| 摘要 |
PURPOSE:To promote the reduction of vibration and noise, by forming a housing, which has a cylindrical part internally mounting rolling bearings and a fixing flat flange part, by a vibro-isolating material having a natural oscillation frequency region with no overlap on the natural oscillation frequency region of a spindle unit. CONSTITUTION:Two rolling bearings 20, 21 are mounted to be fitted separating by a fixed space in the bottom end part of a rotary shaft 10 and its central part. And each rolling bearing 20, 21 is mounted into a cylindrical part 51 of a housing 50. While a flat flange part 52, which is provided being lined to the cylindrical part 51 so as to overhang to the outside in the radial direction, is fixed to a device main unit. In the above constitution, the housing 50 is formed by a vibro-isolating material which absorbs vibration, generated from each rolling bearing 20, 21 in accordance with rotation of the rotary shaft 10, to sufficiently damp vibrative energy transmitted to the outside. And the housing 50 is given a natural oscillation frequency region not overlapping with the natural oscillation frequency region of a spindle unit.
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