Influence of the Number of Starts of the Thread on the Drive Nut of the Planetary Roller-Screw Drive on the Efficiency of the Mechanism

Abstract

Planetary roller screw mechanisms are designed to smoothly convert the rotational movement of the nut into the translational movement of the screw due to the presence of threaded rollers located between the internal thread of the drive nut and the external thread of the driven screw. The position of the rollers around the circumference is determined by two separators located at the ends of the rollers. Smooth cylindrical holes in separators are matched by clearance fit. Both ends of the threaded rollers have gears that mate with the gears at the ends of the screw. Thus, rotating rollers are located between the screw and the nut, and the sliding friction of the threads of the ordinary screw and nut in the planetary roller-screw mechanism is replaced by rolling friction. Friction losses during the operation of the mechanism are significantly reduced. Bearing capacity of the mechanism is increased due to a significant number of contact points in the threads of the nut, screw and rollers. By varying the pitch and setting the thread number of starts on the screw and nut the speed of the axial movement of the screw relative to the nut of the mechanism is regulated. Increasing the thread number of starts on the nut and screw increases the efficiency of the mechanism under study. Increasing a number of starts of the thread on the nut and screw increases the efficiency of the mechanism under study.