Ring magnet and manufacture of ring magnet

PURPOSE: To uniform the magnetic characteristics in the radius direction of a ring-shaped magnet by a method wherein the wall thickness and maximum energy product of the magnet are specified and the magnet posses a radial anisotropy. CONSTITUTION: A power body consisting of Nb-Fe-B superquenching flakes is premolded to obtain a compressed power body, a compacted material 1a formed by compacting the compressed powder in a disc at a high temperature is subjected to back extrusion molding and a cylinder-shaped material 1b is molded using a molding die. The molding of the material 1b is performed by a method wherein the material 1a is extruded, is inserted in the molding die and is heated using a heater at a temperature of 700°C desirable for the molding. A high-performance magnet having a wall thickness of 2nm or thinner and a maximum energy product of 30MGOe or more is obtained. Thereby, a ring- shaped permanent magnet having uniform magnetic characteristics in the respective directions of its radius direction, circumferential direction and extrusion direction can be easily manufactured. COPYRIGHT: (C)1993,JPO&Japio