US3606780A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for manufacturing helical pipe for heat exchangers
Assignee: Individual
•
Filing: 1968-11-18
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Granted: 1971-09-21
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Expires: 1988-11-18
Abstract
Abstract A METHOD FOR FORMING HELICAL CORRUGATED PIPE. A CYLINDRICAL PIPE IS MOVED ALONG A LINE CORRESPONDING TO THE AXIS THEREOF OVER A METAL CORE HAVING A HELICAL GROOVE THEREIN, AND FORMING ROLLERS ARE REVOLVED AROUND THE PIPE FORMING IT AGAINST THE CORE. THE PIPE CAN BE REVOLVED DURING THE TIME IT IS FED ALONG THE CORE.
Inventors
- 👤 Kichisaburo Nagahara
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 04:34
CPC Classifications
B; B21; B21D; B21D15/00; B21D15/04
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) | 1974-09-20 | 1975-03-22 | 1975-09-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-09-20 | 1979-03-22 | 1979-09-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-09-20 | 1983-03-22 | 1983-09-21 | $7700.00 | Window Closed / Lapsed |