Leakage flux flaw detection manner and device

摘要

PURPOSE:To detect even minute defects and defects of thin plate materials by putting one surface of a magnetic body for magnetic recording on the surface to be examined of materials to be examined and putting the other surface on a magnetic body layer with a nonmagnetic body layer between them. CONSTITUTION:When one surface of a magnetic layer 111a is put on the surface to be examined of materials to be examined and the other surface is put on a magnetic body layer with a nonmagnetic body layer 1 between them, lift-off from materials 101 to a magnetized tape 111 is 0. In this state, materials 101 are magnetized by a magnetizer 100 and a magnetic flux 7 is allowed to pass the inside of materials 101, and at this time, a leaked magnetic flux 7a from a defect 103 is recorded by the magnetic body layer 111a. The tape 111 is allowed to pass a magnetic head 112 and an induced voltage is generated in the magnetic coil of the head 112 in accordance with the intensity of the magnetic field of the magnetic flux 7a, and a signal 3 of this voltage waveform is obtained and is amplified by an amplifier and is delayed by a means and is stored in a logic storage 6 and is analyzed by a computer 8 thereafter.