| 摘要 |
PROBLEM TO BE SOLVED: To prevent reduction in a preload of bearings caused by a temperature elevation, reduction in rigidity and a resonance phenomenon caused by these by forming a frontal combinational structure for oppositely installing front faces of the bearings on a shaft, and applying the preload to respective ball bearings. SOLUTION: Outer races of respective ball bearings 3 fixed to the outer periphery of a shaft 2 by an adhesive are inserted into the inner periphery of a housing 4, and the lower end of the shaft 2 is inserted into a hole 21 of a reference base 22. A dead weight 25 is inserted into a reference guide part 24 to press the outer race of the upper side ball bearing 3. Thus, the shaft 2 is pressed downward via the upper side ball bearing, and this pressing force is transmitted to the outer race of the lower ball bearing 3, so that the outer races of the respective ball bearings are pressed in the shaft center direction of the shaft 2. A preload is applied to the bearings by holding the outer races until the adhesive is solidified in this state. Falling of the housing 4 is prevented by the dead weight 25 inserted into the reference guide part 24, and straightness can be excellently kept so that outer peripheral surfaces of the outer races of the respective ball bearings become parallel to each other.
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