Mechanical press overload protection system

摘要

The mechanical press head has its crankshaft connected to several pistons (5), which operate in hydraulic cylinders (7). An upward force (Fv) can be exerted on each piston by the pressure of hydraulic fluid from a pump (10), driven by a motor (M). The space in each cylinder below the piston is connected to a pressure overload valve (15) which has a stepped piston (16). The smaller piston dia. (17) is acted on by the pressure in the hydraulic cylinder (1,2), with the larger piston dia. (18) connected directly to the pump. On an unequal load on the press ram, the pressure in the corresp. cylinder is increased and acts on the smaller dia. The valve is open, when the pressure on the underside of the piston exceeds the pressure on its upper side by a given ratio.