GB787985A - Machinery guard - Google Patents

Abstract

787,985. Machinery guards. BURY FELT MANUFACTURING CO., Ltd., and JEN. NINGS, F. May 2, 1955 [Feb. 2, 1954], No. 3026/54. Class 80 (4). A guard, particularly for a press or a felt guillotine, is associated with both an electrical and a mechanical interlock with the machine drive. As shown, a counterweight-opened guard 18 for an electric motor-driven guillotine knife 13 comprises sliding shutters 18b, 18c which are moved along guides 19 from an overlapping open position beneath a fixed shutter 18a to the closed position shown by a pair of arms 22 on a shaft 21 linked to a treadle 24. The electrical interlock comprises a limit switch 37 which is engaged by the arm 22 as the guard is closed and which releases a normally-engaged powerful auxiliary machine brake, while the mechanical interlock comprises a cam 26 on the guard-actuating shaft 21 coacting with an arm 16a on a hand starting lever 16 which operates the main brake and clutch. The cam 26 ensures that the lever 16 cannot be moved to start the machine until the guard is closed and that the guard cannot be opened until the lever is in the " off " position. A second cam 27 on the shaft 21 has a peripheral cut-out which co-operates with a roller on a bell-crank 30 adjustably linked to a clamp 36 which holds the felt while it is being cut and is moved simultaneously with the guard. In the guard-open position of shaft 21 the roller enters the cut-out in the cam 27 and the clamp 36 is raised by spring means. The cam 27 and its associated linkage may be duplicated at the other side of the machine. In a modification employing the same inter-locking devices the guard itself comprises a first shutter 55, Fig. 4, having an opening which may be covered by a second shutter 57 slidable thereon, the shutter 55 being swing- ably and slidably supported by rollers 59 in fixed guides. The two shutters are moved from the full-line open position to the chain-line closed position by an arm 63 on a shaft corresponding to the shaft 21 in Fig. 2, the arm 63 being secured to a link 62 one end of which is pivoted to the shutter 55 while the other end is linked to the shutter 57. A cable 53 carries counterweights for the shutters. It is stated that the guard may be in the form of a single pivoted shutter.