EP0033878A2
Expired / Lapsed
EP
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Method for treating an electromagnetic steel sheet by laser-beam irradiation
Assignee: Nippon Steel Corp
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Filing: 1981-01-23
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Granted: —
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Expires: 2001-01-23
Abstract
Abstract In a method for producing electromagnetic steels. the steels finally annealed are treated by the steps of: irradiating by using a laser beam the surface of the electromagnetic steel sheet which has been finally annealed, thereby locally forming marks of the laser-beam irradiation on the surface of the steel sheet, and subsequently, subjecting the steel sheet to the formation of an insulating film on the sheet surface at a temperature of the sheet not exceeding 600 DEG C. By this treatment, watt loss, magnetostriction, space factor, workability, ability to withstand high voltage and insulating property are improved over those of conventional electromagnetic steels.
Inventors
- 👤 Tadashi Ichiyama
- 👤 Shigehiro Yamaguchi
- 👤 Tohru Iuchi
- 👤 Motoharu Nakamura
- 👤 Yozo Suga
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 20:35
CPC Classifications
C; C21; C21D; C21D8/00; C21D8/12; C21D8/1294; C21D1/00; C21D1/06; C21D1/09; H; H01; H01F; H01F1/00; H01F1/01; H01F1/03; H01F1/12; H01F1/14; H01F1/147; H01F1/14766; H01F1/14775; H01F1/14783; Y; Y10; Y10T; Y10T428/00; Y10T428/12; Y10T428/12493; Y10T428/12771; Y10T428/12861; Y10T428/12903; Y10T428/12917; Y10T428/12924
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
36 words
An electromagnetic steel sheet, characterized in that said electromagnetic steel sheet has marks-of a laser--beam irradiation in the form of a row on the steel sheet surface and an insulating film on the uppermost surface thereof.
Claim 2
Dependent Claim
36 words
An electromagnetic steel sheet, characterized in that said electromagnetic steel sheet has marks-of a laser--beam irradiation in the form of a row on the steel sheet surface and an insulating film on the uppermost surface thereof.
Claim 3
Dependent Claim
16 words
An electromagnetic steel sheet according to claim 1, wherein said insulating film is free from glass.
Claim 4
Dependent Claim
17 words
An electromagnetic steel sheet according to claim 1, wherein said insulating film is free from colloidal silica.
Claim 5
Dependent Claim
26 words
An electromagnetic steel sheet according to claim 1, wherein an annealing-separator layer free from glass is present between said steel sheet surface and said insulating film.
Claim 6
Dependent Claim
34 words
An electromagnetic steel sheet according to claim 1, wherein a layer to be penetrated by the laser beam, preferably a bluing treatment film, is present between said steel sheet surface and said insulating film.
Claim 7
Independent Claim
76 words
A method for treating an electromagnetic steel sheet comprising the steps of: irradiating by using a laser beam the surface of an electromagnetic steel sheet which has been finally annealed, thereby locally forming marks of the laser-beam irradiation on the surface of the steel sheet, and; subsequently, subjecting the steel sheet to the formation of an insulating film on the sheet surface at a temperature of the sheet not exceeding 600°C, preferably 550°C, more preferably 500°C.
Claim 8
Independent Claim
76 words
A method for treating an electromagnetic steel sheet comprising the steps of: irradiating by using a laser beam the surface of an electromagnetic steel sheet which has been finally annealed, thereby locally forming marks of the laser-beam irradiation on the surface of the steel sheet, and; subsequently, subjecting the steel sheet to the formation of an insulating film on the sheet surface at a temperature of the sheet not exceeding 600°C, preferably 550°C, more preferably 500°C.
Claim 9
Dependent Claim
44 words
A method for treating an electromagnetic steel sheet according to claim 6, further comprising the step of: prior to said laser-beam irradiating step, applying, on the surface of an electromagnetic steel sheet, an annealing separator free from components capable of generating a glass film.
Claim 10
Dependent Claim
41 words
A method for treating an electromagnetic steel sheet according to claim 6, further comprising the step of: prior to said laser-beam irradiating step, forming, on the surface of an electromagnetic steel sheet, a layer to be penetrated by the laser beam.
Claim 11
Dependent Claim
52 words
A method for treating an electromagnetic steel sheet which has been finally annealed and has an annealing separator on the sheet surface according to claim 6, comprising the step of, subsequent to the final annealing which is batchwise, and prior to the laser-beam irradiating step thermally flattening the electromagnetic steel sheet coil.
Claim 12
Dependent Claim
41 words
A method for treating an electromagnetic steel sheet according to claim 8, wherein the electromagnetic steel sheet is subjected to bluing at the withdrawal section of a continuously annealing furnace or a flattening line and then the laser-beam irradiation is applied.
References Cited (Backward Citations)
No citation records indexed.
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