Importance

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Abstract

A method and apparatus for countergravity casting of molten metal with exclusion of air in a gas-pervious mold sealed in an evacuable chamber having a free end of a fill pipe for the mold cavities projecting therefrom. The fill pipe is moved relative to an enclosed crucible containing the molten metal under an air-free atmosphere of inert gas to project the fill pipe free end into the crucible enclosure to a position below the molten metal so that evacuation of the chamber produces filling of the mold. Entry of air into the crucible enclosure is prevented by maintaining the surface of the molten metal and the ambient atmosphere a sufficient distance apart prior to insertion of the fill pipe to prevent circulating air currents from drawing air down to the metal or by blocking entry into the crucible enclosure. Entry of air can be further prevented by maintaining a sufficient pressure of inert gas in the crucible enclosure and by sealing the upper portion of the fill pipe between the chamber and the mold.

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First Claim