Apparatus for regulating the speed of and the pressure of fluid upon the ram in the injection assembly of an injection molding machine

摘要

An injection molding machine wherein the ram in the injection cylinder can be moved at several speeds and can be subjected to different fluid pressures by an apparatus having a two-way valve whose inlet is connectable to one or more pumps by way of discrete check valves and whose outlet is connected with a chamber of the injection cylinder by a conduit containing an electrically adjustable pressure relief valve. The valve member of the two-way valve is movable between a first position in which it completely seals the inlet from the outlet and several second positions in which it acts as a flow regulating means to permit the fluid to flow from the inlet to the outlet at a selected rate. The valve member is movable by a solenoid-operated pilot valve which cooperates with a stop extending into the path of movement of the valve member and being movable axially by a reversible motor which is controlled by the programming system of the injection molding machine. The programming system adjusts the pressure relief valve, moves the valve member of the pilot valve and selects the number of pumps which deliver fluid to the inlet of the two-way valve.