| 摘要 |
PURPOSE:To decide whether or not the welding of a nugget part is acceptable automatically by detecting a lateral ultrasonic wave which reacts with only the nugget part and a sound wave which is transmitted through the nugget part, and decide whether or not a spot weld zone is acceptable. CONSTITUTION:When the lateral ultrasonic wave is applied to a steel late 2 from a transmitting probe 4, the ultrasonic wave is propagated in the steel plate 2 and when the nugget 1 is formed, the ultrasonic wave is propagated to the steel plate 3 through the nugget 1 and received by a receiving probe 5. Then the output of the probe 5 is supplied to a sound wave detecting circuit 6 and its maximum value is held at the peak by a peak holding circuit 7. Then a circuit 8 finds the width (diameter) (a) and area S' of the nugget from a specific expression based upon the output detection time (t) of the circuit 7, the moving speed V of the material to be inspected, and the diameter (d) of an ultrasonic wave source. A storage circuit 9, on the other hand, finds the area S of the nugget from the output of the circuit 7. Then a judgement circuit 10 judges whether or not spot welding is normal from such acceptance/rejection condition that smaller area between S and S' is larger than a prescribed value. |
