Dynamic friction torque modeling and experimental study of ball screw actuators under high-frequency reciprocating motion

The dynamic load and transient lubrication effects strongly influence the friction torque of ball screw actuators (BSAs) under high-frequency reciprocating conditions. However, the available studies rarely consider the transient effects of rough surfaces under dynamic loads. In this paper, a dynamic friction torque model for ball screw actuators is proposed, which integrates low-order finite elements with transient mixed lubrication. Dynamic contact loads are solved on the basis of the tribodynamic model accounting for mechanism vibration. The lubrication, friction, and stiffness under time-varying velocities and dynamic loads are systematically analyzed. The accuracy of the model is verified by experimentally measured dynamic friction torque under high-frequency reciprocation. Within the unified model, the dynamic friction behavior of ball screw actuators subjected to combined high-frequency reciprocation and complex loads is analyzed. The findings demonstrate that, compared with ball screws, locating bearings exhibit superior lubrication performance, primarily due to their lower sliding and spinning speeds, which results in significantly reduced friction torque. Amplitude escalation expands both the high load area and the sliding/spinning speeds, thereby increasing the friction torque. This study provides theoretical support for the dynamic performance optimization of ball screw actuators.