MACHINE PRESS

摘要

The hydraulic drive system of a machine press comprises at least two independent hydraulic drive units. In each of said hydraulic drive units at least one hydraulic cylinder, which is connected via valves and a main pressure line under supply pressure to a pump driven by a motor, raises and lowers the upper tool carrier. The rotational speed of the motor is adjustable via the numeric machine control, in which a rotational speed profile defined across the work cycle is stored. Furthermore, a pressure-limiting unit limiting the level of the supply pressure is provided, which at least during a part of the work cycle limits the supply pressure to the lower pressure of a pressure profile defined across the work cycle and stored in the numeric machine control and the actual load pressure increased by an extra amount at the at least one hydraulic cylinder.