| 摘要 |
PURPOSE:To improve reliability, by detecting the distribution of leaking magnetic flux with a plurality of magnetism sensitive sensors, which are laminated at a specified interval, and comparing the result with a preset value. CONSTITUTION:A laminated sensor probe holder 34 is turned around a material to be checked. Leaking magnetic flux is detected with a laminated sensor. The result is inputted into a defect discriminating part 20. The input signals are amplified in amplifiers 46 so as to correct the differences among sensor coils. The signals are further amplified in amplifiers 48. The signals are compared with preset judging values in a first controller 50, and the size of the defect is determined. Meanwhile, the peak value of the intensity of the vertical component in leaking magnetic-flux distribution corresponding to the lift-off amount of the sensor coils is computed based on the detected signals in the amplifiers 46. The changing rate of the peak ratio is operated in an operator 52. The result is compared with a preset judging value in a second controller 54. Thus the kind of the defect is determined. The determined results of the size and the kind of the defect based on the results of the controllers 50 and 54 are judged in a third controller 56 singly or as a consolidated mode. The result is transmitted to an output device 58. Thus, the discrimination of the size and the kind of the defect can be performed accurately, and the reliability in flaw finding can be improved.
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