| 摘要 |
PROBLEM TO BE SOLVED: To reduce the manufacturing cost of a swing arm for a magnetic disk. SOLUTION: A metal made upper arm base material 12, an intermediate arm base material 22 and a lower arm base material 32 of a swing arm for a magnetic disk are provided with cylinder parts i5, 25, 35 consisting of large diameter upper cylinder parts 16, 26, 36 and smail diameter lower cylinder parts 17, 27, 37 which are continued via differences in ievei 18, 28, 38. A bearing hole 19 is provided in the cylinder part 15 of the upper arm base material 12, and bearing holes 29, 39 consisting of large diameter hole parts 29a, 39a and bearing hole parts 29c, 39c are respectiveiy provided in cylinder parts 25, 35 of tThe intermediate arm base material 22 and the lower arm base material 32. With respect to the upper arm base material 12, the large dismeter upper cylinder part 16 is supported by abutting the difference in leveL 18 on the upper surface opening side of the large diameter hole part 29a of the intermediate arm base material 22, and with respect to the intermediate arm base material 22 and the lower arm base material 32, the large diameter upper cylinder part 26 is supported by abutting the difference in level 28 on the upper surface opening side of the large diameter hole part 29a, and the swing arm is integrally combined by preparing a bearing metal hole 41 with the whole.
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