| 摘要 |
PROBLEM TO BE SOLVED: To prevent the wear progress of a metal ball and improve the device life by setting the surface hardness of the metal ball higher than the surface hardness of a male thread groove in order to make the metal ball more difficult to wear than the male thread groove in operation. SOLUTION: In this ball screw device formed of a screw shaft 3 having a male thread groove 1 formed on the circumference, a cylindrical nut 7 having a female thread groove 5 opposed to the male thread groove 1 on the inside, and a number of metal balls 9 interposed between the male thread groove 1 and the female thread groove 5, the male thread groove 1 and the female thread groove 5 forms one spiral rolling passage 10, so that the metal balls 9 are rolled in the rolling passage 10. In the screw shaft 3 and the nut 7, SCM 415 as the material is quenched to carbonize and to set the surface hardness to HRC 60. In the metal ball 9, SUJ 2 as the material is quenched to carbonize and to set the surface hardness to HRC 63. According to this, the metal ball 9 can be made difficult to wear, compared with both the thread grooves 1, 5 to improve the device life.
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