FABRICATION OF MAGNETIC POLE UNIT

PURPOSE:To facilitate fabrication of a magnetic material unit free from electric loss by a method wherein projections are provided on each confronting face of a pair of magnetic pole pieces to form a non-magnetic member between both the pole pieces and, at the same time, to couple both the pole pieces through the non-magnetic member. CONSTITUTION:The magnetic material unit 10 consists of a pair of pole pieces 12 and the non-magnetic member 14 located between the two pole pices 12. In order to accommodate a rotatable permanent magnet rod, a semicircular cut-out 16 is made on each pole pieces 12 at the center of this magnetic material unit where both the pole pieces 12 face each other. Pole-faces 18 of the magnetic material 10 can be switched from magnetization to damagnetization and vice versa by rotating the rotatable permanent magnet rod. The pole pieces 12 are fabricated by cold drawing, etc. and are provided with, for example, a plural number of projections 22 of non-magnetic or magnetic substance with flanges 22b on flat faces 20 of each pole piece 12 by means of welding or others in order to form the non-mag netic member 14 of, for example, aluminum, zinc or others by casting using the two magnetic pole pieces 12 as part of a metallic casting mold. Thereby, the two pole pieces 12 can securely be fitted.