| 摘要 |
PURPOSE:To manufacture a rare earth magnet in which the reduction in the magnetic characteristic due to the defective orientation, etc., can be prevented from occurring, by subjecting a magnet powder contg. a rare earth element and a transition element to 'magnetic field compacting' while providing the surface of each of the punches with a ferromagnetic body having a specified thickness and applying a magnetic field to the magnet powder. CONSTITUTION:The magnet powder 6 contg. R (an element selected from the rare earth elements including Y) and a transition element is subjected to 'magnetic field compacting' in the space between the upper and lower punches 4 and in a magnetic field having its component in the axial direction of the above punches 4 which is effected by the coils 2. At this time, the surface of each of the upper punch 4 and/or lower punch 4 is provided with a ferromagnetic body 5. The total thickness of the ferromagnetic bodies 5 in the above axial direction (Lm) is selected so as to meet the following relational expressions: (CL-Lc)>=Lm>=1 mm, CL>=(Lm+Lc)>20mm and 20>=Lc>=1mm, wherein CL is the effective length of the coil 2 and Lc is the thickness of the compact out of the magnetic powder 6. As the above ferromagnetic body 5, that having >=10000G saturation magnetization (Bs) is preferred. Further as the above magnetic field, a pulsed magnetic field, the applying direction of which is almost identical to the applying direction of the compacting pressure and which has >=20kOe field strength and 10mus to 0.5s duration time, is preferred. |
