Method and apparatus for examining a workpiece

摘要

An eddy current inspector for imaging of a workpiece shape. A differentially wound test coil mounted next to a workpiece path of travel is energized with a time varying signal to set up eddy currents in the workpiece. A field modifying sleeve is rotated with the field to periodically disrupt the eddy current inducing field. Two signals from the coil, a flaw signal and a shape signal, are time multiplexed and scaled to present a real time image of a workpiece surface as well as the orientation and severity of flaws existing at the workpiece surface.