| 摘要 |
The present invention provides a method for producing a rare earth sintered magnet, capable of reducing variation in magnetic characteristics of a rare earth sintered magnet and suppressing deformation of the rare earth sintered magnet. Disclosed is a method for producing a rare earth sintered magnet, including the steps of:
preparing a slurry including an alloy powder and a dispersion medium at a predetermined ratio, the alloy powder containing at least a rare earth element;
preparing a cavity enclosed with a mold, and an upper punch and a lower punch spaced from and opposed to each other, at least one of the upper punch and the lower punch being movable toward and away from the other one, at least one of the upper punch and the lower punch including an outlet for discharging the dispersion medium of the slurry and filtering the slurry, the mold having a cross sectional shape perpendicular to the sliding direction of the upper punch or the lower punch, the cross sectional shape being enclosed with an approximately arc-shaped outer circumference, an approximately arc-shaped inner circumference, and a pair of side circumferences connecting between the outer circumference and the inner circumference, a ratio of a distance between farthest ends of a pair of side circumferences to a distance between a top end of the outer circumference and a top end of the inner circumference being 1.5 or more, the upper punch or the lower punch being allowed to slide in a through-hole formed in the sliding direction along an outer peripheral surface including the outer circumference, an inner peripheral surface including the inner circumference, and the side circumference surfaces including the side circumferences;
injecting the slurry into the cavity in a state where the upper punch and the lower punch remain stationary to fill the cavity with the slurry, a magnetic field being applied to the cavity;
producing a molded body of the alloy powder by press molding in the magnetic field, the upper punch and the lower punch coming closer to each other while applying the magnetic field; and
sintering the molded body;
wherein the slurry is injected into the cavity so that the slurry travels from one place of the top end in the cross section perpendicular to the sliding direction of one of the outer peripheral surface and the inner peripheral surface, to one place of the top end in the cross section perpendicular to the sliding direction of the other one of the outer peripheral surface and the inner peripheral surface. |
