Apparatus and method of forming parts

A system for molding metal articles wherein the system is maintained in a closed condition to prevent air from entering the molten metal comprising:

• a source of pressurizeable molten metal;
• a mold having a mold cavity therein, said mold maintainable at sufficiently low temperature so that a charge of molten metal located in said mold cavity solidifies to thereby form a solidified casting in said mold cavity;
• a housing having a runner for flow of molten metal therethrough, said runner connecting said mold cavity to said source of pressurizeable molten metal, said runner maintainable at sufficiently high temperature to continuously maintain said molten metal in a molten state so that the mold cavity can be refilled with a fresh charge of molten metal from the runner when a solidified casting is removed therefrom;
• and
• a shut-off valve, said shut-off valve having an open position for allowing molten metal to flow into said mold cavity, a closed position to prevent molten metal from flowing out of said runner as the molten metal in said cavity solidifies and an intensification position to momentarily increase the pressure in the mold cavity to thereby minimize shrinkage and voids in the casting.

A closed system for molding metal articles under pressure comprising:

• a source of pressurizeable molten metal, said source of pressurizeable molten metal including a vat of molten metal having an immersion housing therein with a slidable piston therein for increasing the pressure of the molten metal in the immersion housing, said immersion housing having an inlet maintainable in the lower portion of the vat of molten metal to prevent air from being drawn into the immersion housing when a fresh charge of molten metal is brought into the housing;
• a mold having a mold cavity therein for forming a part, said mold maintainable at sufficiently low temperature so that molten metal located in said mold cavity can solidify to thereby form a solidified part in said mold cavity;
• a housing having a runner, said runner forming a fluid passageway connecting said mold cavity to said source of pressurizeable molten metal, said runner in said housing maintainable at sufficiently high temperature to maintain a charge of molten metal in a molten state so that the mold cavity can be refilled with the fresh charge of molten metal when a solidified casting is removed therefrom;
• and
• a shut-off valve, said shut-off valve having an open position for allowing molten metal to flow into said mold cavity, a closed position to prevent molten metal from flowing out of said runner as the molten metal in said cavity solidifies, an intensification position to momentarily increase the pressure of the molten metal in the mold cavity to thereby minimize shrinkage and voids and a release position to allow the part to be removed from the mold while maintaining the closed system to prevent air from being introduced into the molten metal.