Patent US3207238A successfully refreshed from Google Patents.
US3207238A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Thermal piercing control
Assignee: Caterpillar Global Mining LLC
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Filing: 1962-08-06
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Granted: 1965-09-21
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Expires: 1982-08-06
Abstract
No abstract record available.
Inventors
- 👤 Trevor O Davidson
- 👤 William P Atkinson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 15:54
CPC Classifications
E; E21; E21B; E21B7/00; E21B7/14
Claims Analysis
Total Claims: 1
Claim 1
Independent Claim
107 words
A METHOD FOR DEVELOPING A HOLE BY THERMAL PIERCING COMPRISING: LOWERING A THERMAL PIERCING HEAD AND SENSING THE DEGREE OF RESISTANCE TO THE CONTINUED DESCENT OF THE HEAD IN A HOLE IT IS DEVELOPING WHILE RETAINING THE HEAD ABOVE THE BOTTOM OF THE HOLE; INCREASING THE RATE OF DESCENT OF THE THERMAL PIERCING HEAD, WHILE RETAINING THE HEAD ABOVE THE BOTTOM OF THE HOLE, AS LONG AS THE DEGREE OF RESISTANCE IS BELOW A PRESELECTED AMOUNT; AND DECREASING THE RATE OF DESCENT OF THE THERMAL PIERCING HEAD, WHILE RETAINING THE HEAD ABOVE THE BOTTOM OF THE HOLE, WHEN THE DEGREE OF RESISTANCE IS ABOVE A PRESELECTED AMOUNT.
References Cited (Backward Citations)
US1919611A
Cited
US1913752A
Cited
US2679381A
Cited
US2742555A
Cited
US2945677A
Cited
US2935303A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1968-09-20 | 1969-03-22 | 1969-09-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1972-09-20 | 1973-03-22 | 1973-09-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1976-09-20 | 1977-03-22 | 1977-09-21 | $7700.00 | Window Closed / Lapsed |