Reliability Evaluation Of NC Turret Based On Accelerated Degradation Test

CNC machine tools form the basis for the value creation and are of strategic importance to the engineering industry.As one of the most important functional components of CNC machine tools,the reliability level of the NC turret is of great importance to the reliability of CNC machine tools,so how to scientifically and objectively evaluate the reliability of CNC tool holders in a short period of time is one of the technical problems that need to be solved in the field of NC turret reliability research.The essence of NC turret is a complex electromechanical hydraulic system,but due to its high level of reliability.However,its main performance indicators will be degraded,and after the accumulation of time,these performance indicators will gradually lead to the decline of its function,and eventually lead to failure.If the accelerated degradation test technology is adopted,the NC turret is placed in an environment higher than the normal working stress,the degradation rate of the NC turret is improved,and the accelerated degradation model convert the reliability level in the normal working environment to achieve rapid evaluation of the NC turret;and the failure mechanism of the NC turret is complex,with multiple performance indicators,and binary degradation is the basis for studying multiple degradation.Therefore,with the support of the national major special sub-project "Research on the Reliability Growth of Key Functional Components of CNC Machine Tools",with the NC turret as the research object,this paper proposes a method for evaluating the one-way and binary degradation reliability of the NC turret based on the degradation data obtained by the accelerated degradation test,and verifies the effectiveness of the method through the test.The main work is as follows:Firstly,this paper discusses the research status of NC turret reliability test and accelerated degradation test,analyzes the difficulties and shortcomings faced by the traditional reliability test of NC turret in China at this stage,and then combines the advantages of accelerated degradation test to propose the research content of this paper.Secondly,design NC turret accelerated degradation test.The working principle of the NC turret studied in this paper is elaborated,the NC turret subsystem is divided,and the NC turret is analyzed in combination with the fault data to determine the characteristic indicators that can reflect the performance degradation of the NC turret;the acceleration stress is determined according to the actual situation;and the accelerated degradation test of the NC turret is designed and implemented by relying on the existing conditions of the laboratory.Thirdly,NC turret accelerates degradation test data acquisition.A numerical control tool holder reliability test bench and data acquisition system were built;the degradation amount selected in Chapter 2 was monitored and collected during the test;and the data was preprocessed and feature extracted,laying the foundation for the later chapters.Then,unary degradation reliability assessment based on Wiener process.Compared with the existing acceleration model,the acceleration model suitable for NC turret is selected.Four degradation models based on Wiener process were proposed.Combined with the data processing results,the unitary reliability of NC turret is evaluated.Finally,reliability evaluation of NC turret based on binary performance degradation.The binary reliability evaluation of NC turret is carried out by copula function and MD-CV method;the reliability model of NC turret binary degradation is established by selecting the appropriate copula connection function;the binary reliability evaluation problem is converted into a simple one-dimensional reliability evaluation by using the MD-CV method to establish a reliability model;combined with the NC turret studied in this paper,the binary reliability evaluation results considering the correlation between the degradation amount and the univariate reliability assessment result that does not consider the correlation between the degradation amount are compared to form a completed set of NC turret reliability rapid evaluation methods.