| 摘要 |
PROBLEM TO BE SOLVED: To reduce surface pressure of a contact surface between a male screw and a female screw, and thereby reducing frictional force.SOLUTION: A feed screw mechanism 48 is provided with: a curve part 202 on an outer diameter side tooth surface of an effective diameter φX of a male screw part 112a; and a plane part 200 on an inner diameter side tooth surface of the effective diameter φX of the male screw part 112a. The tooth surface of a male screw is configured to be successive to the plane part 200 and the curve part 202. When a relative angel of the male screw part 112a and a female screw part 114a is zero so as to face each other, the plane surface of the plane part 200 contacts with the tooth surface of the female screw, and when a relative angle θ is formed by the male screw part 112a and the female screw part 114a, the curve surface of the curve part 202 contacts with the tooth surface of the female screw.SELECTED DRAWING: Figure 7 |
