| 摘要 |
PURPOSE:To enable exact measurement of the diameter of a nugget by judging the nugget part and a corona bond part from a difference in the degree of attenuation of a reflected wave. CONSTITUTION:An ultrasonic probe 7 scans from an area I of a non-welded part 5 wherein an upper plate 1 and a lower plate 2 are not joined integrally, to an area V of the non-welded part 5 via an area II of a corona bond part 4 of a welded part 6, an area III of a nugget part 3 and an area IV of the corona bond part 4 again. An ultrasonic reflected wave emitted from the ultrasonic probe 7 is taken in the ultrasonic probe 7 at every time of minute scanning displacement. On the occasion when the welded part 6 including the nugget part 3 and the corona bond part 4 around it is scanned, the degree of attenuation of the reflected wave is determined, the nugget part 3 and the corona bond part 4 are judged from a difference in the degree of attenuation, and the amount of scanning displacement in a part judged to be the nugget part 3 is determined as the diameter of a nugget. By this method, the diameter of the nugget can be measured exactly. |
