| 摘要 |
PROBLEM TO BE SOLVED: To prevent the occurrence of seizure and abrasion caused by oil film exhaustion even when a stroke is short in a ball screw. SOLUTION: This ball screw is provided with a screw shaft 2 having a spiral groove 2a on the outer periphery, a nut body 3 outwardly inserted to it and having a spiral groove 3a on the inner periphery, and a retainer 5 inserted between the outer periphery of the screw shaft 2 and the inner periphery of the nut body 3. Steel balls 4 and balls 4' made of an oil-retaining member such as an oil-retaining plastic are provided as the balls rotatably held body the retainer 5 and rollably coupled with the spiral grooves 2a and 3a. Since oil bleeds from the inside of the balls 4' over a long period, the seizure and abrasion on the rolling face caused by oil film exhaustion can be prevented even when the stroke is short.
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