| 摘要 |
PURPOSE: To detect defects in a metallic pipe along its circumferential direction with high efficiency by placing along the same axis inside a water tank a predetermined number of angle probes each of which is in the form of a conical surface with a specific apex angle. CONSTITUTION: A plurality of probes 11 are angle probes each having a vibrator 12 which transmits and receives ultrasonic waves, with the surface configuration of the vibrator 12 formed by a part of a surface obtained by cutting a cone with an apex angle of 2θi at an outside diameter D and at a height W in the circumferential direction. The probes 11 are arranged along the same axis (pipe axis) inside a water tank 13 by a number and intervals both of which are determined by the spiral feed rate of a steel pipe 1 and the effective probing portion B of the probe 11. A lift portion 16 comprising an adjusting screw is provided between a supporting block 14 and a holding block 15, and the center of curvature of the probe 11 which the tank 13 is made to coincide with the axis of the pipe 1. Since the tank 13 itself is brought close to and away from the pipe 1, it supported by a lift 17. As the result, even if the outside diameter of the pipe 1 varies, the vibrator surface of the probe 11 can be placed concentric with the pipe 1, and defects in the pipe 1 along its circumferential direction can be detected with high efficiency using a simple device constitution. |
