Abstract: A vacuum die casting system has three die casting machines connected to a single vacuum system, all of which is controlled by a programmable logic controller. The controller allows any two of the machines to be operatively connected to the vacuum system so that the casting operation of those two machines are performed under vacuum. The controller comprises six address relays, a sixteen channel input card, a processor, a sixteen channel output card, an interface and two high speed counter cards. The result is an efficient, reliable, and economical vacuum die casting system.

Abstract: A vacuum valve control system for a vacuum die casting machine that controls the opening and closing of a vacuum valve. The system comprises an input device for entering certain values, a detecting device for determining the position and speed of an injection plunger, a processor to calculate when the injection plunger has reached particular values for position and speed and a control device for opening and closing the vacuum valve when the particular values have been reached. The processor includes two counting devices, one to calculate the position of the injection plunger and one to calculate the speed of the plunger. The control device includes solid state relays which energize a solenoid to open the vacuum valve when the plunger has reached a certain position. The solid state relays also deenergize the solenoid to close the vacuum valve when either another particular position of the plunger has been reached or when the plunger is approaching a certain speed.