Abstract: 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.

Abstract: A hydrodynamic bearing device has favorable bearing performance and long endurance life. A thrust bearing part of the hydrodynamic bearing device has a second thrust surface. In the second thrust surface, a dynamic pressure generating groove area having a plurality of dynamic pressure generating grooves is formed in at least a part thereof in a radial direction. The action of dynamic pressure of lubricating oil increases the pressure in a thrust bearing clearance between an end of a flange part of an axial member and the second thrust surface, to support the axial member in an axial direction in a non-contact manner. The dynamic pressure generating groove area of the second thrust surface is formed by press working. The difference in height between the inner and outer peripheral edges of the surface of the dynamic pressure generating groove area regulated between or equal to 0 and 2 ?m.

Abstract: 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 C between a thrust bearing surface 11a including dynamic pressure generating grooves and a smooth thrust receiving surface 11b so as to rotatably support a shaft member 2 in an axial direction. The thrust receiving surface 11b is formed as a flat surface, whereas an inclined plane 17 is provided on the thrust bearing surface 11a so as to provide a reduced portion 15 having a decreasing axial width in a radially outward direction in the thrust bearing gap C.

Abstract: An externally pressurized gas bearing comprising a main shaft, and journal bearing sections having a plurality of axial gas feed rows each having a plurality of circumferentially equispaced gas feed holes, the gas feed holes in the gas feed rows being adapted to spout compressed gas to thereby rotatably radially support the main shaft in a non-contact state, the externally pressurized gas bearing being arranged so that the gas feed holes in the gas feed row are disposed so as to be positioned circumferentially intermediate between gas feed holes in the adjoining gas feed row.

Abstract: A hydrodynamic bearing device has favorable bearing performance and long endurance life. A thrust bearing part of the hydrodynamic bearing device has a second thrust surface. In the second thrust surface, a dynamic pressure generating groove area having a plurality of dynamic pressure generating grooves is formed in at least a part thereof in a radial direction. The action of dynamic pressure of lubricating oil increases the pressure in a thrust bearing clearance between an end of a flange part of an axial member and the second thrust surface, to support the axial member in an axial direction in a non-contact manner. The dynamic pressure generating groove area of the second thrust surface is formed by press working. The difference in height between the inner and outer peripheral edges of the surface of the dynamic pressure generating groove area regulated between or equal to 0 and 2 ?m.

Abstract: An externally pressurized gas bearing comprising a main shaft, and journal bearing sections having a plurality of axial gas feed rows each having a plurality of circumferentially equispaced gas feed holes, the gas feed holes in the gas feed rows being adapted to spout compressed gas to thereby rotatably radially support the main shaft in a non-contact state, the externally pressurized gas bearing being arranged so that the gas feed holes in the gas feed row are disposed so as to be positioned circumferentially intermediate between gas feed holes in the adjoining gas feed row.

Abstract: An air spindle is provided which allows high-speed operation without reducing the bearing stiffness in the air spindle by reducing the heat generation at bearing portions. By increasing the number of nozzles for the radial bearing or increasing the axial distance between the nozzles, the ratio of the supply air flow rate Q to the bearing stiffness H is set at 2-10 to release heat generation at the bearing portions to outside by the gas.

Abstract: An air spindle is provided which allows high-speed operation without reducing the bearing stiffness in the air spindle by reducing the heat generation at bearing portions. By increasing the number of nozzles for the radial bearing or increasing the axial distance between the nozzles, the ratio of the supply air flow rate Q to the bearing stiffness H is set at 2-10 to release heat generation at the bearing portions to outside by the gas.

Abstract: A dynamic pressure type bearing comprises a sleeve rotatably holding a shaft driven by a motor composed of a rotor and a stator, one or both of the sleeve and the shaft being made of a resin material. The sleeve and/or shaft of a resin material may have a thin film of oil or grease formed on the surface thereof. Preferably, the resin material has load flexible temperture of 120.degree. C. or more, modules of elasticity or bending of 10 GPa or more, and coefficient of linear expansion of 3.times.10.sup.-5 /.degree.C. or less.