Patent ID: 6455825
Filing Date: 2002-09-24
Classification: G05D,H05B

Abstract:
A method of monitoring the process of induction heating a workpiece, comprising:(a) providing a workpiece having a region that is being heated by an induction heating coil, the workpiece having a time-varying total surface magnetic field comprising a primary magnetic field component generated by the induction heating coil, and a secondary magnetic field component generated by eddy currents induced in the workpiece by the induction heating coil; (b) placing a magnetic sensor outside of the workpiece in close proximity to the outer surface of the workpiece's heated region; (c) measuring the sensor's response to the time-varying total surface magnetic field, while the workpiece is being inductively heated; (d) identifying a unique feature of the sensor's response that is characteristic of changes in the magnetic properties of the workpiece while being induction heated; and (e) monitoring changes in said unique feature of the sensors response while the workpiece is being inductively heated.