| 摘要 |
PROBLEM TO BE SOLVED: To provide a spindle motor suitable for hard disk rotation driving of a hard disk driving apparatus, which has high rotation precision and hardly any deterioration of rotation precision which is caused by temperature change. SOLUTION: In a spindle motor, a rotor hub 8 as the rotating part member of a motor is rotatably supported around a shaft 2 disposed upright on a base 1, via a plurality of rolling bearings 3, 4 equipped with a rolling element between inner rings and outer rings. A cylindrical sleeve 5 opened in the upper part and the lower part is installed between the outer peripheral surfaces of the rolling bearing and the inner peripheral surface of a central vertical hole 9 of the rotor hub 8. Material of the sleeve 5 and material of outer rings 3b, 4b of the rolling bearings are constituted of iron based metal, having almost the same coefficients of expansion. Material of inner rings 3a, 4a of the rolling bearings and material of the shaft 2 are constituted of iron based metal which has almost the same coefficients of expansion. |
