Research And Evaluation Of The Rigidity And Comprehensive Performance Of The Ball Screw Pair

The ball screw is widely used in feed system of CNC machine tool.Rigidity,positioning accuracy,temperature rise,noise and acceleration is an important performance index of ball screw.The current research on the rigidity and comprehensive performance of the ball screw in China is not perfect enough and the evaluation standard is not perfect,which seriously hampers the independent research and development of the domestic screw.Therefore,it is of great significance to research and evaluate the rigidity and comprehensive performance of the ball screw.The double-nut preloaded ball screw mechanism was taken as the research object in this paper.The force of the ball in two nuts is analyzed based on the Hertz theory.Considering the change of the contact angle when the ball screw is under axial load,the mathematical model of axial stiffness of the double-nut preloaded ball screw mechanism is established.Based on the established mathematical model of axial static stiffness,the fluctuation of frictional torque and screw rotation and torsion on axial static stiffness of the ball screw are discussed,and the relational model are established and validated by the experiment.The influence of preload,the number of ball and fitness on axial static stiffness is theoretically analyzed,and the correctness of axial static stiffness model is verified by experiments.Based on the theory and experimental study of axial static stiffness of the ball screw,the evaluation program of axial static stiffness of the ball screw is formulated.The program includes the selection of sample,the measurement of fitness and axial deformation,the compensation of torsional deformation and rotational deformation,the application and measurement of axial load,the processing of measurement data and the evaluation of axial static stiffness.The measurement principles of the acceleration,positioning accuracy,temperature rise and noise of the ball screw are introduced,and the positioning accuracy,temperature rise and noise measurement scheme are optimized.The positioning accuracy,temperature rise and noise measurement scheme are optimized.Finally,the experiments are carried out and the evaluation results are given.