Patent GB-393959-A (GB)
Title: Improvements in or relating to multiple spindle lathes and like machine tools
IPC: B23B9/10
Filed: 1931-12-08
Abstract: 393,959. Multi-spindle lathes. POTTER, W. W., Newport Avenue, Pawtucket, Rhode Island, U.S.A. Dec. 8, 1931, No. 34074. Convention date, June 4. [Class 83 (iii).] A multi-spindle lathe or like machine tool has an indexable work turret 54 connected to a tubular support 89 on which is slidably mounted a tool slide 93, the slide being reciprocated by a rod extending through the tubular support and connected to the slide in such a way as to permit rotation of the support independently of the slide. The main frame is provided with three spaced aligned housings, viz., a work turret housing 51, gear housing 52, and a tailstock housing 53. The work turret is fitted with an endplate 55 and is bored to receive six work spindles 56. As each spindle approaches the loading station it is automatically disengaged from its drive and braked, and on leaving the loading station the brake is released and the driving clutch re-engaged. Each spindle carries a gear 57 engaged by a gear 58 mounted loosely on a shaft 59 and having teeth coacting with teeth on a fixed clutch part 60. The spindle 59 carries a member 61 having a series of outwardlypressed pins 62, Fig. 4, coacting with an internal cone 65 forming part of the gear 58. When the pinion is moved to the right, Fig. 4, into clutching position the pins engage frictionally with the cone so as to speed up the pinion 58 to facilitate engagement of the clutch teeth. When the pinion 58 is in its left hand (unclutched) position its cone engages a stationary cone 70 thus braking the spindle to prevent rotation. All the shafts 59 are driven from a central pinion 67 driven through change gearing, Fig. 12, from an independent electric motor 122. Each spindle clutch is operated by a yoke member 71, connected, with lost motion, to a rod 72 having a pin 73 engaging a cam track 74 secured to the housing 52. As the work turret indexes to bring any spindle to the loading station, the cam causes the spindle clutch to be disengaged and when the turret is again indexed the spindle clutch is re-engaged. In order to allow a spindle clutch to be manipulated by hand at the loading station, the cam track 74 is formed partly in a rod 80 normally held back by a spring 81 but operable from a hand-lever to allow a spring 75 to engage a spindle clutch at the loading station when required. The work turret has secured thereto the hardened steel tube 89 supported at its outer end in the housing 53. For indexing the work turret the plate 55 is fitted with Geneva slots 94, Fig. 10, coacting with a roll 95 on a crank disc 96 which is driven through worm-gearing 100 and coupling 102 from a separate electric motor 99. The indexing crank-disc 96 is provided with a cam 103 which is arranged to oscillate a shaft 106 connected through toggle links to a linearly-movable wedge 110, Fig. 8. Movement of the wedge forces a pair of spaced spring-pins 112 into contact with steel discs 115 fixed to the work turret to lock the turret firmly in position. When the wedge member is withdrawn the turret is supported for the indexing movement on rollers 116 which are eccentrically mounted and are brought into turret-supporting position by a spring 120. Central sliding tool slide 93 is slidably mounted on the central stem 89 and supported against rotation by means of an extension 136 enclosing a stationary guide bar 137. The tool slide has six holes 140 in alignment with the spindle axes and six faces for the fixing of various tools. Stop screws 142 fixed in the rear housing 53 are fitted with adjustable collars 143 to limit the forward movement of the tool slide. The tool slide is reciprocated by a central bar 145. A ring 147 rotatable in the slide 93 is fitted with bushes carrying pins 149 which project through slots in the stem 89 into a groove in a thimble 146 threaded on the bar 145. Adjustment of the thimble is effected by means of a gear 153 rotated by a hand-operated pinion 154. A stud 160 carries a roller 159 engaging a fixed horizontal guideway 161 to prevent rotation of the bar 145, and the stud 160 also carries a roller engaging a cam drum 170 by which the tool slide is reciprocated. The cam drum is driven by worm gearing 175, 189 driven from a shaft 190, Fig. 13, connected through gearing to an independent electric motor 205 for the high speed idle movements of the cam drum. For the slow working movements, the shaft 193 geared to the cam drum is driven from the spindledriving gear 67 through the change gear train shown in Fig. 12 and worm gear 200. An overrunning clutch 201 and friction clutch 202 are embodied in this mechanism so that when the motor 205 is energized, the high speed drive may overrun the low speed drive. The clutch 202 is disengaged automatically when the main tool slide reaches its rearmost position by a dog on the cam drum acting through lever-mechanism. The clutch 202 may also be operated from a hand-lever. A number of cross slides, Fig. 7, may be provided, mounted on bases 208 or 209 which may receive one or two slides respectively. Each cross slide 210 is provided with an adjustable block carrying a stud fitted with a roller engaging a groove in a cam 213. A stop screw 215 engages the block when it is in its forward position and a cover 216 is provided to exclude dirt. The cam 213 is driven from worm gearing 229 through a clutch which enables the timing of the slides to be altered. All the cross-slide operating worms 229 are driven from a central bull gear 226 through gears 226, 228, the bull gear being driven from shaft 193 through worm gearing 237, Fig. 12, and pinion 239. The cams 171, 213 thus operated from the shaft 193 are geared to rotate at the same speed and each completes one revolution in a working cycle. Where rotary tools are required in the central tool slide they are mounted in the holes 140 in longitudinally movable sleeves 240. The sleeves carry rotatable spindles 241 having a passage-way 243 leading to a fluid-tight chamber connected to a pipe 246 so that cooling fluid may be directed to the tools. The rear of the spindle 241 is castellated and engages a driving sleeve 249 carrying a gear 250 driven by gearing from an independent electric motor. Change gear may be incorporated in this driving mechanism. Each work-spindle may carry a chuck 356 operated by a spindle 357, having a rear clutch face 358. As each spindle indexes to the loading position the shaft 357 is brought into alignment with a motor 359 which drives a clutch part 361 coacting with the teeth 358. The clutch teeth are forced into mesh by a spring 367 when the index crank disc 96 is stationary and the chuck may then be operated by a switch controlling the motor 359. During indexing the clutch is held withdrawn by a cam 363. The electric motors driving the various elements of the machine have interlocked controls to ensure correct sequential operation. The electrical circuits are described in detail in the Specification. In Fig., 17, in which the motors are not shown, a starting push button 281 associated with holding switch 287 energizes the solenoid 282 of the spindle motor contactor, thus starting the spindle drive. If switch 290 is closed, the solenoid 291 for the high speed drill motor is also energized. The slide motor operates a drum carrying a dog 299 actuating switch plunger 298 and the index motor similarly actuates through a dog 307 a switch plunger 319. The automatic cycle is initiated by the operator through a push button 310. This starts the indexing motor, with the tool slide withdrawn and causes dog 307 to leave the plunger 319, thus opening switch 326 to prevent current flowing to the slide motor and while indexing is being effected. At the end of one revolution of the index disc 96, switch 325 is opened to de-energize the coil 314 and stop the index motor. A circuit is then completed through switches 349, 352, coil 317 and switch 326, thus exciting coil 317 and starting the motor for the slide forward movement which continues until a dog on drum 170 depresses a switch 305, thus stopping the slide motor while the drum with the slide is slowly advanced by the above described gearing from the spindle until another dog closes switch 304 to start the slide motor. The slide drum then continues to revolve until the slide reaches its rearmost position, whereupon dog 299 operates plunger 298, thus again stopping the slide motor and starting the indexing motor for a fresh cycle. During the feed cycle above described, the operator chucks a fresh piece of work in the spindle at the loading station. For hand operation, a switch 307a, Fig. 17, is thrown over so as to connect the main 278 with the line 278b, and disconnect the automatic circuit. The index motor is then manually controlled by a push button 311. When this switch is depressed the circuits through the buttons 312, 313 are broken. The switch 312 is operated to complete a circuit through coil 317 for forward movement of the slide feed motor while switch 313 completes a circuit through coil 321 operating the reverse switch of the slide motor.