| 摘要 |
PURPOSE:To enhance the reliability of a welded part by certainly discriminating the welded part from a close adhesive part, by vertically applying a magnetic field to a member to be inspected from an electromagnetic ultrasonic apparatus to generate a vibration wave and detecting the welded part by a transversal wave right-angled to said vibration wave. CONSTITUTION:Electromagnetic ultrasonic apparatuses 20A, 20B each consisting of an electromagnet 21 and a transmission coil 22 are arranged in opposed relation to each other through a pair of thin steel plates 11A, 11B and, when a current is made to flow to an exciting coil 23 from a DC power source 24, eddy currents flow to the surface of the thin steel plates 1 by magnetic fluxes phiA, phiB to vibrate the same to become ultrasonic waves. A transversal wave is generated at a right angle to an ultrasonic wave propagating direction and propagates to the welded part 26 of the thin steel plates to become a transparent transmitted echo but does not propagate to a close adhesive part to become only a nozzle echo. Therefore, the acceptance of the welding of the welded part being a nugget part or the close adhesive part and the welded part can be certainly discriminated and the reliability of the welded area can be increased.
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