US4237359A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for the electroinduction heating of metal workpieces
Assignee: ThyssenKrupp Technologies AG
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Filing: 1977-12-23
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Granted: 1980-12-02
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Expires: 1997-12-23
Abstract
Abstract A method of heating metal workpieces so as to minimize scale formation and decarburization using an electroinduction heater, comprises placing the workpiece in the vicinity of the induction heater, reducing the air present in the vicinity of the workpiece to provide a reduced air atmosphere, and heating the metal by an electroinduction heater in the reduced air atmosphere. The air is advantageously displaced by a protective gas and this is done before the workpiece is heated to a temperature of 350° C. A device for carrying out the heating, comprises a thermally insulated hood which has an interior heating cavity which opens downwardly and which is made gas-proof at its sides and top. A thermally insulated bottom fits into the opening of the hood and substantially fills the cavity and it is provided with a support area for the workpiece which, when the bottom is inserted, is positioned alongside the electroinduction heater. A lifting device is associated with the bottom for raising it into the cavity and for lowering it downwardly out of the cavity when the workpiece is to be removed.
Inventors
- 👤 Gunther Roth
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 15:45
CPC Classifications
C; C21; C21D; C21D1/00; C21D1/74
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
130 words
A method of heating metal workpieces by induction so as to minimize scale formation and decarburization, said method comprising the steps of: providing relative vertical movement between a workpiece surrounded by air and a heat-resistant hood defining a cavity open at the bottom of the air, said relative vertical movement causing said workpiece to be within the upper part of said cavity and closely surrounded above and on the sides by said hood, filling substantially all of the remainder of said cavity below said workpiece with non-conductive, solid, heat-resistant material to displace substantially all of the air originally within said hood but leaving an air passage from said upper part of said cavity down through the lowermost part of said cavity to the surrounding air; and inductively heating said workpiece.
Claim 2
Independent Claim
130 words
A method of heating metal workpieces by induction so as to minimize scale formation and decarburization, said method comprising the steps of: providing relative vertical movement between a workpiece surrounded by air and a heat-resistant hood defining a cavity open at the bottom of the air, said relative vertical movement causing said workpiece to be within the upper part of said cavity and closely surrounded above and on the sides by said hood, filling substantially all of the remainder of said cavity below said workpiece with non-conductive, solid, heat-resistant material to displace substantially all of the air originally within said hood but leaving an air passage from said upper part of said cavity down through the lowermost part of said cavity to the surrounding air; and inductively heating said workpiece.
Claim 3
Dependent Claim
22 words
The method of claim 1 in which said hood is maintained substantially stationary and said workpiece is moved upwardly into said cavity.
Claim 4
Dependent Claim
34 words
The method of claim 1 in which the air is the only gas in said hood from the time of entry of said workpiece into said cavity until the end of said inductive heating.
Claim 5
Dependent Claim
48 words
The method of claim 1 comprising the additional step of displacing substantially all of the remainder of air in said hood by directing protective gas therein only after said workpiece and said non-conductive, solid, heat-resistant material have already displaced substantially all of the air originally in said hood.
Claim 6
Dependent Claim
27 words
The method of claim 4 in which said protective gas is directed into said hood before said workpiece is heated to a temperature of about 350° C.
Claim 7
Dependent Claim
25 words
The method of claim 1 in which inductive heating energy is not supplied inside said hood until after said workpiece is positioned in said cavity.
Claim 8
Dependent Claim
31 words
The method of claim 1 comprising inductively heating said workpiece intermittently to allow temperature equalization to proceed within said workpiece without heating the surface of said workpiece beyond a predetermined temperature.
Claim 9
Dependent Claim
22 words
The method of claim 1 in which said workpiece comprises compressed metal powder prior to said step of inductively heating said workpiece.
Claim 10
Dependent Claim
123 words
Apparatus for inductively heating metal workpieces so as to minimize scale formation and decarburization, said apparatus comprising: a heat-resistant hood comprising a gas-tight top and gas-tight sides defining a cavity open at the bottom; means to effect relative vertical movement between said hood and a workpiece to cause said workpiece to be within the upper part of said cavity, the configuration of said upper part of said cavity relatively closely fitting the top and sides of said workpiece; inductive heating coil means within said hood and adjacent said workpiece within said cavity; and non-conductive, solid, heat-resistant means substantially filling the remainder of said cavity below said workpiece but defining a limited air passage through the bottom of said hood to the surrounding air.
Claim 11
Dependent Claim
123 words
Apparatus for inductively heating metal workpieces so as to minimize scale formation and decarburization, said apparatus comprising: a heat-resistant hood comprising a gas-tight top and gas-tight sides defining a cavity open at the bottom; means to effect relative vertical movement between said hood and a workpiece to cause said workpiece to be within the upper part of said cavity, the configuration of said upper part of said cavity relatively closely fitting the top and sides of said workpiece; inductive heating coil means within said hood and adjacent said workpiece within said cavity; and non-conductive, solid, heat-resistant means substantially filling the remainder of said cavity below said workpiece but defining a limited air passage through the bottom of said hood to the surrounding air.
Claim 12
Dependent Claim
16 words
The apparatus of claim 9 in which said hood comprises a refractory lining defining said cavity.
Claim 13
Dependent Claim
21 words
The apparatus of claim 9 in which said cavity is tapered and is larger at the bottom than at the top.
Claim 14
Dependent Claim
21 words
The apparatus of claim 11 in which said non-conductive, solid, heat-resistant means is tapered substantially to conform to the tapered cavity.
Claim 15
Dependent Claim
18 words
The apparatus of claim 9 in which said solid, heat-resistant means is sufficiently rigid to support said workpiece.
Claim 16
Dependent Claim
34 words
The apparatus of claim 13 in which said hood is substantially stationary and said means to effect relative vertical movement comprises fluid-operated cylinder-and-piston means to support said non-conductive solid means and said workpiece thereon.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-12-02 | 1984-06-02 | 1984-12-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-12-02 | 1988-06-02 | 1988-12-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-12-02 | 1992-06-02 | 1992-12-02 | $7700.00 | Window Closed / Lapsed |