Patent US2694550A successfully refreshed from Google Patents.
US2694550A
Expired / Lapsed
US
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Churn drill for thermal rock piercing
Assignee: Union Carbide Corp
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Filing: 1948-09-01
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Granted: 1954-11-16
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Expires: 1968-09-01
Abstract
No abstract record available.
Inventors
- 👤 Robert B Aitchison
- 👤 George H Smith
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 20:29
CPC Classifications
E; E21; E21B; E21B7/00; E21B7/14
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US318034A
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USRE22964E
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US1842454A
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US1833477A
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US2327499A
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US2327498A
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US2327508A
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US2436002A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1957-11-15 | 1958-05-17 | 1958-11-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1961-11-15 | 1962-05-17 | 1962-11-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1965-11-15 | 1966-05-17 | 1966-11-16 | $7700.00 | Window Closed / Lapsed |