| 摘要 |
PURPOSE:To enable accurate measurement of the thickness of metal material without removing any scale, by measuring the thickness of the scale adhering to material to be inspected varying the permeation depth thereof. CONSTITUTION:An exciting coil 3 is excited with an exciting power source 15 to form a magnetostatic field. Then, a pulse current flows through a receiving /transmitting coil 4 with a controller 14 to generate an eddy current in material to be inspected. The Lorentz's force is generated by the eddy current and the magnetostatic field to cause an elastic vibration in the material being inspected. An ultrasonic wave is generated by the elastic vibration and received with the coil 4. The velocity of the ultrasonic wave can be determined previously according to the quality of the material being inspected and it is compared with the results of measurement obtained by a given sequence to learn the thickness of a tube to which a scale 1c adheres. The true thickness of the tube can be learned by subtracting the thickness of the scale from the total thickness. The thickness of the scale 1c can be found by adjusting the permea tion depth of eddy current in the material being inspected to minimize the sound pressure level.
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