Nippon Seiko Kabushiki Kaisha

Kiyoshi Haginuma

Katsuhiko Tanaka

Ikunori Sakatani

Hiromi Sugi

Takanobu Sato

Hiromitsu Asai

Takeyuki Yoshiba

Toshimi Takajou

Toshimi Takajo

A dynamic pressure type bearing is applicable to a precision mechanical equipment. The bearing includes a hollow inner cylinder to fit a rotatable shaft. The inner cylinder is made of a thermosetting resin containing a 5 wt % to 75 wt % heat treated phenol resin powder and a 5 wt % to 75 wt % silicon dioxide, the total content of the phenol resin powder and the silicon dioxide being 50 wt % to 80 wt %. A spindle unit includes the bearing and a spindle made of an alloy containing aluminum as a main element. The bearing has a superior wear resistance, frictional characteristic and molding accuracy of the inner cylinder. The superior frictional characteristic of the inner cylinder allows a relatively soft spindle to be used in a spindle unit.

Dynamic pressure type bearing and spindle unit

A housing has a vertically extending cylindrical bore, with a radical bearing surface formed on the inner peripheral surface, and a thrust bearing surface formed on the inner bottom surface of the cylindrical bore. A shaft member which is supported rotatably in the cylindrical bore of the housing has a radial receiving surface and a thrust receiving surface respectively formed on the outer peripheral surface and the bottom surface. A dynamic pressure generating groove of a spiral shape is formed in at least one of the radial bearing surface and ther radial receiving surface. When the shaft member is rotated, a gas in the housing is sucked by the pumping action of the dynamic pressure generating groove and flows into a pressure chamber between the thrust bearing surface and the thrust receiving surface through a radial space between the radial bearing surface and the radial receiving surface. The pressure in the pressure chamber maintains the shaft member in a floating position by a predetermined amount. The shaft member has a passage bore formed along a center axis line. The passage bore includes a restricted aperture of a smaller diameter which opens at the thrust receiving surface of the shaft member to thereby allow the gas in the pressure chamber to be exhausted into the housing through the passage bore.

Dynamic pressure type fluid bearing device

Growing community of inventors

Fujisawa, Japan

Kiyoshi Haginuma