US2448283A - Cylindrical grinding machine - Google Patents

Description

H. A. SILVEN CYLINDRICAL annmme ucamn Aug. 31, 1948.

9 Sheets-Sheet 1 Filed Nov. 21. 1945 HERBERT A. SILVEN 8- 31, 8- H. A. SILVEN 2,443,283

CYLINDRICAL GRINDING MACHINE Filed Nov. 21. 1945 9 sheets-sheet 5 -MlN/MUM TRAVEL 1 B RE UIRED TO REvERsE 5W/TCH u. u .u' 230 i 1 B HERBERT A. 5lLvE/v v/ @Mum M Aug. 31, 1948. H. A. SILVEN I 8,

' CYLINDRICAL GRINDING momma I Filed Nov. 21, 1945 9 Sheets-Sheet 6 [9576 i8 I88 I79 l6 18 I8 I78 164 HERBERT A. 51L VEN H. A. SILVZN CYLINDRICAL GRIIDING MACHINE Aug. 31,. 1948.

9 Sheets-Sheet '7 Filed Nov. 21, 1945 llllllLlll Aug. 31, 1948. H. A. SILVEN CYLINDRICAL GRINDING MACHINE 9 Sheets-Sheet 8 Filed Nov. 21. 1945 I If/ HERBERTA. SILVEN H. A. SILVEN CYLINDRICAL GRINDING IACHINB Aug. 31, 1948.

9 Sheets-Sheet 9 Filed Nov. 21. 1945 INVENTOR. HERBERT A. SILV'EN Patented Aug. 31, 1948 CYLINDRICAL GRINDING MACHIN E Herbert A. Silven, Worcester, Mass., assignor to Norton Company, Worcester, Mass., a corporation of Massachusetts Application November 21, 1945, Serial No. 630,045

12 Claims. (CI. 51-95) 1 The invention relates to grinding machines an more particularly to an electrically operate cylindrical grinding machine,

One of the objects of this invention is to provide a simple, thoroughly practical, readily controllable, electrically driven cylindrical grinding machine. Another object is to provide a cylindrical grinding machine with a variable speed table reciprocating mechanism which is arranged so that independently adjustable speeds may be obtained for grinding and for trulng which may be readily shifted from grinding to a truing speed and vice versa without disturbing the independent speed adjustments.

Another object of the invention is to provide an electric table driving mechanism including a variable-speed reversing motor and a gear driving mechanism including a pair of clutches arranged to reciprocate the grinding machine table at a relatively slow speed for a grinding wheel truing operation. Another object of the invention is to provide such. machine with independent adjusting. control mechanism including potentiometers to control the speed of the motor so as to produce either a relatively high speed of the table for a traverse grinding operation or a relatively slow speed of the table for a truing operation. Another object of this invention is to provide means including a control lever for readily shifting from a grinding to a truing speed of the table in which the control lever-is arranged to shift not only the clutches but also to actuate a transfer switch so as to render either a grinding speed potentiometer or a truing speed potentiometer operative.-

A further object of the invention is to provide a table dwell control mechanism for causing an adjustable dwell at both ends or either end of the table stroke including a pair of independent electric time dwell relays for controlling the period of dwell as desired. Another object of the invention is to provide means including a switch actuated by the control lever to render both of the electric timers inoperative when the control lever is shifted to a truing position so as to render the dwell control mechanism inoperative'during a grinding wheel truing operation.

A further object of the invention is to provide a feeding mechanism including a clutch actuated pawl and ratchet mechanism which is arranged to either continuously reciprocate said pawl-for a plunge-cut grinding operation or to intermittently actuate the pawl at the ends of the table stroke for a truing operation. Other objects will be apparent from the foregoing disclosure.

This 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.

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

Fig. 1 is a front elevation of a cylindrical grinding machine embodying the invention;

Fig. 2 is an electrical wiring diagram of the table driving mechanism;

Fig. 3 is a vertical section viewpartly in elevalarged scale, of the parts and mechanisms shown in Fig. 5;

Fig. 7 is a plan view of the table reversing switch;

Fig. 8 is a fragmentary vertical sectional view, on an enlarged scale, taken approximately on the line 8-8 of Fig. 5, through the manual table traverse mechanism;

Fig. 9 is a vertical sectional view, on the enlarged scale, taken approximately on the line 99 of Fig. 5 through the table control lever and mechanism;

Fig. 10 is a fragmentary vertical sectional view, on an enlarged scale, of the table driving mechanism;

Fig. 11 is a development of the feed mechanism the table drive clutches;

Fig. 14 is a fragmentary cross sectional view, on an enlarged scale, taken approximately on the line H-il ofFig. 9:

Fig. 15 is a fragmentary horizontal sectional view, on an enlarged scale, showing the connections between the start and stop lever and the clutch for controlling the manual traverse;

Fig. 16 is a horizontal sectional view taken approximately on the line I6--l6 of Fig. 5, through the control lever mechanism;

Fig. 1'? is a horizontal sectional view taken approximately on the line I'I-II of Fig. 5;

Fig. 18 is a fragmentary vertical sectional view, on an enlarged scale, taken approximately on the line I8-I8 of Fig. 5, through the table reversing lever;

Fig. 19 is a fragmentary vertical sectional view, on an enlarged scale, taken approximately on the line I8I9 of Fig. 6;

Fig. 20 is a fragmentary vertical sectional view, taken approximately on the line 2020 of Fig. 9, through the control lever mechanism;

Fig. 21 is a fragmentary cross sectional view, on a reduced scale, taken approximately on the line 2I--2I of Fig. 15 through the latch mechanism;

Fig. 22 is a fragmentary cross sectional view, taken approximately on the line 2222 of Fig. 20;

Fig. 23 is a fragmentary cross sectional view,

on an enlarged scale, through the feed wheel;

and

Fig. 24 is an electric wiring diagram of the Thy-Mo-Trol electronic motor control apparatus and other electric control apparatus associated therewith.

A grinding machine has been illustrated in the drawings comprising a base I having a longitudinally reciprocable table II mounted thereon on the usual flat way I2 and V-way I3. The table I I serves as a support for a rotatable work piece comprising a head stock I4 having a head stock center I and a foot stock I6 having a foot stock center II. The head stock center I5 and foot stock center I! are arranged rotatably to support a cylindrical work piece I8 for a grinding operation.

The head stock I4 is preferably a motor driven head stock comprising a variable-speed reversible electric motor I9 mounted on the upper surface of the head stock I4. Push button switches 26 and 2| are provided on the front of the machine base IIIfor starting or stopping the motor I9 as desired. A speed control device 22, such as a rheostat, is provided for controlling the speed of the work drive motor I9. A reversing switch 23 is also provided for changing the direction of the rotation of the motor I9 when desired. A jogging switch 24 is provided on the front of the machine base which is operatively connected so that the work drive motor I9 may be jogged to position the work when desired.

A transversely movable slide 30 is mounted on transversely arranged V-way 3| and a flat way 32. The wheel slide 30 is provided with a rotatable wheel spindle (not shown) for supporting a rotatable grinding wheel 33. The Wheel 33 and its supporting spindle are driven by means of an electric motor 34 which is mounted on the upper surface of the wheel slide 30. The motor 34 is provided with an armature shaft 35 which supports a multi-V-grooved pulley 36 which is connected by means of multiple V-belts 31 with a multi-V-grooved pulley 38 which is mounted on the right hand end of the wheel spindle (not shown).

A manually operable traverse mechanism is provided for traversing a work supporting table I I which comprises a manually operable traverse wheel 40. The traverse wheel 40 is rotatably mounted on a stud M which is fixed relative to the base II). A gear 42 is keyed to rotate with the hand wheel 40. The gear 42 meshes with a gear 43 which is rotatably mounted on a stud 44. The gear 43 meshes with a gear 45 which is rotatably supported by means of a ball bearing 46. The gear 45 is provided with an inwardly projecting sleeve which is provided at its inner end with clutch teeth 41. A rotatable shaft 48 is rotatably journalled within a bushing supported by the gear 45 and at its other end by means of a ball bearing 49. A slidably mounted clutch member 50 is slidably keyed with shaft 48 so that it may be moved into or out of engagement with the clutch teeth 41. A pivotally' mounted yoked lever 5I is mounted on the lower end of a rock shaft 52. The yoked arm 5| is provided with diametrically opposed studs which ride in a groove formed in the clutch member 50. An actuated lever 53 is fixedly mounted on the upper end of the rock shaft 52 by means of which the clutch member 50 may be actuated. The lever 53 is arranged to be automatically actuated in timed relation with the power traversing mechanism for the table in a manner to be hereinafter described.

The shaft 48 is provided at its inner end with a bevel gear 55 which meshes with a bevel gear 56. The bevel gear 56 is keyed to a rotatable shaft 51. A worm 58 is formed integral with the shaft 51 and meshes with a worm gear 59 which is keyed on a projecting hub of a gear 60 (Fig. 8). The gear 50 is keyed to a rotatable shaft 6| which is journalled in anti-friction bearings 62 and 63.

,The gear 60 meshes with a rack bar 64 which is fixedly mounted on the under side of the table I I.

A power operated mechanism is provided for reciprocating the work table for a traverse grinding operation. This mechanism preferably comprises a variable-speed reversible motor I0 (Figs. 4 and 10). The motor I0 is provided with an armature shaft "which is keyed within an integral hub of a gear I2 (Fig. 10). The gear I2 is supported by anti-friction bearings 13 and 14 which are in turn supported in a casing I5 which is fixed relative to the base Ill.

The gear 12 meshes with a gear I6 which is supported on a rotatable stud TI. The stud I1 is rotatably supported by anti-friction bearings 18 and III which are in turn supported by the casing 15., The gear I6 meshes with a gear which is mounted on the right hand end of a rotatable shaft 8|. The shaft BI is journalled in anti-friction bearings 82, 83 and 84 which are supported in a casing 85 which is fixed relative to the base Ill. The shaft BI is connected by means of a flexible coupling 86 with a shaft 81.

In a cylindrical grinding machine it is desirable to provide a speed control mechanism for the work table so that it may be traversed either at a desired range of relatively high speeds for a grinding operation or at a very slow speed for a grinding wheel truing operation. The electric motor 10 is a variable speed reversible motor which combined with the control mechanism to be hereinafter described may be adjusted to provide a wide range of speeds to the table II. In order to supplement the electrical speed changes for the table II, it may be desirable to provide a change gear mechanism whereby the speed of the table may be adjusted so as to provide either a fast or a slow reciprocating speed independent of the motor Ill.

In the preferred construction, a gear driving mechanism is provided between the shaft 8'! and the worm shaft 51. The shaft 81 is journalled in a ball bearing 88 at one end and in a bushing '88 -at its other end. The bushing 89 is'mounted teeth 99 which are arranged to be engaged by a slidably mounted clutch member I which is rotatably supported by an anti-friction bearing I 0|. The anti-friction bearing. IN is supported by a slidably mounted clutch casing I02. The clutch member I00 is slidably keyed to a sleeve I03 which isin turn keyed to the shaft 96. A gear I04 is formed integral with the sleeve I03 and meshes with a gear I05. The gear I is fixedly connected to the worm shaft 51 by means of a pin I05. Clutch teeth I01 are either formed integral with or fixedly mounted relative to the gear I05. A slidably mounted clutch member I08 is slidably keyed to a sleeve formed integral with the gear 32. The clutch member I08 is supported in a ball bearing I09 carried by the clutch casing I02.

It will be readily apparent from the foregoing disclosure that if the clutch member I08 is moved toward the left (Fig. into engagement with the clutch teeth I01 the shaft 81 will be connected directly to the worm shaft 51 and will drive the worm 58 at the same speed as the shaft 81 so as to transmit a relatively fast reciprocatory movement to the table. If it 'is desired to change the speed of the table II to a slow truing speed, the clutch casing I02 may be moved toward the right (Fig. 10) to move the clutch member I00 into engagement with the clutch teeth 89 so that the rotary motion of the shaft 81 will be transmitted through the gear 92, the gear 93, the gear I04 and the gear I05 to rotate the worm shaft-5l and the worm 58 at a relatively slow speed during a truing operation.

It is desirable to provide a readily accessible means for shifting the clutch casing I 02 to engage either of the clutches when desired. This mechanism may comprise a rotatable shaft IIO which is journalled in an aperture III which is fixed relative to the base I 0. The shaft H0 is provided at its left hand end (Fig. 9) with an eccentric stud I I2 which meets with and engages ahole formedin a slide block H3. The slide block II3-is slidably supported in a groove II4 formed in the clutch casing I02. operable control lever H5 is provided for rocking the shaft IIO to shift the clutch casing I02 as desired. The lever H5 is preferably pivotally supported on a dial shaped member I I6 by means of a stud III.

It is desirable to provide a yieldable connection between the control lever H5 and the shaft IIO to assist in throwing the clutch members into engagement in case the clutch teeth do not line up at the time the clutch casing I02 is shifted. This mechanism preferably comprises a collar II8 which is fixedly mounted on the right hand end of the shaft IIO (Fig. 9). The collar II 8 is provided with two spaced upwardly extending lugs II9. A downwardly extending lug I is fixedly supported relative to the dial H6 and extends within the space formed between the lugs II9. A circular or ring shaped spring I2I A manually engages opposite sides of the lugs H9 and the lug I20 (Fig. 14). It will be readily apparent from the foregoing disclosure that when the lever H5 is shifted in either direction to shift the clutch casing I02 into either a grinding or a truing position, the spring I2I will provide a yieldable connection in case the clutch teeth do not align each other with the mating clutch teeth so as the shaft rotates the clutch teeth into alignment, the releasedcompression of the spring I2I will throw the clutch casing I02 to engage the clutch member as desired.

v A grinding wheel feeding mechanism is proyided for feeding the grinding wheel 33 and its supporting wheel slide transversely toward and from the work piece I3. This mechanism is preferably arranged so that the grinding wheel may be fed manually, or may be fed continuously by means of a continuous reciprocated picker pawl for a plunge-cut grinding operation or be fed intermittently at the ends of the table stroke for a traverse grinding operation. A Wheel feeding mechanism has been illustrated comprising a rotatable feed screw I which meshes with a half nut I24 depending from the under side of the wheel slide 30. The feed screw I25 is provided with a reduced end portion I25 which is slidably keyed within an aperture I21 formed in a hollow end portion I28 of a rotatable shaft I29. The shaft I29 is rotatably supported in bearings I30 and I3I which are in turn fixedly supported relative to the base I0. A gear I32 is mounted on the right hand end of the shaft I29 .(Fig. 4). The gear I32 meshes with a small gear I33 which is arranged to rotate with a manually operable feed wheel I34. The feed wheel I34 is rotatably supported on the front of the machine base and is provided with a micrometer feed adjusting mechanism I 35 and a stop abutment I35. It will be readily apparent from the foregoing disclosure that by manually rotatingthe feed wheel I34 the screw I25 may be'ro tated in either direction to cause a forward or a rearward movement of the grinding wheel slide-30.

A power operated mechanism is provided for actuating'the feed wheel I34 comprising a gear or ratchet wheel I31 andv a feed picker pawl I38. The feed pawl I38 is pivotally supported by means of a stud I39 on a pivotally mounted arm I40. A power shaft MI is provided in the base of the machine. A crank plate I42 is .fixedly mounted on the front end of the shaft I4I. An adjustable crank pin I43 is adjustably supported byaT-slot formed in the crank plate I42. A connecting rod I45 is connected to the pin I43 at its lower end and by means of a stud I45 carried by the arm I40 at its upper end. The shaft MI is supported in bearings I and I5I which are fixedly mounted Within the base I0.

The power shaft 8| is provided with a spiral gear I52 which meshes with a spiral gear I53. The spiral gear I53 is rotatably supported on the shaft I4I. Clutch teeth I54 are either formed integral with or fixedly mounted relative to the spiral gear I53. A slidably mounted clutch member I55 is slidably keyed to the shaft I 4I. A compressionspring I56 normally serves to hold the clutch member I55 in engagement with the clutch teeth I54 so that a rotary motion of the shaft 8I will be transmitted through the spiral ears, I52 and I53 to rotate the shaft I4I continuously. Continuous rotation of the shaft I4I will impart a continuous revolving movement of the crank pin I43 which in turn transmits an oscillating movement to the feed pawl I38 to cause a continuous intermittent rotation of the feed wheel I34 to impart a continuous infeeding movement to the grinding wheel for a plungecut grinding operation.

In order to provide an intermittent feeding movement of the grinding wheel at the ends of table stroke, a suitable mechanism is provided for de-clutching the clutch member I55. This mechanism preferably comprises a cam I51 which is formed integral with'the clutch member I55. A slidably mounted cam follower I58 is slidably supported and is actuated by a rock arm I62 (Fig. 3). A tension spring I66 is connected to the other end of the rock arm I62 and is arranged normally to hold the follower I58 in operative engagement with the cam I51. A solenoid I6I (Figs. 3 and 4) is operatively connected to actuate the rock arm I62 and is arranged when energized to move the cam follower I58 upwardly (Fig. 3) against the tension of the spring I66. The released compression of the spring I56 moves clutch member I55 in to engagement with the clutch teeth I54 to rotate the shaft I4I continuously so as to impart a continuous reciprocatory movement to the feed pawl I38 for a plunge-cut grinding operation. In order to produce an infeeding movement at the ends of the table stroke, the solenoid I6I is operatively connected in a manner to be hereinafter described so that the solenoid I6I will be energized at the ends of the table stroked during reversal to produce an intermittent infeeding movement of the grinding wheel or a transverse grinding operation.

A manually operable start and stop lever I65 is fixedly mounted on the upper end of a vertical rock shaft I66. The lower end of the rock shaft I66 supports a projecting arm I61 which is connected by means of a stud I68 with a link I69. The other end of the link I69 is connected by a stud I16 with a rock arm I1I. The rock arm I1I is pivotally supported on a stud I12. The rock arm I1I is arranged when rocked to actuate a stop switch I13 and a start switch I14. When it is desired to start the machine, the start and stop lever I65 is rocked in a counterclockwise direction (Figs. 6 and 15) into broken line position I65a. This movement serves to rock the shaft I66 and the arm I61 in a counterclockwise direction (Fig. 15) which in turn serves to rock the arm I1I so as to close the start switch I14. The start switch I14 is operatively connected to start the table driving motor 16 in a manner to be hereinafter described.

When the machine is in motion and it is desired to stop the machine, the start and stop lever I65 is shifted from broken line position I65a. into full line position I65 which movement serves to rock the rock arm "I in the opposite direction so as to actuate the stop switch I13 and thereby to stop the table traverse motor 16.

It is desirable to provide a suitable interlock between the table manual traverse mechanism and the power traverse mechanism so that manually operable hand wheel 46 will be automatically rendered inoperative during a power traversing movement of the table II. This is preferably accomplished by providing an interlock between the start and stop lever I65 and the clutch 56 for controlling the manually operable traverse mechanism. The lever 53 (Fig. 15) is connected by meaneof a stud I11 with a slide rod I18. The slide rod is supported adjacent to other end in a bearing I19. A flanged collar I88 is fixedly mounted on the right hand end of the rod I18. A compression spring I8I surrounds the rod I18 and is interposed between the bearing I19 and the collar I66. The spring I8I normally serves to maintain the clutch 56 in engagament with the clutch teeth 41 to render the manually operable traverse wheel 46 operative.

In order to interlock the table feed clutch actuating mechanism with the clutch for controlling the manual traverse mechanism, the rock shaft I66 is provided with a rearwardly extending arm I82. A pivotally mounted latch arm I83 is pivotally supported on a stud I84. The arm I83 is provided with a notch I85 which is arranged to engage the flange collar I86 when it is desired to lock the manual traverse clutch 56 out of engagement. A tension spring I86 is provided'normally to maintain the latch arm I83 in engagement with the flanged collar I86.

In order to actuate the latch arm I83, the arm I82 is provided with a stud I81 which engages a cam surface I88 formed on the latch arm 183. In the position of the parts (Fig. 15), the stud I81 engaging the cam I68 serves to hold the latch arm I83 in an lnbperative position. When the start and stop lever I65 is moved in a counterclockwise direction into position I65a to start a grinding operation, the stud I81 rides down the cam face I86 and the released tension of the spring I86 rocks the latch arm I63 in a counterclockwise direction. At the same tine the arm I82 engages and moves the collar I86 together with the rod I18 toward the left (Fig. 15) so as to rock the arm 53 and the arm 5| in a counterclockwise direction and thereby to disengage the clutch member 56 so as to render a manually operable traverse wheel 46 inoperative during a power reciprocation of the work table II.

It is desirable to hold the latch member I83 in an inoperative position during a continuous picker infeed during a plunge-cut operation so that the table II can not be traversed. In order to accomplish this result, the control lever II5 is provided with a stud I9I having a downwardly projecting lug I96 which is arranged in the path of a collar I92. The collar I92 is mounted on the right hand end of a slide rod I93 (Fig. 9). A collar I94 is fixedly mounted on the left hand end of the rod I93 and is arranged in the path of a downwardly projecting stud I95 on the latch arm I83. The lever II5 is provided with an adjustably mounted stud I96 which is arranged in the path of a springpressed knob 256. The spring pressed knob 256 is operatively connected to actuate a normally open limit switch I91 when it is desired to provide a continuous picker infeed of the grinding wheel for a plunge-cut grinding operation.

When the control lever II5 is in a vertical position, it may be swung in a clockwise direction (Fig. 9) so that a detent I98 moves into engagement with a notch I99. A pair of notches I99a and I99b are provided to receive the detent I98 when the control lever II5 is swung to either a grinding or a truing position. A pair of stop pins 255 and 266 are provided (Figs. 5 and 22) to limit the rotary movement of the lever I I5 and dial I I6. During the swinging movement of the control lever II5 on the stud II1, the stud I96 moves the spring pressed switch actuating knob 256 toward the left to close the normally open limit switch I91. At the same time the downwardly projectits 75 ing lug I96 moves the slide rod I93 toward the right (Fig. 9) to move the collar I94 into engagement with the stud I05 and thereby to hold the latch member I03 in an inoperative position such .as that shown in Fig. 15 during aplunge-cut grinding operation.

A suitable reversingmechanism is provided for reversing the direction of the movement of the table II. This mechanism may comprise a manually operable reversing lever 200 which is piv otally supported by a horizontally projecting stud 20I which is carried by block 202. The block 202 is fixedly mounted on'the upper end of a vertically arrangedrock shaft 203. A compression spring 204 serves normally to hold the reversing lever 200 in the position illustrated in Fig. 18 with a stop screw 205 in engagement with the block 202. The reversing lever 200 is provided with an inwardly projecting lug 206 which is arranged in the path of a pair of table reversing dogs 201 and 206. The dogs 201 and 208 are adjustably supported by a T-slot formed in the front edge of the work table II.

An arm 2 I -is fixedly mounted to the lower end of the vertical rock shaft 203 and is connected by means of a stud 2 with one end of a link 2I2.

The other'end of the link 2I2 is connected by a stud 2 I3 with the actuating arm 2I4 of a reversing -switch 2I5. The reversing switch 2I5 is operatively connected through an electronic control mechanism to be hereinafter described to reverse the direction of and to control the speed of rotation of the table driving motor 10.

The reversing lever 2I0 is provided with an arrow pointed projection 2I6 which is arranged to engage an arrow pointed spring pressed actuating plunger 2I1 for actuating a normally open limit switch 2I8 during table reversal to energize the picker feed solenoid I6I so as to provide an instantaneous engagement of the feed clutch 50 to produce an infeeding movement of the grinding wheel 33 at the ends of the table stroke during a traverse grinding operation. The energization of solenoid I6I rocks the arm I62 to withdraw the cam follower I58 from engagement with the cam I51. The released compression of the spring I56 will throw clutch I55 into engagement with clutch teeth I54 instantaneously to rotate shaft I4I to impart a feeding movement to the grinding wheel 33. The upward movement of the follower I58 opens a normally closed limit switch I63 to deenergize the solenoid I6I and the released tension of the spring I60 returns the follower I58 into operative engagement with the cam I51 which thereafter disengages the clutch I55.

It is desirable to provide a safety device to prevent the table II from over running at the ends of its stroke. an electrically controlled mechanism comprising a pair of safety limit switches 220 and HI which are arranged to be actuated by a pivotally mounted lever 222 which is pivotally supported on a stud 223. The stud 223 is fixedly supported relative to the base I0. An adjustably mounted stud 224 projects from the upper end of the lever 222 and is arranged in the path of a cam face 225 on the dog 201 and a cam face 226 on a safety dog 221 (Fig. The lever 222 is provided with a switch actuating cam .228. The cam face 228 is arranged in the path of the actuating plungers of the limit switches 220 and 22 I. If the table II runs beyond its normal stroke, the cam face 225 or the cam face 226 will engage the stud 224 and rock the lever 222 to actuate either the switch 220 or the switch 22I which are operatively connected to stop the table driving motor. A

. 10 compression spring 229 is provided (Fig. 2) normally to hold the lever 222 in a central position.

In setting up the grinding machine and for certain grinding operations, it may be desirable to disconnect the picker feeding mechanism so that the wheel feed may be controlled manually or automatically as desired. As shown in Fig. 3, a selector switch 230 is provided which may be turned to an oil position so as to render the automatic picker feed inoperative. If an automatic picker feed is desired the selector switch 230 is turned to an on position which closes a circuit to pass current through a limit switch 231 (Fig. 3).

In a traverse grinding operation, it may be desirable to provide an adjustable period of dwell at the ends of the table stroke. This is preferably accomplished by means of a pair of adjustable instantaneous reset electric time delay relays 235 and 236. The timer 235 is operatively connected to control the dwell at the left hand end of the table stroke and the timer 236 is arranged to control the dwell at the right hand end of the table stroke. The time relays 235 and 236 are connected respectively to normally open limit switches 231 and 230 which are arranged to be automatically closed when the control lever I I5 is turned to a truing position so as to cut out table dwell during a grinding wheel truing operation.

The electric motor 10 is preferably controlled by any standard well known electronic control apparatus such as for example a Thy-Mo-Trol control apparatus manufactured by the General Electric Company.

Thy-Mo-Trol-Principle of operation constitutes a full-wave rectifier which converts This mechanism is preferably I to direct current, the alternating current supplied by an anode transformer 262. The direct current is then fed through the armature of the motor 10. Likewise, tube 263 and tube 264 make up a full-wave rectifier, which supplies direct current to the shunt field of the motor 10. By varying the outputs of these two rectifiers, it is possible to control the operation of the motor 10. Its speed can be varied from zero, by armaturevoltage control, up to maximum for which the motor 10 is designed to operate by field weakening.

Electronic control circuits The means by which the output of the power trol tubes 255, 266, 261, 268 and 269, whose basic circuit is shown in Fig. 24. Acting as amplifiers of current and voltage signals received from the motor circuit, these tubes supply the necessary direct current to the saturating winding of the saturable-core reactor in the resistance-reactance bridge which is used to vary the output voltage of the power rectifiers by the phase-shift method previously described. By varying the current in the saturating winding, the power tubes are turned on or off as required to give the desired motor performance.

To provide for the current-limit acceleration of the motor 10, a current transformer T6PI-- TyP2T6S is used. This has two primary windings T6PI. and T6P2 which are connected in the anode circuit of the two power tubes supplying current to the motor armature. The design is such that an alternating current voltage is produced in the secondary T6S, proportional to the current flowing through the thyratron tubes.

The alternating current voltage is rectified and connected into the circuit in such a way that when it reaches a value as determined by the setting of a potentiometer, it will have the effect of turning off the armature tubes, thus reducing the voltage on the armature and maintaining the current at a fixed maximum value.

If the control had been set to operate the motor 10 in the field-weakening range, the currentlimit control acting through a suitable tube will maintain full field until the armature current starts to reduce. Thus, during acceleration under these conditions the motor will always accelerate from zero to base speed with full field. At this point, the field will be weakened gradually until the motor reaches the preset field weakened speed. Then the armature current will drop to the value necessary to drive the load.

The adjustment of the speed is controlled by two adjustable potentiometers-one controls armature voltage, the other controls field voltage. The potentiometers are operated from a single shaft and are arranged so that approximately half of the rotation of the adjusting knob will vary the armature voltage from approximately zero to maximum. Then the other potentiometer becomes effective, and further turning will tend to reduce the field voltage so that the motor speed can be increased to the value desired, up to the maximum for which the particular motor is designed to operate by field weakening.

To maintain the preset speed, it is necessary to hold armature counter-E. M. F. constant. This can be done by increasing the armature terminal voltage by an amount equal to the IR drop of the armature circuit. In this system, this is accomplished through the use of the same current transformer that controls the current limit. The circuit functions in such manner that as armature current increases, the thyratrons in the armature circuit areturned on, thus increasing the armature voltage. If the load increases, the circuit operates to increase the armature voltage proportionally, which thus acts to maintain the speed at its preset level. An adjustable potentiometer used in the circuit makes it possible to maintain es entially constant speed from no load to full load for any given speed setting, or to provide a drooping speed characteristic where desirable.

When the start and stop lever I I is shifted to actuate the starter switch I14. the motor will be accelerated rap d y and smoothly by current limit as described above until it reached a speed corresponding to the setting of the speed-adjusting potentiometer. The motor 10 will then maintain this speed closely, irrespective of variations in load, within the limits of the IR-drop-compensation feature. When the stop button H3 is pressed, the anode contactor will be dropped out and a resistor will be connected across the armature to bring the motor 10 to a quick stop as full field. is applied. The substitution of a magnetic-reversing switch for the anode contactor makes it possible to reverse quickly the direction of rotation by current-limit regeneration of the motor 10.

This control apparatus is interconnected with the switches above described and the control apparatus to be hereinafter described. An adjustable potentiometer 24lis provided for controlling the speed of the motor 10 during a grinding operation, An adjustable potentiometer 242 is similarly provided independently to control the speed of the table I so as to provide a very slow traversing movement thereof during a grinding wheel truing operation. A transfer switch 243 is provided which is interconnected with the potentiometers 24! and 242. The transfer switch 243 is normally held in a position to render the potentiometer 24| operative. The transfer switch 243 is operatively connected to be actuated by the control lever H5 so that when the control lever H5 is shifted to'a grinding wheel truing position a cam 241 on the inside of the dial H6 actuates the transfer switch 243 so as to render potentiometer 242 operative to change from a grinding speed of the table II to a truing speed thereof. It should be readily apparent from the foregoing disclosure that the grinding speed of the table H may be regulated independently of the truing speed and by means of the transfer switch 243 the machine may be readily shifted from a grinding to a truing speed without disturbing the independent grinding and truing speed control devices.

It may be desirable in setting up the machine to jog the table I l toward the right or toward the left that is to move the table by short increments to position a work piece I8 relative to the grinding wheel 33. This movement is preferably ob-' tained by a jog switch 244 which is operatively connected in the electrical circuit to permit a jogging movement of the table toward the right. A jogging switch.245 is provided for facilitating a jogging movement of the table toward the left.

The dial H6 which is actuated by the control lever H5 is provided with a cam 24! which is arranged in the path of a plurality of spring pressed plungers 248, 249, 250, 25I and 252. These spring pressed plungers are arranged respectively to actuate the limit switches 23!, 243, I91, 231 and .238 when the control lever H5 is moved in a counterclockwise direction (Fig. 5) to shift from a grinding to a truing position. When the control lever H5 is shifted toa truing position, the cam 24! serves to open the normally closed limit switch 23! to render the picker feeding mechanism inoperative, to shift the double throw transfer switch 243 so as to render the potentiometer 24l inoperative and to render the tl'llng potentiometer 242 operative, closes normally open limit switch I91 to energize the picker feed solenoid l6l, closes normally open limit switches 231 and 238 to render the electric time dwell relays 235 and 238 in operative during a grinding wheel truing operation. It ill be readily apparent that these cam actuated limit switches serve as interlocks to prevent table dwell during a wheel truing operation, to prevent a continuous picker feed during truing and automatically to shift the table speed from a grinding to a truing speed through the potentiometers 2M and 242. At the same time the lever H5 is shifted, the slidably mounted clutch member I02 is shifted longitudinally to move the clutch member I00 into engagement with the clutch teeth 99 so as to automatically throw in the gears 92, 93, I04 and I05 thereby to shift the mechanical drive mechanism from a high speed to a low speed during a grinding wheel truing operation, Similarly when the control lever I I5 is shifted from a truing to a grinding position the cam 241 is moved out of engagement with the spring pressed plungers 248, 249, 250, 25f and 252 to allow the switches to resume their former positions during a plunge-cut or a traverse grinding operation.

When the control lever I I5 is in a vertical posi-- tion such as shown in Fig. 5 the parts are set for auaaea the'wheel drive motor 94 is started by pressing the push button starter switch 39. The work drive motor I9 is then started by actuating the push button starter switch 20. With the control lever H5 in a central position (Fig. 1) a plungecut grinding operation may be obtained by rocking the control lever H5 toward the operator,.

that is, in a clockwise direction (Fig. 9) to actuate the switch I91 and thereby to start a continuous reciprocation of the feed pawl I 38 to provide a continuous intermittent picker feed to grind the work piece I8 to the desired and predetermined extent.

If it is desired to set the machine up for a traverse grinding operation the table dogs 201 and 208 are adjusted to give the desired reciprocatory stroke of the table II. The control lever H5 may be then rotated in a clockwise direction into a grindin position to move the clutch member I08 into engagement with the clutch teeth I01 so as to reciprocate the table at a relatively high speed for a traverse grinding operation. The start and stop lever I65 is then shifted toward the right (Fig. 1) to start the table drive motor 10. The s eed of table I I may be precisely regulated by ad ustrnent of the potentiometer 2. An adjustable dwell may be obtained at either or both ends of the table stroke comprising electric timers 235 and 23" which may be adjusted to produce a dwell of a desired "and predetermined extent.

When it is desired to true the grinding wheel, the control lever H5 is rocked in a counterclockwise direction into a truing position so that the clutch member I engages the clutch teeth 99 so as to traverse the table II' at a rela ively slow truin speed which may be precisely adjusted and controlled by the potentiometer 242. Movement of the control lever I I to a truing position serves to automatically actuate the table double throw transfer switch 243 so that the speed control of the motor I0 is shifted from potentiometer 2 to 242. Movement of the control lever H5 into a truing position also serves to actuate the limit switches 23! and 238 to cut out the electric timers 235 and 236 thus eliminating table dwell at the ends of the stroke during a grinding wheel truing operation.

After the control lever H5 has been set' in either a grinding or a truing position, the table may be set in motion by shifting the start and stop control lever I65. The start and stop lever I65 serves to actuate the starter switch I'll to start the rotation of the work driving motor III.

The selector switch 230 permits the operator to render the power infeeding mechanism inoperative to facilitate a manual feeding of the grinding wheel if desired. When the selector switch 230 is in an on position the power infeeding mechanism is rendered operative and a continuous plunge-cut feed or an intermittent traverse feed may be obtained as desired.

Table jogging switches of the push button type are provided, push button switch 2 serving to log the table II toward the right and push button switch 245 serving to jog the table toward the left.

The jogging button 24 is provided to facilitate jogging the work drive motor I9 if desired in a setting up operation. A reversing switch- 23 is provided whereby the work drive motor I9'may be readily reversed to reverse the direction of rotation of the head stock when desired. The speed control or potentiometer knob 22 is provided for precisely adjusting and regulating the speed of the head stock motor I9 so as to produce the desired speed of the work piece I8 during a grinding operation.

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.

I claim:

1. In a grinding machine having a base, a transversely movable wheel slide, means rotatably to support a grinding wheel on said slide, a longitudinally reciprocable table, a reciprocating mechanism therefor including a variable speed reversible electric motor. driving connections between said motor and table, an electronic control apparatus to control said motor so as to produce either a relatively highspeed reciprocation of the table for a gr nding operation or a relatively slow speed for a truing operation, table actuated means to reverse said motor, a control lever for said driving connections. independent manually operable electrical control means operatively connected with said control apparatus to adjust and regulate the speed of said motor for a gr nding and for a truing speed, and independent means actuated by and in t med relation with v said control lever to render either of said speed ad u ting means operative.

2. In a grinding machine having a base. a transversely movable wheel slide. means rota ably to support a gr nding whee on said slide. a longitudinally reciprocable table, a reciprocating mechanism therefor including a variable speed reversible electric motor, driving connections between said motor and tab e. table actuated means to reverse said motor. said motor and driving connect ons being arranged to produce ether a relatively high speed reciprocation of the table for a grinding operation or a relatively slow speed for a truin ope-ration, a control lever for said driving connections, independent manually operable means independently to adjust and regulate the speed of sa d motor for a grinding and independent manually operable means independently to adjust and regulate the speed of the motor for a truing speed. and independent means actuated by and in timed relation with said control lever to render either of said speed adjusting means operative.

3. In a grinding machine having a base, a transversely movable wheel slide, means rotatably to support a grinding wheel on said slide, a longitudinally reciprocable table, a reciprocatin mechanism therefor including a variable speed reversible electric motor, means including a reversing lever to reverse said motor, driving connections between said motor and table, said motor timed relation with said control lever to render one-or the other of said speed control means operative.

4. In a grinding machine having a base, a transversely movable wheel slide, means rotatably to support a grinding wheel on said slide, a longitudinally reciprocable work table, a reciprocating mechanism therefor including a variable-speed reversible electric motor, a multi-speed change gear mechanism connecting said motor with said table which is arranged to produce either a relatively high speed reciprocation of the table for a grinding operation or a relatively slow speed reciprocation of the table for a truing operation, means including adjustable dogs on said table for reversing said motor, a control lever to actuate said change gear mechanism, a pair of independent manually operable rheostats independently to adjust and regulate the speed of said motor for a grinding and independently to adjust and regulate the speed of said motor for a truing speed, and independent means actuated by and in timed relation with said control lever to render one or the other of said speed control means operative when said lever is shifted to a grinding or a truing position.

5. In a grinding machine having a base, a transversely movable wheel slide thereon, means rotatably to support a grinding wheel on said slide, a longitudinally reciprocable Work table, a reciprocating mechanism therefor including a variable-speed reversible electric motor, a multispeed change gear mechanism including a pair of clutches to connect said motor with said table, one, of said clutches being arranged to produce a relatively high speed reciprocation of the table for a grinding operation and the other clutch being arranged to produce a relatively slow speed reciprocation of the table for a truing operation, means including adjustable dogs on said table for reversing said motor, a control lever to actuate both of said clutches, a pair of independent manually adjustable electric speed control means independently to adjust and regulate the speed of said motor for agrinding and independently to adjust and regulate the speed of said motor for a truing speed, and means including a switch which is actuated by and in timed relation with said control lever to render one or the other of said speed control means operative when said lever is shifted to a grinding or to a truing position.

6. In a grinding machine having a base, a transversely movable wheel slide thereon, means rotatably to support a grinding wheel on said slide, a longitudinallyreciprocable table, a reciprocating mechanism therefor including a variable-speed reversible electric motor, a twospeed change gear mechanism including a pair of clutches connecting said motor with said table, one of said clutches being arranged to produce a relatively high speed reciprocation of the table for a grinding operation and the other clutch being arranged to produce a relatively slow speed reciprocation of the table for a truing operation, table actuated means for reversing said motor, a control lever to actuate both of said clutches, a pair of independent manually adjustable electric speed control means independently to adjust and regulate the speed of said motor for a grinding and independently to adjust and regulate the speed of said motor for a truing speed, and means including a transfer switch which is actuated by and in timed relation with said control lever to render one or the other of said speed control means-operative when said lever is shifted to a grinding or a truing position.

7. In a grinding machine having a base, a transversely movable wheel slide thereon, means rotatable to support a grinding wheel on said slide, a longitudinal-1y reciprocable work table, a reciprocating mechanism therefor including a variable-speed reversible electric motor, a twospeed change gear mechanism including a pair of clutches connecting said motor with said table, one of said clutches being arranged to produce a relatively high speed reciprocation of the table for a grinding operation and the other clutch being arranged to produce a relatively slow speed reciprocation of the table for a truing operation, means including adjustable table dogs and a switch to reverse said motor, a manually operable control lever to actuate both of said clutches, a pair of independent manually adjustable rheostats independently to adjust and regulate the speed of said motor, one rheostat serving to adjust the speed of the motor for a grinding operation and the other rheostat serving to adjust the speed of the motor for a truing speed, and means including a transfer switch which is actuated by and in timed relation with said control lever to render one or the other of said rheostats operative when said lever is shifted to a grinding or a truing position.

8. In a grinding machine as claimed in claim 1, the combination with the parts and features therein specified, of means including an independent electrical time delay relay to cause an adjustable dwell during reversal of the table drive motor so as to produce a table dwell at either or both ends of the reciprocatory stroke of said table, a pair of independent limit switches to render said relays inoperative, and means actuated by and in, timed relation with said. control lever to actuate said limit switches when the control lever is shifted to a truing position so as automatically to cut-out table dwell during a grinding wheel truing operation.

9. In a grinding machine having a base, a transversely movable grinding wheel slide, means rotatably to support a grinding wheel on said slide, a longitudinally reciprocable Work table, means including a table actuated reversing lever to reciprocate said table, means to feed said slide, a pawl and ratchet mechanism to actuate said feeding means, means including a normally engaged clutch continuously to actuate said pawl, a normally inoperative cam and a follower intermittently to disengage said clutch to provide a plunge-cut feeding movement of the slide, yieldable means normally to maintain said follower engaged with said cam, an electric solenoid to shift said follower out of operative engagement with said cam, and a limit switch actuated by and in timed relation with said table reversing lever to energize said solenoid and thereby shift said follower out of operative engagement with said cam to produce an intermittent infeeding and a reversing lever to reciprocate said table,

means including a nut .and screw mechanism to feed said slide, a pawl and ratchet mechanism to feed said slide, a pawl and ratchet mechanism to rotate said screw, means including a normally engaged clutch continuously to actuate said pawl,

. a normally inoperative cam and a follower intermittently to disengage said clutch to provide a continuous intermittent plunge-cut feeding movement of said slide, yieldable means normally to maintain said follower engaged with said cam, an electrical solenoid toshift said follower out of engagement with said cam, and a limit switch actuated by movement of said table reversing lever to energize said soleniod and thereby to shift said follower out of'operative engagement with said cam to provide an intermittent feeding movement of the grinding wheel during reversal for a traverse grinding operation.

11. In a grinding machine having a base, a transversely movable wheel slide thereon, means rotatabl to support a grinding wheel on said slide, a longitudinally reciprocable table, means including adjustable dogs on said table, and a reversing lever to reciprocate said table, means including a nut and screwmechanism to feed said slide, a pawl and ratchet mechanism to rotate said screw, a plunge-cut feeding mechanism including a normally engaged clutch continuously to actuate said pawl, a normally inoperative cam and a follower intermittently to engage said clutch to provide a continuous intermittent plunge-cut feed of said slide, yieldable means normally to maintain said follower engaged with said cam, an electrical solenoid to shift said follower out of engagement with said cam, and a traverse-grinding feeding mechanism including a limit switch actuated by movement of the table assaaas Number Name Date '1 2,011,068 Miner et al. Aug. 13,, 1935 2,021,061 Huxford et al. Nov. 12, 1935 2,131,107 Krause Sept. 2'7, 1938 2,165,898 Mathewson et a1. July 11, 1939 2,262,721 Fiygare et al. Nov. 11, 1941 2,281,930 Fiygare et al. y 5, 1942 2,419,940 Balsiger et a1. May 6, 1947 reversing lever to energize said solenoid and thereby to shift said follower out of operative engagement with said cam to provide an intermittent movement of the grinding wheel during reversal at the ends of the table stroke for a traverse grinding operation.

12. In a grinding. machine having a base, a transversely movable wheel slide thereon, means rotatably to support a grinding wheel on said slide, ailongitudinally reciprocable table, means including a nut and screw mechanism to feed said slide, a pawl and ratchet mechanism to rotate said screw, a plunge-cut feeding mechanism including a normally engaged clutch continuously to actuate said pawl, a normally operative cam and a follower intermittently to engage and disengage said clutch to provide a continuous intermittent plunge-cut feed of said slide, yieldable means normally to maintain said follower engaged with said cam, an'electrical solenoid to shift said follower out of engagement with said cam, a traverse grinding feeding mechanism including a limit switch actuated by movement of the table reversing lever to energize said solenoid r and thereby to shift said follower out of operative engagement with said cam to provide an intermittent movement of the grinding wheel during reversal for a traverse grinding operation, and means including a selector switch to render either said plunge-cut of said traverse grindingfeed operative.

HERBERT A. SILVEN.

REFERENCES CITED The following references are of record in the file of this patent: 1

UNITED STATES PATENTS

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