US3681878A - Deep feed mechanism - Google Patents

Abstract

A grinding wheel feed mechanism for high speed heavy duty grinding machines including a rough feed means arranged to be advanced and retracted over an adjustable substantially extended feeding stroke, means automatically operative when a workpiece approaches its desired final size to initiate the operation of a finish feed means over a predetermined short distance within which the workpiece being ground reaches its final size. The rough feed means includes a high speed rotary hydraulic motor and the finish feed means includes a reciprocating hydraulic motor.

Description

United States Patent [54] DEEP FEED MECHANISM [72] Inventor: Oiva E. Hill, Holden, Mass. [73] Assignee: Norton Company, Worcester, Mass. [22] Filed: Sept. 21, 1970 [21] App1.No.: 74,053

[52] US. Cl .Q. ..5l/l65.8, 51/1659 [51] Int. Cl. ..B24b 49/08 [58] Field of Search ..'.5l/l65.77, 165.8, 165.9, 165.91,

[56] References Cited UNITED STATES PATENTS 2,333,341 11/1943 Scrivener"; 1/l65.8 X 2,522,485 9/1950 Silven et al. ..5 H951 2,984,952 5/1961 Gebel ..5l/l65.9

[15] 3,681,878 1 Aug.-8, 1972 3/1965 Hin ..51/105 SP 1/1971 Price ..smsss Primary Examiner-Lester M. Swingle Attomey-bewis M. Smith, Jr.

[571 ABSTRACT A grinding wheel feed mechanism for high speed heavy duty grinding machines including a rough feed means arranged to be advanced and retracted over an adjustable substantially extended feeding stroke, means automatically operative'when a workpiece approaches its desired final size to initiate the operation of a finish feed means over a predetermined short distance within which the workpiece being ground reaches its final size. The rough feed means includes a high speed rotary hydraulic motor and the finish feed means includes a reciprocating hydraulic motor.

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ATTORNEY DEEP FEED MECHANISM BACKGROUND OF THE INVENTION I cludes an elongated feed screw assembly slidably and rotatably supported upon the machine base parallelto the respective ways and threadably connected to a feed nut secured to'the wheel slide assembly so that longitudinal movement of the feed screw produces relatively rapid advance of the grinding wheel and continuous rotation of the feed screw produces advance of the grinding wheel at an intermediate rate and intermittent rotation of the feed screw produces advance of the grinding wheel at a relatively very slow rate for fine or finish feed. Two such wheel feed mechanisms are illustrated and described in U.S. Pat. No. 2,522,485, issued Sept. 12, 1950 and in US. Pat. No. 3,171,234, issued Mar. 2, I965.

The wheel feed mechanism in such grinding machines is alternatively operable manually by'means of a hand operablefeed wheel usually located on the front of the machine base and readily accessible to the machine operator, for set-up and adjustment of the machine and optionally for manual operation, if desired. 7 I

The hand wheel referred to above usually connected through a suitable gear train to the feed screw for rotation therewith, with the gear ratio such that the hand wheel completes less than one full revolution during V 2 grind substantially exceeds the capacity of a reciprocating hydraulic cylinder of practical length.

SUMMARY THE INVENTION The present invention provides a deep feed mechanism used in combination with and for rotating 8 the feed screw of agrinding machine such as described and shown in US. No. 2,522,485 referred to above which the deep feed mechanism includes a high speed rotary hydraulic motor inherently capable of unlimited rotation of its output shaft slidably and nonrotatably engaging a feed worm in turn operatively engaged with a worm wheel operatively connected through a suitable gear train to rotate a feed screw sufficiently move a wheel slide and to produce a rough grind "portion of the wheel feed cycle sufficient to. reduce the radius of a workpiece by an inch or more.

The present invention also includes means to maintain the stop pawl outof the path of the cam plate while the hand wheel rotates the number of times required to nearly complete the extended rough feed portion of the wheel feed cycle and then operative to release the pivot arm supporting the stop pawl during the final half 'turn of the hand wheel, so that the stop'p'awl may coact with cam surfaces on the cam plate to deenergize the rotary hydraulic motor and to energize a reciprocating hydraulic cylinder operative to produce a predetermined longitudinal displacement of the feed worm which acts through the worm wheel operatively engaged therewith to produce a short finish feed movementof sufficient length to bring the workpiece being 7 ground to final size.

the complete wheel feed cycle. Consequently, the hand wheel may have a circular cam plate adjustably secured thereto and provided with a ramp or shoulder operative to engage a stop pawl or other control means commonly supported in engagement with-the surface of the cam plate by attachment to the free end of a pivotally supported arm located adjacent to the hand wheel. For example, the cam plate may be adjusted angularly relative to the hand wheel so that a stop pawl actuated thereby interrupts the wheel feed cycle at a predetermined desired workpiece size.

The portion of the wheel feed mechanism which produces rotation of the feed screw typically includes a pinion or wormwheel connected to an operative to rotate the feed screw, operatively engaged and rotated by a reciprocating rack or worm, the later also rotatable incrementally to produce a very fine feed. Since the reciprocating rack or worm is customarily moved longitudinally by a reciprocating hydraulic cylinder, the practical length of the hydraulic cylinder which can be provided within the space available in the grinding machine is limited. In the existing grinding machines, this limitation poses no problem because-the length of the stroke for the fine feed portion of the wheel feed V Referring now to the drawings wherein like reference numerals refer to like or corresponding parts,

FIG. 1 is a vertical section of the portion of the preferred embodiment of the present invention showingthe feed worm and its operatively associated worm wheel through which the rotaryhydraulic rough feed drive motor and the reciprocating hydraulic finish feed drive motor are operatively connected to the wheel feed mechanism of a precision grinding machine,

FIG. 2 is a detailed end view of the adjustable means for controlling transition from the rough feed to the finish feed and for limiting the retraction to the rough feed mechanism,

FIG. 3 is a longitudinal vertical section through the adjustable means shown in FIG. 2,

FIG. 3a is an exterior end view of the adjustment means shown in FIG. 3,

FIG. 4 is a longitudinal vertical section through an alternative embodiment of the adjustable means shown in FIG. 2, 1

FIG. 5 is a detailed end view of the embodiment of the adjustable means shown in FIG. 4 taken on line 5- 5 of FIG. 4,

FIG. 6 is a simplified electrical and hydraulic schematic diagram of the combination of related elements together comprising the present invention, and

FIG. 7 is a vertical cross sectional view through the grinding wheel feed mechanism of a grinding machine comprising the instant invention.

Referring now to FIGS. 1 and 7, a housing generally designated by the reference numeral 10, fixedly secured to the base of a grinding machine, such as, disclosed in the above mentioned US. Pat.- No. 2,522,485

to which reference may be had for details of construction and operation thereof not disclosed herein. The housing supports a high speed rotary hydraulic motor 11 and an hydraulic cylinder assembly generally designated by the reference numeral 12, including a cylinder 13, a piston 14 with a hollow piston rod 15 connected thereto, and bearing assemblies 16 mounted within piston 14 and supporting one end of an elongated shaft 21 supporting feed worm 22 midway of its length. By means of key 23 the other end of the elongated shaft 21 is slidably but nonrotatably supported within one end of hallow shaft 24 rotatably supported by bearing assemblies 26 in housing 10. The other end of hollow shaft 24 is nonrotatably engaged with and driven by the output shaft 28 of the rotary hydraulic motor 1 1.

With the piston 14 immobilized in its retracted position as shown in FIG. 1, rotation of the rotary hydraulic motor 11 produces rotation of the feed worm 22 and thence of the worm wheel 32 to produce rough feeding movement of the grinding wheel, and with the rotary hydraulic motor 11 at rest, movement of the piston 14 to the right, as seen in FIG. 1, displaces feed worm 22 to the right to rotate worm wheel 32 sufficiently to produce the required finish feeding movement.

Referring next to FIG. 3, the adjustable means for limiting the retraction of the rough feed and for transferring from the rough feed to the finish feed as the workpiece approaches final size is shown mounted adjacent to the assembly described above including the feed worm 22 and the worm wheel 32 supported in spaced bearing assemblies and keyed slidably to shaft 43 also supporting the clutch assembly generally designated by reference numeral 41 and controlled by manually operated control rod 42 to engage and disengage the adjustable means from the wheel feed drive tram.

In order to provide for operation of the reset and finish feed limit switches, 57 and 58, shown best in FIG. 2 and schematically in FIG. 6, at the proper positions in the wheel feed cycle, the sleeves 35 and 36 respectively supporting the radially projection stop pins 37 and 38 are sequentially angularly adjusted by means of the external knobs 70 and 72 shown in FIGS. 3 and 3a and fixedly secured by a clamping nut 74 to their supporting shaft 34 fixed to a gear 76 meshing with a pinion gear 78 on shaft 42 fixed to the shaft 43 fixed to the gear 185 and driven in timed relation to the wheel feed drive train when the clutch assembly 41 is engaged in the position shown in FIG. 3.

By example only, the applicants invention as shown in FIG. 7 is a modification of the feed mechanism of the grinding machine disclosed in U.S. Pat. No. 2,522,485 issued to H. A. Silven et al on Sept. 12, 1950. However it may be used in combination with other conventional grinding wheel feed screw mechanisms, such as, disclosed in U.S. Pat. No. 3,171,234 issued on Mar. 2, 1965 to the applicant.

The present invention replaces and is an improvement in that portion of the hydraulic feed mechanism shown in FIGS. 3 and 5 of the U.S. Pat. No. 2,522,485 designated by the characters 182, 183, 184, 185, 192 and 1920 and concerned with the rough and fine feed portion of the feed cycle.

The hydraulic piston 183 and cylinder 182 are replaced by the rotatable, slidable and reciprocable feed worm 22 meshing with a worm wheel 32 instead of a spur gear, a hydraulic cylinder 12 for reciprocating the feed worm 22 to rotate worm wheel 32, and a rotary hydraulic motor 11 for rotating the feed worm 22 In FIG. 6 there is diagrammatically shown the appli- 2 cents invention connected to operate with portions of the feed mechanism and controls disclosed and described in U.S. Pat. No. 2,522,485. Only those portions of the feeding mechanism to which the invention pertains and its operation during the feeding cycle will be described.

Means for terminating the rough feeding movement and initiating the finish feeding movement are provided and shown in FIG. 2, 3 and 6 cooperating with the hand wheel 25 on which the cam plate 191 is fixed for rotation therewith during the rough and finish feeding movements of the feeding cycle. The cam plate 191 is has two camming surfaces or steps X and Y and a stop abutment or surface Z for engaging a stop pawl 192a on and movable with a pivot arm 192 which are both modified versions of the same parts shown in U.S. Pat. No. 2,522,485. When the pivot arm 192 is in the operative position shown in FIG. 6 the rotary motor 11 is stopped and the body feed piston 14 moves the worm 22 axially to continuously rotate the worm wheel 32' and the engaged clutch 41 at a slower rate. Theclutch 41 drives gear 185, 176 and 175 to simultaneously rotate both the hand wheel 25, the feed screw 19, and the pinion gear 78, which in turn rotates the gear 76, the shaft 34, the sleeves 35 and 36, and the projecting stop pins or cams 37 and 38 for actuating the limit switches 57 and 58. 7

At the-beginning of a grinding wheel feeding cycle the feeding mechanism is in a reset position and the pivot arm 192 and the stop pawl 192a are pivoted counter clockwise to the inoperative position, shown in phantom lines, out of the path of the stop abutment or cam plate 191 by a fluid operated piston and cylinder 200 actuated by shifting a conventional four way fluid directional control valve V2 to a position opposite from that shown in FIG. 6. Pivoting the pivot arm 192 counter clockwise actuates a limit switch LS12 which is preferably provided to close a circuit actuating a conventional timer not shown. The timer may be incorporated in the feeding cycle to automatically provide a dwell in a plunge grinding feed cycle, to retract the grinding wheel, and reset the feeding mechanism in the well known manner taught in U.S. Pat. Nos. 2,572,529, 3,171,234 and 2,932,136.

In addition pivotal movement of the pivot arm 192 mechanically shifts a fluid directional control valve V1 into various positions to deactuate as well as actuate various other components of the grinding machine such as the piston and cylinder 154 for operating a steadyrest such as disclosed in U.S. Pat. No. 2,932,136 wherein the control valve is similar to and operated substantially in the same manner as the valve V1 shown in FIG. 6.

Operation The operating of the deep feeding mechanism is similar in most respects to that disclosed in US. No. 2,522,485 except that the stop pawl 192a is held out of the rotation path of the cam plate 191 to allow the hand wheel to rotate more than one revolution and rough feed the grinding wheel into the workpiece until the stop cam or pin 37 actuates the limit switch 57. Actuating limit switch 57 causes deactuation of valve V3, stopping the rotating of the rotary motor 11 and the rough feeding movement, deactuates control valve V2 which actuates piston 200 to shift stop pawl 192a into the path of the cam plate 191, and begin the finish or body feeding movement of piston 14 by causing actuation of valve V4.

Upon energizing solenoid S1 control valve 129 is shifted to initiate a rapid approaching movement of the grinding wheel toward the workpiece by directing fluid under pressure to the cylinder 128 to simultaneously I advance the piston 127, the piston rod 126, the feed screw 19, and the grinding wheel support toward the left until the piston 127 comes to a cushioned stop at the opposite left hand end of the cylinder 128 in the manner taught in US. Pat. No. 2,522,485. At the end of the rapid approaching movement a conventional limit switch and relay not shown are actuated to provide a circuit energizing solenoid S3a which shifts valve V3 from its centered position toward the left. Fluid under pressure passes to drive the rotary fluid motor 11 forward under the control of an adjustable throttle valve VT and a fixed restrictor R.

Shifted valve 129 also admitted fluid under pressure through throttle valves VT] and VT2 to opposite ends of the finish feeding cylinder 13, the piston 14, and through adjustable throttle valve VT3 to a blocked port of a two way fluid directional control valve V4. Piston V4 is held in a balanced position at the reset or left hand end of the cylinder 13.

Rotary fluid motor 11 continues to rotate the feed screw 19 and plunge feed the grinding wheel at a rough feeding rate into the workpiece, the hand wheel 25, and the stop pins 37 and 38 until the limit switch 57 is actuated by stop pin 37. Limit switch 57 breaks a circuit deenergizing solenoids S3a allowing valve V3 to center and stop rotary motor 11, de-energizing solenoid S2 deactuating control valve V2 allowing fluid under pressure to opposite ends of piston and cylinder 200 to move the pivot arm 192 and stop pawl 192a clockwise into the position shown in the path of the cam plate or stop abutment 191, and to make a circuit energizing solenoid S4 shifting valve V2 to allow fluid to exhaust from the right hand end of cylinder 13 and begin the body or finish feeding movement.

Fluid under pressure passes first through the throttle valve VTl and then an unrestricted middle port into the opposite or left hand end of cylinder 13. The piston 14 moves axially to the right at a rate controlled by the adjustable throttle valve VT3 and worm 22 .rotates worm wheel 32 which continues to rotate the feed screw 19 and hand wheel 25, and the stop pins or cam 37 and 38 at a predetermined slower finish feed rate.

Hand wheel 25 rotates counter clockwise toward the stop pawl 192a and the camming surface x pivots the pivot arm an amount sufficient to shift the valve V1 so as to actuate the steadyrest piston and cylinder 154 and operate the steadyrest, not shown, in the well known manner. When camming surface Y engages and pivots the pivot arm 192 an additional amount counter clockwise valve V1 is shifted sufficiently to reverse the flow of fluid under pressure to the piston and cylinder 154 and retract the steadyrest. Also, if desired, the limit switch LSl2 may be provided and actuated at this time to start a timer not shown, but discussed above for automatically providing a dwell in the feed cycle after the stop surface Z engages the stop pawl 192a and resetting the feeding mechanism in the known manner after the timer times out. Thus, the infeed movement of the grinding wheel into the workpiece is positively stopped by the engagement of the surface Z with the stop pawl 192a. Obviously, the feeding mechanism could be operated either manually or automatically. However, automatic operation of the wheel feed mechanism is preferred and less time consuming.

When either the timer times out or the controls ar manually operated in the reverse order the grinding wheel is retracted by reversing the sequence to reset the wheel feed mechanism back to the initial starting position. Solenoids S1, S2 and 83b are energized and energized and solenoid S4 de-energized shifting control valves 129, V2, V3 and V4. Valve V4 blocks exhaust of fluid and prevents movement of piston 14 to the right. Valve 129 allows fluid under pressure to left side of cylinder 128 to rapidly retract piston 127 and hence the grinding wheel. Fluid under pressure also passes through a check valve CV to right side of cylinder 13 to, move piston 14 and worm 22 axially toward the left to the reset position shown causing rotation of the worm wheel 32 and hand wheel 25 clockwise. Valve V2 admits fluid under pressure to cylinder 200 which retracts and pivots the pivot arm 192 and the stop pawl 192a out of the path of the cam plate 191. Pivot arm shifts valve V1 to right maintaining the piston and cylinder 154 and the steadyrest in the inoperative position. Valve V3 directs fluid under pressure to rotate the rotary motor 11, the hand wheel 25, and the stop pins 37 and 38 in the reverse direction until the stop pin 38 ac tuates the limit switch 58 whereupon solenoid S321 is de-energized. Valve V3 centers and stops rotation of rotary motor 11 and the hand wheel in the initial reset or starting position for the next feeding cycle.

The conventional electrical circuitry has not been shown since it would be obvious to those skilled in the art how the various controls, switches, and relays would be connected in the well known manner, to produce the sequence of operation described above.

In FIGS. 4 and 5 there is shown an alternative or modified form of the construction shown in FIG. 3 wherein similar parts are designated by like characters followed by a prime, such as, 72', 74', 76', 36', 35, 34', 57', 37, 38' and 58'. The construction differs from that shown in FIG. 3 in that the gear 76' drives, the shaft 34' rotatably mounted within a central bore in the sleeve 35' rotatably driven in one direction by a conventional one way clutch 60 between the shaft 34 and a hub of the sleeve 35. About the hub of sleeve 35 is a torsion spring 62 with a plurality of coils extending between an axially spaced shoulder and a flange 64 fixed to the right hand end of the hub on sleeve 35. A pin 66 fixed to the flange 64 adjacent one end of the spring 62 extends inwardly parallel to the axis of rotation of the shaft 34' and is engaged by a tang 62a of the spring 62. The opposite end of the the 62 has another tang 62b engaging a second projecting pin or boss 68 fixed relative to a supporting wall of an apron cover fixed to the machine base. Initially the spring is wound up so it has the tendency to unwind and exert a predetermined torsional force between the boss 68 and the pin 62a tending to rotate the flange 66 and the sleeve 35' clockwise as seen in FIG. 5.

The one-way clutch'60 allows the torsion spring 62 to drive and rotate the sleeves 35 and stop pin 37 the flange 64, and the pin 66 clockwise during a wheel feeding cycle when the gear 76 and the shaft 34' are likewise simultaneously rotated clockwise, as viewed in FIG. 5, by the grinding wheel feeding mechanism. Clamp nut 74 keyed to an rotatable with the sleeve 35', drives the knobs 70' and'72' which is keyed to drive sleeve 36 and stop pin 38' therewith.

During the infeed movement of the grinding wheel compensate for unexpected and expected changes in a present relationship between the grinding wheel and the finish size of the workpiece. Such changes as wheel wear, thermal drift, distortion, truing tool wear, and so forth may require the grinding wheel to be advanced an 332? 2% 3351 eillifoiie m%3$ftfi 60 compensates for change in the preset relationship during the infeeding movement, but maintains a substantially constant amount of reset movement of the feed mechanism and the retracted position of the grinding at a substantially constant distance from the finish size of the workpiece. The initial reverse, or reset position of the gear 76' being preset and at thepoint where stop pin 38' actuates limit switch 58'. When the feeding mechanism is reversed the shaft 34' rotates counter clockwise causing clutch 60 to drive and rotate sleeve 35, flange 64 and pin 66 counter clockwise and windup the spring 62 until pin 38. actuates limit switch 58. As the spring 62 winds up its potential driving force increases so that it will rotate the sleeve 53' clockwise at toward the workpiece both the shaft 34' and the sleeve 35' rotate, clockwise, together allowing the torsion spring to unwind. However, during clockwise rotation the pin 66 contracts a stop bolt 69 fixed to a second boss or portion 68a projecting from and fixed to the supporting wall of the apron cover mentioned above. Rotation of the flange 64, pin 66 and the sleeves 35 and 36' stop, but the shaft continues to rotate relative to the stationary sleeve 35' due to the fact that the spring 62 is no longer exerting a force to rotate the sleeve along with the overrunning clutch and the shaft. Thus the clutch 60 and shaft 34' are allowed to slip and rotate relative to the stationary sleeve 35' an amount determined by the means controlling the final size of the workpiece being ground.

The alternative embodiment described above and shown in FIGS. 4 and 5 is most suitable when a plunge grinding cycle is controlled by a conventional inprocess gaging system known in the art, instead of a timer or positive stop controlled grinding machine feed cycle. An in-process gaging system continually gages the workpiece as it is being ground and terminates the grinding cycle when it detects the workpiece is to size. Otherwise, the operation of the feeding mechanism incorporating the alternative embodiment shown in FIG. 4 and 5 is the same as that described above in regard to the positive stop and timer controlled grinding cycle. Likewise, the stop limit switch 57' and 58' are operated by the stop pins 37 and 38 in the manner taught above. With in-process gage control it makes no difference if the stop surface Z on the cam plate engages or does not engage the stop pawl 192a before the workpiece is ground to final size. Also the workpiece may be ground to size either before or after the pin 66 contacts the stop bolt 69. However, the alternative embodiment shown in FIG. 4 and 5 has the advantage whereby it can the same rate of rotation as the shaft 34' is'driven on the next infeed cycle. Hence, the sleeve 53' follows and rotates together with the shaft 34' because of the torque or torsional force exerted by the spring 62 as it unwinds, and the one way clutch prevents the sleeve 53' from overrunning the shaft 34.

It is to be understood that the preferred embodiment of the present invention described herein is intended to be illustrative and not limiting in any manner as the invention is limited only by the scope of the appended claims.

I claim: 1. In a given grinding machine having a given rotating grinding wheel thereon mounted for reciprocating movement into andv out of engagement with a rotating workpiece supported by the given grinding machine, a deep feed wheel feeding mechanism comprising:

a rotary feed mechanism including a rotatably and slidably movable driving element,

first rotatable drive means having unlimited rotary motion and operative for rotating said driving element to produce a relatively very long rough feeding movement of the given grinding wheel,

second reciprocable drive means operative by slidable movement of said driving element to produce a relatively very small finish feeding movement of the given grinding wheel, and

means operative as a workpiece being ground by the given grinding wheel closely approaches its desired final size to terminate the rough feeding movement and to initiate the finish feeding movement.

2. In grinding machine according to claim 1, wherein:

said first rotatable drive means comprises a rotary hydraulic motor, and

said second reciprocal drive means comprises a reciprocating hydraulic motor.

Claims (2)

1. In a given grinding machine having a given rotating grinding wheel thereon mounted for reciprocating movement into and out of engagement with a rotating workpiece supported by the given grinding machine, a deep feed wheel feeding mechanism comprising: a rotary feed mechanism including a rotatably and slidably movable driving element, first rotatable drive means having unlimited rotary motion and operative for rotating said driving element to produce a relatively very long rough feeding movement of the given grinding wheel, second reciprocable drive means operative by slidable movement of said driving element to produce a relatively very small finish feeding movement of the given grinding wheel, and means operative as a workpiece being ground by the given grinding wheel closely approaches its desired final size to terminate the rough feeding movement and to initiate the finish feeding movement.

2. In grinding machine according to claim 1, wherein: said first rotatable drive means comprises a rotary hydraulic motor, and said second reciprocal drive means comprises a reciprocating hydraulic motor.

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