Patent GB-798858-A (GB)
Title: Improvements in or relating to power operated chucks for lathes
IPC: B23B31/16
Filed: 1956-01-17
Abstract: 798,858. Chucks; lathe details. GIDDINGS & LEWIS MACHINE TOOL CO. Jan. 17, 1956 [Aug. 2, 1955], No. 1556/56. Class 83 (3). [Also in Group XXXVII] A power-operated lathe chuck comprises a number of jaw slides 54 movable radially by a motor 75 driving through an electromagnetic clutch 90. As applied to a vertical turret lathe, the chuck is secured by bolts 52 to a sub-table 26 which is rotated by a bevel-ring gear 42 and a pinion 41 driven by an electric motor 40 through a clutch (not shown). The slides 54 are each connected by a screw-threaded shaft 55 to an operating-tube 56 slidable in the face plate 50 of the chuck by rotation of a screw 60 having a bevel pinion 62 meshing with a bevel ring gear 64. One or more shafts 70 with end sockets 70a carry bevel gears meshing with the ring gear 64, and manual adjustment of all the slides simultaneously is effected by turning any of the shafts 70 through its key socket 70a. Manual adjustment of an individual slide is effected by rotating the appropriate shaft 55, which has threads of opposite hand on its ends and a key socket 55a, rotation of the tube 56 being prevented by the engagement of a pin 59 in a projection at the end of the tube. The power drive for the slides is conveyed to one of the shafts 70 through a bevel gear 121 on the shaft, a cooperating bevel gear 115 on a pin 118 supported by a yoke 119 in the face plate, and a lostmotion impact coupling 116 provided by cooperating spaced impact teeth on the gear 115 and on a spur gear 110 mounted on a hollow shaft 112 secured by a bolt to the sub-table 26, and which receives the end of the pin 118 when the face-plate is positioned. The impact coupling affords a positive drive between the gears 110, 115 to release the jaws after the motor 75 has been reversed, and upon the lost-motion between the impact teeth being taken up. A further gear 105, meshing with the gear 110, is driven by a ring gear 99 secured to a sleeve 98 within the table-spindle 27 and supporting at its lower end the upper element 90b of the electromagnetic friction clutch 90 by a ring 95, towards which the element 90b is pressed by springs 96 surrounding pins 94 on the element 90b. The lower element 90a of the clutch is driven by the tubular extension 86a of a worm wheel 86 meshing with a worm driven by the motor 75. Transverse keyways 54b in the slides 54 receive keys on the jaws 41. Electrical control. The electric control circuit is so arranged that a time-delay relay, energized when the table-rotating motor and clutch are operative, opens contacts in series with ganged switches controlling the reversible jaw-slide motor 75 and clutch 90, thus preventing operation of the two motors simultaneously. Upon de-energization of the relay, the time delay defers closing of the contacts for a predetermined interval while the table rotates under its own inertia. The current to the coil 90d of the jaw clutch 90, and hence the slipping torque of the clutch and gripping pressure of the chuck-jaws, is controlled by a variable resistance. Chuck mounting. The sub-table is supported on a mounting 30 by bearings 32, 34, of which bearing 34 is pre-tensioned by a collar 36 and a shim 38 positioned by bolts 35. Catching cuttings &c. A housing for the shaft of the motor 75 passes through a trough 80 arranged to catch tool coolant.