Abstract: A weld line formed by injection molding of a sealing member is formed at a circumferential position out of deepest portions of axial grooves, which form thinned portions of the sealing member (optimally, in a region of a cylindrical surface between the axial grooves in a circumferential direction). Thus, the sealing member is prevented from being provided with parts having locally markedly low strength, and hence damage to be caused by press-fitting is prevented.

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: An inner peripheral surface and a lower end surface of a bearing sleeve made of a sintered metal are each formed into a smooth cylindrical surface or a flat surface that does not have a dynamic pressure generating portion. Thus, a step of forming the dynamic pressure generating portion can be omitted from a manufacturing step of the bearing sleeve, and cost of dies can be markedly reduced. Further, the inner peripheral surface of the bearing sleeve is formed into the smooth cylindrical surface, and hence a radial dynamic pressure generating portion is formed on an outer peripheral surface of a shaft member. However, the outer peripheral surface of the shaft portion is accessible to tools, and hence the radial dynamic pressure generating portion can be formed easily with high accuracy. As a result, accuracy of a radial bearing gap is enhanced so that a bearing rigidity is enhanced.

Abstract: A sintered metal bearing member is provided that includes radial bearing surfaces arranged at two regions spaced apart from each other in an axial direction on an inner peripheral surface. The bearing member includes radial dynamic pressure generating portions in contact with the radial bearing surfaces. The radial dynamic pressure generating portions are formed on the radial bearing surfaces. The bearing member includes a thrust bearing surface arranged on at least one of the end surfaces and a thrust dynamic pressure generating portion for generating a dynamic pressure in the lubricating oil in contact with the thrust bearing surface. The thrust dynamic pressure generating portion is formed on the thrust bearing surface. The bearing member includes a middle relief portion arranged between the radial bearing surfaces in the axial direction. The middle relief portion has a larger diameter than the radial bearing surfaces.

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: A weld line formed by injection molding of a sealing member is formed at a circumferential position out of deepest portions of axial grooves, which form thinned portions of the sealing member (optimally, in a region of a cylindrical surface between the axial grooves in a circumferential direction). Thus, the sealing member is prevented from being provided with parts having locally markedly low strength, and hence damage to be caused by press-fitting is prevented.

Abstract: An inner peripheral surface and a lower end surface of a bearing sleeve made of a sintered metal are each formed into a smooth cylindrical surface or a flat surface that does not have a dynamic pressure generating portion. Thus, a step of forming the dynamic pressure generating portion can be omitted from a manufacturing step of the bearing sleeve, and cost of dies can be markedly reduced. Further, the inner peripheral surface of the bearing sleeve is formed into the smooth cylindrical surface, and hence a radial dynamic pressure generating portion is formed on an outer peripheral surface of a shaft member. However, the outer peripheral surface of the shaft portion is accessible to tools, and hence the radial dynamic pressure generating portion can be formed easily with high accuracy. As a result, accuracy of a radial bearing gap is enhanced so that a bearing rigidity is enhanced.

Abstract: When a bearing member (bearing sleeve (8)) is formed of a sintered metal comprising a middle relief portion (E), a lubricating oil can be impregnated and retained in inner pores of the sintered metal. Thus, when the lubricating oil in a middle relief space (E0) is drawn into a radial bearing gap side and lubricating oil pressure in the middle relief space (E0) decreases, the lubricating oil impregnated in the inner pores of the bearing sleeve (8) is drawn out from surface pores of the middle relief portion (E) and supplied into the middle relief space (E0). Thus, generation of negative pressure is prevented.

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 weld line formed by injection molding of a sealing member is formed at a circumferential position out of deepest portions of axial grooves, which form thinned portions of the sealing member (optimally, in a region of a cylindrical surface between the axial grooves in a circumferential direction). Thus, the sealing member is prevented from being provided with parts having locally markedly low strength, and hence damage to be caused by press-fitting is prevented.

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: 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.