US4363677A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for treating an electromagnetic steel sheet and an electromagnetic steel sheet having marks of laser-beam irradiation on its surface
Assignee: Nippon Steel Corp
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Filing: 1981-01-22
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Granted: 1982-12-14
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Expires: 2001-01-22
Abstract
Abstract A process of providing electromagnetic steel strips or sheet with excellent magnetic properties. The process comprises the steps of: irradiating with 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, 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.
Inventors
- 👤 Tadashi Ichiyama
- 👤 Shigehiro Yamaguchi
- 👤 Tohru Iuchi
- 👤 Motoharu Nakamura
- 👤 Yozo Suga
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 08:08
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: 9
Claim 1
Independent Claim
108 words
A method for treating an electromagnetic steel sheet to reduce its watt loss after completion of its final heat treatment, and comprising irradiating at least one surface of the finally heat-treated sheet with a laser beam having an energy density of from 0.01 to 1000 J/cm 2 so as to mark the sheet's surface and cause a substantial reduction in the sheet's watt loss, and thereafter a liquid insulating film-forming agent requiring treating at temperatures not higher than 600° C. is coated on the surface and the coated sheet is treated at temperatures not higher than 600° C. so as to form an insulating film on the surface.
Claim 2
Independent Claim
108 words
A method for treating an electromagnetic steel sheet to reduce its watt loss after completion of its final heat treatment, and comprising irradiating at least one surface of the finally heat-treated sheet with a laser beam having an energy density of from 0.01 to 1000 J/cm 2 so as to mark the sheet's surface and cause a substantial reduction in the sheet's watt loss, and thereafter a liquid insulating film-forming agent requiring treating at temperatures not higher than 600° C. is coated on the surface and the coated sheet is treated at temperatures not higher than 600° C. so as to form an insulating film on the surface.
Claim 3
Dependent Claim
16 words
The method of claim 1 in which the treating temperature is not higher than 550° C.
Claim 4
Dependent Claim
16 words
The method of claim 1 in which the treating temperature is not higher than 500° C.
Claim 5
Dependent Claim
15 words
The method of claim 1 in which the agent is substantially free from colloidal silica.
Claim 6
Dependent Claim
26 words
The method of claim 1 in which the agent is coated on the sheet's surface in an amount of from 2 to 3 g/m 2 .
Claim 7
Dependent Claim
22 words
The method of claim 1 in which at the time of the irradiating the sheet's surface is free from a glass film.
Claim 8
Dependent Claim
46 words
The method of claim 1 in which at the time of the irradiating the sheet's surface is coated with a thin film of a substance selected from the class consisting of steel blueing, chromic acid solution and copper and through which the laser beam can penetrate.
Claim 9
Dependent Claim
40 words
The method of claim 7 in which the thin film is steel blueing and is formed by exposing the sheet at temperatures of at least 600° C. to oxidizing conditions, and enhances the sheet's absorption of the laser beam irradiation.
References Cited (Backward Citations)
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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) | 1985-12-13 | 1986-06-14 | 1986-12-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-12-13 | 1990-06-14 | 1990-12-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-12-13 | 1994-06-14 | 1994-12-14 | $7700.00 | Window Closed / Lapsed |