| 摘要 |
PURPOSE:To make it possible to detect a flaw on a body to be checked having the curved surface by providing a normal-direction control means by which the direction of the central axis of an ultrasonic wave beam which is transmitted from an ultrasonic probe is made to agree with the direction of a normal line at each position of the surface of the body to be checked. CONSTITUTION:A distance detecting means 9 operates the distance between a probe 1 and the surface of a body to be checked 15 and outputs the distance to a control means 10. At first, the means 10 moves the probe 1 to the initial scanning position with a signal from an input means 7. Constant distance control for making said distance constant is executed. With said distance kept constant, normal direction control is performed with the probe 1. The central axis of an ultrasonic wave beam is made to agree with the direction of the normal line on the surface of the body to be checked. Thereafter, ultrasonic flaw detection is executed under this state. When the ultrasonic wave beam is irregularily reflected by the effect of a flaw and the like in the surface of the body to be checked 15 during the period and the reflected wave cannot be received, constant distance control and normal direction control are performed at least at two points before and after the position of said flaw so as to hold said position. The distance and the normal direction at the position of the flaw undergo interpolation based on said controls. Thus the flaw detection is performed at the position of the flaw. |
