GB517659A - Improvements relating to guard or fence mechanisms for hydraulic presses - Google Patents

Abstract

517,659. Guards for hydraulic presses. UDAL, J. D. Aug. 10, 1938, No. 23563. [Class 69 (ii)] [Also in Group XXIV] A guard mechanism for a hydraulically operated press with a vertically movable ram, comprises the combination of a guard that can be raised or lowered, a catch lever or. levers associated with the guard, and an abutment or abutments mounted on the ram, the catch lever or levers being adapted to co-operate with the abutment or abutments to prevent accidental movement of the ram, and to be moved to an unobstructive position by movement of the guard to its operative position, the abutment or abutments being adapted by co-operation with the catch lever or levers to prevent movement of the guard excepting when the ram is in its inactive position. The bed a supports the lower tool carrying platen b and vertical posts c which support the hydraulic cylinder d with press ram e and upper tool-carrying platen f sliding on the posts c. Liquid can flow from a replenishing chamber g past a valve h to the cylinder d. The guard m slides on a pair of rods j and has a balance weight n. A lever r is pivoted to the press frame at t and is connected by a link s to the guard. A bell-crank catch lever u is pivoted at v to the press frame and is connected by a link w to the lever r. The other arm x of the lever is shaped as a hook adapted to pass beneath an abutment y on the ram to prevent accidental downward movement thereof. With the parts in the positions shown, to start the press, the guard m is pulled down and this removes the hooked end x from the path of the abutment y. While the ram is in motion, this hooked end bears against the abutment y to prevent the guard from being raised. As a further precaution against accidental movement of the ram, the pre-filler valve h may be held open until the lower end of the abutment y has been moved past the upper edge of the hook x. For this purpose, the valve is connected by a rod 2 to a lever 3 pivoted at 4 and having at one end an actuating rod 5. The other end is connected by a rod 6 to a bell-crank lever 7 one arm of which carries a roller 9 adapted to bear against a cam 10 on the ram which serves to keep the valve h open until the lower end of the abutment y has moved past the upper edge of the hook x and it will be held there without any building-up of pressure in cylinder d, if the guard m has been inadvertently left in the ,upper position. Alternatively, a relief valve on the pipe supplying pressure to the cylinder d may be connected to the guard mechanism in such manner as to be open until the guard is in its operative position.