Abstract: A fluid dynamic pressure effect can be sufficient without receiving a large effect of viscous friction of lubricating oil with changes in the environmental temperature in which it is used, and smooth starting of the rotating shaft can be ensured by regulating the gap between the rotating shaft and bearing within a suitable range. An outer diameter of the bearing, D, a length in an axial direction of the bearing, L, a gap at a radial side which is between the rotating shaft and the bearing, C, and an inclining height of the bearing end surface to which the flange is faced, ?, satisfy the expression L/D<C/?. It is preferable that the inclining height, ?, be 2 to 6 ?m, the inner diameter of the bearing be 1 to 3 ?m, and the gap at a radial side, C, be 1 to 4 ?m.

Abstract: A sintered fluid dynamic pressure bearing completely seals or decreases the sizes of gaps formed in pores by shrinkage when a resin impregnated therein shrinks. The fluid dynamic pressure bearings can be reliably and easily produced using fewer processes while superior quality is maintained.

Abstract: A production method for a fluid dynamic pressure sintered bearing includes: preparing a sintered bearing having a porosity of 8 to 20 vol % as a material; and controlling at least one of an overall length, an outer diameter, and an inner diameter of the sintered bearing by repressing the sintered bearing. The production method further includes: forming grooves for generating a fluid dynamic pressure on a bearing surface of the sintered bearing by performing repressing and plastic working on the sintered bearing; and sealing pores exposed on the bearing surface by infiltrating a resin into at least the pores; and barreling entire surface of the sintered bearing by magnetic barreling or electromagnetic barreling.

Abstract: A production method for sintered bearing member comprises: compacting a metal powder into a green compact, sintering the green compact into a sintered compact; impregnating a resin solvent into the sintered compact, and removing the resin solvent adhering to a surface of the sintered compact, thereby exposing a matrix as sintered on a surface of the sintered compact. Pores existing in portions other than the surface are sealed with the resin.

Abstract: A fluid dynamic pressure effect can be sufficient without receiving a large effect of viscous friction of lubricating oil with changes in the environmental temperature in which it is used, and smooth starting of the rotating shaft can be ensured by regulating the gap between the rotating shaft and bearing within a suitable range. An outer diameter of the bearing, D, a length in an axial direction of the bearing, L, a gap at a radial side which is between the rotating shaft and the bearing, C, and an inclining height of the bearing end surface to which the flange is faced, ?, satisfy the expression L/D<C/?. It is preferable that the inclining height, ?, be 2 to 6 ?m, the inner diameter of the bearing be 1 to 3 ?m, and the gap at a radial side, C, be 1 to 4 ?m.

Abstract: The spindle motor includes a rotational shaft 30 which has a conical portion 34, whose outer surface gradually widens toward a thrust dynamic pressure bearing 70, and a straight portion 33 with a fixed outer diameter. Radial dynamic pressure bearing 60 supports the radial load of the rotating shaft 30. The radial bearing has a conical bearing surface 64 and a straight bearing surface 63 corresponding to the conical portion 34 and the straight portion 33 of the rotating shaft 30, respectively. Rotating shaft 30 is supported and aligned during rotation by fluid dynamic forces generated by the conical portion 34.

Abstract: A fluid dynamic pressure bearing composed of a cylindrical sintered compact includes: a thrust region which is formed on an end surface of the bearing and receives at least a thrust load; a roughed portion having small peaks and valleys formed on the thrust region; and thrust recesses for generating thrust fluid dynamic pressure, which are formed on the thrust region.

Abstract: A cylindrical fluid dynamic pressure bearing includes: a shaft hole which has an inner peripheral surface and into which a shaft is inserted; plural separation grooves formed at equal intervals on the inner peripheral surface in a circumferential direction, the separation grooves extending in an axial direction and dividing the inner peripheral surface in the circumferential direction; and circular arc surfaces formed on the inner peripheral surface between the separation grooves, the circular arc surfaces being eccentric with respect to a center of an outer diameter of the bearing and being inwardly biased toward one circumferential direction, wherein the number of the separation grooves is 3 to 6, the number of the circular arc surfaces is the same as the number of the separation grooves, and the separation groove has a width corresponding to an angle of 8 to 20 degrees in the circumferential direction of which a center is an axial center of the bearing, and has a maximum depth of 0.05 to 0.15 mm.

Abstract: A production method for sintered bearing member comprises: compacting a metal powder into a green compact, sintering the green compact into a sintered compact; impregnating a resin solvent into the sintered compact, and removing the resin solvent adhering to a surface of the sintered compact, thereby exposing a matrix as sintered on a surface of the sintered compact. Pores existing in portions other than the surface are sealed with the resin.

Abstract: A sintered bearing is produced by a production method comprising: compacting a metallic raw material powder into a bearing green compact; sintering the green compact into a sintered compact; forming a resin coating 20 over the entire surface of the sintered compact; removing the resin coating 20 on a bearing surface 14a of the sintered compact; and impregnating a lubricating fluid L through the bearing surface 14a from which the resin coating 20 is removed.

Abstract: A bearing unit comprises a bearing 60 formed of a sintered metal in which a magnetized magnetic powder is dispersed in its matrix and at least pores exposed on a bearing surface thereof are sealed by impregnation with a resin; a non-magnetic housing 90 accommodating the bearing 60; and a lubricating fluid M made of a magnetic fluid.

Abstract: A production method for a sintered bearing, comprises compacting a raw metallic material powder into a bearing green compact; sintering the green compact into a sintered compact; and forming a resin coating over the entire surface of the sintered compact by electrodeposition.

Abstract: A spindle motor for magnetic disc device includes a hub having an inside and an outer peripheral side on which a magnetic disc is mounted, a rotary shaft having an axial direction and coupled with the hub so as to be integrally rotated therewith, with the motor being arranged on the inside of the hub. The hub, the rotary shaft and a part of the motor constitute a rotary body. A radial bearing having a length in the axial direction of the rotary shaft, for supporting the rotary body in a direction crossing the rotary shaft, and a thrust bearing for supporting the rotary body in the axial direction of the rotary shaft are provided. The thrust bearing has an outer diameter greater than the length of the radial bearing, and is arranged at a position which is inside of the motor and diametrically inward of the hub.

Abstract: A spindle motor comprises a housing 10 including a through hole with a pair of apertures, one of the apertures being closed by a thrust plate 70 and the other aperture being open; a bearing 60 accommodated in the housing 90; a rotating shaft 30 inserted into the bearing 60; a displacement restraining structure for restraining movement of the rotating shaft 30 toward the open aperture by engaging the rotation shaft 30 with the bearing 60; a rotating member secured to the rotating shaft; and a motor generating electromagnetic function for rotating the rotating member. The through hole of the housing 90 includes a large diameter portion 92A at the thrust plate 70 side and a small diameter portion 92B at the open aperture side, and a stepped portion 93 is formed at a transition portion between the large diameter portion 92A and the small diameter portion 92B.

Abstract: A production method for a sintered bearing, comprises compacting a raw metallic material powder into a bearing green compact; sintering the green compact into a sintered compact; and forming a resin coating over the entire surface of the sintered compact by electrodeposition.

Abstract: A spindle motor used in a magnetic disc apparatus having a hub to which a magnetic disc is mounted and a rotary shaft to which the hub is fixed. The rotary shaft is located in a bearing casing having one end opened and the other end closed by a hydrodynamic pressure radial bearing, the rotary shaft being supported by a hydrodynamic pressure thrust bearing and the hydrodynamic pressure radial bearing. An inner diameter D and a width L of the hydrodynamic pressure radial bearing having a relationship of L/D<1.

Abstract: A spindle motor comprises a housing 10 including a through hole with a pair of apertures, one of the apertures being closed by a thrust plate 70 and the other aperture being open; a bearing 60 accommodated in the housing 90; a rotating shaft 30 inserted into the bearing 60; a displacement restraining structure for restraining movement of the rotating shaft 30 toward the open aperture by engaging the rotation shaft 30 with the bearing 60; a rotating member secured to the rotating shaft; and a motor generating electromagnetic function for rotating the rotating member. The through hole of the housing 90 includes a large diameter portion 92A at the thrust plate 70 side and a small diameter portion 92B at the open aperture side, and a stepped portion 93 is formed at a transition portion between the large diameter portion 92A and the small diameter portion 92B.

Abstract: A sintered bearing is produced by a production method comprising: compacting a metallic raw material powder into a bearing green compact; sintering the green compact into a sintered compact; forming a resin coating 20 over the entire surface of the sintered compact; removing the resin coating 20 on a bearing surface 14a of the sintered compact; and impregnating a lubricating fluid L through the bearing surface 14a from which the resin coating 20 is removed.

Abstract: A bearing unit comprises a bearing 60 formed of a sintered metal in which a magnetized magnetic powder is dispersed in its matrix and at least pores exposed on a bearing surface thereof are sealed by impregnation with a resin; a non-magnetic housing 90 accommodating the bearing 60; and a lubricating fluid M made of a magnetic fluid.

Abstract: The spindle motor includes a rotational shaft 30 which has a conical portion 34, whose outer surface gradually widens toward a thrust dynamic pressure bearing 70, and a straight portion 33 with a fixed outer diameter. Radial dynamic pressure bearing 60 supports the radial load of the rotating shaft 30. The radial bearing has a conical bearing surface 64 and a straight bearing surface 63 corresponding to the conical portion 34 and the straight portion 33 of the rotating shaft 30, respectively. Rotating shaft 30 is supported and aligned during rotation by fluid dynamic forces generated by the conical portion 34.