GB523599A - Improvements in guards for presses - Google Patents

Abstract

523,599. Machinery guards. HYDRAULIC ENGINEERING CO., Ltd., and ELLINGTON, N. B. Dec. 6, 1938, No. 35588. [Class 80 (iv)] [Also in Group XXIX] Hydraulic presses, more particularly of the down-stroke type, are provided with a guard panel a having a counterweight so that it may be moved up and down. When in the down or safety position it is locked by turning a handle c integral with a shaft connected by a link d to an arm h engaging a valve control cam i on a shaft i<1> carrying the cams i<2> controlling the valves i' of the press. A spring- urged stop e is depressed by a lug e<1> when the guard is down, thus permitting the handle c to lock the guard. The stop e may be replaced by a long downward projection from the guard frame. One or more props f are connected by linkage g to the locking handle shaft in such a manner that the props cannot be moved inwards under the ram, i.e., the guard cannot, when in its service position, be unlocked, unless the ram is in its upper position and, on the other hand, the props are in the withdrawn position to allow the ram to descend only when the guard has been locked. As a further safeguard not only must the ram be in its upper position before the guard can be unlocked, but it must be connected to exhaust. This is effected by the linkage d, h and cam i the latter being so shaped that the locking lever can only be turned when the cam is in a position in which the ram is connected to exhaust. In a modification, the guard panel is hinged, and attached to the hinge is a cam working in conjunction with an annularly recessed cylindrical prop movable with the ram. In a further modification, Fig. 5, the guard a is locked by a catch k engaging a bar l the catch being on a rod m rotatable by a handle n. A prop o on the rod m is moved under the platen p when the guard is unlocked, the prop also forming an obstruction to prevent the guard from being unlocked unless the platen is up. The rod m also carries a notched plate m<1> which engages a second notched plate m<2> rigid with the valve spindle q. The respective notches are so arranged that (1) the valve spindle can only turn when the guard is locked and (2) the rod m can only turn when the valve spindle is in the position corresponding to the ram being open to exhaust. The bar l attached to the guard prevents the rod m from being turned unless the guard is in the closed position.