Determining metal workpiece joint condition during heating involves deriving joint state from workpiece specific resistance or magnetic permeability determined from induction coil current decrease time constant or shape after voltage pulse

摘要

The workpiece (2) is heated by pulsed induction and the method involves determining the magnetic permeability of the workpiece from the variation of the current in the induction coil. The specific resistance or magnetic permeability of the workpiece is determined by determining the time constant or shape of the decrease in induction coil (5) current after a voltage pulse and the joint state is derived from the specific resistance or magnetic permeability. An independent claim is also included for a device for determining the joint condition of a metallic workpiece during heating.