Patent US2639896A successfully refreshed from Google Patents.
US2639896A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Rotary rock drilling bit
Assignee: Individual
•
Filing: 1950-02-14
•
Granted: 1953-05-26
•
Expires: 1970-02-14
Abstract
No abstract record available.
Inventors
- 👤 Daniel H Francis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 21:27
CPC Classifications
E; E21; E21B; E21B4/00; E21B4/006; E21B10/00; E21B10/08
Claims Analysis
Total Claims: 0
No claims parsed yet. Click Sync Now above to re-index claims from Google Patents.
References Cited (Backward Citations)
US1778966A
Cited
US1854624A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1956-05-25 | 1956-11-24 | 1957-05-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1960-05-25 | 1960-11-24 | 1961-05-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1964-05-25 | 1964-11-24 | 1965-05-26 | $7700.00 | Window Closed / Lapsed |