PURPOSE: To detect the presence or absence of a defect and the direction in metallic flat plate or the like.
CONSTITUTION: Amplitude-modulated high-frequency current is supplied into exciting coils 52a, 52b and 52c in three-phase AC from a flaw detector 70 through a connecting cable 60. The magnetic field generated is this way is rotated with time. Therefore, the eddy current generated in a metal body under test is rotated with the time. The degree of the hindrance of the above-described eddy current is changed in time based on the direction of a defect. Therefore, the direction of the defect can be detected by observing the time relatioship between the waveforms 73 of the voltages induced in detecting coils 53a, 53b and 53c and the waveform 72 of AC, which is supplied into the exciting coils 52a, 52b and 52c. The waveforms 73 and 72 are displayed on a screen 71 of the flaw detector 70.
KAMIMURA TAKEO
ARAKI YASUO
INOUE SHINYA
