rotatable master cam spindle thereon, a master cam on said spindle, a rotatable master cam roller, means to rotate said spindle and a rock bar actuating mechanism comprising a piston and cylinder operatively connected to move the rock bar to and from an operative position and to maintain the master cam in operative engagement with the follower roller with the desired operating pressure during rotation of the master cam, a control valve to control the admission to and exhaust of fluid from said cylinder, means including a pressure regulating valve to supply fluid under pressure to said control valve, a check valve to maintain fluid pressure on the pressure side of the piston during grinding to maintain the master cam in engagement with the follower roller, and a fluid accumulator operatively connected to the pressure end of said cylinder which serves to facilitate displacement of fluid from said cylinder caused by the rocking movement of the rock bar due to rotation of the master cam during grinding.

RUSSELL P. HOOK. CLARENCE J. GREEN.

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

UNITED STATES PATENTS Number Name Date 1,840,231 Harrison et al. Jan. 5, 1932 2,185,837 Crompton, Jr. Jan. 2, 1940 2,194,434 Silven Mar. 19, 1940

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