Patent GB-637273-A (GB)
Title: Improvements in turret lathes and like machine tools
IPC: B23B7/12
Filed: 1948-01-05
Abstract: 637,273. Automatic turret lathes. POTTER & JOHNSTON MACHINE CO. Jan. 5, 1948, No. 337. Convention date, Oct. 9, 1947. [Class 83 (iii)] An automatic turret lathe comprises a tool-carrying slide 23, with fast and slow feed motion drives and clutches, and means acting alternately to engage, disengage and place the clutches in neutral position, which means includes a fluid-actuated plunger 452, Fig. 12, biassed to engage the feed clutch, a detent device 464 biassed to hold the plunger when moved to fast motion or neutral positions, and control means selectively to actuate the detent device according to the clutch position desired. The lathe spindle 21, Figs. 1 and 4, is rotated by an electric motor M driving through a four-speed clutch system selected by clutch cones 43, 44, change-gears 53, 54 and a sliding- gear 57, 57a, operated manually by a yoke 57c, rack 57d and shaft 57f. The latter gears rotate a shaft 60 driving a sleeve 62 in which the spindle is splined and which is formed with teeth 68. These teeth 68 mesh with a gear 69 to provide the feed for the turret- and cross-slides 23, 25, 26. The gear 69 drives, through shafts 72, 74, change-gears 101, 103, 105 and 102, 104, 106, any pair of which may be selected by clutch cones 91, 92, 93, to drive a shaft 77 through a cluster gear 88-90. Alternatively, the shaft 77 is rotated by'a fast motion, continuously-rotating, electric motor 100 driving through gears 98, 99, 95 and selected by a clutch-cone 96 which automatically disengages the feed drive. The clutch-cone may also assume a neutral position to cut off the drive to the shaft 77. The shaft 77 drives a worm 148 and a worm-wheel 151 mounted coaxially with a disc-cam 135 which controls all slide-movements, the turret-slide 23 being moved by a pin 147 engaging a slot 135a therein. The shaft 77 also drives a dog-drum 121 carrying dogs 122 which selectively actuate electric switches B-L. These switches may also be hand-operated by levers b-l accessible from the side of the headstock. The switches operate pneumatic valves B<SP>1</SP>-L<SP>1</SP>, on a pressure-line 439, to control air-operated pistons. Switches B-E control double-acting pistons 417, 418, to move clutch-cones 43, 44 by means of lever-yokes whose movements are finely adjusted by screwed stops abutting arms projecting from the levers. Switches J-L control single-acting pistons 428-430 to move clutch-cones 91-93. The cylinders are pivotally mounted to allow for operating movements of the pistons which are connected by bell-crank levers to the clutch-operating yokes. As one clutch is engaged the clutch previously engaged is automatically disengaged by a system of interlocking levers 436, 437, 438. Switches F and H control the clutch cone 96 via the plunger mechanism P and a yoke carried on a lever 459 which is moved by the piston 452. The piston 452 is normally biassed into feed position by a spring 458, Fig. 12, in which position the solenoid H<SP>1</SP> is energized to withdraw the detent rod 464 to allow a groove 467 to open the pressure line 439 to atmosphere and so render the fast-motion ineffective should the lever f be manually raised at that time or the valve F<SP>1</SP> be slow to exhaust its outlet line. When the turret slide is in feed motion and a feed-stop switch G, Figs. 4 and 12, is actuated, the piston 452 moves the clutch to its neutral position. If the slide is in fast motion, actuation of the switch G moves upwards the piston 452 which, in its movement, actuates switches 469, 470 through bell-crank levers. These switches condition the electrical circuit so that the piston completes its upward movement, momentarily engages the feed clutch to slow up the slide and then moves the clutch-cone 96 to neutral. In neutral and fast-motion positions the plunger 452 is held against upward movement by the latch 464 engaging shoulders 455, 454 on the plunger. Should the airpressure fall below that necessary to actuate the clutches a switch 440, Fig. 4, is actuated to stop both motors. The motor M is stopped quickly by a plugging switch M<SP>1</SP>. For setting- up purposes, a switch I stops the spindle motor M but allows the slide to be moved by the fastmotion motor 100. To cut off all power to the slides a switch A is actuated manually to stop both motors M and 100 and condition the circuit so that only the motor M is started when the start or jog-buttons 485, 489, Fig. 1, are pressed, thus providing a safety measure when hand-cranking. The whole machine is stopped at any time by pressing a stop-button 488. Overload relays are incorporated in the two motor circuits. The cross-slides are controlled by a selector S, Fig. 7, which is rotated by a pin 240 on the cam 135 engaging slots 239. The selector engages or disengages a projection 230 in or from a slot r in each slide push-rod 205. This is more fully described in Specification 630,068. Specification 588,610 also is referred to. Interlocking hand and power feeds.-In order to engage a tool on the squared end 118a of a shaft 118, Figs. 1 and 4, for hand-cranking, a lever 129 must be raised, which lever actuates the switch A described above. Spindle mounting.-The spindle 21, Fig. 4, is journalled in a sleeve 64, which is adjustable axially by a manually operated rack-andpinion, and is slidingly splined to the driving sleeve 62. Rack-and-pinion tool feed.-Slide-tools, if any, on the turret faces are operated by an actuator T, Fig. 7, which moves a notched member to feed the tool. The actuator T is controlled by a pin 410, Fig. 9, which is mounted on the underside of the cam 135 and which abuts a spring- held member 407 on a rod 400 formed with rack-teeth which mesh with an elongated pinion 404, Fig. 7, engaging rack teeth on the actuator T. The tool is withdrawn by a pin 413, also on the underside of the cam 135, which turns a bell-crank lever 414. Mechanism, not described, may be fitted to enable a turret face to be skipped. Horizontal turret-rotating and locking.-The turret 165, Fig. 7, is unlocked by a plate-cam 182 which is attached to the disc-cam 135 and contacts a roller 183, on an arm 184 pivoted to the slide 23, to withdraw a locking wedgebolt 175 from between a wedge-shaped block 163 on the slide and a wedge-shaped groove 178 in the turret base. The turret is then indexed by a pin 180 on the cam 135 engaging slots 176 in the turret base, one complete revolution of the cam occurring for each turret position. The turret is relocked by a spring 190 which is anchored to the slide and is connected to the wedge-bolt by a bell-crank 196 and link 195, the bell-crank being pivoted to a toggle 196a to produce a snap action. Lubricating machines.-A pin 344, Fig. 7, on the selector S rotates a lubricating pump 346 once during each revolution. Cooling tools and work.-A coolant pump, driven by an electric motor in the machine circuit, is provided.