DEFECT DETECTOR FOR LONG-SIZED BODY

摘要

PURPOSE:To detect a defect without requiring a submerged running mechanism by using ultrasonic transmitter-receivers arranged in a ring. CONSTITUTION:A transmission signal is successively transmitted to ultrasonic transmitter-receivers 5A to 5N at intervals of two or three ultrasonic transmitter-receivers from a transmitter 7 by a switch 9 to generate an ultrasonic wave 11, and this transmission is circulated once within one second. Dimensions of ultrasonic wave generation parts of transmitter-receivers 5A to 5N in the lengthwise direction of a long-sized body 3 are matched to the feed speed per minute of the long-sized body 3 to prevent omission of the check in the peripheral direction. Reflected waves obtained through transmitter- receivers 5A to 5N are detected by a receiver 10, and a single defect of >=10mum size is detected by observation of periodical reflected waves, and a group defect 4 of <1mum size is detected by frequency analysis of reflected waves. Thus, defects on all of the peripheral surface of the long-sized body are detected without a submerged running mechanism.