Wellman Thermal Systems Corporation

August J Pelsor

Dennis R Blackburn

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.

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Sunman, IN, United States of America

August J Pelsor