A spindle motor includes a housing, a rotor hub section arranged rotatably with respect to the housing, a sleeve section, a shaft fit rotatably in the sleeve section, and a thrust plate mounted to the sleeve section opposite to an end surface of the shaft. A thrust dynamic pressure bearing has a dynamic pressure bearing groove formed on the thrust plate, the thrust dynamic pressure bearing including lubricating oil at a relative slide interface between the thrust plate and the end surface of the shaft. The dynamic pressure bearing groove and a circumferential portion of the thrust plate are formed by etching, and a radial dynamic pressure bearing includes lubricating oil at a peripheral interface between the shaft and the sleeve section.
A spindle motor having a bearing housing and a thrust bearing fitted in the bearing housing at the lower end of the latter, in which an inclined part is formed on the outer peripheral edge at the lower end of the thrust bearing, and the outer diameter part of the thrust bearing is fitted in a coupling bore formed in the end surface of the bearing housing, the end surface of the bearing housing being pressed uniformly in the axial direction over the entire circumference around the coupling bore to cause the bearing housing to plastically flow around the coupling bore in order to cover the above-mentioned inclined part of the thrust bearing. The above-mentioned covering part formed in the bearing housing through plastic flow can exhibit a high bonding strength between the bearing housing and the thrust bearing in the spindle motor without deteriorating the sealing ability of the spindle motor, due to a shearing force and a residual contact pressure of the covering part.
The fixed shaft type spindle motor of the invention has a fixed shaft extending from a base and a rotor hub rotatably supported thereon through a bearing. Where the bearing is a compound ball bearing, a larger diameter portion of a stepped connection member is fixed within the upper end the outer ring of the compound ball bearing and a smaller diameter portion of the connection member is fixed to the rotor hub. The rotary shaft type spindle motor has a rotary shaft extending within the rotor hub, and the rotary shaft is rotatably supported through the bearing, with the larger diameter portion of the connection member fixed within the lower end of the outer ring of the compound ball bearing and the smaller diameter portion of the connection member fixed to the base.
