| 摘要 |
PROBLEM TO BE SOLVED: To provide a relatively large ball screw having a long service life to be mounted to a device such as an electric injection molding machine or a pressing machine on which high load is charged. SOLUTION: This ball screw comprises a screw shaft having a spiral male screw groove in its outer peripheral surface, a nut having a spiral female groove facing the male screw groove in its inner peripheral surface, a plurality of balls rollingly interposed between the male screw groove and the female screw groove, a retaining pieces arranged between adjacent balls if necessary, and a ball circulation passage for scooping a ball at one end of a ball rolling space and moving the ball to the other end. Grease composition containing conductive material at a ratio of 0.1-10 mass% is filled. COPYRIGHT: (C)2004,JPO
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