| 摘要 |
PURPOSE:To improve the roundness of a ring-shaped magnetic material of rectangular rolled material by concentrically superposing more than two magnetic materials so that the butted parts of the materials are not superposed and spot welding the prescribed positions in the vicinity of the butted parts. CONSTITUTION:A ring-shaped magnetic material having a butted part is formed by forming a rolled material cut in rectangular shape in the prescribed length and comprening and rotating the material between a mandrel and a rubber roller, and a plurality of such as two ring-shaped magnetic materials of inside and outside rings 2, 3 are concentrically superposed by displacing them so that the butted parts C, D are not superposed. The rings in the vicinity of the butted parts C, D of the rings 2, 3 are spot welded. In this manner, the rings 2, 3 can be reduced in thickness. Accordingly, the bending work can be facilitated, thereby improving the roundness. Further, the magnetic discontinuity can be improved. |
