Manufacturing method of sintered magnet, graphite mold for hot press, and manufacturing method of graphite mold for hot press

摘要

To provide a method of manufacturing an R-Fe-B based sintered magnet, high in shape accuracy and less in material loss, and a graphite mold for hot press.SOLUTION: An R-Fe-B based sintered magnet is manufactured by placing an R-Fe-B based porous magnet 4 in a graphite mold 1 for hot press and pressurizing with punches 2, 2' while heating a dice 3. The graphite mold 1 for hot press includes the dice 3 and the punches 2, 2' which have a direction defined by a pressure axis direction (Z axis) and a vertical direction vertical to the pressure axis direction. The coefficient (α) of thermal expansion in the pressure axis direction of the dice 3 is larger than the coefficient (α, α) of thermal expansion in the vertical direction of the dice 3. Irregular deformation of a material can be prevented by setting a cutting direction, where a coefficient of thermal expansion is largest, to the pressure axis direction of the dice 3.SELECTED DRAWING: Figure 1