Design And Analysis Of Wear Resistance And Preload Reliability Of Ball Screw Pair

Ball screws are the most important precision rolling functional component of high-end CNC machine tools,and also an important basic component in the fields of aerospace,nuclear power,national defense and military industry.Its application range is more and more extensive,and the performance reliability index is the most important.Based on the national science and technology major project,this paper analyzes the failure mode and failure mechanism of the ball screw and combines the wear model and preload model of the ball screw to focus on the wear resistance reliability design and preload reliability design of the ball screw,so as to lay a technical foundation for improving the inherent reliability of the ball screw.(1)Based on the structural and functional characteristics of the ball screw,the reliability model of ball screw is given.Based on this,the failure mode and failure mechanism of the ball screw are classified and analyzed,and the FMECA table of the ball screw is established to provide a basis for reliability analysis and design.(2)Based on the friction and wear theory and wear model of the ball screw,the wear resistance reliability is defined and the stress-strength interference theory and the improved first-order second-moment method are used to establish a wear resistance reliability calculation model.The sensitivity of each parameter is analyzed and the concept of unit sensitivity is defined to reasonably reflect the influence of each parameter on the reliability.Based on this,the reliability design of ball screw is carried out and the wear resistance reliability of the 1004 ball screw is increased from 78.0073% to 99.9090%.(3)Based on the analysis of the force between the ball and the raceway,a calculation model of preload based on the interference of the ball is put forward and verified.Based on this,the calculation model of preload reliability is established and analyzed with an example and the preload reliability of the 4010 ball screw is increased from 92.09% to 99.17%.Based on the analysis of the influence of preload on the rigidity and other properties,the idea of performance optimization design method of the ball screw based on the objective function and constraint conditions is put forward.(4)In view of the reliability analysis of wear resistance and preload,the preload and wear amount of the ball screw under the fixed number of revolutions are indirectly measured through the relationship among the no-load torque,preload and wear amount.The sample standard,environmental requirements and test steps of the reliability test are formulated,and the reliability data are processed and analyzed,so as to improve the reliability test of the wear resistance and preload.