| 摘要 |
PURPOSE:To improve the performance in the detection of defects in an axial direction by winding spirally a coil. CONSTITUTION:Magnets 11 of a disc shape which are magnetized in an axial direction are successively arranged via disc-shaped cores 12 in such a way that the magnetic poles thereof face each other, thereby forming a circular cylindrical body 13. A coil 14 is spirally wound on the outside circumferential surface of said body. When such transducer is inserted into a fine tube and is operated, eddy current is generated by the high frequency current flowing in the coil 14, and the magnetic field in the direction perpendicular or parallel to the axial direction is generated. The force changing periodically in direction is generated by the mutual effect of the magnetic field and eddy current changing at a specified period. A plate wave is generated by said force, and propagates spirally in the wall of the fine tube. The reflection wave thereof is generated in a defective part whereby the detection of the defect is made possible. |
