Apparatus for controlling the volume and pressure of a pressure medium in a die-casting machine

Claim 1

Apparatus for controlling the volume and pressure of a flow of hydraulic fluid from a supply to a drive of a die-casting machine comprising: an inlet line, an outlet line, volume flow limiting means between the inlet and outlet lines, pressure control means connected to the outlet line, the volume flow limiting means including a plurality of diaphragms of fixed area arranged in parallelism, a respective one-way valve and a respective actuating valve backing each diaphragm of the volume flow limiting means, the actuating valves being selectively operable for opening any selected number of one-way valves under the pressure of fluid in the inlet line and for allowing flow through a corresponding selected number of diaphragms, a cascaded plurality of spring-loaded valves each opening at a specific pressure, the pressure control means including a connecting line between the outlet line and the first of the spring-loaded valves, a pressure actuating valve in parallel with each of the spring-loaded valves, with selective operation of the pressure actuating valves being effective to cause a selected number of the spring-loaded valves to be series connected for causing the prevail of any one of a range of pressures in the connecting line and in the outlet line, and a pressure-biased relief valve having its biasing pressure taken from the connecting line and being responsive to the pressure in the inlet line for relieving that pressure upon rising above the biasing pressure.