| 摘要 |
A magnetic disk unit comprises a rotor (9), on which a magnetic disk (18) is mounted, and which is integrally formed with a sleeve portion (10) of a ball bearing unit, or with a spindle (5) of a spindle motor for driving the disk, or with an inner or an outer race of the ball bearing unit in a disk drive unit of the magnetic disk unit, so that the need for alignment of the rotor with respect to the rotary axis of the ball bearing unit is eliminated in assembly of the magnetic disk unit and the rotor (9) is free from radial vibrations in operation whereby the recording density and reliability of the disk unit can be improved and whereby the number of parts of the magnetic disk unit and the number of assembly steps are reduced. Consequently the manufacturing cost of the magnetic disk unit is reduced as compared with known units. |
