Abstract: A fluid dynamic bearing device 1 includes: a shaft member 2; a bearing sleeve 8 that has the shaft member 2 inserted into the inner periphery thereof; a housing 7 that holds the bearing sleeve 8 on the inner periphery thereof and has a bottomed cylindrical shape having an opening at an end portion on one axial side; and a seal member 9 provided at the opening of the housing 7. The seal member 9 has a disk portion 9a disposed on one axial side of the bearing sleeve 8, and a protrusion (cylindrical portion 9b) protruding to the other axial side from an outer diameter end of the disk portion 9a. An outer peripheral surface 9c of the seal member 9 is fixed to an inner peripheral surface 7a1 of the housing 7.

Abstract: A fluid dynamic bearing device 1 includes: a shaft member 2; a bearing sleeve 8 that has the shaft member 2 inserted into the inner periphery thereof; a housing 7 that holds the bearing sleeve 8 on the inner periphery thereof and has a bottomed cylindrical shape having an opening at an end portion on one axial side; and a seal member 9 provided at the opening of the housing 7. The seal member 9 has a disk portion 9a disposed on one axial side of the bearing sleeve 8, and a protrusion (cylindrical portion 9b) protruding to the other axial side from an outer diameter end of the disk portion 9a. An outer peripheral surface 9c of the seal member 9 is fixed to an inner peripheral surface 7a1 of the housing 7.

Abstract: A shaft member for a fluid bearing device includes, on an outer peripheral surface thereof, two bearing surfaces (31 and 32) separated from each other in an axial direction, and a middle relief portion (33) formed between the bearing surfaces (31 and 32) and having a diameter smaller than a diameter of the bearing surfaces. The middle relief portion (33) includes a cylindrical surface portion (331) having a ground surface, and stepped portions (332) arranged on both axial sides of the cylindrical surface portion and having a diameter difference from the cylindrical surface portion.

Abstract: A shaft member for a fluid bearing device includes, on an outer peripheral surface thereof, two bearing surfaces (31 and 32) separated from each other in an axial direction, and a middle relief portion (33) formed between the bearing surfaces (31 and 32) and having a diameter smaller than a diameter of the bearing surfaces. The middle relief portion (33) includes a cylindrical surface portion (331) having a ground surface, and stepped portions (332) arranged on both axial sides of the cylindrical surface portion and having a diameter difference from the cylindrical surface portion.

Abstract: Grinding is performed on an outer peripheral surface of a shaft member while rotationally driving the shaft member under a state in which both end surfaces of the shaft member are sandwiched between a pair of support portions. A convex surface is formed on one axial end surface of the shaft member or an end surface of one of the pair of support portions, and a flat surface is formed on the other of the one axial end surface of the shaft member and the end surface of the one of the pair of support portions. The flat surface and an apex of the convex surface are brought into contact with each other to support one axial end portion of the shaft member.

Abstract: Grinding is performed on an outer peripheral surface of a shaft member while rotationally driving the shaft member under a state in which both end surfaces of the shaft member are sandwiched between a pair of support portions. A convex surface is formed on one axial end surface of the shaft member or an end surface of one of the pair of support portions, and a flat surface is formed on the other of the one axial end surface of the shaft member and the end surface of the one of the pair of support portions. The flat surface and an apex of the convex surface are brought into contact with each other to support one axial end portion of the shaft member.

Abstract: Grinding is performed on an outer peripheral surface of a shaft member (2) while rotationally driving the shaft member (2) under a state in which both end surfaces of the shaft member (2) are sandwiched between a pair of support portions (a backing plate (74) and a pressure plate (75)). A convex surface (2a6) is formed on one axial end surface of the shaft member by swelling an inner-diameter portion thereof, and a flat surface is formed on an end surface (75a) of the pressure plate (75) configured to support the convex surface in a contact manner. The end surface (75a) of the pressure plate (75) and an apex (2a7) of the convex surface (2a6) of the shaft member (2) are brought into contact with each other to support one axial end portion of the shaft member (2).

Abstract: Providing a fluid dynamic bearing device, wherein the outer member comprises a member formed by a pressing process on a plate member, the radial bearing surface and at least the one of the thrust bearing surfaces of the outer member being formed by the pressing process, and wherein at least a part of the inner member, which forms the radial bearing surface and the thrust bearing surfaces of the inner member, is made of a sintered metal.

Abstract: A shaft member is provided with a shaft portion and a flange portion coupled with a lower end surface of the shaft portion. The shaft portion is formed into a complete circular shape in cross section, and the flange portion is provided with a through-hole in which a part of a circumferential region is retracted to a radially outer side with respect to a lower end of the shaft portion so as to exhibit a non-circular shape. The shaft portion and the flange portion are coupled with each other in a state of butting the lower end surface of the shaft portion and an upper end surface of the flange portion against each other. With this, a fluid path is formed by opening both end surfaces of the flange portion.

Abstract: Providing a fluid dynamic bearing device, wherein the outer member comprises a member formed by a pressing process on a plate member, the radial bearing surface and at least the one of the thrust bearing surfaces of the outer member being formed by the pressing process, and wherein at least a part of the inner member, which forms the radial bearing surface and the thrust bearing surfaces of the inner member, is made of a sintered metal.

Abstract: To manufacture a shaft member, which is excellent in both accuracy and strength at low cost, a shaft member (2) includes a shaft portion (21) and a flange portion (22) provided to one end of the shaft portion (21). The flange portion (22) has an annular shape, and the shaft portion (21) and the flange portion (22) are fixed by a welded portion (23), which is formed by applying a laser beam (35) to an upper end of an inner periphery thereof.

Abstract: A shaft portion is press-fitted to a flange portion, and a plastic working portion of a first jig is pressed against an upper end surface of the flange portion, whereby the flange portion is partially subjected to plastic deformation toward an inner peripheral side. With this, a caulked portion is formed between the flange portion and the shaft portion. Further, press-fitting and caulking are performed in a state in which both end surfaces of the flange portion are bound by a second jig and a third jig.

Abstract: In order to prevent degradation of accuracy and decrease of strength when a hydrodynamic bearing device is assembled and to reduce a cost of the hydrodynamic bearing device, a guide face serving as a guide when a disc hub is press fitted into a shaft member is formed on the shaft member. Then, the guide face, an outer circumferential surface of the shaft member adjacent to the guide face, and a boundary portion between the guide face and the outer circumferential surface are ground simultaneously, thereby forming a blunting portion having a radius r in the boundary portion. Thus, no edge remains between the guide face and the outer circumferential surface. Therefore, press-fitting resistance when the disc hub is press fitted to an end of the shaft member can be reduced.

Abstract: In order to easily and inexpensively manufacture a shaft member provided with a flange, which is capable of stably yielding excellent bearing performance, a shaft member (2) is provided with a shaft portion (2a) and a flange portion (2b) coupled with a lower end surface (2a2) of the shaft portion (2a). The shaft portion (2a) is formed into a complete circular shape in cross section, and the flange portion (2b) is provided with a through-hole (2c) in which a part of a circumferential region is retracted to a radially outer side with respect to a lower end of the shaft portion (2a) so as to exhibit a non-circular shape. The shaft portion (2a) and the flange portion (2b) are coupled with each other in a state of butting the lower end surface (2a2) of the shaft portion (2a) and an upper end surface (2b1) of the flange portion (2b) against each other.

Abstract: A hub (10) is a product formed by injection molding of a resin together with a core metal (13) as an inserted component, and the core metal (13) is exposed on a surface of the hub (10). With this configuration, a cavity of a die for molding the hub (10) is not divided by the core metal (13), and hence it is possible to suppress deterioration in fluidity of a resin due to arrangement of the core metal (13) in the cavity.

Abstract: To manufacture a shaft member, which is excellent in both accuracy and strength at low cost, a shaft member (2) includes a shaft portion (21) and a flange portion (22) provided to one end of the shaft portion (21). The flange portion (22) has an annular shape, and the shaft portion (21) and the flange portion (22) are fixed by a welded portion (23), which is formed by applying a laser beam (35) to an upper end of an inner periphery thereof.

Abstract: [Object] To manufacture at lower cost a shaft member for a fluid dynamic bearing device, which is excellent in accuracy of bearing surfaces and shape accuracy between the bearing surfaces, and which has high fixation strength between a shaft portion and a flange portion. [Solving Means] A shaft portion (21) is press-fitted to a flange portion (22), and a plastic working portion (31c) of a first jig (31) is pressed against an upper end surface (22a) of the flange portion (22), whereby the flange portion (22) is partially subjected to plastic deformation toward an inner peripheral side. With this, a caulked portion (23) is formed between the flange portion (22) and the shaft portion (21). Further, press-fitting and caulking are performed in a state in which both end surfaces (22a and 22b) of the flange portion (22) are bound by a second jig (32) and a third jig (33).

Abstract: In order to prevent degradation of accuracy and decrease of strength when a hydrodynamic bearing device is assembled and to reduce a cost of the hydrodynamic bearing device, a guide face 2c serving as a guide when a disc hub 3 is press fitted into a shaft member 2 is formed on the shaft member 2. Then, the guide face 2c, an outer circumferential surface 2a3 of the shaft member 2 adjacent to the guide face 2c, and a boundary portion between the guide face 2c and the outer circumferential surface 2a3 are ground simultaneously, thereby forming a blunting portion 2d having a radius r in the boundary portion. Thus, no edge remains between the guide face 2c and the outer circumferential surface 2a3. Therefore, press-fitting resistance when the disc hub is press fitted to an end of the shaft member 2 can be reduced.