Vacuum die casting machine

In a vacuum die casting machine including matching die assemblies relatively movable between open and closed positions and defining a die cavity when in their closed position, a plunger for injecting molten metal into said cavity and having a reciprocating cycle that includes an initial injection stroke, with a final molten metal injection movement and a retraction stroke, means associated with one of said die assemblies for evacuating atmosphere from said cavity during operation of said plunger and valve means in said one die assembly and movable linearly between open and closed positions for interrupting the evacuation of atmosphere from said cavity, the improvement which comprises:

• fluid cylinder operated actuating means removably mounted on said one die assembly and having a piston adapted for linear travel, and in alignment with said valve means;
• removably mounted coupling means operatively connecting said piston to said valve means;
• electrically operated means for controlling said fluid cylinder means;
• first electrical switch means operable by said plunger for actuating said means for controlling said fluid cylinder means for initiating closing movement of said valve means at a desired time during injection of molten metal;
• timing means actuated by said plunger for initiating a predetermined time interval;
• second electrical switch means operatively associated with said coupling means for initiating said final molten metal injection movement of said plunger when said valve means is closed;
• and
• third electrical switch means actuated by said timing means at the end of said time interval for actuating said electrically operated control means to cause retraction of said plunger in the event said valve means does not close completely to actuate said second electrical switch means before expiration of said time interval.