EP0156545A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Heat treatment with an autoregulating heater
Assignee: Metcal Inc
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Filing: 1985-03-05
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Granted: —
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Expires: 2005-03-05
Abstract
Abstract Apparatus and process for selectively heat treating at least a portion of an article in the field with autoregulated heating. The autoregulated heating is provided by a heater including at least a first magnetic material disposed along the portion of the article to be heat treated. The first magnetic material has a magnetic permeability which sharply changes at temperatures at or near the autoregulating (AR) temperature thereof. The changes in permeability result in corresponding changes in the skin depth of the first magnetic material and, hence, the heating produced therein responsive to a.c. current passing therethrough. By maintaining the a.c. current constant in amplitude and frequency, the first magnetic material and the portion of the article are regulated at substantially the AR temperature of the first magnetic material. By selecting the first magnetic material to have AR temperature substantially corresponding to the temperature at which metal anneals, tempers, hardens, softens, stress relieves or the like, heat treating at an autoregulated temperature is achieved. The autoregulated heater can be incorporated into the article or can be applied to the article thereafter, in each case permitting in field heat treating. Autoregulated heating can also be achieved by any of various multilayer structures to provide desired autoregulation effects.
Inventors
- 👤 Rodney L. Derbyshire
- 👤 Paul F. Busch
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-01 15:56
CPC Classifications
C; C21; C21D; C21D11/00; C21D1/00; C21D1/34; C21D9/00; C21D9/08
Claims Analysis
Total Claims: 39
Claim 1
Independent Claim
104 words
A process for altering the metallurgical properties of an article, the process comprising the steps of: generating autoregulated heat by at least a first magnetic material having an autoregulating (AR) temperature and a magnetic permeability which sharply varies as the temperature of the first magnetic material varies above and below the AR temperature thereof, the heat generating step including the step of: applying an a.c. current of at least substantially constant amplitude and frequency to the first magnetic material; and heat treating a portion of the article in situ substantially at the AR temperature of the first magnetic material with the generated autoregulated heat.
Claim 2
Dependent Claim
104 words
A process for altering the metallurgical properties of an article, the process comprising the steps of: generating autoregulated heat by at least a first magnetic material having an autoregulating (AR) temperature and a magnetic permeability which sharply varies as the temperature of the first magnetic material varies above and below the AR temperature thereof, the heat generating step including the step of: applying an a.c. current of at least substantially constant amplitude and frequency to the first magnetic material; and heat treating a portion of the article in situ substantially at the AR temperature of the first magnetic material with the generated autoregulated heat.
Claim 3
Dependent Claim
27 words
A process as in claim 1, comprising the further step of: forming the first magnetic material integrally with the portion of the article to be heat treated.
Claim 4
Dependent Claim
22 words
A process as in claim 2, wherein said heat treating includes the step of annealing at least a portion of the article.
Claim 5
Dependent Claim
22 words
A process as in claim 2 wherein said heat treating includes the step of tempering at least a portion of the article.
Claim 6
Dependent Claim
22 words
A process as in claim 1, wherein said heat treating includes the step of annealing at least a portion of the article.
Claim 7
Dependent Claim
22 words
A process as in claim 1, wherein said heat treating includes the step of tempering at least a portion of the article.
Claim 8
Dependent Claim
44 words
. 7. A process as in claim 1 comprising the further step of: forming the first magnetic material as an element separate from the article; and positioning the first magnetic material in heat transfer relationship with the portion of the article to be heated.
Claim 9
Dependent Claim
22 words
A process as in claim 7, wherein said heat treating includes the step of annealing at least a portion of the article.
Claim 10
Dependent Claim
28 words
A process as in claim 7 comprising the further step of dimensioning the first magnetic material to correspond with the portion of the article to be heat treated.
Claim 11
Dependent Claim
114 words
A process for altering the metallurgical properties_of a metal article, the process comprising the steps of: uniting the article with an autoregulating heater which is operable in the field to provide autoregulated heat to at least a portion of the article; forming the autoregulating heater to include a first magnetic material having an autoregulating ( AR ) temperature substantially corresponding to at least a heat treating temperature of the article; and driving the temperature of the heater and the article united therewith to at least approximately the Curie temperature of the first magnetic material, which includes the step of: applying an a.c. current of substantially constant amplitude and frequency to the first magnetic material.
Claim 12
Dependent Claim
114 words
A process for altering the metallurgical properties_of a metal article, the process comprising the steps of: uniting the article with an autoregulating heater which is operable in the field to provide autoregulated heat to at least a portion of the article; forming the autoregulating heater to include a first magnetic material having an autoregulating ( AR ) temperature substantially corresponding to at least a heat treating temperature of the article; and driving the temperature of the heater and the article united therewith to at least approximately the Curie temperature of the first magnetic material, which includes the step of: applying an a.c. current of substantially constant amplitude and frequency to the first magnetic material.
Claim 13
Dependent Claim
34 words
A processas in claim 10 wherein the forming step includes the step of selecting a first magnetic material having an: effective magnetic permeability which is at least 100 at temperatures below the AR temperature.
Claim 14
Dependent Claim
91 words
A process as in claim 10, wherein the forming step includes the steps of: defining the first magnetic material. as a first layer; defining a second layer of material which differs from the first magnetic material; and positioning the first layer and the second layer against each other in electrical contact; wherein current flows mainly through a shallow depth of the first layer when the magnetic permeability thereof greatly exceeds one; and wherein substantial current flows in the second layer when the magnetic permeability of the first layer is substantially one.
Claim 15
Dependent Claim
92 words
A process as in claim 11, wherein the forming step further includes the step of: defining the first magnetic material as a first layer; defining a second layer of material which differs from the first magnetic material; and positioning the first layer and the second layer against each other in electrical contact; wherein current flows mainly through a shallow depth of the first layer when the magnetic permeability thereof greatly exceeds one; and wherein substantial current flows in the second layer when the magnetic permeability of the first layer is substantially one.
Claim 16
Dependent Claim
27 words
A process as in claim 13, wherein the defining of the second layer includes the step of selecting the second layer to be of low electrical resistance.
Claim 17
Dependent Claim
40 words
A process as in claim 13, wherein tthe defining of the second layer includes the step of selecting the second layer to be a second magnetic material having an AR temperature higher than the AR temperature ot the first layer.
Claim 18
Dependent Claim
16 words
A process as in claim 10, wherein the dri- 'ving step is performed in the field.
Claim 19
Dependent Claim
46 words
A process as in claim 16, wherein the article and the heater are separate elements; and wherein the uniting step is performed in the field and includes the step of positioning the heater in heat transfer relationship with the portion of the article to be heated.
Claim 20
Dependent Claim
23 words
A process as in claim 17, wherein the driving step includes the step of maintaining the temperature of the article to achieve annealing.
Claim 21
Dependent Claim
23 words
A process as in claim 17, wherein the driving step includes the step of maintaining the temperature of the article to achieve tempering.
Claim 22
Dependent Claim
39 words
A process as in claim 15, comprising the further step of selectively regulating the temperature of the heater and the article to the AR temperature of the first magnetic material or the AR temperature of the second magnetic material.
Claim 23
Dependent Claim
46 words
A process as in claim 10, wherein the article is initially in a ductile state; and wherein the process includes the further step of: shaping the metal to a desired configuration prior to said temperature driving step, said temperature driving step serving to strengthen the article.
Claim 24
Dependent Claim
22 words
A process as in claim 10 comprising the further step of: surface treating the article in situ after the temperature driving step.
Claim 25
Dependent Claim
19 words
A process as in claim 22 wherein the surface treating step comprises the step of: nitriding the article surface.
Claim 26
Dependent Claim
18 words
A process as in claim 22 wherein the surface treating step comprises the step of: carborizing the article.surface.
Claim 27
Dependent Claim
102 words
Apparatus for heat treating in the field at least a portion of a metal article, the apparatus comprising: an autoregulating heater comprising: (a) a first layer of a magnetic material having a magnetic permeability which greatly exceeds one when below a first autoregulating (AR) temperature and at least approximates when above the first AR temperature, the first AR temperature substantially corresponding to the temperature at which the portion of the article is heat treated; and (b) means for passing a.c. current thnough said first layer; said autoregulating heater being disposed along the portion of the article which is to be heat treated.
Claim 28
Dependent Claim
102 words
Apparatus for heat treating in the field at least a portion of a metal article, the apparatus comprising: an autoregulating heater comprising: (a) a first layer of a magnetic material having a magnetic permeability which greatly exceeds one when below a first autoregulating (AR) temperature and at least approximates when above the first AR temperature, the first AR temperature substantially corresponding to the temperature at which the portion of the article is heat treated; and (b) means for passing a.c. current thnough said first layer; said autoregulating heater being disposed along the portion of the article which is to be heat treated.
Claim 29
Dependent Claim
27 words
Apparatus as in claim 25 further comprising: a source of current having a constant amplitude and a constant frequency connected across the points on said first layer.
Claim 30
Dependent Claim
39 words
Apparatus as in claim 26, wherein the article is of annealable metal; and wherein the AR temperature of said first layer substantially corresponds to the annealing temperature of the portion of the article that is to be heat treated.
Claim 31
Dependent Claim
40 words
Apparatus as in claim 26, wherein the article is of temperable metal; and wherein the AR temperature of said first layer substantially corresponds to the heat tempering temperature of the portion of the article that is to be heat treated.
Claim 32
Dependent Claim
24 words
Apparatus as in claim 25, wherein said autoregulating heater is integrally incorporated into and along the portion of the article to be heat treated.
Claim 33
Dependent Claim
35 words
Apparatus as in claim 25, wherein the article is cylindrical in shape; and wherein said autoregulating heater comprises a strap which wraps around an annular band of the article and directs heat treating heat thereto.
Claim 34
Dependent Claim
35 words
Apparatus as in claim 25, wherein the article is a Beryllium-copper alloy spring; and wherein the AR temperature of said first layer substantially corresponds to a temperature at which the spring achieves enhanced strength properties.
Claim 35
Dependent Claim
49 words
Apparatus as in claim 25, wherein the article is a metallic alloy; and wherein the AR temperature of said first layer substantially corresponds to a temperature at which brittleness of the alloy along the portion of the article to be heat treated is reduced and stress relief therein achieved.
Claim 36
Dependent Claim
47 words
Apparatus as in Claim 25, wherein the article is a metallic alloy; and wherein the AR temperature of said first layer substantially corresponds to a temperature whereat the alloy softens to enhance the ductility of the alloy along the portion of the article to be heat treated.
Claim 37
Dependent Claim
106 words
Apparatus as in claim 26, wherein the autoregulating heater further includes: a second layer laying against said first layer, said second layer having resistivity and magnetic permeability characteristics which differ from said first layer; said two points on said first layer and said second layer being respectively positioned so that current from said source is confined mainly to a shallow depth of said first layer at temperatures below the AR temperature thereof and so that the skin depth of said first layer exceeds the thickness thereof at temperatures above the AR temperature of said first layer to enable substantial current to flow through said second layer.
Claim 38
Dependent Claim
131 words
An article capable of heating itself in the field to a heat treating temperature, the article comprising: an autoregulating heater including: (a) a first layer of a magnetic material having a magnetic permeability which greatly exceeds one when below a first autoregulating (AR) temperature and at least approximates one when above the first AR temperature, the first AR temperature substantially corresponding to the temperature at which the portion of the article is heat treated; and (b) means for coupling a source of a.c. current to provide a.c. current flow through said first layer, said coupling means enabling the source to be coupled to said first layer in the field; said autoregulating heater being fixedly incorporated within the article along the portion thereof which is to be heat treated in the field.
Claim 39
Dependent Claim
131 words
An article capable of heating itself in the field to a heat treating temperature, the article comprising: an autoregulating heater including: (a) a first layer of a magnetic material having a magnetic permeability which greatly exceeds one when below a first autoregulating (AR) temperature and at least approximates one when above the first AR temperature, the first AR temperature substantially corresponding to the temperature at which the portion of the article is heat treated; and (b) means for coupling a source of a.c. current to provide a.c. current flow through said first layer, said coupling means enabling the source to be coupled to said first layer in the field; said autoregulating heater being fixedly incorporated within the article along the portion thereof which is to be heat treated in the field.
References Cited (Backward Citations)
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