R-TM-B RADIAL ANISOTROPIC RING MAGNET, PROCESS FOR PRODUCTION OF THE SAME, METAL MOLD FOR PRODUCING THE SAME, AND ROTOR FOR BRUSHLESS MOTOR

摘要

A method for producing a radially anisotropic ring magnet having at least one axial groove on the inner surface comprises using a die comprising a cylindrical, magnetic core, a magnetic sleeve having an axial ridge in alignment with the groove on the outer surface and disposed on an outer peripheral surface of the core, and an outer, cylindrical die member defining a cavity for forming the ring magnet with the magnetic sleeve, and compression-molding magnet powder charged into the cavity while applying a magnetic field in a radial direction, and a radially anisotropic ring magnet substantially having a composition of R-TM-B, wherein R is at least one of rare earth elements including Y, TM is at least one of transition metals, and B is boron, having at least one axial groove on the inner surface, and magnetized such that centerlines between magnetic poles do not overlap grooves.