GB885262A - Improvements in or relating to automatic friction drop hammers - Google Patents

Abstract

885,262. Drop hammers. MASSEY Ltd., B. & S., WELLS, L. W., and MIDDLETON, B. March 29, 1960, No. 10997/60. Class 83 (4). An automatic friction drop hammer whose holdup gear comprisesa band brake and whose lifter mechanism includes a band-type friction clutch released by a spring and actuated by a pull cord 14, Fig. 8, wrapping around a revolving shaft, both being controlled pneumatically by a foot threadle 16, Fig. 1, to give one or a succession of light or heavy blows dependent upon the lift of the tup, has its pull cord passing through a tubular guide 39 on an air cylinder 36 and actuated by a piston-rod 38 projecting out of the air cylinder by means of a finger 41 engaging an adjustable stop 40 on the cord, and adjustable stop means 75, 83 are provided to positively arrest the downward movement of the pistonrod thereby to release the pull on the cord and hence determine the lift of the tup. The hammeris similar to that described in Specification 842,169, wherein the foot threadle 16 upon being moved to the short stroke position S, operates a pilot valve 18 controlling a relay valve 31 which energizes air cylinder 28 to release the hold-up brake. The tup thus falls and near the end of its downstroke a trip block 60 driven by a chain 61 to reproduce the movement of the tup, actuates a pick-up valve 63 which acts through a distributing valve 92, short stroke flow-control valve 95 and relay valve 87 to allow air above piston 37 in cylinder 36. The flow control valve 95 restricts air flow on short stroke working to ensure the down stroke of the tup is completed. Thus pistonrod 38 moves downwardly to actuate the pull cord 14, Fig. 8, and is arrested upon engaging the short stroke stop 76. Air is released instantly from above the piston 37 which rises due to constant air pressure below it, thereby releasing the tup ; the upstroke of the piston 37 is cushioned by piston 99 in chamber 98, as described in Specification 885,219. When long strokes are required, the threadle 16 is depressed to position L, whereby the short stroke stop 76 is withdrawn by air motor 45 and linkage 78, 79, Fig. 8. The downstroke of piston-rod 38 is then arrested by long stroke stop 83 and a long stroke flowcontrol valve 96 delays the release of air above piston 37 and thus delays release of the pull cord. Both of the stops 75, 83 are adjustable independently along guide rods 69 after releasing clamping handles 74, 85. A rotary valve 97, Fig. 1, selects automatic or manual operation of the hammer. Specifications 813,045 and 842,877 also are referred to.