CORRECTING METHOD FOR ANGLE OF REFRACTION IN ANGLE BEAM FLAW DETECTION BY ULTRASONIC PROBE OF HOLLOWED AXLE

PURPOSE:To precisely set a flaw detecting gate without being influenced by an outside temperature change in the angle beam flaw detection by an ultrasonic probe of the hollowed axle of a rolling stock. CONSTITUTION:The distance M between the position of a probe 1a detecting the flaw of one axle seat corner part A and the position of a probe 1b detecting the flaw of the other axle seat corner part B is detected. At the flaw detection, the thickness between each wheel seat surface of an axle 100 and the inner circumferential surface of a hollowed part is further detected. From the difference between the length L between both the axle seat corner parts A, B and the distance M at flaw-detecting both the axle seat corner parts A, B of a holding body, and the value of the detected thickness T, the actual angle of refraction theta' of the probe at flaw detection is detected, and the error from the angle of refraction theta when the probes are arranged is detected by use of an arithmetic means to correct the set position of a flaw detecting gate.