| 摘要 |
PROBLEM TO BE SOLVED: To support a shaft member constituting a spindle by a single ball bearing by setting raceway grooves formed between inner/outer rings of the ball bearing into Gothic arc grooves, press fitting the shaft member into the inner ring by right fit, and applying a radial preload thereto. SOLUTION: Respective raceway grooves 1a, 2a between an inner ring 1 and an outer ring 2 of a ball bearing A are machined into Gothic arc grooves. In a state before attaching a shaft member B into the inner ring, the ball bearing A has a plus radial clearance, however, an elastic displacement of the raceway groove 1a in the direction enlarging the diameter, which is generated in attaching the shaft member B in the inner ring 1 by press fit in its interference fit state, is set larger than the radial clearance so that the ball bearing unit after attaching the shaft member B becomes a radially preloaded state. The presence of the preload makes the ball 3 is brought in a contact state at all times in two points P separated axially relative to the raceway grooves 1a, 2a so that the single ball bearing A can surely support the shaft member B rotated about the shaft.
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