Reliability Evaluation Technology Of Meta-Action Assembly Unit For Numerical Control Machine Tool

CNC machine tools are developing towards the direction of precision,optoelectronic integration and intelligence.Reliability is an important indicator to measure its level.Reliability evaluation is the process of analyzing and confirming the level of reliability.meta-action unit as the smallest basic motion unit of machine tool products,the research on its performance and evaluation technology has become one of the key issues of machine tool reliability.This paper mainly studies the mechanical system with motion function,and takes the basic motion unit realized by machine tool function as the research object to complete the reliability evaluation and verification of meta-action assembly unit.Because CNC machine tool is a complex system which integrates mechanical,electrical,hydraulic and pneumatic systems,it is difficult to analyze and model the performance of the machine.The thesis establishes a function-meta-action unit mapping model.By analyzing the structure of the meta-action assembly unit,the composition of the meta-action unit is obtained and a unified structural model is established.Analyze the attributes of the meta-action unit,and use the variable precision rough set theory to get the key meta-action unit studied first.Aiming at the problem that the reliability evaluation of the meta-action assembly unit sometimes cannot accurately reflect its reliability level,combined with the uncertainty of the assembly process,the fuzzy mathematics theory is introduced into the analysis of thereliability of the meta-action assembly accuracy,and an assembly based on fuzzy mathematics theory is proposed.Accuracy reliability evaluation method;according to the composition mechanism of the assembly accuracy,the accuracy information of the element action assembly unit is mapped to the matching accuracy of each assembly item,and the fuzzy characteristics of the assembly accuracy meeting the ideal accuracy are analyzed,and the membership function of the assembly accuracy reliability of the element action is determined,Carrying out the reliability evaluation to get the assembly reliability of the worm element movement.Taking into account that the assembly of the meta-action unit will cause errors and weak points,for the evaluation of the assembly weakness,a finite element-based method for evaluating the reliability of the meta-action assembly is proposed.Establish a three-dimensional model of the worm meta-action assembly unit,combine its material properties,select the interference assembly contact pressure parameter from the actual assembly behavior to impose assembly constraints on the meta-action,perform the finite element analysis of the meta-action assembly unit,and obtain the meta-action assembly unit Weaknesses in the assembly.In order to verify the reliability evaluation test,the reliability test plan,process and test composition were designed,and the meta-action reliability test platform was built.Using speed,vibration,and noise sensors to carry out the operation reliability test of the meta-action unit,and compare the test results with the reliability evaluation conclusions of the meta-action assembly unit.The results show that the conclusions drawn from the test are consistent with the reliability evaluation conclusions of the meta-action assembly unit,verifying the rationality of the reliability evaluation method.