| 摘要 |
PURPOSE:To detect a welding defect in the welded part of a thin sheet whose thickness is a specific value or lower. CONSTITUTION:The position of a welded part 7 in a material 6 under test is detected by a welded-position detection part 8 with reference to the material 6, under test, which has been conveyed and whose thickness is 1mm or lower. The material 6 under test is fixed under a condition under which an ultrasonic beam from an ultrasonic probe 9 coincides with the welded part 7. The ultrasonic probe 9 is moved in the lengthwise direction of the welded part 7 by a flaw-detection mechanism part 10 by keeping a condition under which ultrasonic waves impinge vertically on the surface of the welded part 7. On the other hand, the ultrasonic probe 9 which has received an electric signal from the transmission side of a transmission-reception part 12 generates ultrasonic waves, it receives reflected waves from the surface of the welded part 7 again, it sends the reflected waves to the reception side of the transmission-reception part 12, an amplified signal is judged by a judgment and processing part 13 by using a predetermined judgment level as a reference, and whether the welded part 7 is good or not is judged. |
