| 摘要 |
PURPOSE:To obtain a cylindrical Mn-Al-C alloy magnet for multipolar magnetization having uniform distribution of the magnetic characteristic in the axial direction by a method wherein when outer periphery restricting compression processing is to be performed to a hollow body type billet, the billet is made to have thinner thickness in proportion to nearness to the edge face part of the billet. CONSTITUTION:Inclining parts as to reduce continuously the inside diameter in proportion to going to the inside from the edge face are provided at the edge parts of a cylindrical body type billet consisting of an alloy for Mn-Al-C magnet, and compression processing is performed in the axial direction of the hollow body in the condition constricting the outer periphery, and making inner periphery freely at the temperature of 530-830 deg.C. Accordingly, the edge parts receive compressive force per unit area larger as compared with the other part to make plastic deformation to be generated easily, and receive nearly the uniform plastic processing with the other part. Therefore, distribution of the magnetic characteristic in the axial direction is unified, distribution of surface magnetic flux density when multipolar magnetization is performed can be nearly unified, and can be made to have high performance as a magnet for multipolar magnetization to be used for a motor including a magnet for rotor. |
