| 摘要 |
PROBLEM TO BE SOLVED: To provide a ball screw capable of being appropriately lubricated for a long time of period without increasing the driving torque. SOLUTION: A plurality of balls 4 are housed to be freely rotatable in the spiral circulative passage 9 formed between screw grooves 7, 8 of the screw shaft 2 and a nut 3. An oiler 5 supplying a lubricant to the circulative passage 9 is arranged at the end of the nut 3. The oiler 5 is formed of an oil reservoir 11, a recession 12, and an oil transfer ball 14. The oil reservoir 11 is loosely fitted on the outer periphery of the screw shaft 2 with a specified radial gap. The recession 12 is formed in the inner diameter part of the oil reservoir 11 to communicate with the oil reservoir. The oil transfer ball 14 is housed to be freely rotatable between the recession 12 and the screw groove 7 of the screw shaft 2 and the lubricant of the oil reservoir 11 is transferred to the screw groove 7 through the ball 14.
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