Patent GB-636043-A (GB)
Title: Improvements in and relating to turret lathes and like machine tools
IPC: B23B7/12
Filed: 1947-05-12
Abstract: 636,043. Turret lathes. WARNER & SWASEY CO. May 12, 1947, No. 12806. Convention date, June 6, 1946. [Class 83 (iii)] [Also in Group XXXVII] A turret lathe or like machine-tool comprising a support, a slide carrying a turret which is indexed as the slide reaches its rearmost position, an electrical control circuit, a work-spindle drive, a support - carried, normally-open, automaticallyactuated, start-and-stop switch, co-operating means on said slide and support for actuating said switch, a slide - carried normally - closed start- and-stop switch in series with the first-mentioned switch, actuating means for the second switch including an indexible element provided with a number of switchactuating members corresponding in number to the operation steps of the work-cycle and presettable to an active or inactive position, and operating connections between said turret and said element for indexing the latter in correlation with the turret, is characterized in that a manually-actuated switch is provided in series with said first and second switches in a start and stop portion of said control circuit. The turret lathe to which the invention relates is similar to that described in Specification 603,286, employing a reversible high and low speed electric motor 40 for driving the spindle 39, Fig. 29, with means for controlling the speeds, direction of rotation, and starting and stopping of the motor for each step of a work-cycle and this means can be pre-set and then actuated in part by the indexing of the turret 52, Fig. 2, and in part by the movements of the turret slide 51. The turret lathe of the present invention also employs a toothed back gear drive 44-47, Fig. 29, operated by a dog clutch 48 controlled by solenoids 114, 115 thus giving an automatic choice of four spindle speeds. The spindle is also provided with an adjustable camring 208, switch means LS8 and solenoid brake 207 for automatically stopping the spindle in a predetermined position as described in Specification 622,209. The turret 52, Fig. 6, carried by the rack-and-pinion manually-operated slide 51 is indexed automatically by movement to the maximum rearward position of the slide and is locked and clamped by mechanism not described. Bevel gearing 56, 57, connects the turret through shaft 58 to a stop rod drum 60 which has a gear 98 at one end engaging gears 99-102 on indexible elements or drums in the manner described in Specification 603,286. Stop rods 64 carried by the drum 60 are adjustable to contact in the operative location a member 65 carried in the bed 50 on a slidable rod 66. A compression spring 69 returns the rod when released by the stop member. The rod 66 operates a transverse stop-rod 73 to move button 79 of a switch LS3 for reversing the spindle drive motor. This switch is carried in a pivoted block 77 and may be arranged to operate "early" or "late" according to whether a manually settable finger 85 is engaged with a notch 80 or 81, respectively, in the lever. " Early " operation is used when threading with " solid " taps or dies whereas " late " operation is used when self-opening or collapsible die-heads or taps are employed and there is no danger of the turret slide feeding towards the spindle due to coasting of the drive motor prior to reversal. The box 76, Fig. 2, for the switch LS3 carries at one side a further switch-box 87 having a switch LS5 Fig. 4, which is momentarily depressed when an actuating member 89 secured to the turret slide passes over it on rearward movement of the slide for indexing the turret. A still further switch LS11 is provided in this box which is only operated when a member 96 is turned up at right angles to the necked spring-returned plunger 93. The switch is then actuated by the edge of the plate which secures member 89 to the slide. This switch is only employed when one face of the turret above is used and the turret is not required to index. The switch is opened to stop the motor 40 so that the workpiece may be changed and the turret slide is prevented by the member 96 from moving sufficiently rearwardly to index the turret. The indexible elements or drums at the rear of the turret slide are housed in a casing 63, Figs. 7 and 8, with a hinged access cover 63A. Each drum is provided with settable switch-actuating tappets 109 adapted to be moved as required into projected positions to actuate switches provided on a fixed part of the casing, the number of tappets on each drum being equal to the number of turret faces provided. The drums in the lowermost and L.H. position, Fig. 7, are similar and the tappet members thereon may operate switches LS10 and LS4 respectively. The former controls the solenoids operating the back gear clutch while the latter controls the " high " and " low " speed of the driving motor. The drum 105 in the top position, Fig. 7, operates switches LS2 and LS7, in the reversing part of the control circuit. An intermediate tappet is provided for these two switches and is so arranged that either one switch LS2 may be operated or both switches may be operated together. The R.H. drum 106 controls switch LS6 located in the start and stop circuit and spring-held shoes are provided on the tappets for this drum so that when turned with their longitudinal axes in a chordal direction the switch may be held open throughout an indexing operation. A manually-settable switch LS9, Fig. 7, is provided on the housing 63 which when set to " ON " position gives a high-speed reverse from a low-speed forward drive while when in the " Off position gives a low-speed reverse from a low-speed forward spindle drive. A control panel 145, Fig. 17, is provided on the machine headstock with switch control members 202, 203, 204 and a fourposition control lever 146, the latter may be pulled towards the operator to reverse the motor drive and is returned to normal position by spring pressure. The lever positions from right to left give " high speed," " low speed," " brake release " and " off while control 202 has three positions, " hand," " safe stop setup" and "auto." Control 203 is for automatic spindle positioning and has " on " and " off " settings. Control 204 is for the toothed back gear and has " low " and " high " positions. Operation. For entirely manual operation of the machine the tappets on the indexible drums 103-106 are all turned to their inoperative positions. The control 202 is turned to " hand " and with the turret slide completely retracted the spindle is brought into loading position by moving control 203 to the " on " position, control circuit is thus conditioned to release brake and give a slow non-working rotation to spindle until high point of cam ring 208, Fig. 29, operates switch LS8 to apply brake and cut the current to the motor 40. The work is loaded and control lever 146 moved to " high ". Turret slide is brought forward by hand wheel and actuating member 89 momentarily closes switch LS5 to establish a holding circuit and start up the high-speed rotation of motor in forward direction (back gear may be in " high " or " low " speed position). Assuming the second operation after indexing turret requires low motor speed, control lever 146 is moved to " low ". If a third operation is required at slightly higher speed then control 204 may be turned to " high " position and solenoid 114 is energized to engage gears H5, 47. If reversal is required, for example at the end of a tapping operation lever 146 is pulled outwardly and spindle reverses, the turret slide being backed-off the work by the hand wheel. High or low speed reversal is determined by the setting of switch LS9 as described above. On automatic operation the tappets on the indexible drums 103- 106 are turned as required to project into the path of the stationary switches to give the sequence of operations required and the turret slide is moved backwards and forwards by the hand wheel for the feed movements and indexing of the turret, the machine spindle automatically changing speed and reversing according to the operation performed. Electrical connections. The wires 236, 237, 238, Fig. 31, of a multi-phase circuit from a supply source extend through a main disconnect switch DS1-3 and the outside wires 240, 241 are led to the primary of a transformer T, Fig. 32, the secondary of which energizes the control circuit. Wires 242, 243 extend from the primary of the transformer T to a circuit including brake solenoid B switches MS7 and other contacts and relays. Main supply wires are further led to : (a) auto-transformer ATF ; (b) forward motor contactor 256 ; (c) reverse direction contactor 267; (d) low-speed contactor 272 ; (e) high-speed contactor 279 ; (f) contactors CRI-3 and back to autotransformer and finally to spindle drive motor 40 having low-speed windings T1, T2, T3 and high-speed windings T4, T5, T6. When the contacts of the high-speed contactor are closed the low-speed windings are in an endless circuit. The forward and reverse contactors and the low and high-speed contactors are mechanically interlocked to prevent more than one pair being actuated at a time. The motor operates at high speed in forward or reverse direction by reversing polarity of the power circuit but may operate at low speed in the forward direction only. A slow non-working speed for spindle positioning prior to stopping in a predetermined position is obtained by reduced voltage current from the auto-transformer ATF. A plugging switch PLS, Fig. 29, is provided for the drive motor 40 which may automatically energize it in the reverse direction to plug the forward coasting rotation prior to stopping. Specifications 603,286 and 622,209 are referred to.