| 摘要 |
PURPOSE:To aim at the stabilization of a bearing characteristic with out being too strict on axial dimension in spherical bearing parts provided at both ends of a rotating part by disposing a spherical body provided with a dynamic pressure generating groove at its peripheral surface on the upper side and a receiving member provided with a semi-spherical recessed part to be fitted at a spherical body on the lower side. CONSTITUTION:A lower spherical bearing part 12 located at the lower end part of a main spindle 18 is formed of a lower spherical body 22 provided with a dynamic pressure generating groove 26 at its peripheral surface coaxially with an axis of rotation, a lower receiving member 24 provided with a semi-spherical recessed part 23 to be fitted at the lower spherical body 22, and a lower cover 25 for preventing the outflow of lubricating oil. An upper spherical bearing part 13 to be fixed at the upper end part of the main spindle 18 is formed of an upper receiving member 28 provided with a semi-spherical recessed part 27 at its upper face, an upper spherical body 29, located at the upper part of the upper receiving member 28, to be fitted at a semi-spherical recessed part 27 and provided with a dynamic pressure generating groove 31 formed at its peripheral surface, and an upper cover 30. The upper spherical bearing part 13 is further supported by an axis 32, a linear bearing 33, and the like. Accordingly, axial dimensional accuracy can be moderated so as to like process assembling easy as well as the leakage of lubricant can be prevented. |
