| 摘要 |
PURPOSE:To prevent a surface echo from mixing in a gate, by a method wherein the reflected waves from a reflector arranged to the advance direction of ultrasonic waves reflected from a surface to be inspected are used as a reference echo and a gate position is set from the transmission requiring time. CONSTITUTION:When pulse voltage with several hundred volt is applied to a probe 2 from an ultrasonic flaw detector 1, ultrasonic waves 3 reflected from said probe 2 are transmitted through water 6 to reach the outer surface of a cylinder 4 to be inspected and divided into a pervious wave into the cylinder 4 to be inspected and a reflected wave. When the cylinder 4 to be inspected has no defect, the pervious wave is advanced through the cylindrical wall in a zigzag pattern but, when a defect 8 is present, a defect echo 9 is detected by the probe 2 through the course reverse to the incident wave. In addition, the reflected wave reflected from the mirror surface of the cylinder 4 is transmitted through water to reach a reflecting plate 13 and a reference echo 14 is generated. By the transmission requiring time of this reference echo 14, the gate position in the next ultrasonic pulse transmission cycle is set. |
