Fluid dynamic bearing device and manufacturing method therefor

Abstract

To provide a fluid dynamic pressure bearing device that achieves high rigidity against moment without degradation in assembly precision and bearing performance, bearing sleeves are arranged in an axial direction and coaxiality of radial bearing surfaces formed on inner peripheral surfaces of the bearing sleeves is set to 3 μm or less. This secures width precision between the radial bearing gaps to prevent a degradation in bearing performance and a failure such as wear etc. caused by contact between a shaft member and the bearing sleeves. Further, a first radial bearing surface and a second radial bearing surface are provided on at least one sleeve, and this allows a sleeve assembly constructed from the bearing sleeves to be supported at least three positions in the axial direction in a process of assembling the sleeve assembly. As a result, assembly work can be carried out with two bearing sleeves prevented from being bent at a midway thereof, and highly accurate coaxiality between both the bearing sleeves is secured.