LOW-PRESSURE CASTING APPARATUS AND METHOD OF FILLING INERT GAS

摘要

A low-pressure casting apparatus in which there can be avoided oxidation of any molten metal remaining in a guide hole having its proximal portion connected in communicating relationship to an inferior portion of a pressurization compartment for pressurization of molten metal and having its distal end portion connectable in communicating relationship to a pour port of mold so as to guide the molten metal to the mold. The low-pressure casting apparatus has a molten metal retaining compartment (1) for retention of molten metal; a pressurization compartment (2) for pressurization of molten metal, disposed so as to allow communication with the molten metal retaining compartment; an opening/closing valve (5) for opening/closing of a communication hole (4) for communication between the molten metal retaining compartment and the pressurization compartment; a guide hole (7) having its proximal portion connected in communicating relationship to an inferior portion of the pressurization compartment and having its distal end portion connectable in communicating relationship to a pour port of mold (6) so as to guide the molten metal to the mold; a float (9) disposed so as to be movable up and down in the interior of the pressurization compartment; and a tank storing an inert gas connected via a conduit (13) and the opening/closing valve to a superior portion of the pressurization compartment. The low-pressure casting apparatus is characterized in that the proximal portion of the guide hole is connected to a position of height of the pressurization compartment such that filling of the mold with the molten metal is attained by immersion of the float in the molten metal leading to elevation of the upper surface level of the molten metal, and such that after solidification of the filled molten metal, when the float is elevated to thereby lower the upper surface level of the molten metal, the space made superior to the molten metal in the pressurization compartment is brought into communication with the interior of the guide hole.