Vacuum casting method and vacuum casting apparatus

A vacuum casting apparatus comprising:

• (a) a mold support chamber having an upper opening and a bottom opening, and being hermetically fitted to a cover at said upper opening by a sealing means;
• b) a mold having a runner and a mold cavity communicating with said runner, said mold being disposed in said mold-support chamber so that the lower open end of said runner is positioned below said bottom opening;
• (c) a preferential suction zone formed in the vicinity of the top of said mold cavity;
• (d) a suction head slidably mounted through said cover, and placed in said upper opening of said mold support chamber so that the lower open end of said suction head completely covers said preferential suction zone and sealingly fits the outer upper surface of said mold;
• (e) a pressing means for continuously and constantly pressing, in cooperation with said suction head, said mold toward the inner bottom surface of said mold support chamber;
• and
• (f) a vacuum means communicating with said suction head, for evacuating said mold to fill said mold cavity with said molten metal while pressing said mold toward the inner bottom surface of said mold support chamber.

A vacuum casting method comprising the steps of:

• (a) disposing a mold having a runner and a mold cavity communicating with said runner through a plurality of filling passages in a mold support chamber having an upper opening and a bottom opening so that the lower open end of said runner is positioned below said bottom opening;
• (b) forming a preferential suction zone in the vicinity of the top of said mold cavity;
• (c) placing a suction head in said upper opening of said mold support chamber so that the lower open end of said suction head completely covers said preferential suction zone and sealingly fits the outer upper surface of said mold while continuously applying a constant downward pressure to said mold by pushing said suction head downwardly with a pressing means which is cooperatively attached to said suction head;
• and
• (d) evacuating said mold through said preferential suction zone while pressing said mold toward the inner bottom surface of said mold support chamber by applying a downward pressure from said pressing means and a downward pressure which results from a difference between a pressure in said mold and a pressure in said mold support chamber surrounding said mold, thereby filling said mold cavity with a molten metal through said runner.

A vacuum casting apparatus comprising:

• (a) a mold support chamber having an upper opening and a bottom opening and being hermetically fitted to a cover at said upper opening by a sealing means;
• (b) a mold having a runner and a mold cavity communicating with said runner through a plurality of filling passages, said mold being disposed in said mold support chamber so that the lower open end of said runner is positioned below said bottom opening;
• (c) a preferential suction zone formed in the vicinity of the top of said mold cavity;
• (d) a suction head slidably mounted through said cover and placed in said upper opening of said mold support chamber so that the lower open end of said suction head completely covers said preferential suction zone and sealingly fits the outer upper surface of said mold;
• (e) a pressing means for continuously and constantly pressing, in cooperation with said suction head, said mold toward the inner bottom surface of said mold support chamber;
• and
• (f) a vacuum means communicating with said suction head, for evacuating said mold to fill said mold cavity with said molten metal while pressing said toward the inner bottom surface of said mold support chamber.