JPS6439548A - Ultrasonic flaw detector - Google Patents

Abstract

PURPOSE:To obtain an inexpensive flaw detector of simple structure which can detect a defect in a flaw detection object layer nearby the surface of an object of flaw detection by acquiring a surface reflected wave from the surface of the object of flaw detection in a sound absorption cylinder and separating and extracting a defect reflected wave from the defect. CONSTITUTION:A transmitting probe 2 and a receiving probe 4 which are provided at a distance are fitted to an X-Y driving part 12 through a holding mechanism 13, the interval distance and angle direction between the transmission point of the probe 2 and the reception point of the probe 4 are adjusted freely and held, and the probes are driven in an X-Y direction. The probe 2 is equipped with the sound absorption cylinder 14 which is formed cylindrically at one end and in a truncated conic tube shape at the other end part, and a sound absorber is provided on the internal surface. Then the probe 2 is arranged at such an angle that a transverse wave of 45 deg. in refraction angle is generated at the point of incidence of a sent wave on the surface of the object 20 of flaw detection, and the surface reflected wave which is reflected at the incidence point with a sent wave as its longitudinal ultrasonic wave is acquired, scattered, and absorbed by the sound absorption cylinder 14. If there is a defect in the flaw detection object layer, a defective reflected wave based upon the transverse wave generated in the object 20 of flaw detection is received by the probe 4 and those respective waves are displayed as a display oscillogram for the flaw detection.