| 摘要 |
PURPOSE:To detect a surface or internal flaw with high sensitivity, by providing an inspection coil to the surface of a material to be inspected in a separable manner to form a high static magnetic field to the material to be inspected and vibrating the inspection coil by the change in the static magnetic field when there is a flaw in the material to be inspected. CONSTITUTION:A slab 1 being a material to be inspected is fed to the longitudinal direction and N and S poles 2 are provided to both sides of said slab 1 in the lateral direction thereof to form a static magnetic field. An inspection coil 3 is suspended from a support material 5 by a coil spring 6 so as to be capable of being contacted with and separated from the slab 1. Then, a flaw is inspected by the inspection coil 3 while the slab 1 is fed. When the slab 1 has the flaw 14 at this time, disturbance is generated in the static magnetic field and an induction current is flowed to the inspection coil 3 which is, in turn, vibrated in the up-and-down direction by the Fleming's rule and the moving distance thereof is detected by a distance sensor 4. Because the static magnetic field of the material to be inspected is made high to detect the movement of the inspection coil, flaw detection can be performed with high sensitivity and lift-off can be made large. |
