| 摘要 |
PROBLEM TO BE SOLVED: To facilitate assembly and to favorably maintain bearing characteristics irrelevant to a change in the environment such as temperature. SOLUTION: A bronze outer cylindrical body 38 is fastened around a bronze inner cylindrical body 36 in the axial intermediate position by an interference fit so as to be formed into a sleeve body 32 and a lubricating oil retainer hole 40 is formed between them. After cutting the swelling part of the internal circumferential face of the inner cylindrical body 36 after the fastening, herringbone grooves 42 are provided in the top/bottom of the internal circumferential face of the inner cylindrical body 36, and spiral grooves 44 are provided in the top/ bottom end surfaces of the inner cylindrical body 36. Then, electroless nickeling is applied on the internal circumferential surface and the top/bottom end surface part of the inner cylindrical body 36. The sleeve body 32 is externally fitted around a shaft part 16 of a fixed shaft body 14 between the top/bottom thrust members 18 and 20 in the inner cylindrical body 36. Lubricating oil is made to continuously flow over the lubricating oil retainer hole 40, top/bottom thrust dynamic pressure bearing parts 52 and 54, and top/bottom radial dynamic pressure bearing parts 48 and 50. A rotor hub 34 is externally fitted and fixed to the upper end outer circumferential part of the outer cylindrical body 38.
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