| 摘要 |
PROBLEM TO BE SOLVED: To dispense with a friction brake without an expensive gear by making a friction angle of a feed screw mechanism larger than a lead angle. SOLUTION: It is supposed that all force is uniformly applied to a screw surface A and concentrated on the position of an effective diameter. A lead angleβis an angle in a position of an effective diameter. The force in the loosening direction is taken as Q, and a coefficient of friction in the screw surface A is taken asμ. The force applied in the vertical direction to the screw surface A is taken as N, the frictional force isμN, and the angleηwhich satisfies the angleμ=tanρis taken as friction angle. The condition that rotation of a screw shaft is not started to rotate by the axial force applied to a nut holder, it will be sufficient that Q is positive, andρ>β. Thus, the friction angleρof the feed screw mechanism and the lead angleβare set. During rotation of the screw shaft, various frictional resistance are applied, whereby during non-operation of a motor, the screw shaft is further hardly rotated and the possibility of naturally rotating the screw shaft by load can be decreased.
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