US3819840A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Control system for torch current in a plasma arc furnace
Assignee: United States Steel Corp
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Filing: 1972-05-18
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Granted: 1974-06-25
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Expires: 1992-05-18
Abstract
Abstract A CONTROL SYSTEM FOR THE TORCH CURRENT OF A PLASMA ARC TORCH HAS A THERMAL CONVERTER PROVIDING A SIGNAL REPRESENTATIVE OF THE TORCH CURRENT. A FUNCTION GENERATOR, ABSED ON THE IONIZING GAS USED, ALTERS THE SIGNAL TO PROVIDE AN INVERSE TORCH CURRENT CHARACTERISTIC SIGNAL WHICH IS COMPARED TO A DESIRED INVERSE TORCH CHARACTERISTIC SIGNAL AND THE RESULTANT ERROR USED TO CONTROL GAS FLOW TO THE TORCH. WHEN GAS PRESSURE BECOMES TOO HIGH OR TOO LOW, A CONTROLLER ALTERS A REACTANCE IN THE SERIES WITH THE PRIMARY WINDING OF THE POWER SUPPLY TRANSFORMER TO CHANGE THE ELECTRODE VOLTAGE.
Inventors
- 👤 R Schultz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 15:43
CPC Classifications
G; G05; G05F; G05F1/00; G05F1/10; G05F1/12; G05F1/14; G05F1/147; H; H05; H05B; H05B7/00; H05B7/005
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) | 1977-06-24 | 1977-12-24 | 1978-06-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-06-24 | 1981-12-24 | 1982-06-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-06-24 | 1985-12-24 | 1986-06-25 | $7700.00 | Window Closed / Lapsed |