GB678653A - Driver for lathes - Google Patents

Abstract

678,653. Chucks. FISCHER AKT.-GES., G. March 28, 1951 [April 1, 1950], No. 7204/51. Class 83 (iii). A lathe driver comprises at least two clamping jaws 25 which are pivotally mounted on a floating ring 11 and engage pins 15 on a ring 8 keyed to the conical end of the machine spindle 1, the clamping jaws being brought into engagement with the work by rotating the floating ring in the opposite direction to the driver's rotation; at least two further jaws 27 are also pivoted on the floating ring and are brought into engagement with the work by rotating an outer retaining ring 16, which has pins 21 engaging the jaws 27, and clamping it in position. When the machine spindle is braked, the inertia of the work causes the jaws 27 to grip more firmly so that the work is still gripped if the clamping jaws 25 are lifted under centrifugal force and the inertia of the work. The floating ring 11 is supported on three leaf-springs 22 and is prevented from moving axially by guide-plates 12 engaging a peripheral groove 14 in the ring. The clamping surfaces of the jaws are in the shape of logarithmic spirals and are knurled or serrated. To grip work between the driver and the tailstock, a clamping-screw 19 engaging a groove 9 on the ring 8 is released and an outer casing 29 secured by screws 31 and a reinforcing ring 30 to the pivot pins 24 is rotated in the direction opposite to the direction of rotation. The jaws 25 are thus rotated about the pins 15 until they engage the work, two projections 32 on the floating ring engaging lugs 17 on the outer retaining ring 16 and carrying the latter round with them. The outer ring 16 is then rotated further in the direction opposite to the direction of rotation, causing the other jaws 27 to pivot about the pins 23 until they engage the work, and the ring 16 is clamped in position by the screw 19. To prevent the floating ring 11 from being rotated too far with respect to the fixed ring 8, so that the pins 15 would be able to come out of the slots 26 in the jaws, a pin 35 on the ring can engage with two stop pins on the fixed ring 8.