AIR DYNAMIC PRESSURE BEARING APPARATUS HAVING INCREASED RADIAL STIFFNESS

摘要

PURPOSE: An air dynamic pressure bearing device having increased rigidity in a radial direction is provided to reduce a size and a manufacturing cost by removing a spacer and reducing the number of hemispheres and to secure stability in rotation by increasing the rigidity against tilting of a bushing. CONSTITUTION: An air dynamic pressure bearing device having increased rigidity in a radius direction includes a step bearing(150) fixed on an upper portion of a shaft(120), a hemisphere(130) fixed on a lower portion of the shaft and having a plurality of dynamic pressure generating holes(135), and a bushing(140) inserted into the shaft to rotate between the step bearing and the hemisphere and having a through hole(146) at the center. The step bearing has a first diameter plate member(152) fixed on an end of the shaft for covering an upper end of the bushing, a second diameter air pocket member(154) axially piled up on the plate member and a third diameter recess member(156) axially piled up on the air pocket member. The first diameter is larger than the second diameter and the second diameter is larger than the third diameter. The bushing has a hemispherical hole for receiving the hemisphere at a lower end surface and a receiving hole(141) for receiving the air pocket and the recess member at an upper end surface.