Abstract

A method of model-based ingot solidification control for the vacuum arc remelting process is presented. Specifically, the model predicts the pool depth as a function of radial position from ingot centerline and time, given melting current, and electrode melting efficiency. The analysis leading to the model assumes that the electrode gap is being accurately controlled during the melting process. The controller has both 2-dimensional and 3-dimensional embodiments.

IPC Classes  ?

• H05B 3/60 - Heating arrangements wherein the heating current flows through granular, powdered or fluid material, e.g. for salt-bath furnace, electrolytic heating
• H05B 7/07 - Electrodes designed to melt in use
• H05B 7/148 - Automatic control of power

Abstract

The invention comprises 2-dimensional and 3-dimensional versions of a model-based ingot solidification controller for the vacuum arc remelting process. The invention predicts the pool depth as a function of radial position from ingot certerline and time. Unlike the prior art, the invention provides an effective means of controlling the ingot pool depth through normal process upsets; and is a closed loop system with respect to pool depth or shape. The prior art VAR process control does not respond to process upsets that affect pool shape but not melt rate. A method of closed-loop feedback control of the pool depth/shape allows control of the pool shape directly and in response to process upsets that directly affect solidification. Additionally, the invention allows dynamic control of the pool shape so that process control can be optimized during non-steady state operation at the process' beginning and end.

IPC Classes  ?

• H05B 7/00 - Heating by electric discharge