| 摘要 |
PROBLEM TO BE SOLVED: To provide a linear-motion device which can be used over a long period of time even under such severe use conditions as high-speed, high-load and short-stroke reciprocating operation. SOLUTION: A ball screw 1 includes a screw shaft 3 formed with a male screw groove 3a, a nut 5 formed with a female screw groove 5a and a plurality of balls 9 arranged between the male screw groove 3a and the female screw groove 5a. At least one of the screw shaft 3, the nut 5 and the ball 9 is made of alloy steel containing 0.3 mass % or more and 0.8 mass % or less carbon and 3 mass % or more and 18 mass % or less chromium. The alloy steel may further contain one of or both of 0.3 mass % or more and 2 mass % or less molybdenum and 0.3 mass % or more and 1 mass % or less silicon. Furthermore, the sum of the carbon concentration and the nitrogen concentration of the surface section serving as the raceway surface of the male screw groove 3a or the female screw groove 5a or the rolling contact surface of the ball 9 is 0.8 mass % or more and 1.5 mass % or less, and the amount of retained austenite of the surface section is 10 volume % or more and 36 volume % or less. COPYRIGHT: (C)2005,JPO&NCIPI
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