| 摘要 |
PURPOSE:To offer a brushless motor suitable for driving a hard disc to decrease thermal variation, and a manufacturing method. CONSTITUTION:A shaft 50, a hub 56 and a motor base 58 are formed of a material having the same linear coefficient of expansion as that of a hard disc 30. Accordingly, a brushless motor side is also deformed in correspondence with the deformation of the hard disc 30 when there is temperature variations therein. C surfaces MA and MB are formed on a disc holder 64 and clamper 72, so that contact displacement with the hard disc 30 is the same in up and down to lower thermal-off-track. The shaft 50 and motor base 58 are molded together as a unit by cold casting, so that corrosion, etc., caused by cavities in diecasting are diminished. The shaft 50, bearings 52, 54 and hub 56 are incorporated by press-fitting, so that clearance is reduced, and the thermal-off-track is also lowered. |
