Ntn Corporation

Isao Komori

Kenji Ito

Fuminori Satoji

Kazuo Okamura

Natsuhiko Mori

Yasuhiro Yamamoto

Tetsuya Yamamoto

Masaharu Hori

Ryouichi Nakajima

Seiji Shimizu

Tetsuya Kurimura

Toshiyuki Mizutani

Makoto Shiranami

Yoshiharu Inazuka

Masafumi Okuma

Katsuo Shibahara

Kenichi Mitani

Kenji Hibi

Masaaki Toda

Hiroshi Niwa

Kimihiko Bitou

Masaki Egami

Nobuyoshi Yamashita

Tsugito Nakazeki

Tatsuo Kawase

Hiroyuki Noda

Fuyuki Ito

Kazutoyo Murakami

Masakazu Hirata

Jun Hirade

Kazuto Shimizu

Kazuyoshi Harada

Kimihiko Bito

Tatsuya Hayashi

Kiyotaka Kusunoki

Toshihiko Tanaka

Hiromichi Kokumai

A fluid dynamic bearing device () includes: a shaft member (); a housing () as an outer member which is arranged on a radially outer side of the shaft member () and is opened at both ends; a radial bearing gap which is formed on a radially inner side of the housing () and faces an outer peripheral surface of the shaft member (); and a lid member () closing an opening on one end side of the housing (), wherein the lid member () is fitted to an outer peripheral surface of the housing () with a fastening allowance which does not affect accuracy of a surface defining an outer diameter dimension of the radial bearing gap so that the housing () and the lid member () are bonded and fixed to each other.

Fluid dynamic bearing device

It is an object of the present invention to provide a bearing member having a highly accurate dynamic pressure generating portion stably at low cost. Dynamic pressure grooves () and () are formed as the dynamic pressure generating portions on an inner circumferential surface of the electroforming portion () by an electroforming process, and injection molding is performed by using a resin while inserting the electroforming portion (), thereby forming a bearing member (). A shaft member () is inserted into an inner circumference of the bearing member.

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.

A fluid dynamic bearing device which can exhibit high bearing performance is provided at low costs by forming a highly accurate bearing gap. At least a region in the outer circumferential surface of a shaft which faces the radial bearing gap is constituted of an electroformed part, and the region of the shaft excluding the electroformed part is constituted of a resin portion.

A fluid dynamic bearing device which exhibits high bearing performance at low cost has a highly accurate bearing gap. At least a region in the outer circumferential surface of a shaft, which faces the radial bearing gap, is constituted of an electroformed part, and the region of the shaft excluding the electroformed part is constituted of a resin portion.

A fluid dynamic bearing device (), comprising a dynamic pressure generating groove region (B) being provided on an inner peripheral surface () of a bearing member (), which forms a radial bearing gap, the region (B) comprising: a first region (B) for generating a fluid dynamic pressure when the bearing member () and a shaft member () are rotated relative to each other in a forward direction; and a second region (B) for generating a fluid dynamic pressure when the bearing member () and the shaft member () are rotated relative to each other in a reverse direction. A portion of the region (B), corresponds to an end portion on an open-to-air side of the radial bearing gap, comprises an annular projecting portion () provided closer to the shaft member () with respect to a groove bottom of each of the plurality of dynamic pressure generating grooves ().

Provided is a housing for a resin fluid dynamic bearing device in which deterioration with time of a fixing force for another member is mitigated and which can maintain a high bearing performance for a long period of time. The housing formed of a resin composition exhibiting a compression creep amount of 8% or less when a compressive pressure of 80 MPa is applied for 168 hours at an atmosphere temperature of 80&#xb0; C., provides a sufficient fixing force for the another member fixed with a press-fitting force, for example, a bearing sleeve press-fitted into an inner periphery of the housing even after a long term use. Thus, there is no fear of fixing positions of the another member with respect to the housing being deviated and a high bearing performance is maintained for a long period of time.

Housing for fluid dynamic bearing device

A fluid dynamic bearing device includes: a shaft member; a bearing sleeve which forms a radial bearing gap between the bearing sleeve and an outer peripheral surface of the shaft member; a housing which accommodates the bearing sleeve and is opened at both ends; and a lid member which closes an opening on one end side of the housing and forms thrust bearing portions. The housing is an injection-molded product into which the bearing sleeve is inserted, and the housing has another end with which a seal portion forming a seal space is integrally formed. The lid member is fitted with the outer peripheral surface of the housing by loose fitting so that the lid member and the housing are bonded and fixed to each other.

The present invention has an object of improving wear resistance of a thrust bearing portion. A pressure is generated by a dynamic pressure effect of a lubricating oil in a thrust bearing gap between a thrust bearing surface including dynamic pressure generating grooves and a smooth thrust receiving surface so as to rotatably support a shaft member in an axial direction. The thrust receiving surface is formed as a flat surface, whereas an inclined plane is provided on the thrust bearing surface so as to provide a reduced portion having a decreasing axial width in a radially outward direction in the thrust bearing gap.

Dynamic bearing device having a thrust bearing portion

Fine particles () are retained by an electroformed portion () in a dispersed state, and the fine particles () exposed from an outer peripheral surface () of the electroformed portion () are molten so as to form micro projections () integrated with a resin portion (). The micro projections () enters into fine-particle traces () formed in the electroformed portion () to exert an anchor effect, to thereby increase a fixation force between the resin portion () and the electroformed portion ().

Electroformed bearing and method of manufacturing same

A first axial gap (L) is formed between a seal portion () and a sleeve portion (). With this, it is possible to set a moving amount of a shaft member () in an axial direction with high accuracy irrespective of accuracy of members such as the sleeve portion ().

Fluid dynamic bearing device and assembling method thereof

Fixation strength of a bearing sleeve with respect to a housing is increased so that stable bearing performance can be achieved. A fluid dynamic bearing device () includes a housing () and a bearing sleeve () fixed to an inner periphery of the housing (). The housing () and the bearing sleeve () have therebetween a press-fitting part () at which the housing () and the bearing sleeve () are fixed by press-fitting, and an adhesive-filled part () formed on an opening side with respect to the press-fitting part ().

Fluid dynamic bearing device and process for manufacturing the same

The present invention aims to achieve a reduction in cost for a fluid dynamic bearing device. The fluid dynamic bearing device supports a shaft member () radially in a non-contact fashion by a dynamic pressure action generated in a radial bearing gap between an outer peripheral surface of the shaft member () and an inner peripheral surface () of a bearing member (), and is composed of the shaft member (), the bearing member (), a cover member (), and a seal member (). The shaft member () is inserted into an inner periphery of the bearing member (), and an opening at a lower end thereof is sealed by the cover member (). The seal member () is attached to an opening at an upper end of the bearing member (), forming a seal space (S) between itself and the outer peripheral surface of the shaft member (). Dynamic pressure grooves (G) of radial bearing portions (Rand R) are formed in an inner peripheral surface () of the bearing member () by molding.

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.

Shaft member for fluid bearing device and method of producing the same

A fluid dynamic bearing device includes a housing injection molded with a bearing sleeve as an insert. Accordingly, the molding of the housing and the assembly of the housing and the bearing sleeve can be performed in a single step. In addition to this, by simply increasing the die precisions the housing and the bearing sleeve can be fixed easily with high precision. Since the housing is opened at both ends, it is possible to sandwich the bearing sleeve, and accordingly, the bearing sleeve can be accurately positioned inside the dies with reliability.

Growing community of inventors

Kuwana, Japan

Isao Komori