As a key transmission component in computer numerical control(CNC) machine tools,the ball screw mechanism(BSM) is usually investigated under working load conditions. Its accuracy degradation process is relatively long...As a key transmission component in computer numerical control(CNC) machine tools,the ball screw mechanism(BSM) is usually investigated under working load conditions. Its accuracy degradation process is relatively long,which is not conducive to the design and development of new products. In this paper,the normal wear depth of the BSM nut raceway is calculated under the variable speed operation condition using the fractal wear analysis method and the BSM’s accelerated degradation proportional wear model. Parameters of the acceleration degradation model of the double-nut preloaded ball screw pair are calculated based on the physical simulation results. The accelerated degradation test platform of the BSM is designed and manufactured to calculate the raceway wear model when the lubrication condition is broken under the variable-speed inertial load and the boundary lubrication condition under the uniform speed state. Three load forces and two samples are selected for the accelerated degradation test of the BSM. The measured friction torque of the BSM is employed as the evaluation index of the accuracy degradation test. In addition,the life cycle of the accuracy retention is accurately calculated by employing the parameters of the physical simulation model of the BSM. The calculations mentioned above can be used to estimate BSM’s accuracy performance degradation law under normal operating conditions. The application of the proposed model provides a new research method for researching the precision retention of the BSM.展开更多
This manuscript presents an innovative methodology for the assessment of the friction torque of ball slewing bearings.The methodology aims to overcome the limitations of state-of-the-art approaches,especially when the...This manuscript presents an innovative methodology for the assessment of the friction torque of ball slewing bearings.The methodology aims to overcome the limitations of state-of-the-art approaches,especially when the friction torque is conditioned by the preload of the balls.To this end,the authors propose to simulate the preload scatter when solving the load distribution problem,prior to the friction torque calculation.This preload scatter allows to simulate a progressive transition of the balls from a four-point contact state to a two-point contact one.By implementing this capability into an analytical model,the authors achieve a successful correlation with experimental results.Nonetheless,depending on the stiffness of the structures to which the bearing is assembled,it is demonstrated that the rigid ring assumption can lead to inaccurate friction torque results when a tilting moment is applied.The methodology described in this research work is meant to have a practical application.Therefore,the manuscript provides guidelines about how to use and tune the analytical model to get a reliable friction torque prediction tool.展开更多
基金Supported by the National Natural Science Foundation of China(No.51575014,51505020)the Key Foundation Project of China Academy of Railway Sciences(No.2021YJ200).
文摘As a key transmission component in computer numerical control(CNC) machine tools,the ball screw mechanism(BSM) is usually investigated under working load conditions. Its accuracy degradation process is relatively long,which is not conducive to the design and development of new products. In this paper,the normal wear depth of the BSM nut raceway is calculated under the variable speed operation condition using the fractal wear analysis method and the BSM’s accelerated degradation proportional wear model. Parameters of the acceleration degradation model of the double-nut preloaded ball screw pair are calculated based on the physical simulation results. The accelerated degradation test platform of the BSM is designed and manufactured to calculate the raceway wear model when the lubrication condition is broken under the variable-speed inertial load and the boundary lubrication condition under the uniform speed state. Three load forces and two samples are selected for the accelerated degradation test of the BSM. The measured friction torque of the BSM is employed as the evaluation index of the accuracy degradation test. In addition,the life cycle of the accuracy retention is accurately calculated by employing the parameters of the physical simulation model of the BSM. The calculations mentioned above can be used to estimate BSM’s accuracy performance degradation law under normal operating conditions. The application of the proposed model provides a new research method for researching the precision retention of the BSM.
基金supported by the German Federal Ministry for Economic Affairs and Climate Action through the iBAC project with grant number 0324344A.
文摘This manuscript presents an innovative methodology for the assessment of the friction torque of ball slewing bearings.The methodology aims to overcome the limitations of state-of-the-art approaches,especially when the friction torque is conditioned by the preload of the balls.To this end,the authors propose to simulate the preload scatter when solving the load distribution problem,prior to the friction torque calculation.This preload scatter allows to simulate a progressive transition of the balls from a four-point contact state to a two-point contact one.By implementing this capability into an analytical model,the authors achieve a successful correlation with experimental results.Nonetheless,depending on the stiffness of the structures to which the bearing is assembled,it is demonstrated that the rigid ring assumption can lead to inaccurate friction torque results when a tilting moment is applied.The methodology described in this research work is meant to have a practical application.Therefore,the manuscript provides guidelines about how to use and tune the analytical model to get a reliable friction torque prediction tool.
