GB1270654A - Improvement relating to brakes in or for power presses and the like machines - Google Patents

Abstract

1,270,654. Brakes; dashpots. BROUGHTON ENG. Ltd. 21 April, 1969 [19 April, 1968], No. 18610/68. Headings F2E and F2S. An hydraulic brake which prevents overshoot of the driving crank of a press comes into operation on over-travel of the crank beyond its normal stopping position (usually top deadcentre) and incorporates means for compensating for fall in retardation with fall in crank-shaft velocity. By this means the crank is brought completely to rest within 30 degrees over-shoot. The crank-shaft 13 of the press is coupled on over-shoot to a damper piston 12 moving in an hydraulic cylinder 11 by means of a catch 14 on the crank-shaft and having a cut-out portion 14a leaving radial shoulders 14b. A plate 17 rotating about the shaft, carries a pivoted latch 15 which is linked to a mechanical guard on the work-table of the press. In the " safe " position of the guard, the latch 15 is in the dotted position 15a in which it is free of the catch 14, but when the guard is open, the latch 15 is in the operative position shown in full lines so that it may engage a shoulder 14b to rotate the plate 17 in a clockwise direction about the crankshaft to operate the damper rod 12. This damper may be as shown in Fig. 2 in which liquid is forced through spring-loaded valve 124. This movement moves piston 130 which in turn moves a further piston 131 against constant air pressure supplied at 133. A resilient buffer 134 may complete the braking. An outlet 149 may be provided to energize an hydraulic brake acting on the fly-wheel or other rotary element of the press (Fig. 9, not shown). In an alternative form of damper, Fig. 3, a piston 212a closes successive outlets 241a-241g to progressively increase the braking effort. A floating annular piston 242 takes up the fluid displaced. An outlet 249 may be provided to feed the fly-wheel brake as already described.