Abstract: A hydrodynamic bearing having a high performance and a long life and a manufacturing method for the same are provided by forming hydrodynamic grooves to have a sufficient depth with a high accuracy, and sealing remaining pores on a bearing surface. A shaft is inserted into a bearing hole of a sleeve so as to be relatively rotatable. The bearing hole has a bearing surface having hydrodynamic grooves.

Abstract: To generate the desired dynamic pressure with an inexpensive structure. A hydrodynamic bearing device comprises a sleeve 1, a shaft 2, and oil 100. With the sleeve 1, a stepped portion 1b provided at one end and an inner peripheral face 1e extending linearly in the axial direction and continuously with the stepped portion 1b are formed by a working method that involves the use of a metal mold. The shaft 2 is inserted so as to be capable of relative rotation in the inner peripheral face 1e of the sleeve 1. The oil 100 fills the space formed between the inner peripheral face 1e of the sleeve 1 and the outer peripheral face 2a of the shaft 2. Dynamic pressure generation grooves 9a and 9b, which open in the axial direction at at least one end in the axial direction of the inner peripheral face 1e and are continuous in the axial direction from one end, are formed in the inner peripheral face 1e.

Abstract: A bearing stiffness of a sintered metal sleeve is prevented from lowering. A sleeve includes an inner section formed of metal powder for sintering and a resin for impregnation, and a surface deformation section which covers a surface of the inner section and is formed by shot blast process. Since the surface deformation section is formed by the shot blast process, the number of pores formed between the metal powder for sintering near the surface can be reduced. In this way, a supporting pressure at a bearing portion can be prevented from being released out through the pores, and the bearing stiffness can be prevented from lowering.

Abstract: A spindle motor including a rotor hub which is rotationally driven by a magnetic action of a rotational magnetic field generated when a current is applied to a wire wound around teeth of a stator core and a magnetic field of a magnet provided on a rotor. Herein, the stator core formed by laminating magnetic steel plates is mounted to an outer periphery of a supporting part of a rotation support shaft of the rotor hub, and the supporting part is made of sintered metal containing a ferromagnetic material. This spindle motor can suppress generation of vibration and noise even when it is reduced in size.