PROCESS FOR PRODUCING RADIALLY ANISOTROPIC MAGNET

摘要

A process for producing a radially anisotropic magnet through charging of a magnet powder in a cavity of cylindrical magnet molding die assembly equipped with a die, a core and upper and lower punches, applying of a magnetic field to the magnet powder and pressurizing of the magnet powder by means of the upper and lower punches to thereby attain molding of the magnet powder according to a horizontal magnetic field vertical molding technique, characterized in that the upper punch is formed in divided form so as to realize partial pressurization, and that in the molding of the magnet powder charged in the die assembly cavity according to a horizontal magnetic field vertical molding technique, the magnet powder is partially pressurized by the use of divided part of the upper punch and the lower punch so as to attain at the partially pressurized part of the magnet powder a density increase to a level of from 1.1 times the packing density to below the density of molded item, and that thereafter the whole magnet powder within the cavity is pressurized under a pressure not lower than that at the preceding partial pressurization by means of the entirety of the upper and lower punches to thereby carry out principal molding.