Locating welds in strip - in a continuous strip rolling line

摘要

The weld zones are detected by two coils which have partially split circular cores and are arranged in an offset manner. When a weld zone passes the gap in a coil, the flux change produced is concentrated at the heat-affected zone. The two coils are in two arms of a bridge circuit which compares changes in impedance in one coil w.r.t. the other. False signals are thus avoided and the weld zone is located accurately.