Patent ID: 8230897

Claim:
A low-pressure casting apparatus comprising a compartment for holding a molten metal, a vertically extending pressure chamber having a bottom that communicates with the compartment, wherein the molten metal can be pressurized in the chamber, an on-off valve that opens and closes an opening through which the compartment can communicate with the pressure chamber, a horizontally extending conduit that communicates the pressure chamber with a mold to conduct the molten metal to the mold, wherein one end of the horizontally extending conduit is connected to a lower part of the vertically extending pressure chamber at a level spaced vertically upward from the bottom of the pressure chamber to communicate the conduit with the chamber, an opposite end of the conduit communicating with a sprue of the mold, wherein the level at which the conduit is connected to the pressure chamber is vertically higher than a level at which the compartment communicates with the pressure chamber, a float in the pressure chamber and an electric cylinder for raising and lowering the float vertically up and down in the pressure chamber, and means for supplying an inert gas to an upper part of the interior of the pressure chamber, wherein the mold is filled with molten metal by flowing molten metal from the compartment into the pressure chamber and the horizontally extending conduit and thereafter by lowering the float in the chamber which causes the level of molten metal to rise and enter the mold and wherein the level at which the horizontally extending conduit is connected to the lower part of the vertically extending pressure chamber permits a space formed in an upper part of the conduit to communicate with a space in the upper part of the interior of the pressure chamber that contains the inert gas when the float is raised and the level of the molten metal in the chamber and the conduit is lowered after the molten metal in the mold has solidified.