Theoretical and experimental analysis of drag torque for accelerated motion of ball screw mechanism

Dynamic model of the ball in space for ball screw mechanism is established under different angular accelerations of the screw, and non-linear equations of the ball acceleration motion model were solved in accordance with ball movement characteristics during acceleration process of the ball screw mechanism. Forces and motion on the ball were analyzed taking into consideration acceleration state and the characteristics of the ball. Using the existing structural parameters of the ball screw mechanism and accelerating operating conditions of the ball, motion parameters of the ball were theoretically analyzed using simulations at different angular accelerations of the screw, along with motion parameters of the ball, which included contact angle, helix angle, the ball center locus helix path radius, normal force at contact points of the ball, the tangential velocity of ball center, relative sliding velocity of ball, and drag torque of the ball screw mechanism. A ball screw comprehensive test bench was used to experimentally measure drag torque of the ball screw mechanism under different angular accelerations of the screw. Changing regularity was found to be consistent between measured data with simulation results. As a result, acceleration dynamic model of the ball in space was demonstrated to be accurate and feasible.