GB1437948A - Machine guards - Google Patents

Abstract

1437948 machinery guards AHM MACHINES Ltd 1 Aug 1973 [12 Aug 1972] 37697/72 Heading F2J A vertically, or horizontally (not shown) movable machine guard comprises a number (three as shown) of relatively movable overlying frames 7, 8, 9 slidably mounted on guide rails 5 and each frame carrying a meshed guard panel 16, 17, 18 each of which corresponds to about one third of the machine (not shown) access area to be opened and closed, the arrangement being such that the frames 16, 17, 18 may be pneumatically moved at 21 along the guide rails 5 between the upper and lower positions of Figs. 3 and 4, respectively in which the guard panels 16, 17, 18 are nested together, so that the machine access area is open, or the guard panels 16, 17, 18 extend adjacent one another to provide a continuous shutter completely closing the machine access area. The pneumatic cylinder 21 is coupled to an interlock system so that actuation of the guard is controlled in conjunction with the cycle or sequence of machine operation. As shown, in the event of failure in the pneumatic supply the machine guard automatically returns to the closed lowered position. The machine guard further includes a safety leading edge (Figs. 6, 7 and 8, not shown) comprising a strip (26) mounted by bolt-slot connections (27) on the innermost frame 7 for relative movement thereto on contact with an obstruction, the upper edge of the strip (26) engaging a roller arm (28) for actuating a microswitch in the machine control circuit to prevent further lowering of the guard and, if required, to raise the guard. The pneumatic operation of the guard may be replaced by a counterweight system manually operated, or by an electrical system.