Metal material remote field eddy current flaw detector

摘要

PURPOSE:To enable the diagnosing of a defect of a sample pipe at a high accuracy by making an AC signal with a phase and an amplitude preset overlap a received signal to be outputted from a receiving coil to prevent the generation of an abnormal flaw detection data. CONSTITUTION:An excitation signal f0 is applied to an excitation coil EC to generate received signals f1-f9 in receiving coils RC1-RC9, a noise of the same phase and a high frequency component are removed with a differential amplifier 7 of received signal interfaces RB1-RB9 and LPF8 and the results are applied to an adder 11. On the other hand, the signal f0 is applied to an addition terminal RT1 of addition signal processing modules RCC1-RCC9 and attenuated with an attenuator 5 of addition signal generation modules RA1-RA9. A phase angle is set 6, for example, at 15, an addition signal delayed in the phase angle by 15 is applied to a received signal modules RQ1-RQ9 to be added 11 to the signals f1-f9 applied previously and a noise is removed to send the results to a phase comparator 13 being kept at a fixed level. This enables stable phase detection thereby outputting a normal flaw detection data to a flaw detection data terminal RT5.