| 摘要 |
PURPOSE:To improve sensitivity in flaw detection by providing plural magnet bands which are so formed as to be wound at alternately different polarities in the circumferential direction with the same axial line and a coil wound perpendicularly to the respective winding directions of said bands. CONSTITUTION:For example, six pieces of bar-shaped magnets 30a-30f having respectively different polarities are wound on the circumferential surface of a cylindrical core 31 in such a way that the N poles and S poles thereof are arrayed alternately spirally at the same pitch Tr. A high frequency current coil 32 is wound atop the circumference of such plural magnet 30a-30f bands perpendicularly to the respective winding directions of the magnets 30a-30f, thereby constituting a titled transducer. The voltage signal by a Lamb wave L and the voltage signal by an SH wave are separated with time and only the ultrasonic wave SH reflecting and propagating in the direction theta3 from a defective part 23 is detected, by which the measurement is made possible even with the slight voltage signal generated from the slight defect and the defective part 23 is surely detected. |
