| 摘要 |
PROBLEM TO BE SOLVED: To provide a feed screw which includes a spiral rod having a shape formed by twisting around a major axis as a screw axis, capable of having high positional accuracy, excellent durability, and capable of withstanding a high load. SOLUTION: A spiral groove 9 surface-contacting with a spiral surface of the spiral rod 5 is provided on a nut 8. A width of the spiral groove 9 has relief widths on both sides of a thickness of material of the spiral rod 5. A cross section of the spiral groove 9 cut on a surface vertical to a rotation axis of the nut 8 is rectangle, and both corner parts of a bottom part of the rectangle cross section have relief grooves 10 with a width larger than twice the relief width. COPYRIGHT: (C)2008,JPO&INPIT
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