Calculation and Experimental Study on Friction Coefficient of Ball Screws Considering Speed Effect

Aiming at the present situation that the friction coefficient of the ball screw is chosen based on the bearing experience value and considering about the structural characteristics of the ball screw, the kinematics, dynamic model of the ball and the screw were established. Meanwhile, the principle of measuring friction coefficient was analyzed and a friction coefficient calculation method was derived. The novel preload-adjustable ball screw mechanism can achieve the adjust preload and real-time monitoring of the double nut ball screw. The drag torque and preload of ball screw, with this mechanism, can be measured directly through the drag torque measuring system, so that the actual friction coefficients at different preload and speed can be calculated. As a result of the measurement system rotational speed limit, the test was carried out at a low speed of 400 r/min or less. Finally the variation of the friction coefficient under the rotational speed and preload were obtained. The selection range of the friction coefficient under the low speed of the ball screw was given. It is important to research the friction coefficient of the ball screw through experiments.