Cold hearth melting configuration and method

Claim 2

A bottom-pour cold hearth melting system comprising an open-top container, a downwardly directed intense heat source mounted thereover, an outer side wall of said container being made of high thermal conductivity material and an outer bottom wall constituting a diaphragm nozzle and having a centrally-located orifice extending through the thickness thereof whereby during use a charge of solid metal placed in said container can be heated at the top of the charge to produce a continually deepening centrally-located molten pool of said metal held within an inner solidified mass of said metal, said solidified mass being located between said pool and said outer side walls and bottom diaphragm wall until said deepening pool reaches said diaphragm orifice and is discharged therethrough, at least the inner central portion of the structure of said bottom diaphragm wall being a refractory metal diaphragm nozzle in which a nozzle orifice is located, said metal diaphragm nozzle having an effective lateral diameter of at least about 1.5 inches with the ratio of effective lateral diameter to thickness being at least about 10 to 1.

Claim 3

The improvement of claim 1 wherein the material of said metal diaphragm is selected from the group consisting of tungsten and alloys containing tungsten and having a melting point at least as high as about 3000° C.

Claim 4

The improvement of claim 2 wherein the orifice diameter is in the range of from about 0.20 to about 0.15 inch and the outer effective diameter is at least about 5 inches.

Claim 5

The improvement of claim 2 wherein the thickness of the metal diaphragm is about 0.020 inch.

Claim 6

The improvement of claim 1 wherein the ratio of the outer effective diameter of the diaphragm to the diameter of the orifice is at least about 6:1.

Claim 7

The improvement of claim 1 wherein the metal sheet is covered with a thin imperforate solid layer made of the metal or an alloy thereof.

Claim 8

The improvement as recited in claim 1 wherein the intense heat source is an arc electrode.

Claim 9

The improvement as recited in claim 1 wherein the intense heat source generates a plasma.

Claim 12

The improvement of claim 9 wherein the material of the metal sheet is tungsten or an alloy containing tungsten and having a melting point at least as high as about 3000° C.

Claim 13

The improvement of claim 9 wherein the mass of metal subjected to melting is titanium or a titanium alloy.

Claim 14

The improvement of claim 9 wherein the mass of metal subjected to melting is a nickel-base alloy.

Claim 15

The improvement of claim 9 wherein the gas pressure applied to discharge the molten metal is about 2 to about 12 psi greater than the pressure below the orifice.

Claim 16

A bottom-pour cold hearth melting system comprising an open-top container having a downwardly directed intense heat source mounted thereover, the side walls of said container being made of high thermal conductivity material and the bottom wall being a diaphragm nozzle having a centrally-located orifice extending through the thickness thereof whereby during use a charge of solid metal placed in said container can be heated at the top of the charge to produce a continually deepening centrally-located molten pool of said metal held within a solidified mass of said metal, said solidified mass being located between said pool and said side walls and said bottom diaphragm wall until said deepening pool reaches said orifice of said diaphragm wall and is discharged therethrough, at least the central portion of the structure of said bottom diaphragm wall is a diaphragm nozzle in which said orifice is located, said metal diaphragm being made of a material selected from the group consisting of tungsten, an alloy containing tungsten and having a melting point of at least about 3000° C., cemented tungsten carbide and tantalum carbide.

Claim 17

A bottom-pour cold hearth melting system comprising an open-top container having a downwardly directed intense heat source mounted thereover, the side walls of said container being made of high thermal conductivity material and the bottom wall being a diaphragm nozzle having a centrally-located orifice extending through the thickness thereof whereby during use a charge of solid metal placed in said container can be heated at the top of the charge to produce a continually deepening centrally-located molten pool of said metal held within a solidified mass of said metal, said solidified mass being located between said pool and said side walls and said bottom diaphragm wall until said deepening pool reaches said orifice of said diaphragm wall and is discharged therethrough, at least the central portion of the structure of said bottom diaphragm wall is a diaphragm nozzle in which said orifice is located, said metal diaphragm being made of a material selected from the group consisting of tungsten, an alloy containing tungsten and having a melting point of at least about 3000° C., cemented tungsten carbide and tantalum carbide.

Claim 18

The improvement of claim 14 wherein the cementing agent for the cemented tungsten carbide is tungsten or molybdenum.