| 摘要 |
A ball screw device has a screw shaft which has a shaft rolling groove in a spiral shape formed on an outer surface of the screw shaft, a nut which has a nut rolling groove formed on an inner surface of the nut and opposed to the shaft rolling groove, wherein the screw shaft is to be screwed in the nut so that the shaft rolling groove and the nut rolling groove are faced through a plurality of rolling balls, and a lubrication ring which is made of a lubricant-including material, comes in slide contact with the screw shaft, and is arranged in an end portion of the nut, wherein a non-contact portion, which does not come in slide contact with the screw shaft, is formed on the slide contact surface of the lubrication ring.
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