| 摘要 |
PURPOSE:To obtain a cylindrical rare-earth magnet with stable finished dimensions and shape by a method wherein a column shape or cylindrical magnetic unit is inserted inside a cylindrical molded body made of rare-earth metal, iron and boron and the whole assembly is sintered. CONSTITUTION:Alloy, for instance alloy of the composition of Nd15Fe77B8, which is melted and cast under the argon gas atmosphere in a radio frequency melting furnance is ground into magnetic powder by a stamping mill or the like. The magnetic powder is made to fill a cylindrical mold and compression- molded to form a cylindrical magnetic unit 2. A cylindrical magnet 1 made of pure ion is formed and inserted inside the cylindrical magnetic unit 2. Then the assembly is sintered and aged under the argon the gas atmosphere at the optimum temperature. With this constitution, the cylindrical magnet is unified with the cylindrical unit made of pure iron and the difference between the maximum inner diameter and the minimum inner diameter can be minimized. |
