US2281930A - Cylindrical grinding machine - Google Patents

Description

May 5, 1942- c. G. FLYGARE ETAL 2,281,930

CYLINDRICAL` GRINDING MACHINE Filed March 4, 1941 4 sheets sheet l rwwbw- CHRL 511:7. VGH/:.15 ETEWHHT 5./WHDER a* www;

May 5, 11942- c. G. FLYGARE ET AL 2,281,930

' CYLINDRIC'AL GRINDING MACHINE Filed 'Maron 4, 1941 4 sheets-sheet 2 'EH/QL E. FL VERRE 57E WHRT .5. NEUER .May 5, 1942- c. G. FLYGARE ET A1. 2,281,930

CYLINDRICAL GRINDING MACHINE,

Filed March 4, 1941 4 Sheets-Sheet 5 m I v JMW C'HHL. EFL VSH/:e5 .STE WERT 5 M5275? May 5, 1942- n 'c. G. LYGARE ETAL 2,281,930

CYLINDRIQAL GRINDING MACHINE CHU-7L E FL f5/SWE STE WHR T EMHDER l Patented May 5, 1942 UNITED STATES PATENT OFFICE ter, Mass.,

assigner-s to Norton Company,

Worcester, Mass., a corporation of Massachusetts Application March 4, 1941, 'serial No. 381,710

10 Claims.

The invention relates to grinding machines, and more particularly to an improved cylindrical grinding machine.

One object of the invention is to provide a simple and thoroughly practical cylindrical grinding machine. Another object of the invention is to provide an improved table traversing and reciprocating mechanism. A further object of the invention is to provide a power operated grinding wheel feeding mechanism which is arranged for a continuous operation during a plunge-cut grinding operation or for an intermittent operation at the ends of the table stroke during a traverse grinding operation.

A further object of the invention is to provide an improved table dwell control mechanism whereby the table may be caused to dwell for a denite and predetermined time interval at the ends of its reciprocatory stroke. A further object of the invention is to provide a table reciprocating and reversing mechanism, in which a fluid shock absorbing device is provided between the reversing clutch and the table to eliminate shocks and vibrations incident to reversal which might be transmitted to the table. Other objects will be in part obvious or in part pointed out hereinafter.

The invention accordingly consists in the features of construction, combinations of elements, and arrangements of parts, as will be exemplified in the structure to be hereinafter described, and the scope of the application of which will be .indicated in the following claims.

ln the accompanying drawings, in which is shown one of various possible embodiments of the mechanical features of this invention,

Fig. 1 is a front elevation of the improved grinding machine;

Fig. 2 is a fragmentary vertical cross-sectional View, on an enlarged scale, taken approximately on the line 2-2 of Fig. 1;

Fig. 3 is a fragmentary vertical cross-sectional view, on an enlarged scale, taken approximately on the line 3-3 of Fig, 1;

Fig. 4 is a fragmentary vertical longitudinal sectional View, on an enlarged scale, of the table driving and reversing mechanism;

Fig. 5 is a fragmentary cross-sectional View, on an enlarged scale, taken approximately on the line 5-5 of Fig. 4, showing the shock absorbing device;

Fig. 6 is a fragmentary front elevation, on an enlarged scale, with the table reversing and stopstart levers shown in full lines and some of the interior mechanism shown in dotted lines;

Vconnected by a Ibelt drive contained Within the y bearings (not shown) in the base l5.

Fig. '7 is a fragmentary horizontal sectional view, showing the reversing and stop-start Iclutches together with part of the actuating mechanism for the stop-start clutch; and

Fig. 8 is an electrical Wiring diagram of the clutch shifting-time delay control mechanism.

A grinding machine has been illustrated in the drawings, comprising a base I5 which supports a longitudinally reciprocable work table I I on the usual fiat way I2 and V-way I3 (Fig. 2) for a longitudinal movement relative to the base It. A rotatable work support is provided on the table i l, comprising a headstock M and a footstock I5 which are in turn provided with Work supporting centers It and I1, respectively. The headstock I4 `is preferably a motor driven headstock, in which an electric motor I3 is mounted on the upper portion of the headstock. Thevmotor iS is operatively connected by awbelt drive (not shown) to rotate a face plate I9 which carries an adjustably positioned work driving pin or stud 20. It will be readily apparent from the foregoing disclosure that a work piece to be ground is mounted in supporting engagement on the headstock center It and footstock center il and is rotated by means of the driving pin 2i) which preferably engages a driving dog adjustably attached to the left-hand end of a work piece,

The base l0 also serves as a support for a rtransversely movable grinding wheel slide 25.

The wheel slide 25 supports a rotatable wheel spindle 26 in suitable bearings (not shown). The wheel spindle 26 serves as a support for a grinding wheel 2l. An electric motor 28 is mounted on the upper surface of the Wheel slide 25 and is guard 29 to rotate the spindle 26 and thereby to transmit a rotary motion to the grinding wheel 2l.

The table I l may be reciprocated longitudinally by `means of a rack and gear mechanism, comprising a rack bar 35 depending from the under side of the table 2i). A gear 36 'which is supported on a rotatable shaft 31 meshes with the rack bar 35. The shaft 3l is journalled in suitable The shaft 37 also supports a worm gear 33 which meshes with a worm 39 which is either formed integral with or fiXedly mounted on a shaft 4U. The shaft 4U is journalled in anti-friction Abearings 4| and 42 which are in turn supported in an apron 43.

The apron 43 is iixedly mounted on the base l0.

A reversing mechanism is provided, comprising a pivotally mounted reversing lever 5 which is iixedly mounted on the outer end of a shaft shaped member is arranged to straddle and' engage a groove 52 formed in the periphery of a slidably mounted clutch member 53. The clutch member -53 is slidably keyed on a rotatable 'dri-ve shaft 54 which is journalled in bearings 55 and 56.

When the clutch member 53 is shifted toward the right (Fig. 4), it engages or mates with clutch teeth 51 formed integral -wtha gear-58.v The gear is rotatably supported relative-tothe shaft 54 and meshes with a gear 59 whichA is keyed to a sleeve 60. The sleeve is rotatably supported on a reduced portion 6| of the shaft 40. The outer end of the reduced portion '6| 'is rotatably supported by an anti-friction bearing E2. The sleeve 50 is operatively connected `with the portion 6| of the shaft 40' in a manner to be hereinafter described.

When the clutch member 53 is shifted toward the left (Fig. 4), the clutch teeth on the righthand end of the clutch member 53 will be shifted into engagement with a set of clutch teeth E3 formed integral with or i'lXedly mounted on a gear 94. The gear 54 is rotatably supported on the shaft 54 and meshes with an idler gear 65 which in turn meshes with a gear 6E formed :in-

tegral with the sleeve 60. It will be readily apparent from the foregoing disclosure that when the clutch member 53 shifts toward theleft (Fig. 4), a rotary motion will be Ytransmitted by the shaft 54, through the clutch member 53;' through the clutch teeth 03, the gear 04, the gear 65, and

the gear 65, to rotate the sleeve 60 in the reverse direction.

A power operated driving mechanism is provided for rotating the shaft 54. This mechanism may comprise a change speed gear unit 10 which is fixedly mounted within the base I0 of the machine. Power is supplied to the gear unit 10 by means of a driving belt 1| from any suitable source of power such as, for example, an electric motor mounted on the rear of the base I0. The driving belt 1| drivingly engages a pulley 12 mounted on the right-hand end of a rotatable shaft 13. The shaft 13 is journalled at one end in an anti-friction bearing 14 which is supported in the casing 19.l The other end of theshaft 13 is journalled in a bearing 15 formed in the hollow end of a rotatable shaft 16 to be hereinafter described. A clutch member 11 is slidably keyed on the shaft 13. lA gear 18 is formed integral with the clutch member 11 and is arranged to be thrown into `and out of mesh with a gear 19 which is keyed to the right-hand end of a rotatable shaft 80. The shaft is journalled in suitable anti-friction bearings 8| and 82, respectively, which are supported in the housing 10. A gear 83 isformed integral with the shaft 80 and meshes with a gear 84 which is keyed to the right-hand end of the shaft 16. The clutch member 11 is provided with clutch teeth 85 which are arranged to be thrown into or out of mesh with a set of clutch teeth 86 formed integral with the gear 84.

It will be readily apparent from the foregoing disclosure that when the clutch member 11 is :aesinet moved toward the left, the shaft 13 will be connected directly to rotate the shaft 16 at the same speed. If a reduced or slower speed is required on the shaft 16, the clutch member 11 may be moved toward the right to throw the gear 18 into mesh with the gear 19 so that rotary motion of the shaft 13 will be transmitted through the gear 18, the gear 19, the shaft 8|), and the gear 93, to rotate the gear 84 and the shaft 10 at a reduced or slower speed.

The right-hand end of the shaft 15 is rotatably supported by an anti-friction bearing 81 carried by the casing 10. The other end of the shaft 16 is rotatably journalled in a bearing bushing 99 formed in a hollow end portion of av rotatable shaft 89.` The shaft 89 is journalled in an anti-friction bearing 90 supported by the casing 10. The shaft 89 serves as a support for a. slidably mounted clutch member 9| having clutch teeth 92 which are arranged to be thrown into or out of engagement with a set of clutch teethA 93 formed on a clutch member 94 which is` iixedly mounted on the right-hand end of the shaft 54 (Fig. 4). The clutch member 9| together with its associated parts serves as a stop and start clutch whereby the reciprocatory movement of the table may be started and stopped as desired. A manually operable clutch shifting lever 95 on the front of themachine base is provided for actuating the clutch member 11 so that either a slow or a fast speed may be provided for traversing the table at either a slow or a rapid speed as desired. A control lever 96 is mounted on the front of the machine base and serves as a stop and start lever for actuatingl theclutch 9| to stop and start the movement of thetable I as desired.

The stopand start lever 96 is pivotally sup.- portedfon, astud 91 which is in turn supported by a boss-99; whichprojects from the front of the base l0. The lower end of the lever 9S is connected by means of a stud 99 (Figs. 6 and 7) with the forward end of a slidably mounted plunger |00 which is journalled in a suitable bearing |0| `formed in the base I0. The inner end of the plunger |00 is provided with a cam surface |02 which is arranged to engage a roller |03.l The roller |03 is rotatably supported on a yoked member |04. The yoked member |04 is provided with diametrically opposed studs |05 and |06 which ride in a groove |01 formed in the clutch member 9|. A tension spring |08 is connected between the yoked member |94 and a fixed portion of the machine base and serves normally to exert a thrust on the clutch member 9| tending to hold it in an engaged position. When it is desired to disengage the clutch member 9| to stop the table Il, the upper end of the lever 96 is rocked toward the base l0, that is, so that its downward end (Fig. 6) exerts an outward pull on the plunger |00 (Fig. 7) which moves the cam into engagement with the roller |03, -after which continued movement serves through the roller to move the yoked member |04 toward the right (Fig. 7) to shift the clutch member 9| also toward kthe right to disengage the same, thus disconnecting the power drive to the table l.

In order to attain one of the objects of the invention, a suitable shock absorbing device is provided to substantially eliminate the shocks and vibrations incident to reversing a rapidly reciprocating machine tool part. In the preferred construction, a fluid shock absorbing device is provided and is interposed between the sleeve E9 and the drive shaft 6|. Thesleeve 6.0 is provided with an enlarged portion H within which are formed fluid chambers HI, H2, H3 and H4. A rotor ||5 is contained within the chambers and is provided with diametrically opposed vanes H5 and H1. An inwardly projecting wall H8 is formed integral with the sleeve 5U and serves to separate the chamber IH from the chamber H2. Similarly, an inwardly projecting partition H9 formed integral with the sleeve 30 serves to separate the fluid chambers H3 and ||4. The chambers H2, H3 and H4 are initially substantially lled with a fluid, such as a shock absorbing fluid or grease of the desired consistency and these chambers are maintained in a lled condition by injecting uid or grease through the grease cups and 2| When the reversing clutch 53 (Fig. 4) is shifted in either direction to start the traversing movement of the table the rotation of the sleeve 63 by means of the gearing above described first shifts the partitions H8 and H9 either in a clockwise or counterclockwise direction, the rotary motion of which cushions against the fluid or grease contained within the chambers H2, H3 and ||4 before rotation of the shaft 6| is started by the vanes H6 and H1. If the sleeve 6U is rotated in a clockwise direction (Fig. 5), the partition I8 will rotate and grease or iiuid within the chamber will squeeze out or be forced through between the inner face of the partition H8 and the peripheral face of the hub joining the vanes H6 and ||1 into the chamber H2.

Similarly, fluid or grease within the chamber H3 will be placed under pressure and it will be squeezed or forced in part through the clearance space between the inner surface of the partition H9 and the peripheral surface of the hub H5. Due to this action of the grease or fluid within the chambers H2, H3 and H4, each time the rotation of the worm shaft 40 is reversed by the automatic table actuated shifting of the reversing clutch 53, the iiuid cushioning above described takes place before the worm starts rotating in the reverse direction, thus substantially eliminating the shocks and vibrations at reversal.

A dwell control mechanism is provided so that at reversal the table may remain stationary at the end of its stroke in either direction to facilitate the grinding wheel grinding entirely around the work piece at its extreme end position before the table starts traversing in the reverse direction. This mechanism is preferably an electrically controlled mechanism actuated by and in timed relation with the table movement. A load and re mechanism is provided for the clutch mechanism, comprising an arrow-pointed, spring-pressed plunger carried by the downwardly extending arm 5|). This arrow-pointed plunger rides on a roller |26 which is fixed relative to the base of the machine.

A rock arm |21 is rotatably supported on the sleeve 65 and is provided with a downwardly extending arm |23 having a projecting lug |29 which is adapted to t within the groove 52 in the clutch member 53 when the clutch member is in a central or neutral position. The rock arm |21 is provided with an upwardly extending arm |30. A tension spring |3| is connected at its upper end to a lug |32 formed on the arm |3|). The lower end of the spring |3| is connected to a stud |33 fixed to the casing 43. It will be readily apparent from the foregoing disclosure that the spring 3| normally tends to hold the lug |29 in engagement with the groove |52 in the clutch member 53.

Y.A pull type solenoid |34 is connected by a stud |35 with the upper end of the arm |30 of the rock arm |21, A normally closed limit switch |36 is arranged to be opened at reversal by the upward movement of a plunger |31 which is actuated by means of a cam |38 carried by the hub of the lever arm 5|). The solenoid |34 is normally maintained in an energized condition during the traversing movement of the table H. Power lines |39 supply power to the solenoid |34. The .solenoid |34 together with the normally closed limit switch |36 are interconnected with an electrical time delay relay |40 such as, for example, a Microflex time delay relay such as is manufactured bythe Signal Electric Corporation. The solenoid |34, limit switch |35, and time relay |40 are so connected that when the reversing lever is shifted by either of the table dogs 41 or 48 to cause a reversal in direction of movement of the table, the initial movement of the lever serves to disengage the clutch member 53 'and at the same time, through the plunger |31', opens the normally closed limit switch |38 which breaks the circuit to deenergize the solenoid |34 and at the same time set the time relay |40 in motion. As soon as the solenoid |34 is deenergized, the released tension of the spring 3| serves to rook the rock arm |21 in a clockwise direction to move the downwardly extending lever |28 and the lug |29 into engagement with the groove 52 in the clutch member 53. The mechanism is timed so that the lug |29 drops into the groove in the clutch member just as the arrow point |25 of the load and re mechanism rides over the high point of the roller |25, sothat the plunger |25 tends to shift the reversing clutch into the reverse direction, but lsuch movement is prevented by engagement of the lug |29with the groove 52 of the clutch 53. The parts remain in this position for a predetermined time interval as governed by the setting of the electric time delay relay |49. After the predetermined time interval has elapsed, the time relay |40 operates to close a circuit to energize the solenoid |34 which operates against the tension of the spring 3| to rock the rock arm |21 in a counterclockwise direction so as to withdraw the lug |29 from the groove 52 of the clutch 53. As soon as the lug |29 has been Withdrawn, the released compression of the spring-pressed arrow point |721 immediately shifts the clutch 53 into its reverse position, thus starting the traversing movement of the table in the opposite direction.

A grinding wheel feeding mechanism is provided to feed the wheel slideV 25 together with the grinding Wheel 21 supported thereby toward and from the table to grind a cylindrical work piece supported thereby thereon. This feeding mechanism may comprise a half nut |45 depending from the under side of the wheel slide 25 which meshes with or engages a rotatable cross feed screw |45. The feed screw |46 is rotatably supported in bearings |41 (only one of which has been shown in the drawings) in the base Ill. The outer end of the feed 'screw shaft supports a gear |48 (Fig. 3) which meshes with a small gear (not shown) which is supported to rotate with a manually operable feed wheel |49. The feed wheel |49 may be rotated to manually adjustmthe position of the wheel slide 25. f

- In order to feed the grinding wheel slide automatieally by power'either'atthe ends vof the work table reciprocatory stroke or continuously in case of a plunge-cut grinding operation, a feed pawl |56 is provided. The pawl |50 is oscillated by a mechanism to be hereinafter described while in engagement with a ratchet wheel or gear carried by the hand wheel |49. This part of the wheel feeding mechanism is an old and well known construction such as, for example, that shown in the expired patent to Norton, No; '762,838 dated June 14, 1904, towhich reference may be had for details of disclosure not contained herein, The ratchet pawl |50 is connected by a connecting rod ||'with a crank plate |52 which is supported on a rotatable shaft |53. The shaft |53 is journalled in anti-friction bearings |54 and |55 in the base of the machine. The lower end of the connecting rod or link |5| is adjustably connected to the crank plate |52 'and is arranged so that its connecting stud may be positioned in alignment with the axis of the shaft |53, in which case no motion is transmitted through the link |6| to oscillate the pawl |50, 'or may be adjusted eccentric relative to the axis of the shaft |53 to provide the desired oscillatory stroke to the feed pawl |50, as desired.

The shaft |53 is preferably operatively connected to be rotated by power either at a continuous rate of rotation for a plunge-cut infeed of the grinding wheel, or rotated intermittently at the ends of the work table stroke to provide an infeed in a traverse grinding operation. As shown in the drawings, a spiral gear |55 is rotatably supported on theshaft |53 (Fig. 3) The spiral gear |55 meshes with a spiral gear |56 (Figs. 3 and 4) which is `formed integral with a shaft |51. The shaft |51 is journalled in bearings |58 and |59 which are in turn supported in the casing v10. A clutch member |60 is slidably keyed to the shaft 16. A gear |6| is formed integral with the clutch member |60 and is arranged to be thrown into or out of mesh with a gear |62 which is keyed to the shaft |51 (Fig. 4) A gear |63 is keyed to the shaft |51 and meshes with a gear |64 which is'keyed to the shaft 89.

If it is desired to transmit a relatively slow rotation to the shaft |53, the clutch member |60 (Fig. 4) is shifted toward the right to mesh the gear' |6| with the gear |62.' In this position of the gears, a slow rotation will be imparted to the shaft |53 and also a slow rotation of the shaft 89 will be transmittedfror'n the shaft |51 through the gears |63 and |64 to produce a slow traversing movement of the work supporting table In case 'a rapid wheel feeding movement is desired in combination with a comparatively fast speed of the table I'I, the clutch member |66is moved toward the left (Fig. 4) so that clutch teeth on its left-hand end are thrown into mesh with clutch teeth |65 formed on the end of the shaft 89 and thus iixedly mounted relative to the gearV |62, In this position of the parts, rotation of the shaft 16 will be transmitted directly to rotate the shaft 89 and through the connecting mechanism to traverse or reciprocate the table at a comparatively fast speed. At the same time, the gear |64 will transmit a rotary motion through the gear |63 to rotate the spiral gear |56 which in turn rotates the spiral gear |55 at a comparatively fast rate of speed.

The slidably mounted clutch member |66 is keyed to the shaft |53 and is arranged so that it may be thrown into or out of engagement with clutchteeth |61 formed on the left-hand end face of the spiral gear member |55. When the clutch member |66'is in a disengaged position, no rotary motion will be transmitted by the gear |55. A compression spring |68 surrounds a hub portion on the clutch member |66 and is interposed between a shoulder on the clutch member and a thrust collar |69 and serves to exert a pressure tending to hold the clutch member |66 in engagement with the clutch teeth |61.

The clutch member |66 is normally held in a disengaged position. The clutch member |66 is provided with a cam groove |10. A slidably mounted plunger |1| is normally maintained in the position shown in Fig. 3 in engagement with the cam groove |10 to hold the clutch |66 in its left-hand or disengaged position. When it is desired to obtain a feeding movement of the grinding wheel at the ends of the table stroke', it is necessary to withdraw the pin |1| so that the releasedA compression of the spring |68 may throw the clutch |66 toward the right into engagement with the clutch teeth |61 so that the continuously rotating spiral gear |55 will impart an oscillating movement to the feed pawl |50, thereby producing an infeeding movement of the grinding wheel.

In order that the feeding movement of the grinding wheel may take place at the ends of the table stroke when the reversing mechanism is operative, it is desirable to provide an interlocking mechanism whereby the pin |1| may be instantaneously withdrawn from the cam groove |10 in timed relation with the movement of the reversing lever 45. The pin I1| is connected by a stud |12 which is carried by a rock arm |13. The rock arm |13 is pivotally supported on a stud |14 which' is journalled in a bracket |15 within the machine base. A rock arm |16 is 4also supported by the stud |14 and is xedly mounted to move with the rock arm |13 so that in effect the rock arms |13 and |16`constitute a bell crank lever. A detention spring |11 is connected between a stud |18 carried by the rock arm |16 and a stud |19 which is xed relative to the base I0 of the machine. The tension of the spring |11 serves normally to exert a presstue on the bell crank lever |13-I16 tending to hold the pin |1| within the cam groove |10.

A rock arm (Fig. 6) is pivotally supported on a stud |8| which is fixed relative to the base Il)` The right-hand end of the rock arm |80 is `arranged in the path of'an adjustable stop screw |82 carried by the rock arm |16. An adjustable rotatable stop cam |83 serves to limit the counterclockwise movement of the rock arm |68, thus limiting the clockwise movement of the bell crank lever |13-|16. By adjustment of the screw |82, the position of the stud |1| maybe varied relative to the cam path |16.

The rock arm |80 is provided with an adjustably positioned member |84 at its left-hand end which pivotally supports a pawl |85 which is arranged in the path of an arrow point |86 which is fixedly mounted on the rock shaft 46 so that it is moved by and in timed relation with the reversing lever 45. It will be readily apparentl from the foregoing disclosure that each time the reversing lever is shifted at the ends of the table stroke, the arrow point |86 engaging the pawl |85 serves to rock the rock arm |80 in a clockwise direction. This movement in turn transmits a counterclockwise movement to the bell crank |13|16 to withdraw the pin |1| from the cam path |10, thusreleasing the compression of the spring |68 to' engage the clutch member |66 with the clutch teeth |61, and connecting the continuously rotated gear |55 with the shaft |53 to impart an infeeding movement to the grinding Wheel slide 25 and the grinding wheel 21.

The withdrawal of the pin is only for an can drop into the cam slot |16. During this time interval the shaft |53 is only rotated a small portion of a complete rotation. The shaft continues to rotate until the cam slot |70 through the cam pin |l| again throws the clutch member |66 into a disengaged position (Fig, 3). It should be noted that when this mechanism is set for an infeeding movement at the end of the table stroke in a traverse grinding operation, the clutch |66 together with its actuating mechanism isA arranged so that the shaft |53 will rotate only one completed rotation before the clutch |66 is again disengaged, thus providing an infeeding movement of the grinding wheel during the period of table reversal.

If it is desired to set up the machine for a piunge-cut grinding operation, that is, for a continuous infeeding movement, a mechanism is provided for rendering the pin |T| inoperative so that the shaft |53 will be continuously rotated to impart a continuous oscillating movement to the feed pawl |50, thus continuously feeding the grinding wheel into the work piece. In order to accomplish this result, the cam or eccentric |83 is rotatably supported on a stud |81. An actuating knob |88 is mounted on the outer end of the stud |81. When it is desired to provide a plungecut grinding operation, the knob |88 may be rotated through 180 degrees, during which movement the eccentric |83 will rock the lever |80 in a clockwise direction and this in turn will rock the bell crank lever IIS-|76 in a counterclockwise direction so as to withdraw the pin thus releasing the compression of the spring |68 which in turn throws the clutch member |66 into engagement with the clutch teeth |57. The parts will remain in this condition as long as desired. rIhe continuous infeeding movement may be stopped and started either by rotation of the knob |88 or by actuation of the clutch member |66 (Fig. 4).

The operation of the improved cylindrical grinding machine will be readily apparent from the foregoing disclosure. Assuming all of the parts to have been previously adjusted; a work piece may be mounted in position on the headstock center |6 and footstock center l1, after which the grinding operation may be started. The table reciprocation may be started by actuation of the stop and start lever 96 which engages or disengages the clutch 9|. At the ends 0f the table stroke as governed by the table dogs 41 and 43, a predetermined dwell may be obtained by adjustment of the time relay |40. Vibrations at reversal are substantially eliminated by means of the hydraulic shock absorbing device above described. The grinding wheel may be advanced at the ends of the reciprocatory stroke of the table in a manner previously described. Each time the reversing lever 45, is shifted by the table dogs il and 4S to change the direction of movement of the table the pin Ill is instantaneously withdrawn from the cam groove |10 so that the clutch is instantaneously connected to provide the desired infeeding movement of the wheel slide and the grinding wheel 21. If it is desired to set up the machine for a plunge-cut grinding operation, the work table remains stationary and a grinding wheel of a width equal to the length of the surface to be ground is mounted on the spindle 26. For such an operation, the knob |88 is rotated degrees to render the pin |1| inoperative, thus providing a. continuous rotation of the shaft |53 which serves continuously to oscillate the feed pawl |50, thus providing a continuous infeed of the grinding wheel.

' 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 grinding machine having a base, a longitudinally reciprocable work supporting table, means including a reversing lever to reciprocate said table, a rotatable grinding wheel, a transversely movable Wheel slide therefor, a wheel feeding mechanism including a continuously rotated power driven shaft to move said slide transversely, a clutch biased to an engaged position which is interposed between said shaft and wheel slide, means to hold said clutch disengaged during the longitudinal traversing movement of the table, and means actuated by said reversing lever during table reversal to release said clutch holding means to facilitate an infeeding movement of the grinding wheel.

2. In a grinding machine having a base, a longitudinally reciprocable table, means including a reversing lever to reciprocate said table, a rotatable grinding wheel, a transversely movable wheel slide therefor, a feeding mechanism therefor including a nut and screvv mechanism, means including a continuously rotated power driven shaft to actuate said nut and screw mechanism, a clutch biased to an engaged position which is interposed between the nut and screw mechanism and the shaft, means to hold said clutch disengaged during the longitudinal movement of said table, and means actuated by said vreversing lever during table reversal to release said clutch holding means to facilitate an infeeding movement of the grinding Wheel.y

3. In a grinding machine having a base, a

longitudinally reciprocable work supporting table, means including a reversing lever to reciprocate said table, a rotatable grinding wheel, a transversely movable wheel slide therefor, a feeding mechanism therefor including a nut and screw mechanism, a pawl and ratchet mechanism to rotate said screw, a power driven mechanism to actuate said pawl, a spring engaged clutch between said power mechanism and said pawl and ratchet mechanism, means including a cam and a follower to'hold said clutch disengaged during table reciprocation, and means actuated by said reversing lever instantaneously to withdraw the'follower from engagement with said cam to provide an infeeding movement of the grinding wheel during reversal.

4. In a grinding machine having a base, a longitudinally reciprocable table, means including a reversing lever to reciprocate said table, a rotatable grinding wheel, a transversely movable wheel slide therefor, a feeding mechanism therefor including a nut and screw mechanism, a pawl and ratchet mechanism to rotate said screw, a power driven mechanism to actuate said pawl, a normally engaged clutch therebetween, means including a cam and a follower to hold said clutch disengaged during the table reciprocation, yieldable means to maintain said follower in operative engagement with said cam, and means actuated by movement of the reverse lever instantaneously to withdraw said follower to provide an infeeding movement of the grinding wheel during reversal.

5. In a grinding machine having a base, a longitudinally reciprocable table, means including a reversing lever to reciprocate said table, a rotatable grinding wheel, a transversely movable wheel slide therefor, a feeding mechanism therefor including a nut and screw mechanism, a pawl and ratchet mechanism to rotate said screw, a power driven mechanism to actuate said pawl, a normally engaged clutch therebetween, means including a cam and a follower tor hold ,said clutch disengaged during the table reciprocation, yieldable means to maintain said follower in operative engagement with said cam, and means actuated by movement of the reverse lever instantaneously to withdraw said follower to provide an infeeding movement of the grinding wheel during reversal, said cam being shaped automatically to disengage said clutch after one complete rotation thereof.

6. In a grinding machine having a transversely movable rotatable grinding wheel, a longitudinally reciprocable table, means including a table-actuated lever to reciprocate said table, a grinding wheel feeding mechanism including a rotatable feed screw and a nut, a power operated mechanism to rotate said screw, a clutch interposed between said power mechanism and screw, a spring automatically to engage said clutch, a cam on said clutch, a pivotally mounted follower engageable with said camnormally to hold said clutch disengaged, yieldable means normally to maintain said follower in engagement with said clutch, and means actuated by said reversing lever automatically todisengage said follower from said cam at each actuation of the reversing lever automatically to impart an infeeding movement of the grinding wheel during the table reversal.

7. In a grinding machine having a transversely movable rotatable grinding wheel, a longitudinally reciprocable table, means including a table-actuated reversing lever to reciprocate said table, a grinding wheel feeding mechanism including a rotatable feed screw and a nut, a power operated mechanism to rotate said screw, a clutch interposed between said power mechanism and screw, a compression spring automatically to engage said clutch, a cam on said clutch, a movable mounted follower engageable with said cam normally to hold said clutch disengaged, a spring normally to maintain said follower in engagement Vwith said cam, and operativeconnec'tions between said reversing lever and said follower whereby the follower is automatically disengaged from the cam at each actuation of the reversing lever automatically to impart an infeeding movement to the grinding wheel when the table move'- ment is reversed.

8. In a grinding machine having a base, a longitudinally reciprocable work supporting table, means including a reversing lever to reciprocate said table, a rotatable grinding wheel, a transversely movable wheel slide therefor, a feeding mechanism therefor including a nut and screw mechanism, a power driven mechanism to rotate said screw, a normally engaged clutch between said power mechanism and screw, means including a cam and a follower to hold said clutch disengaged during table movement, means actuated by said reversing lever instantaneously to withdraw said follower from engagement with said cam to provide an infeeding movement of the grinding wheel during reversal in a traverse grinding operation, and manually operable means to maintain said follower in an inoperative position to provide a continuous infeed of the grinding wheel for a plunge-cut grinding operation.

9. In a grinding machine having a transversely movable rotatable grinding wheel, a longitudinally reciprocable work supporting table, means including a reversing clutch to reciprocate said table, a groove in said clutch, a reversing lever operatively connected with said groove to actuate said clutch, a pivotally mounted latch which is yieldably biased toengage said clutch groove, a solenoid operatively connected to swing said latch out of engagement with said groove during the traversing movement of said table, a limit switch operatively connected with said solenoid, means actuated by said reversing lever to actuate said switch during reversal to actuate said solenoid so that the latch swings into engagement with said groove to hold the reversing clutch in a neutral position, and means including an electrical time delay relay which is set in motion by actuation of said switch to actuate the solenoid after a predetermined time interval, thereby withdrawing said latch from said groove so that the clutch may shift into a reverse position.

l0. In a grinding machine having a transversely movable rotatable grinding wheel, a longitudinally reciprocable work supporting table, means including a reversing clutch to reciprocate said table, a groove in said clutch, a reversing lever operatively connected with said groove to actuate said clutch, a pivotally mounted latch which is yieldably biased in engagement with said clutch groove, a solenoid operatively connected to swing said latch out of engagement with said groove' during'the traversing movement of said table, a normally closed limit switch operatively connected with said solenoid, means actuated by said reversing lever toopen said switch during reversal to deenergize said solenoid so that the latch swings into engagement with said groove to hold said clutch in a neutral position, and means including an electrical time delay relay which is set in motion by the opening of said switch to energize' said solenoid after a predetermined time' interval, thereby to with-- draw said latch from said groove so that the clutch may shift into a reverse position.

CARL G. FLYGARE. STEWART VS. MADER.

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