US Pat. No. 9,636,743

DUAL-CHAMBERED MOLTEN METAL HOLDING FURNACE FOR LOW PRESSURE CASTING

TOUNETSU CO., LTD., Fuji...

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.

US Pat. No. 10,462,851

MOLTEN METAL HOLDING FURNACE

Tounetsu Co., Ltd., Fuji...

1. A molten metal holding furnace comprising:a furnace body including a bottom wall, a ceiling wall, and a side wall extending between the bottom wall and the ceiling wall to form a molten metal containing space defined by the bottom wall, the ceiling wall, and the side wall, the furnace body including at least one insertion hole formed to extend through the side wall or the ceiling wall; and
a heating tube including a heat generator and inserted in the at least one insertion hole, the molten metal holding furnace for holding a molten metal contained in the molten metal containing space at a predetermined temperature by using heat generated by the heat generator,
wherein the at least one insertion hole includes an inside cylindrical portion and an outside cylindrical portion in a region from an inside end portion to an outside end portion of the side wall or the ceiling wall, the inside cylindrical portion extending from a starting point at or adjacent the inner end portion to an intermediate point between the inside and outside end portions, the outside cylindrical portion extending from the intermediate point to a terminal point at or adjacent the outside end portion, the inside cylindrical portion having an inner diameter increasing gradually from the starting point to the intermediate point and the outside cylindrical portion having a constant inner diameter,
wherein the heating tube includes a distal cylindrical portion corresponding to the inside cylindrical portion and a proximal cylindrical portion corresponding to the outside cylindrical portion, the distal cylindrical portion having an outer diameter increasing discontinuously from the starting point toward the intermediate point and the proximal cylindrical portion having a constant outer diameter smaller than an outer diameter of the distal cylindrical portion at the intermediate point,
wherein the heating tube is inserted and positioned in the at least one insertion hole with the distal cylindrical portion of the heating tube located at the inside cylindrical portion of the at least one insertion hole and with the proximal cylindrical portion of the heating tube located at the outside cylindrical portion of the at least one insertion hole,
wherein a filling material is filled between the distal cylindrical portion of the heating tube and the inside cylindrical portion of the at least one insertion hole,
wherein the heating tube has a stepped portion formed of an annular surface extending radially between the distal cylindrical portion and the proximal cylindrical portion of the heating tube,
wherein a tubular member is disposed between the proximal cylindrical portion of the heating tube and the outside cylindrical portion of the at least one insertion hole,
wherein a fixing member is disposed outside the tubular member,
wherein the fixing member is coupled to the furnace body through a fastener, and
wherein the tubular member is pressed against the stepped portion of the heating tube by the fastener.