Claims
- 1. An induction furnace for melting a metal charge, comprising:a crucible for holding said metal charge, said crucible formed substantially from a material selected from the group consisting of silicon carbides, high electrical resistivity steels and high permeability steels; at least one induction coil comprising a cable wound of a plurality of conductors isolated one from the other, said at least one induction coil surrounding said crucible; and an electrically and thermally insulating isolation sleeve of low magnetic permeance separating said crucible from said at least one induction coil.
- 2. An induction furnace for melting a metal charge, comprising:a crucible for holding said metal charge, said crucible formed substantially from a material having a high electrical resistivity or high magnetic permeability; at least one induction coil comprising a cable wound of a plurality of conductors isolated one from the other, said at least one induction coil surrounding said crucible; and an electrically and thermally insulating isolation sleeve of low magnetic permeance separating said crucible from said at least one induction coil wherein said isolation sleeve comprises an air-bubbled ceramic disposed between at least one inner and at least one outer layer of ceramic.
- 3. The induction furnace of claim 1 wherein said isolation sleeve comprises a composite ceramic material.
- 4. The induction furnace of claim 3 wherein said composite ceramic material comprises an air-bubbled ceramic disposed between at least one inner and at least one outer layer of ceramic.
- 5. An induction melting system for melting a metal charge comprising:at least one power supply comprising an inverter arranged to provide AC electric power of a selected frequency; a crucible for holding said metal charge, said crucible formed substantially from a material having a high electrical resistivity or high magnetic permeability; at least one induction coil consisting of a cable wound of a plurality of conductors isolated one from the other, said at least one induction coil surrounding said crucible; and an isolation sleeve to electrically and thermally isolate said crucible from said at least one induction coil; wherein the depth of penetration into said crucible of a magnetic field generated by a current of the selected frequency in said at least one induction coil is in the range of from half the thickness to die thickness of the crucible; whereby the magnetic field generated by said current in said at least one induction coil is inductively coupled to said crucible to heat said crucible with heat transfer from said crucible melting said metal charge.
- 6. The induction melting system of claim 5, wherein said crucible is formed substantially from a silicon carbide or a high permeability steel.
- 7. The induction melting system of claim 5 wherein said isolation sleeve is a composite ceramic material.
- 8. The induction melting system of claim 7 wherein said composite ceramic material comprises an air-bubbled ceramic disposed between an inner and an outer layer of ceramic.
- 9. The induction melting system of claim 5 wherein said at least one power supply and said at least one induction coil are air cooled.
- 10. The induction melting system of claim 5 wherein said at least one power supply is mounted adjacent to said at least one induction coil.
- 11. The induction melting system of claim 10 wherein an airflow sequentially cools components of said at least one power supply and said at least one induction coil.
- 12. The induction melting system of claim 5 wherein the selected frequency of said at least one power supply results in the depth of penetration into said crucible of the magnetic field being approximately equal to 1.2 times the thickness of the crucible.
- 13. A method of melting a metal charge comprising the steps of:placing said metal charge in a crucible formed substantially from a material of high electrical resistivity or high magnetic permeability; inductively heating said crucible by supplying a current of a selected frequency to at least one induction coil consisting of a cable wound of multiple conductors isolated one from the other, said at least one induction coil surrounding said crucible and being electrically and thermally isolated from said crucible; and melting said metal charge by the conduction of heat from said crucible to said metal charge; wherein the depth of penetration into the crucible of the magnetic field generated by said current in said at least one induction coil is in the range of from half the thickness to the thickness of the crucible.
- 14. An induction melting system for separating a metal from a scrap metal containing heavy metal inclusions comprising:at least one power supply; a dry chamber induction furnace for receiving and heating said scrap metal to produce a molten metal, said dry chamber induction furnace further comprising: a dry chamber crucible for holding and heating said scrap metal, said crucible formed substantially from a material having a high electrical resistivity or having a high magnetic permeability to limit the penetration depth of a dry chamber material current into said dry chamber crucible; at least one dry chamber induction coil consisting of a cable wound of conductors isolated one from the other, said at least one dry chamber induction coil surrounding said dry chamber crucible; and an isolation sleeve to electrically and thermally insulate said dry chamber crucible from said at least one dry chamber induction coil; whereby a dry chamber magnetic field is generated by a first current in said at least one dry chamber induction coil; the at least one dry chamber induction coil connected to said at least one power supply; the dry chamber magnetic field inductively coupled to said dry chamber crucible to induce the dry chamber material current and heat said dry chamber crucible with heat transfer from said dry chamber crucible producing said molten metal from said scrap metal; means for run out of said molten metal from said dry chamber induction furnace; a wet chamber induction furnace for receiving said molten metal by said means for run out of said molten metal, said wet chamber induction furnace further comprising: a wet chamber crucible for holding said molten metal, said wet chamber crucible formed substantially from a material having a high electrical resistivity or having a high magnetic permeability to limit the penetration depth of a wet chamber material current into said wet chamber crucible; at least one wet chamber induction coil consisting of a cable wound of conductors isolated one from the other, said at least one wet chamber induction coil surrounding said wet chamber crucible and arranged to be connected to said at least one power supply; and an isolation sleeve to electrically and thermally insulate said wet chamber crucible from said at least one wet chamber induction coil; whereby a wet chamber magnetic field is generated by a second current in said at least one wet chamber induction coil; the at least one wet chamber induction coil connected to said at least one power supply; the wet chamber magnetic field inductively coupled to said wet chamber crucible to induce the wet chamber material current and heat said wet chamber crucible with heat transfer from said wet chamber crucible to heat said molten metal; and means for removal of said heavy metal inclusions from said dry chamber induction furnace.
- 15. The induction melting system of claim 14 wherein said dry chamber crucible and said wet chamber crucible are formed substantially from a silicon carbide or a high permeability steel.
- 16. The induction melting system of claim 14 wherein said isolation sleeves for said dry chamber induction furnace and said wet chamber induction furnace are a composite ceramic material.
- 17. The induction melting system of claim 16 wherein said composite ceramic material further comprises an air-bubbled ceramic disposed between at least one inner and at least one outer layer of ceramic.
- 18. The induction melting system of claim 14 wherein said at least one power supply and said at least one induction coils of said dry furnace induction furnace and said wet furnace induction furnace are air cooled.
- 19. The induction melting system of claim 14 wherein said at least one power supply is mounted adjacent to at least one of said induction coils, and wherein said at least one power supply, and said at least one induction coil of at least one of said dry chamber induction furnace and said wet chamber induction furnace, are air cooled.
- 20. The induction melting system of claim 19 wherein an airflow sequentially cools components of said at least one power supply and said at least one induction coil.
- 21. The induction melting system of claim 14 wherein said means for run out of said molten metal from said dry chamber induction furnace to said wet chamber induction furnace comprises a trough disposed in the bottom of said dry chamber induction furnace.
- 22. The induction melting system of claim 14 wherein said means for removal of said heavy metal inclusions comprises a hinged bottom in said dry chamber induction furnace.
- 23. The induction melting system of claim 22 wherein said means for removal of said heavy metal inclusions further comprises a cylinder supporting said hinged bottom to selectively open said hinged bottom and a slag bin to receive said heavy metal inclusions when said hinged bottom opens.
- 24. The induction melting system of claim 14 wherein said dry chamber induction furnace has a lid that includes an exhaust duct for exhausting fumes from heating said scrap metal.
- 25. The induction melting system of claim 14, further comprising a vibratory conveyor to place said scrap metal in said dry chamber crucible.
- 26. The induction melting system of claim 14 further comprising one or more additional wet chamber induction furnaces, and wherein said means for run out of said molten metal from said dry chamber induction furnace to said wet chamber furnace includes transfer means to transfer said molten metal from said dry chamber induction furnace selectively among said wet chamber induction furnace and said one or more additional wet chamber induction furnaces.
- 27. The induction melting system of claim 26 wherein said transfer means to transfer said molten metal from said dry chamber induction furnace selectively among said wet chamber induction furnace and said one or more additional wet chamber induction furnaces further comprises an adjustable launder.
- 28. The induction melting system of claim 26 wherein said dry chamber crucible is removable from said dry chamber induction furnace.
- 29. The induction melting system of claim 14 wherein said at least one power supply operates at a frequency selected to make the penetration depth into said dry chamber crucible of the dry chamber magnetic field and the penetration depth into said wet chamber crucible of the wet chamber magnetic field equal to approximately 1.2 times the thickness of said dry chamber crucible and said wet chamber crucible, respectively.
- 30. A method of separating a metal from a metal scrap containing heavy metal inclusions comprising the steps of:placing said metal scrap in a dry chamber crucible formed substantially from a material of high electrical resistivity or high magnetic permeability; inductively heating said dry chamber crucible by supplying current to at least one induction coil consisting of a cable wound of a magnitude of copper conductors isolated one from the other, said at least one induction coil surrounding said dry chamber crucible and electrically and thermally isolated from said dry chamber crucible; melting said scrap metal into a molten metal from said metal scrap by the conduction of heat from said dry chamber crucible to said metal charge; selectively running out said molten metal from said dry chamber crucible into one or more wet chamber crucibles formed substantially from a material of a high electrical resistivity or high magnetic permeability; inductively heating one or more said wet chamber crucibles by supplying current to at least one induction coil consisting of a cable wound of a magnitude of copper conductors isolated one from the other, each of said one or more wet chamber crucibles being surrounded by and electrically and thermally isolated from at least one said induction coil; and heating said molten metal in said one or more wet chamber crucibles by the conduction of heat from said wet chamber crucibles to said molten metal charge.
- 31. The method according to claim 30 further comprising the step of removing said one or more wet chamber crucibles.
- 32. An induction furnace for forming a casting from a molten metal comprising;at least one power supply; a crucible for holding and heating said molten metal, said crucible formed substantially from a material having a high electrical resistivity or high magnetic permeability to limit the penetration depth of a material current into said crucible; sealing means to seal the interior of said crucible; at least one induction coil consisting of a cable wound of a magnitude of copper conductors isolated one from the other, said at least one induction coil surrounding said crucible, the material current being induced by a magnetic field generated by a current in said at least one induction coil, said current supplied by the at least one power supply and operating at a selected frequency; an isolation sleeve to electrically and thermally isolate said crucible from said at least one induction coil; a tube protruding through said sealing means, said tube having a first end emerged in said molten metal and a flanged end opposite said first end; a mold disposed upon said flanged end, said mold having its gate aligned with the opening of said tube; and a port in said sealing means for injecting gas at a pressure into the interior of said crucible to exert a force against the surface of said molten metal in said crucible; whereby said molten metal is forced through the opening in said tube and into the gate of said mold to fill the cavities within tile mold.
- 33. The induction furnace of claim 32 wherein said crucible is formed substantially from a silicon carbide or a high permeability steel.
- 34. The induction furnace of claim 32 wherein said isolation sleeve is a composite ceramic material.
- 35. The induction furnace of claim 34 wherein said composite ceramic material comprises an air-bubbled ceramic disposed between at least one inner and at least one outer layer of ceramic.
- 36. The induction melting system of claim 32 wherein said at least one power supply and said at least one induction coil are air cooled.
- 37. The induction melting system of claim 32 wherein said at least one power supply is mounted adjacent to said at least one induction coil.
- 38. The induction melting system of claim 37 wherein an airflow sequentially cools components of said at least one power supply and said at least one induction coil.
- 39. The induction furnace of claim 32 wherein the selected frequency of said at least one power supply results in the depth of penetration into said crucible of the magnetic field being approximately equal to 1.2 times the thickness of the crucible.
- 40. A method of casting a mold from a molten metal comprising the steps of:placing said molten metal in a crucible formed substantially from a material of high electrical resistivity or high magnetic permeability; sealing the interior of said crucible; inductively heating said crucible by supplying current to at least one induction coil consisting of a cable wound of a magnitude of copper conductors isolated one from the other, said at least one induction coil surrounding said crucible and electrically and thermally isolated from said crucible; heating said molten metal by the conduction of heat from said crucible to said molten metal; positioning said mold on a flanged end of a tube protruding through said crucible to seat the gate of said mold over the opening in said flanged end; immersing an end of said tube opposite said flanged end into said molten metal; injecting gas into said crucible to pressurize the interior of said crucible and force molten metal through said tube and into said mold; filling said mold with molten metal; depressurizing said crucible; and removing said mold from said tube.
- 41. An induction melting system for providing a continuous supply of a molten metal comprising:at least one power supply; a crucible for holding and heating said molten metal, said crucible formed substantially from a material having a high electrical resistivity or high magnetic permeability selected to limit the penetration depth of a material current into said crucible; sealing means to seal the interior of said crucible; at least one induction coil consisting of a cable wound of a magnitude of copper conductors isolated one from the other, said at least one induction coil surrounding said crucible and having a current supplied from the at least one power supply to generate a magnetic field to create the material current; an isolation sleeve to electrically and thermally isolate said crucible from said at least one induction coil; an inlet conduit protruding through said sealing means, said inlet conduit having an exit end immersed in said molten metal and a receiver end opposite said exit end, said receiver end arranged to accept a continuous supply of feed material into said molten metal; an outlet conduit protruding through said sealing means, said outlet conduit having a first end submerged in said molten metal and an exit end opposite said first end; and a port in said sealing means for injecting gas at a pressure into the interior of said crucible to exert a force against the surface of said molten metal in said crucible; whereby said molten metal is continuously forced through said outlet conduit and out of said exit end of said outlet conduit.
- 42. The induction melting system of claim 41 wherein said outlet conduit forms a siphon to draw a continuous flow of said molten metal from said crucible without said force exerted against the surface of said molten metal in said crucible.
- 43. The induction melting system of claim 42 further comprising a port in said outlet conduit for injecting gas at a pressure into said outlet conduit to form a gas break in said continuous flow whereby said continuous flow is terminated.
- 44. The induction melting system of claim 41 wherein said crucible is formed substantially from a silicon carbide or a high permeability steel.
- 45. The induction furnace of claim 41 wherein said isolation sleeve is a composite ceramic material.
- 46. The induction furnace of claim 45 wherein said composite ceramic material comprises an air-bubbled ceramic disposed between at least one inner and at least one outer layer of ceramic.
- 47. The induction furnace of claim 41 wherein said at least one power supply and said at least one induction coil are air cooled.
- 48. The induction melting system of claim 41 wherein said at least one power supply is mounted adjacent to said at least one induction coil.
- 49. The induction melting system of claim 48 wherein an airflow sequentially cools components of said at least one power supply and said at least one induction coil.
- 50. The induction melting system of claim 41 wherein the selected frequency of said at least one power supply results in the depth of penetration into said crucible of the magnetic field being approximately equal to 1.2 times the thickness of the crucible.
- 51. A method of continuously providing a continuous supply of a molten metal comprising the steps of:continuously supplying a feed material into a sealed crucible formed substantially from a material of high electrical resistivity or high magnetic permeability; inductively heating said crucible by supplying current to at least one induction coil consisting of a cable wound of a magnitude of copper conductors isolated one from the other, said at least one induction coil surrounding said crucible and electrically and thermally isolated from said crucible; heating said feed material by the conduction of heat from said crucible to said molten metal; and partially immersing an outlet conduit in said molten metal for continuously drawing molten metal from an exit opening in said outlet conduit protruding from the enclosed crucible.
- 52. The method of claim 51 further comprising the step of continuously injecting a gas at a pressure into said sealed crucible to continuously force molten metal through the exit opening in said outlet conduit.
- 53. The method of claim 52 further comprising the step of injecting a gas at a pressure into said sealed crucible to initiate a continuous siphoning of molten metal through said outlet conduit.
- 54. The method of claim 53 further comprising the step of injecting a gas at pressure into said outlet conduit to interrupt said continuous siphoning of molten metal.
- 55. A process for heating a metal comprising the steps of:placing said metal in a container formed substantially from a material of high electrical resistivity or high magnetic permeability; inductively heating said container by supplying a fast current of a selected frequency to at least one induction coil consisting of a cable wound of multiple conductors isolated from each other, said at least one induction coil surrounding said container and being electrically and thermally isolated from said container by an isolation sleeve; adjusting said current so that the penetration depth of an induced current into the container is in the range of from half the thickness to the thickness of the container, the induced current being induced by a magnetic field generated by said first current; and heating said metal by the conduction of heat from said container to said metal.
- 56. The method of claim 55, wherein said container is formed substantially from a silicon carbide or a high permeability steel.
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of U.S. Provisional Application No. 60/165,304 filed on Nov. 12, 1999.
US Referenced Citations (12)
Provisional Applications (1)
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Number |
Date |
Country |
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60/165304 |
Nov 1999 |
US |