METHOD FOR HARDENING RARE EARTH BASED PERMANENT MAGNET

摘要

PROBLEM TO BE SOLVED: To provide a method for hardening a rare earth based permanent magnet for which sinter has neither surplus nor deficit even having a thin thickness and a small diameter shape and which has a high magnetic characteristic and a proper forming size precision. SOLUTION: In this method rare earth based metal powder is minimized to make anisotropic magnet powder by a hydrogen occlusion method and the anisotropic magnet powder is filled into a mold and afterwards is hardened by excitation sinter in a predetermined heating pattern. In this case when a shrinking velocity of a deviation of the body to be hardened during the excitation sinter becomes blow 0.15mm/min, an electric current value is controlled to keep the shrinking velocity and also is held in the condition during a predetermined period.