| 摘要 |
PURPOSE:To increase demagnetizing effects by a method wherein a positively and negatively inversional demagnetizing pattern is caused to act on a material to be demagnetized repeatedly in harmony with the movement of the material being rotated and moved. CONSTITUTION:A U-shaped magnet comprising a yoke, magnetic poles 6, 7 and exciting coils 8, 8A are installed on a support 9, the magnet being in contact with the under surface of a steel material 1. The steel material 1 is moved forwardly at low speed by a turning roller 10. Then the steel material 1 is divided into meshes to be demagnetized equivalent to the interval lp of N, S magnetic poles 6, 7 mutually different polarity and demagnetized on a mesh basis. A demagnetizing pattern applied to each mesh is such that it is positively and negatively inversional on a mesh basis, whereas the exciting coils 8 and 8A are connected in series. Each coil is then wound so that the current flowing through the exciting coils 8 and 8A are inversional. Accordingly, the magnetic pole 6 has the N polarity and the magnetic pole 7 has the S polarity in the first half semicycle in each mesh. On the contrary, the magnetic poles 6 and 7 have the S and N polarity, respectively in the second semicycle. Thus demagnetizer makes one or two rounds of the mesh to be demagnetized to link the demagnetized zones of the steel material 1 in an annular from. |
