US3834947A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Two-stage process of surface-hardening workpieces of hardenable ferrous alloys
Assignee: Gebrueder Boehler and Co AG
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Filing: 1971-09-21
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Granted: 1974-09-10
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Expires: 1991-09-21
Abstract
Abstract AN ELECTRIC CIRCUIT IS OPERATED AT A STABILIZED, HIGH FREQUENCY. A COLD PLASMA IS PRODUCED, WHICH CLOSES SAID CIRCUIT. ENERGY IS SUPPLIED BY SAID PLASMA AT A UNIFORM RATE TO SUCCESSIVE ADJOINING ELEMEMTAL SURFACE AREAS OF A WORKPIECE OF A HARDENABLE FERROUS ALLOY TO FORM IN SAID ELEMENTAL SURFACE AREAS METASABLE AUSTENITIC PORTIONS HAVING CONSTANT CROSS-SECTIONAL SHAPES AND CONSTANT PROPERTIES.
Inventors
- 👤 R Bloech
- 👤 K Swoboda
- 👤 A Kulmburg
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 07:56
CPC Classifications
H; H05; H05H; H05H1/00; H05H1/24; H05H1/26; H05H1/30; C; C21; C21D; C21D1/00; C21D1/06; C21D1/09
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-09-09 | 1978-03-11 | 1978-09-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-09-09 | 1982-03-11 | 1982-09-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-09-09 | 1986-03-11 | 1986-09-10 | $7700.00 | Window Closed / Lapsed |