Provided is a molten metal holding furnace with heat dissipation and insulating properties. An insertion hole 20 of a molten metal holding furnace 10 has an inside cylindrical portion (tapered surface) 21 and an outside cylindrical portion 22 (cylindrical surface). A heating tube 30 has a distal cylindrical portion 35 corresponding to the inside cylindrical portion 21 and a proximal cylindrical portion 36 corresponding to the outside cylindrical portion 22. The heating tube 30 is inserted and positioned in the insertion hole with the distal cylindrical portion 35 positioned at the inner cylindrical portion 21 and the proximal cylindrical portion 36 positioned at the outside cylindrical portion 22. A filling material 60 is filled between the heating tube 30 and the insertion hole 20.

An immersion-type burner heater includes a heater protection tube that is installed so as to penetrate a furnace wall or an upper lid of the molten-metal holding furnace with the tip end thereof being closed; an inner cylindrical member arranged inside the tube so as to define a combustion flow passage S between the tube and itself with the tip end side thereof being open and the inside thereof serving as an exhaust gas flow passage; and a gas burner part supplying fuel gas and air to the combustion flow passage. A helically extending projecting part is provided on at least one of the outer peripheral surface of the member and the inner peripheral surface of the tube at a position that is closer to its tip end side than to the part penetrating the furnace wall or the upper lid.

An immersion-type burner heater includes a heater protection tube that is installed so as to penetrate a furnace wall or an upper lid of the molten-metal holding furnace with the tip end thereof being closed; an inner cylindrical member arranged inside the tube so as to define a combustion flow passage S between the tube and itself with the tip end side thereof being open and the inside thereof serving as an exhaust gas flow passage; and a gas burner part supplying fuel gas and air to the combustion flow passage. A helically extending projecting part is provided on at least one of the outer peripheral surface of the member and the inner peripheral surface of the tube at a position that is closer to its tip end side than to the part penetrating the furnace wall or the upper lid.

The invention relates to a device for heating molten metal by the use of a heater that can be immersed into the molten metal. This immersion heater includes an outer cover formed of one or more materials resistant to the molten metal in which the immersion heater is to be used, and a heating element inside of the outer cover, where the heating element is protected from contacting the molten metal.

The invention relates to a device for heating molten metal by the use of a heater that can be immersed into the molten metal. This immersion heater includes an outer cover formed of one or more materials resistant to the molten metal in which the immersion heater is to be used, and a heating element inside of the outer cover, where the heating element is protected from contacting the molten metal.

A method for obtaining a product made of titanium alloy or a titanium-aluminum intermetallic compound by plasma torch melting, the alloy having an oriented structure, the method including heating the molten alloy surface in a casting ring with a plasma torch; cooling a cold zone of the casting ring over a length L1, the cooling forming a semi-solid crown of alloy; heating a hot zone of the casting ring over a length L2, thereby forming a solidification front, the flatness of which relative to a plane perpendicular to a drawing direction is less than 10?; and drawing the solidified alloy at a speed of more than 10.sup.?4 m/s in the drawing direction. The present disclosure also relates to a plant having one or more devices for implementing the method.

A method for obtaining a product made of titanium alloy or a titanium-aluminum intermetallic compound by plasma torch melting, the alloy having an oriented structure, the method including heating the molten alloy surface in a casting ring with a plasma torch; cooling a cold zone of the casting ring over a length L1, the cooling forming a semi-solid crown of alloy; heating a hot zone of the casting ring over a length L2, thereby forming a solidification front, the flatness of which relative to a plane perpendicular to a drawing direction is less than 10?; and drawing the solidified alloy at a speed of more than 10.sup.?4 m/s in the drawing direction. The present disclosure also relates to a plant having one or more devices for implementing the method.

Provided is a molten metal holding furnace with heat dissipation and insulating properties. An insertion hole 20 of a molten metal holding furnace 10 has an inside cylindrical portion (tapered surface) 21 and an outside cylindrical portion 22 (cylindrical surface). A heating tube 30 has a distal cylindrical portion 35 corresponding to the inside cylindrical portion 21 and a proximal cylindrical portion 36 corresponding to the outside cylindrical portion 22. The heating tube 30 is inserted and positioned in the insertion hole with the distal cylindrical portion 35 positioned at the inner cylindrical portion 21 and the proximal cylindrical portion 36 positioned at the outside cylindrical portion 22. A filling material 60 is filled between the heating tube 30 and the insertion hole 20.

Provided is a molten metal holding furnace with heat dissipation and insulating properties. An insertion hole 20 of a molten metal holding furnace 10 has an inside cylindrical portion (tapered surface) 21 and an outside cylindrical portion 22 (cylindrical surface). A heating tube 30 has a distal cylindrical portion 35 corresponding to the inside cylindrical portion 21 and a proximal cylindrical portion 36 corresponding to the outside cylindrical portion 22. The heating tube 30 is inserted and positioned in the insertion hole with the distal cylindrical portion 35 positioned at the inner cylindrical portion 21 and the proximal cylindrical portion 36 positioned at the outside cylindrical portion 22. A filling material 60 is filled between the heating tube 30 and the insertion hole 20.

There is provided a melting device including a melting cylinder that is heated to a predetermined temperature, melts a molding material supplied from a material supply port, and generates a molten material; an inert gas supply device configured to supply an inert gas onto a melting surface of the molten material and form an inert gas layer; and a low specific gravity gas supply device configured to supply a low specific gravity gas which is a gas having a different type from the inert gas and form a low specific gravity gas layer on the inert gas layer, wherein the low specific gravity gas layer has a lower specific gravity than the inert gas layer.