MAGNETIC POWDER FLAW DETECTOR

PURPOSE:To shorten a working time and to enhance the reliability of flaw detection by generating a magnetic field in the axial direction of an object to be inspected and also generating a revolving magnetic field in the diameter direction thereof and passing the object to be inspected through the magnetic fields to simultaneously detect flaws in longitudinal and lateral directions. CONSTITUTION:The steel pipe 1 to which a magnetic powder dispersion is scattered by magnetic powder dispersion scattering equipment 4 is passed through a magnetizing mechanism by a feed conveyor. A direct current is supplied to a cylindrical coil 2 and alternating currents shifted in phase by 120 deg. are supplied to a pair of frame-shaped coils X, Y. As a result, a magnetic field is generated in the steel pipe 1 inserted in the coil 2 in the axial direction thereof by the coil 2 and magnetic fields are generated in the diameter direction of the steel pipe 1 by a pair of the coils X, Y to rotate in the cross-section of the steel pipe 1. Therefore, magnetic fields in all directions can be generated on the outer surface of the steel pipe 1.