Patent ID: 9636743
Date: 2017-05-02
CPC Classifications: B22D

Claim:
1. A dual-chambered molten metal holding furnace for a low pressure casting, comprising: a molten metal storage container partitioning a molten metal holding chamber and a pressurizing chamber on an inside thereof and is formed of a monolithic refractory material; a cover plate composed of a steel product that covers a bottom surface, a side surface, and a top surface of the molten metal storage container via a heat insulation layer and/or a fireproof layer around the circumference of the molten metal storage container; a molten metal passage opening provided between the molten metal holding chamber and the pressurizing chamber; a lifting cutoff valve opening and closing the molten metal passage opening; and tube heaters placed, respectively, in the interior of the molten metal holding chamber and the interior of the pressurizing chamber, wherein the pressurizing chamber comprises a pressurizing part and a molten metal output part which are communicated with each other at the bottom thereof, a pressurizing pipe and a molten metal output pipe, each of which is a heat-resistant integral sintered product molded from a material having impermeability or permeability, are mounted inside the pressurizing part and the molten metal output part, respectively, a part of the molten metal storage container other than the pressurizing part is opened to the atmosphere via an air passage part positioned above the fixed molten metal surface level position, whereby, even when pressurized gas enters a material constituting the molten metal storage container from the pressurizing pipe, the pressurized gas is released to the outside of the furnace using the air passage part so as to prevent release of the gas to the molten metal and the occurrence of air bubbles in the molten metal.