US2079007A - Cross feed mechanism for grinding machines - Google Patents

Description

May 4, 1937. w. A. GIGGER CROSS FEED MECHANISM FOR GRINDING MACHINES Filed Nov. 14, 1955 2 Sheets-Sheet 1 Zfnvggtor Witness May 4, 1937. 2,079,007

CROSS FEED MECHANISM FOR GRINDING MACHINES W. A. GIGGER Filed Nov. 14, 1935 2 SheeEs-Sheet 2 N ER Witness My a m Patented May 4, 1937 CROSS FEED MECHANISM FOR GRINDING MACHINES Walter A. Gigger, Providence, R. 1., assignor to Brown and Sharpe Manufacturing Company, a corporation of Rhode Island Application November 14, 1935, Serial No. 49,723 9 Claims. (01. 51' 1s5) This invention relates to a grinding machine, and particularly to a novel and improved power cross feed for the grinding wheel and the supporting carriage therefor.

The invention is herein disclosed as embodied ,in agrinding machine of the general description set forth in a copending application No. 49,772 of Maxwell I. Mathewson and August L. Krause, filed of even date herewith. The machine comprises preferably a base on which is supported a work supporting table which is arranged for reciprocatory movements in a plane transversely of the grinding wheel, and a wheel spindle carriage which is supported on ways to move toward and away from the work. The movementof the carriage is controlled by means of a cross feed 'mechanismcomprising across feed hand wheel mounted on the machine base, and driving con- 'nections including a feed screw and nut carried respectively on the base and on the wheel spindle carriage.

Power operation of the cross feed is obtained by means of a ratchet carried on the cross feed hand wheel and a cooperating pawl which has imparted thereto reciprocatory movements by means of a power driven crank, which may be alternatively connected through clutch connections for continuous rotation from the table driving motor of the machine to provide a continuous cross feed, or may be alternatively connected for intermittent operation from the reversing lever, so that an increment of feeding movement is imparted to the grinding wheel upon each reversal in the direction of table travel.

It is a principal object ofthe present invention to provide a novel and improved mechanism for driving the cross feed pawl actuating crank to impart a reciprocatory feeding movement to the pawl upon movement of the reversing lever from one operating position to the other which will operate accurately and certainlyto produce the desired pawl reciprocation regardless of variations in the throw ofthe reversing lever upon reversal.

With this and other objects in view, as may' hereinafter appear, a principal feature of the to stop the crank during the continued movement of the reversing lever to its final rest position,

The several features of the present invention consist also in the devices, combinations and arrangement of parts hereinafter described and claimed, which together with the advantages to be obtained thereby will be readily understood by one skilled in the art from the following description taken in connection with the accompa'nying' drawings, in which Fig. l-is a view in front elevation of a portion of a grinding machine embodying applicants grinding wheel cross feed mechanism, only so much of the machine being shown as is necessary to illustrate the connection of the present invention therewith; Fig. 2 is a detail view similar to Fig. 1, but with a portion of the casing and certain overlying parts broken away to illustrate particularly the table slow-down and reversing switches, and actuating connections from the table reversing lever; Fig, 3 is a sectional view taken on the line 33 of Fig. 2, to illustrate particularly the automatic connections for actuating the cross feed pawl from the reversing lever; and Fig. 4 is a detail sectional view taken on the line 44 of Fig. 3, to illustrate particularly the dwell connections for imparting a constant reciprocatory movement to the cross feed pawl from the reversing lever irrespective of variations in the length of movement thereof.

The machine illustrated in the drawings as embodying in a preferred form the several features of the present invention, comprises a base generally indicated at H], a reciprocable work table l2 supported on ways l4 on the base, and a wheel spindle carriage (not shown) which may be of any ordinary description and is supported on cross Ways for movement toward and away from the work. A work holder comprising a headstock and a tailstock which may be of ordinary description, are preferably mounted on the table for rotatably supporting the work.

With the present construction the table is driven by means of a variable speed reversible electric motor 28'supported in the base Ill through connections generally indicated in dotted lines in Fig. 1, which comprise a pinion 30 on the armature shaft 32 of the motor, a gear 34 meshing therewith mounted on a stud shaft 36, and a driving gear 38 which meshes with the gear 34.

A clutch assembly including two gears 40 and 42 is mounted in axial alignmentwith the driving gear 38 and a table hand wheel 44 to connect the table alternatively for power or hand operati'on; The gears 40' and 42 mesh respectively with a table high speed driving gear 46 and a table slow speed driving gear 48 which may be alternatively connected through a fast-slow clutch (not shown) to drive the table through connections including gears 50 and 52, a table driving pinion 54, and a table rack 56. For a more complete description of these connections for driving the table, reference may be had to the copending application of Mathewson and Krause above referred to.

The reciprocation of the work table is controlled by means of table dogs and a reversing lever which operate through switch connections hereinafter to be described, to stop and thereafter to reverse the direction of rotation of the table motor 28. Two reversing dogs 90 and 92 are provided as best shown in Fig. 1, adjustably mounted in a T-shaped slot 04, and arranged for engagement with a reversing lever 96 supported on a rock shaft 98 carried in bearings I00 on the machine frame. In order to provide a positive limit for movement of the table in each direction where it may be desired to move the grinding wheel beyond the normal stop position against or closely adjacent a shoulder on the work, two positive stop lugs I02 and I04 are provided on the machine frame which are arranged to engage with and positively stop movement of the table and reversing lever in each direction when moved manually an appreciable distance beyond the normal stop position. The reversing lever 96 is bifurcated to fit over a flattened portion I06 formed on the rock shaft 98, and is pivotally connected theretoby means of a cross pin I08, so that the lever may be swung forwardly out of the path of the reversing dogs, to permit manual operation of the lever independently of the dogs. Secured to the rock shaft 90 is a downwardly extending hook-shaped lever arm H0 which has formed thereon a gear segment H2 arranged for engagement with a pinion H4 secured to a control shaft I I6 which is supported in bearings on.

.the machine frame in parallel relation to the rock shaft 98. With the connections above described, the movement of the reversing lever 96 from one operating position to the other, will cause a corresponding rotational movement to be imparted to the control shaft H6 in an opposite direction by an amount which will depend exactly upon the amplitude of movement of the lever 06. The gear segment H2 and pinion H4 are proportioned so that a maximum throw of the reversing lever will cause the shaft II6 to rotate through less than one complete revolution. The oscillatory movements of the control shaft I I6 are utilized to operate a reversing switch to reverse the direction of drive of the table motor, and also to impart a step-by-step advancing movement to the cross feed pawl.

The reversing switch connections for reversing the table motor comprise a switch cam shaft I I8 which is in axial alignment with and keyed to turn with the control shaft H6 and a cam I20 supported thereon which is provided with a low portion extending around substantially one-half the periphery of the cam, somewhat higher portions at either side thereof, and a still higher portion on the opposite side of the cam. Two identical switch actuating levers I22 and I24, pivoted respectively at I26 and I28 on the machine frame, are provided at their free ends with cam rolls arranged for engagement with the cam, and lugs I30 and I32 which are yieldingly engaged by two downwardly spring-pressed switch plungers I34 and I36 for actuating the switch connections for reversing the direction of drive of the table motor. Two tension springs I38 and I40 connected respectively to the switch levers I22 and I24 tend normally to move the levers downwardly into engagement with the switch cam I20. Stop pins I42 and I44 serve to limit the downward movement of the levers.

The switch plunger I34 has mounted thereon a right slow-down contactor I46 and a left limit or reversing contactor I48, which are arranged in such a manner that when the switch lever I22 rests on an intermediate level of the cam I20, both contactors are closed. The movement of the switch lever I22 onto the low portion of the cam will then operate to open the right slowdown contactor I46, while conversely the movement of the switch lever I22 onto the high po1'- tion of the cam will operate to open the left limit or reversing contactor I48. The switch plunger I36 has similarly mounted thereon a left slowdown contactor I50 and a right limit or reversing contactor I52 which are so arranged that when the switch plunger I36 occupies an intermediate position, both contactors are closed. The movement of the plunger I36 to its low position as the lever I24 rides onto the low portion of the cam, causes the left slow-down contactor I50 to open, and conversely the movement of the lever I24 onto the high portion of the cam causes the right limit or reversing contact I52 to open.

The operation of the reversing lever and switch connections controlled thereby to effect a reversal in the direction of drive may be briefly described as follows:-

Assuming that the reversing lever has been moved to its left hand position causing the cam I20 to rotate in a clockwise direction, and that the table is traveling right, the switch plunger I34 now occupies a fully raised position, the right slow-down contactor I46 being closed and contactor I48 open, and the switch plunger I36 occupies a low position, the right limit switch contactor I52 being closed and the contactor I50 open. The movement of the reversing lever from its left toward its right position upon engagement with the dog 90, causes the cam I20 to rotate in a counterclockwise direction so that the cam lever I22 rides first onto the intermediate portion of the cam depressing the plunger I34 to close the contactor I48, and then as the lever rides onto the low portion of the cam, to open the right slow-down contactor I46 to slow down the motor. The continued movement of the reversing lever to the right with the corresponding counterclockwise rotation of the cam I20, now causes the cam lever I24 to ride first onto the intermediate portion of the cam, raising the plunger I36 to close the contactor I50, and finally as the cam lever rides onto the high portion of the cam, to open the right reversing contactor I52 to effect a reversal of the motor. Similarly, upon a reversal of table travel from left to right, the left slow-down contactor I50 is opened to slow down the motor, and subsequently the left reversing contactor I48 is opened to reverse the direction of drive. Inasmuch as the subsidiary electrical connections controlled by the operation of these switches to slow down and to reverse the table motor form no part of the present invention, further description and illustration of these connections has been omitted. For

a full description and illustration of these connections, reference may be had to the copend- -ing application above referred to, filed of even date herewith.

With the construction above described for reversing the direction of table travel in which the to check the further movement of and reverse the table; it has been found that the overrun of the" table at each endof-its-movemnt and-conse quently the amplitude of movementof "the reversing lever 96will-vary to an appreciable extent in actual operation dependingup'on the rate of table movement at reversal and the weightor mass of the table assembly including the work carried thereon. j

Cross feeding, movements are imparted to the carriage and spindle supported thereonby means of a cross feed hand wheel I I0 adjustably secured to a rotatable shaft I12 which is connected" to a cross feed'screw which may be of any ordinary description, and is not here shown. For a detailed description of this mechanism, reference may be had to the application of Mathewson and Krause above referred'to. V I

For effecting a power operation of the cross feed, actuating connections" are provided which comprise a ratchet I18 provided on' the external periphery of the hand wheel I" for enga em nt by a pawl I80 adjustably mourited on a pawl lever I82 which is pivotally mounted'on' a carrier arm I84 pivotedat I86 on the machine frame. A tension spring I88 connected between a pointon the pawl lever I82 and a lug I90 on the link 200here-" i'nafter described, tends normally to maintain the pawl in engagementwith the ratchet. Re-

ciprocatory movements are imparted to the lever I82 and pawl I60 by meansof a crank shaft I92 supported in the machine frame parallelto the control shaft II6 abovefdescribed; The crank comprises a pivot block I94 adjustably supp rted in guideways I96 in a disk I98 on theforward end of the crank shaft I92, and is connected by an upwardly extending link 200. to the carrier lever I 84'. In order to vary the amount of reciprocation of the feed pawl I80 and thus to control the rate of feed, the carrier head block I94 is adjustably positioned in the guideway I96 toward or away from the axis of rotation of the crank shaft I92 by means of an adjusting screw 202 which is rotatably mounted in a bracket 204 mounted across the endof thegui'deway, and screw-threaded into the carrier block I94.

With the present construction, driving connections are provided for driving the crankshaft alternatively from the table motor to' impart a continuous reciprocatory movement to the pawl for a continuous cross feed, or'from the reversing lever to providean intermittent cross feed. The driving connections for the feed crank shaft I92 include a clutch element 206 rigidly secured to a shaft 208 which is in axial alignment with the feed crank shaft' l92, and is connected to turn with and for axial movement relatively thereto by means of a loose coupling 2I 0; Atits rear end the shaft 208 is supported within a sleeve member 2I2 which is externally supported in a bearing 2 I4, and has formed thereon a clutch member 2I6 for engagement with the clutch 206. At its forward end the shaft 208 is supported within a sleeve member 2I8 which is externally supported in a bearing 220 in the machine frame, and is provided with a single tooth clutch member 222 arranged for engagement with the corresponding element on the clutch member 206, so that the crank shaft I92 and sleeve member 2I8 will always be connected in the same angular driving relationship.

the clutch 206* by means-of connections which include a shaft 226'provided atone end with a bevel gear ;'228 arrangedto mesh witha bevel gear 238 carried on the shaft 36 driven from the table motor- 28,- and atits other end with a spiral gear 232 which meshes with a corresponding spiral gear 234 formed on the sleeve member 2I2.

In accordance with a principal feature of the present invention, connections are 1 provided which are actuated during the movement of the reversing lever from one operating position to the other in either direction to rotate the clutch sleeve element 2I8 and crank shaft I92 when engaged therewith through exactly one revolution regardless of any variations in the amplitude of movement of the reversing lever in order to impart a'uniform increment of feeding movement to the grinding wheel cross feed upon each reversal of the table. These connections are actu-- ated by the rotational movement of the control shaft H6, and include a dwell mechanism which is arranged to stop and to maintain the sleeve men't of the control shaft H6 in each direction.

5 A driving gear 236 having formed thereon a dwell surface 23"! extending aroundsubstantially one-halfits periphery/is mounted on the'reciprocable control shaft H6 for engagement with a pinion 238 on the sleeve member 2 I8,-so that the member 2I8 is rotated firstin one direction and then in the other as the reversing lever isshifted at the end of the table travel in eachdirection. The dwell gear 236 and pinion 238 are mounted and proportioned so that the rotational movement impartedto the dwell gear 236 by the movement of the reversing lever will cause the pinion 238 and sleeve member 2I8 to be rotated through exactly one revolution and thereafter to be stopped as the pinion 238 comes into engagement with the dwell surface 231. The crank is connected through the one tooth clutch above described, to turn with the sleeve member 2I8 through a complete revolution in each direction from a center low position to back feed and then to advance the pawl as the crank returns again to its initial starting position. In order to provide a positive stop for the gear 238 and sleeve member 2I8 at the end of one complete revolution in either direction, a semi-circular segment 240 is provided integral with the dwell surface of the gear 236 and adjacent thereto, to engage in a correspondingly concaved sector 242 of a disk 244 carried on the sleeve member 2I8 adjacent the gear 238.

r The clutch member 206 may be shifted manually to the left from the intermediate position shown in Fig. 3 for clarity of illustration, into engagement with the clutch member 2I6 to secure a continuous automatic feed, or to the right into engagement with the single tooth clutch member 222 to secure Ian intermittent power cross feed; by means of connections which include a clutch control shaft 246 which extends parallel to the feed crank shaft I92, and is loosely mounted for axial and rotational movement in bearings 248 and 250 formed in the machine frame. At its forward end the control shaft 246 is arranged to engage with a rod 252 which is supported in axial alignment therewith in a bearing 253, and is provided at its outer end with a manually operable control knob 254. A clutch shifting yoke 256 rigidly secured to the control shaft 2 46','i'sar'ranged to engage in aperipheral groove 258 formed in the clutch member 206. A compression'spring 280' coiled about the control shaft 246 between the bearing 248 and the clutch shifting yoke 256 tends normally to maintain the clutch shaft 246 and yoke 256 in advanced position with the clutch member 206 in engagement with the-single tooth clutch member 222 for the intermittent power feed. A cross pin 262 secured to the rod 252, is arranged to slide in a slot 264 formed in an extension of the bearing 253 for the forward position of the control shaft 246 and rod 252. In order to shift the clutch sleeve 206 into engagement with the clutch member 2l6 for continuous power operation of the pawl I80 from the table motor 28, the rod 252 is pushed rearwardly against the pressure of the spring 260 to engage the clutch, and is then rotated so that the cross pin 262 is moved out of its slot 264 and engages against the end portion of the bearing 253 to lock the clutch in continuous feed position.

The invention having been described, what is claimed is:

1. An automatic cross feed mechanism for grinding machines which include a reciprocable work support and a control member movable through a variable distance in opposite directions with each reversal in the direction of support movement, comprising a reciprocaable wheel feed member, mechanical connections rendered operative by the movement of said control member in either direction to impart a reciprocatory feed movement to said wheel feed member, and a lost motion connection in said connections operative during the latter portion of the movement of the control member in each direction to arrest the movement of said feed member in a predetermined limiting position.

2. An automatic cross feed mechanism for grinding machines having a reciprocal work support and a reversing member movable in opposite directions to reverse the direction of support movement, which comprises a reciprocable wheel feed member and mechanical connections rendered operative by the movement of said reversing member in either direction to impart a reciprocatory feed movement to said feed wheel member, said connections including a driving member positively actuated by said reversing member through a distance proportional to the length of travel of said reversing member in each direction, and a driven member arranged to be positively actuated thereby during a portion only of the movement of said driving member in each direction, and means for arresting said driven member in one or the other of two predetermined limiting positions against continued movement with the driving member.

3. An automatic cross feed mechanism for grinding machines having a reciprocable work support and a reversing member movable in opposite directions toreverse the direction of support movement, which comprises a cross feed ratchet wheel, a pawl, a crank for reciprocating the pawl, and connections for actuating the crank from said reversing member comprising a pinion connected to drive the crank, a driving gear having a toothed sector meshing with said driven pinion of a length to impart one revolution to said crank, and connections rendered operative by the movement of said reversing member to rotate said driving gear in a corresponding direction through an angle in excess of that covered by said toothed sector.

4. An automatic cross feed mechanism for a grinding machine having a reciprocable work site directions to reverse the direction of support movement, which comprises a cross feed ratchet wheel, a pawl, a crank for reciprocating the pawl, and con nections for actuating the crank from said reversing member comprising a pinion connected to rotate the crank, an oscillatory driving member comprising a toothed segment meshing with said driven pinion of a length to impart one revolution to said crank, and connections rendered operative by the movement of said reversing member to move said driving member in a corresponding direction through a distance in excess of that covered by said toothed segment.

5. An automatic cross feed mechanism for a grinding machine having a reciprocable work support and a reversing member movable in opposite directions to reverse the direction of support movement, which comprises a cross feed ratchet wheel, a pawl, a crank for reciprocating the pawl, and connections for actuating the crank from said reversing member .comprising a pinion connected to rotate the crank, an oscillatory driving member comprising a toothed segment meshi'n'g'with said driven pinion of, a length to impart one revolution to said crank, connections rendered operative by the movement of said reversing member to move said driving member in a corresponding direction through a distance in excess of thatcovered by said toothed segment, and means for locking said pinion against further rotation when disengaged from said toothed segment.

6. A cross feed mechanism for a grinding machine having a reciprocable work table, driving means for the table and reversing means for the table including reversing dogs and a reversing lever actuated thereby which comprises a cross feed ratchet wheel, a pawl, a crank for actuating the pawl, a pinion connected to rotate the crank and having associated therewith a stop dwell surface, a dwell gear having a toothed sector arranged to mesh with said pinion, a supplementary stop dwell surface arranged alternatively for mating engagement with said pinion stop dwell surface, and connections rendered operative by the movement of the reversing lever to rotate the dwell gear in a corresponding direction through an angle in excess of that covered by the toothed sector.

, 7. A cross feed mechanism for a grinding machine having a reciprocable work table, driving connections therefor including a reversible electric motor, reversing switch connections for the 'motor, and a table actuated reversing lever for reversing the switch connections, which comprises a cross feed ratchet Wheel, a pawl, a crank for reciprocating the pawl, a pinion connected to rotate the crank, a segmental toothed member arranged to mesh with the pinion, connections from the reversing lever to oscillate the toothed member through a distance in excess of that covered by the toothed. portion thereof, ,and

means for locking said pinion against further rotation when disengaged from said toothed segment.

from the reversing lever for intermittently rotating the crank including a pinion, a dwell gear 5 through a distance in excess of that covered by the toothed sector, and clutch connections having a single position engagement with the pinion shiftable to connect the crank alternatively in driving relation to the pinion or to said 10 table motor.

9. A cross feed mechanism fora grinding machine having a reciprocable work table, driving connections therefor including a reversible electric motor, reversing switch connections for the 15 motor, and a table actuated reversing lever for reversing the switch connections, which comprises a cross feed ratchet wheel, a pawl, a crank for reciprocating the pawl, a pinion connected to rotate the crank, a dwell gear having a toothed sector arranged to mesh with the pinion, connections rendered operative by the movement of said reversing lever to rotate the dwell gear through an angular distance in excess of that covered by the toothed sector to reciprocate the pawl through a predetermined distance, and lock-

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