Patent GB-613483-A (GB)
Title: Improvements in and relating to speed control for electric motors
IPC: G05B19/04
Filed: 1946-06-12
Abstract: 613,483. Lathes. MONARCH MACHINE TOOL CO. June 12, 1946, No. 17652. Convention date, Jan. 23. [Class 83 (iii)] [Also in Group XXXVII] A turret lathe comprises a bed 10 upon which is mounted a headstock mechanism 12, a turret 18 being mounted on a turret slide in a turret slide bed 22. A cross slide 24 is provided for cutting-off operations and the like. A spindle 26 may be driven by an electric motor 38 through an adjustable transmission 30. A feed rod 40 is driven from the spindle or from the transmission 30, this rod passing through an apron 42 connected with the slide bed 22. A generator 44 is driven by a motor 46 and supplies the motor 38. A control system is provided, [see Group XXXVII], for varying the speed of the motor 38 between wide limits by adjusting the generator and motor field excitation, the spindle and feed rod speeds being likewise varied for varying the cutting speed and feed of the tools. A shaft 48 is keyed to the turret, (see Fig. 4), is journalled in the turret slide on bearings 50, and is connected with a gear 52 and ratchet wheel 54. The gear 52 meshes with a gear 56 which drives one of a pair of mitre gears 58, the other of which is connected to a rod 60 carrying a tail rod 62 which supports a number of cams. The ratchet wheel 54 is adapted to engage an arm (Fig. 5, not shown), when the turret slide is retracted to index the turret into its next operative position. The turret 18 comprises a number of recesses that receive locking bushings 66 adapted to be engaged by a reciprocable locking pin so that the turret is accurately positioned. During the retraction of the slide the locking pin releases the turret which is locked in the fully retracted position. The turret slide is reciprocated in the bed 22 by a rack 72, Fig. 3, carried on the slide and a pinion mounted on a shaft operable by a handwheel 78 through a clutch 80, 82. The clutch member 82 may be driven from the feed rod 40, the clutch being engaged by movement of a lever 90 and being disengaged by means of a spring. A panel at the rear of the machine carries a switch 186 which may be normally operated to select a desired speed for the motor 38. This panel also mounts the operating members of resistors for controlling the motor speed, forward and reverse switches, and a number of lamps for indicating the exact position of the cycle in which the machine is operating. In a modification (Fig. 17, not shown) the switch 186 is adapted to be actuated by a cam carried on the turret slide, When the turret is fully retracted the switch is moved to another operative position in which it automatically selects the next feed speed. A limit switch (Fig. 18, not shown) may be engaged by a cam when the turret slide has moved a pre-determined distance into the work so that a tool may be retracted at a given speed by reversing the driving motor, or the speed in the original direction may be modified if so desired. The spindle and feed rod may be driven by separate motors each provided with a separate generator, the two generators being driven by a common motor.