| 摘要 |
PURPOSE:To attain to enhance flaw detection capacity, by allowing ultrasonic beam to be obliquely incident at a specific angle from the bottom part of a turning stop in groove by a spot focusing probe while said beam is converged using water dipping method. CONSTITUTION:A turning stop pin groove under a clamping state sets a hexagon head bolt 13 in water 18 and a spot focusing probe 19 transmitting and receiving an ultrasonic wave is arranged in the vicinity of the surface of the water. The ultrasonic wave 20 emitted from the probe 19 is converged by an acoustic lens 21 and effectively propagated in the bolt 13 from the narrow area of the turning stop pin groove. The probe 19 is set in a state inclined with respect to the bottom part of the groove so that the refractive angle beta of an incident angle alphacomes to about 25-60 deg.. The ultrasonic wave propagated through the bolts 13 impinges against the outer periphery of the head part 14 of the bolt 13 and is reflected therefrom to reach the throat part 23 under a nech. If a flaw 24 is present in the throat part 23, the ultrasonic wave is reflected from the flaw part and a reflected wave (flaw echo) 25 is received by the probe 19 through the route reverse to the forward route. By this method, flaw detection capacity can be enhanced.
|
