| 摘要 |
PURPOSE:To enable a decrease in manufacturing manhour by compression- molding a magnetic material layer on the inner peripheral face of a cylindrical cover made of a nonmagnetic substance and by magnetizing the magnetic material layer. CONSTITUTION:A cavity 6 is filled with a mixture 7 of ferromagnetic powder and plastic powder, and a plunger 8 is advanced into the cavity 6 to compress and tamp the mixture 7 in it. Thus, a layer of the mixture 7 is formed into a cylinder on the inner peripheral face of the cylindrical cover 3. A flange 3a covers the end face of the gap between the cylindrical cover 3 and the circular hole 1a of a fixed die. After the mixture 7 layer is compression-molded, the cylindrical cover 3 is removed out of the die with the result that plastic is hardened. After the plastic hardens, the flange 3a is folded inward by stepwise press work and the like. After an iron core is inserted into the layer of the mixture 7 to bond both, the ferromagnetic powder is magnetized. |
