US4423512A
Expired / Lapsed
US
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Plasma melting furnace
Assignee: Voestalpine AG
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Filing: 1982-01-04
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Granted: 1983-12-27
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Expires: 2002-01-04
Abstract
Abstract A plasma melting furnace includes a water-cooled bottom electrode of copper and a temperature probe connected with the bottom electrode. A wearing part of steel is provided in the bottom of the furnace, covering the bottom electrode. At least one counter electrode is arranged at a distance above the wearing part for the formation of the plasma jet. In order to prevent the risk of a melting through of the bottom electrode as far as to its water-cooled section on account of a secondary arc, a metal layer is provided between the bottom electrode and the wearing part. The metal layer is formed by a metal having a low thermal conductivty and a low melting point, as compared to copper, as well as a high melting enthalpy. Preferably, a metal layer of lead or its alloys with tin and/or zinc is provided.
Inventors
- 👤 Walter Lugscheider
- 👤 Ernst Riegler
- 👤 Ernst Zajicek
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 12:07
CPC Classifications
F; F27; F27B; F27B3/00; F27B3/08; C; C22; C22B; C22B9/00; C22B9/16; C22B9/22; C22B9/226; H; H05; H05B; H05B7/00; H05B7/02; H05B7/06; H05H; H05H1/00; H05H1/24; H05H1/26; H05H1/32; H05H1/34; F27D; F27D99/00; F27D99/0001; F27D99/0006; F27D2099/0031; H05H1/3473
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
108 words
In a plasma melting furnace of the type including a water-cooled bottom electrode made of copper, a temperature probe connected to said bottom electrode, and a wearing part of steel for covering said bottom electrode in the bottom of said plasma melting furnace, at least one counter electrode being arranged at a distance above said wearing part and adapted to form a plasma jet, the improvement comprising a metal layer provided between said bottom electrode and said wearing part, said metal layer being composed of a metal having a low thermal conductivity and a low melting point, as compared to copper, as well as a high melting enthalpy.
Claim 2
Dependent Claim
108 words
In a plasma melting furnace of the type including a water-cooled bottom electrode made of copper, a temperature probe connected to said bottom electrode, and a wearing part of steel for covering said bottom electrode in the bottom of said plasma melting furnace, at least one counter electrode being arranged at a distance above said wearing part and adapted to form a plasma jet, the improvement comprising a metal layer provided between said bottom electrode and said wearing part, said metal layer being composed of a metal having a low thermal conductivity and a low melting point, as compared to copper, as well as a high melting enthalpy.
Claim 3
Dependent Claim
42 words
A plasma melting furnace as set forth in claim 1, wherein said metal layer comprises a material selected from the group consisting of lead, a lead alloy with tin, a lead alloy with zinc, and a lead alloy with tin and zinc.
Claim 4
Dependent Claim
37 words
A plasma melting furnace as set forth in claim 1, wherein said metal layer comprises materials selected from the group consisting of lead, zinc, cadmium, gallium, indium, tin, antimony, bismuth, and alloys thereof, in the binary system.
Claim 5
Dependent Claim
37 words
A plasma melting furnace as set forth in claim 1, wherein said metal layer comprises materials selected from the group consisting of lead, zinc, cadmium, gallium, indium, tin, antimony, bismuth, and alloys thereof, in the compound system.
Claim 6
Dependent Claim
22 words
A plasma melting furnace as set forth in claim 1, wherein said metal layer contacts the front face of said bottom electrode.
Claim 7
Dependent Claim
38 words
A plasma melting furnace as set forth in claim 1, wherein said bottom electrode has an upper section and said metal layer is designed as a hood surrounding said upper section, an edge flange projecting from said hood.
Claim 8
Dependent Claim
23 words
A plasma melting furnace as set forth in claim 1, wherein said metal layer has a thickness of between 5 and 30 mm.
Claim 9
Dependent Claim
21 words
A plasma melting furnace as set forth in claim 7, wherein said metal layer has a thickness of about 20 mm.
Claim 10
Dependent Claim
46 words
A plasma melting furnace as set forth in claim 1, wherein said bottom electrode has an upper section, and which further comprises a connection part for combining said wearing part, said metal layer and said upper section of said bottom electrode into a coherent construction unit.
Claim 11
Dependent Claim
19 words
A plasma melting furnace as set forth in claim 9, wherein said connection part has an L-shaped cross section.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-12-26 | 1987-06-27 | 1987-12-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-12-26 | 1991-06-27 | 1991-12-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-12-26 | 1995-06-27 | 1995-12-27 | $7700.00 | Window Closed / Lapsed |