| 摘要 |
799,306. Chucks. BUTTERWORTH BRITISH AUTOMATIC MACHINE TOOL CO., Ltd. July 23, 1956 [July 27, 1955], No. 21650/55. Class 83 (3). Chuck-operating mechanism for a fluidpressure jaw or collet-chuck comprises a piston 16, 17, displaceable axially of the chuckspindle 11 within a non-rotatable cylinder 18 surrounding the spindle, the piston acting on a thrust-bearing 32 to displace a chuck-operating member 13 rotating with the spindle. As applied to closing a bevel-closing collet 12 which is opened by its own resilience when the closing-force on the draw-spindle 13 is released, the bearing 32 is constructed to transmit thrust only in the required direction. The annular piston, in two parts 16, 17 clamped on the outer race 32a of the bearing as by screws 36, acts on the member 13 through a sleeve 15 bearing against a collar 14 secured to the spindle 13, the piston being prevented by a peg 19 from rotating in the cylinder, while the sleeve 15 rotates with, and is movable axially along, the hollow-spindle 11. The path of the reaction to the clamping-force passes through the cylinder-head 20, a thrust-bearing 21 engaged by the head 20, the inner-race 22b of a roller-bearing 22, a sleeve 23 and a nut 24 into the spindle, without passing through the main spindle-bearings in the headstock 26. Springs 35, between the cylinder-head 20 and the piston, assist the fluid-pressure in closing the collet, and a non-return valve and a pressure-control valve are provided in the oil-supply circuit, (not shown), to the collet-closing port B in the cylinder, which is attached to the headstock 26 by screws 38, a cover 27 excluding dust. An annular member 31, fixed to the shoulder 14 by a screw, carries a spring-pressed key 30 lodged in a keyway 29a in a feed-tube 29 for keeping the spring-finger 28 on the tube in correct angular relationship to the collet. The finger is withdrawn from the collet, by means not described, during a maching operation on the work, which is advanced through the spindle up to a stop when a valve (not shown), open the port B to admit fluid-pressure, and connects a port A, on the opposite side of the piston, to exhaust. In a modification, without a feedtube, Fig. 2, the piston has an increased length of stroke and an enlarged rear-face to facilitate opening of the collet or, as shown, the jawchuck 44, by means of the fluid-pressure admitted behind the piston through the port A. Screws secure the sleeve 15, moved by the piston, to the collar 14 of the draw-spindle 13. The Provisional Specification refers also to the use of a solid draw-spindle. |
