US3589950A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Valve spring processing
Assignee: Ford Motor Co
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Filing: 1969-04-21
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Granted: 1971-06-29
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Expires: 1989-04-21
Abstract
Abstract COILED STEEL INTERNAL COMBUSTION ENGINE VALVE SPRINGS ARE PRODUCED BY HARDENING CARBON STEEL WIRE, TEMPERING THE HARDENED WIRE TO AN RC HARDNESS OF 50 TO 51 AT ABOUT 700*F., COILING THE TEMPERED WIRE INTO SPRINGS, AND THEN STRESS RELIEVING THE COILED SPRINGS AT A TEMPERATURE ABOVE THE TEMPERING TEMPERATURE AND TO A HARNESS NOT SIGNIFICANTLY GREATER THAN RC 47. THIS RESULTS IN A SPRING STEEL OF DEFINITELY HIGHER RESISTANCE TO RELAXATION IN SERVICE.
Inventors
- 👤 William M Justusson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 21:40
CPC Classifications
C; C21; C21D; C21D9/00; C21D9/02; Y; Y10; Y10T; Y10T29/00; Y10T29/49; Y10T29/49609; Y10T29/49611
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) | 1974-06-28 | 1974-12-28 | 1975-06-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-06-28 | 1978-12-28 | 1979-06-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-06-28 | 1982-12-28 | 1983-06-29 | $7700.00 | Window Closed / Lapsed |