US4700315A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for controlling the glow discharge process
Assignee: Wellman Thermal Systems Corp
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Filing: 1986-08-14
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Granted: 1987-10-13
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Expires: 2006-08-14
Abstract
Abstract A control system to control a glow discharge apparatus, as for ion nitriding, utilizing operator selected parameters. Normally, the control system in an automatic state sequences through a glow discharge process by progressively changing modes. The sequence includes an idle mode, a pumpdown mode, a warming mode, a processing mode, a cooldown mode, and a cycle complete mode. The sequence can be interrupted by the control system to provide a plurality of special states, other than the automatic state, including a manual state, a hold state, a manual reentrant state, a power supply shutdown state, or a furnace shutdown state. While in the processing mode the control system regulates the pressure of an ionized gas in a chamber and the temperature of a workpiece within the chamber. The pressure is regulated as a function of the temperature whereby the pressure in the chamber is held to a first level until the workpiece temperature exceeds a threshold and thereafter is varied in accordance with a pressure-temperature profile responsive to the measured temperature.
Inventors
- 👤 Dennis R. Blackburn
- 👤 August J. Pelsor
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 08:42
CPC Classifications
H; H01; H01J; H01J37/00; H01J37/32; H01J37/32431; H01J37/32623; G; G05; G05D; G05D27/00; G05D27/02; H01J37/32917; H01J37/3299; H05; H05B; H05B7/00; H05B7/16; H01J2237/00; H01J2237/32; H01J2237/33; H01J2237/338; H01J2237/3387
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
207 words
A control system for an apparatus including a housing forming a chamber to receive a workpiece and a low pressure ionizable gas atmosphere and means for establishing a glow discharge between an anode and a cathode with the workpiece connected as the cathode; said control system including: means for regulating the temperature of the workpiece responsive to a predetermined time temperature rate of increase reference relation as the workpiece is heated to a predetermined operating temperature; temperature measurement means for measuring the temperature of the workpiece; means for regulating the pressure of the ionized gas in the chamber responsive to said temperature measurement means including means for regulating the pressure in the chamber to a first predefined level until the measured temperature exceeds a first predefined threshold, and means for increasing the pressure in the chamber to a predefined process pressure level in accordance with a predefined pressure-temperature profile responsive to the measured temperature when the measured temperature exceeds said first predefined threshold; and wherein said pressure-temperature profile is a curve-fit relationship with the pressure increasing from the first predefined level to the process pressure as the temperature increases from the first predefined threshold to a predefined process temperature in accordance with the predefined pressure-temperature profile curve.
Claim 2
Dependent Claim
207 words
A control system for an apparatus including a housing forming a chamber to receive a workpiece and a low pressure ionizable gas atmosphere and means for establishing a glow discharge between an anode and a cathode with the workpiece connected as the cathode; said control system including: means for regulating the temperature of the workpiece responsive to a predetermined time temperature rate of increase reference relation as the workpiece is heated to a predetermined operating temperature; temperature measurement means for measuring the temperature of the workpiece; means for regulating the pressure of the ionized gas in the chamber responsive to said temperature measurement means including means for regulating the pressure in the chamber to a first predefined level until the measured temperature exceeds a first predefined threshold, and means for increasing the pressure in the chamber to a predefined process pressure level in accordance with a predefined pressure-temperature profile responsive to the measured temperature when the measured temperature exceeds said first predefined threshold; and wherein said pressure-temperature profile is a curve-fit relationship with the pressure increasing from the first predefined level to the process pressure as the temperature increases from the first predefined threshold to a predefined process temperature in accordance with the predefined pressure-temperature profile curve.
Claim 3
Dependent Claim
212 words
A control system for an apparatus including a housing forming a chamber to receive a workpiece and a low pressure ionizable gas atmosphere and means for establishing a glow discharge between an anode and a cathode with the workpiece connected as the cathode; said control system including: means for regulating the temperature of the workpiece responsive to a predetermined time temperature rate of increase reference relation as the workpiece is heated to a predetermined operating temperature; temperature measurement means for measuring the temperature of the workpiece; means for regulating the pressure of the ionized gas in the chamber responsive to said temperature measurement means including means for regulating the pressure in the chamber to a first predefined level until the measured temperature exceeds a first predefined threshold, and means for increasing the pressure in the chamber to a predefined process pressure level in accordance with a predefined pressure-temperature profile responsive to the measured temperature when the measured temperature exceeds said first predefined threshold; and wherein said pressure-temperature profile is a hyperbolic function derived to pass through the end points of the first predefined pressure level, the first predefined threshold, the process pressure level and a predefined process temperature threshold, and further derived to curve under a linear profile for the same levels.
Claim 4
Dependent Claim
212 words
A control system for an apparatus including a housing forming a chamber to receive a workpiece and a low pressure ionizable gas atmosphere and means for establishing a glow discharge between an anode and a cathode with the workpiece connected as the cathode; said control system including: means for regulating the temperature of the workpiece responsive to a predetermined time temperature rate of increase reference relation as the workpiece is heated to a predetermined operating temperature; temperature measurement means for measuring the temperature of the workpiece; means for regulating the pressure of the ionized gas in the chamber responsive to said temperature measurement means including means for regulating the pressure in the chamber to a first predefined level until the measured temperature exceeds a first predefined threshold, and means for increasing the pressure in the chamber to a predefined process pressure level in accordance with a predefined pressure-temperature profile responsive to the measured temperature when the measured temperature exceeds said first predefined threshold; and wherein said pressure-temperature profile is a hyperbolic function derived to pass through the end points of the first predefined pressure level, the first predefined threshold, the process pressure level and a predefined process temperature threshold, and further derived to curve under a linear profile for the same levels.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-10-12 | 1991-04-13 | 1991-10-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-10-12 | 1995-04-13 | 1995-10-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-10-12 | 1999-04-13 | 1999-10-13 | $7700.00 | Window Closed / Lapsed |