Patent US4825680A successfully refreshed from Google Patents.
US4825680A
Expired / Lapsed
US
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Method of manufacturing metal substrates for disk for memory storage media
Assignee: Itochu Corp
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Filing: 1987-01-05
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Granted: 1989-05-02
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Expires: 2007-01-05
Abstract
Abstract A method for manufacturing a metal substrate for a memory disk wherein a metal blank material (6) is sandwiched between two dies within a metal mould (3) limiting the extent to which the material spreads, using a core member (4) if necessary, each of the dies having a flat and smooth working surface, the compression force and sheet gauge reduction ratio being regulated or the surface roughness and amount of coating lubricants employed being regulated.
Inventors
- 👤 Thomas U. Coe
- 👤 Atsushi Yamazaki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 08:14
CPC Classifications
B; B21; B21D; B21D39/00; G; G11; G11B; G11B5/00; G11B5/84; C; C21; C21D; C21D7/00; C21D7/02; C21D7/10; G11B23/00; G11B23/0014; G11B23/0021
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
134 words
A method of manufacturing a metal substrate used for a memory disk characterized in that a coining operation is performed under conditions wherein: a metal blank material having surface roughness Rmax below 20 μm and coated with lubricant is sandwiched between two dies within a metal mold limiting the extent to which the material can spread, the amount of said lubricant being arranged to be less than 100 mg/m 2 and each of said dies having a flat and smooth compressing surface, the coining pressure (kg/mm 2 ) being arranged to be less than 5 times the tensile strength σB (kg/mm 2 ) of said metal blank material; and the sheet gauge reduction ratio being arranged to be below 4%, whereby the surface of the substrate is finished to be extremely smooth and flat.
Claim 2
Independent Claim
134 words
A method of manufacturing a metal substrate used for a memory disk characterized in that a coining operation is performed under conditions wherein: a metal blank material having surface roughness Rmax below 20 μm and coated with lubricant is sandwiched between two dies within a metal mold limiting the extent to which the material can spread, the amount of said lubricant being arranged to be less than 100 mg/m 2 and each of said dies having a flat and smooth compressing surface, the coining pressure (kg/mm 2 ) being arranged to be less than 5 times the tensile strength σB (kg/mm 2 ) of said metal blank material; and the sheet gauge reduction ratio being arranged to be below 4%, whereby the surface of the substrate is finished to be extremely smooth and flat.
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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) | 1992-05-01 | 1992-10-31 | 1993-05-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-05-01 | 1996-10-31 | 1997-05-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-05-01 | 2000-10-31 | 2001-05-02 | $7700.00 | Window Closed / Lapsed |