| 摘要 |
PROBLEM TO BE SOLVED: To avoid three-contact state of a ball with a ball screw groove during operation of a double nut preloading type ball screw, prevent increase of rotary torque by increase of friction loss, thereby maintaining good power transmission efficiency, and realize easy assembling. SOLUTION: This double nut preloading type ball screw 1 comprises a ball screw shaft 2 forming a screw groove 3; ball nuts 4, 5 externally fitted on the ball screw shaft 2 and forming screw grooves 6, 7 facing the screw groove 3; a plurality of balls 8 contained rotationally between the screw grooves, the ball nuts 4, 5 are being arranged through a spacer ring 9. A sectional shape of the screw groove is formed by a single diameter, and an initial contact angleϕof the ball 8 with the screw groove, or the like is optimized, whereby a ball 8 and the screw groove maintain two point contact state.
|
