Methods of producing radial anisotropic cylinder sintered magnet and permanent magnet motor-use cyclinder multi-pole magnet

摘要

A method involves the steps of using a mold having a core made of a ferromagnetic material, charging a mold cavity with a magnet powder, compacting the magnet powder while applying an orienting magnetic field according to the vertical compacting in horizontal magnetic field process, and sintering the compact, thereby producing a radially anisotropic annular sintered magnet in which the remanence in a radial direction of the annulus increases and decreases at intervals of 90° in a circumferential direction of the annulus, and the remanence in a radial direction over the entire circumference of the annulus has a maximum of 0.95-1.60 T and a minimum equal to 50-95% of the maximum. A method for preparing an annular multi-pole magnet for a permanent magnet motor involves magnetizing the magnet so that the boundary between N and S poles is located within the range that is centered at the radial direction where the remanence exhibits the minimum and extends ±10° therefrom in a circumferential direction.