Patent US2978047A successfully refreshed from Google Patents.
US2978047A
Expired / Lapsed
US
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Collapsible drill bit assembly and method of drilling
Assignee: Individual
•
Filing: 1957-12-03
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Granted: 1961-04-04
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Expires: 1977-12-03
Abstract
No abstract record available.
Inventors
- 👤 Vaan Walter H De
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 06:53
CPC Classifications
E; E21; E21B; E21B10/00; E21B10/64; E21B10/66
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US923677A
Cited
US2338670A
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US2546950A
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US2807131A
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US2804956A
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US2784942A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1964-04-03 | 1964-10-03 | 1965-04-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1968-04-03 | 1968-10-03 | 1969-04-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1972-04-03 | 1972-10-03 | 1973-04-04 | $7700.00 | Window Closed / Lapsed |