A method of manufacturing a sintered-type permanent magnet and die

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PROBLEM TO BE SOLVED : To provide a method for producing a radially anisotropic ring-shaped sintered R-Fe-B permanent magnet free from the occurrence of deformation and cracking and having excellent magnetic orientation, and to provide a die suitable for producing the magnet. SOLUTION : The method for producing a sintered permanent magnet comprises the steps of : pulverizing a coarse powder for a sintered R-Fe-B permanent magnet (R denotes at least one kind of rare earth element selected from rare earth elements including Y) to fine powder, and recovering the fine powder directly in a mineral oil, a synthetic oil or their mixture to form a slurry; injecting the slurry under pressure into a die cavity, in which the slurry is wet-molded in a magnetic field; heating the resultant green body under reduced pressure to remove the mineral oil, the synthetic oil or their mixture from the green body; and sintering the green body in vacuum, wherein the die comprises a die member with a hollow structure and a core arranged at the inner circumferential side of the die member via a ring-shaped cavity, the die member is provided with a slurry-injecting aperture for injecting the slurry under pressure, and an axial direction of the injecting aperture is deviated from a center of the core. COPYRIGHT : (C)2008, JPO&INPIT