Ntn Corporation

Kimihiko Bito

Jun Hirade

Fuminori Satoji

Natsuhiko Mori

Tetsuya Kurimura

Masaharu Hori

Isao Komori

Tetsuya Yamamoto

Yasuhiro Yamamoto

Fuyuki Ito

Toshiyuki Mizutani

Hiroyuki Noda

Yoshiharu Inazuka

Hiroshi Niwa

Kazuyoshi Harada

Tatsuya Hayashi

Toshiaki Niwa

Kouyou Suzuki

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.

Method of injection molding a sealing member for a fluid dynamic bearing

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.

Fluid dynamic bearing device and assembly method for same

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.

Fluid dynamic bearing device

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.

Bearing member and fluid dynamic bearing device using same

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.

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

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Kuwana, Japan

Kimihiko Bito