| 摘要 |
PURPOSE:To obtain a cylindrical permanent magnet, in which there is no crack and which has excellent magnetic characteristics and a multipolar and anisotropic section and an isotropic section in the diametral direction as coaxial cylindrical sections, by controlling distances among magnets and distances among ferrite powder and the magnets. CONSTITUTION:A plurality of magnets 2 are arranged to a cylindrical cavity section 10 so as to generate a magnetic field in the radial direction, and distances (p) among the magnets 2 and distances (t) among ferrite powder and the magnets 2 are adjusted, thus integrally forming an anisotropic section and an isotropic section to a cylindrical ferrite magnet after sintering to coaxial cylindrical shapes. The thickness (t) of a cylinder 5 consisting of a non-magnetic material disposed to the inside of the magnet bodies 2 is brought to 0.5-4.0mm., preferably, 1.5-3.0mm.. When the thickness (t) is too thin, the cylinder 5 cannot resist pressure on molding and is broken: when the thickness (t) is too thick, the intensity of a magnetic field in the cavity section 10 of the permanent magnets 2 used for orienting slurry reduces. The intervals (p) of the permanent magnets 2 are brought to 0<=K<=5, preferably, 0<=K<=3 when the width of the permanent magnet body 2 is pm and p=K.pm is formed. |
