ULTRASONIC INSPECTION FOR PRESS-FIT PART

PURPOSE:To enable sensitive reception of a reflected wave due to a vertically cracked defect discriminated from those from press fit starting and finishing ends and the like, by emitting an ultrasonic wave to a press-fit part to receive reflected waves toward the cource different from the incident course. CONSTITUTION:A shaft 1 and an outer ring 2 and fastened together by shrink fitting and has a press-fit surface 12. As an impuse voltage 5a is generated with a pulser circuit 5, an ultrasonic pulse beam is of Is of transverse wave mode is transmitted from an angle beam probe 3. When there is no defect at the position 12S, reflected waves Rs of transverse wave mode are generated dominantly and received with the probe 3. On the other hand, when a vertical defect Fs is caused, a reflected wave RSF of transferse wave mode due to the defect is generated while a reflected wave RLF of longitudinal wave mode is generated and received with an ultrasonic probe 4 for longitudinal waves. Then, a defect signal RLF of longitudinal wave mode reaching a received signal amplifier 6 is selected with a gate circuit 7 and shown on a display unit 8. Thus, the existence of a defect is detected at the press-fit part.