Assembly Reliability Control Technology Of Element Action Unit Of Numerical Control Machine Tool

The reliability control of assembly process is an important link to ensure the reliability of products.As a "machine tool",CNC machine tool is a typical complex electromechanical product.It will be very difficult to study the reliability of assembly process directly.This paper studies the reliability control and experimental technology of the assembly process of meta action unit based on the non divisible and independent meta action unit of machine tool.(1)Aiming at the problem that the transmission and accumulation of assembly errors eventually lead to the reduction of assembly reliability,a simulation method of error transmission accumulation model is proposed and the analysis of assembly error transmission is carried out.Taking the worm element action unit as an example,by analyzing the composition structure of the element action assembly unit,combined with the error source and the assembly dimension chain,the error transmission model of the element action assembly process is established,and the assembly error transmission directed graph is constructed.Based on the directed graph,the assembly error transfer accumulation model is established,and the simulation analysis of the assembly error transfer accumulation of the element action unit is carried out.It is concluded that the error accumulation result exceeds the threshold.It is necessary to further carry out the research on the assembly scenario identification affecting the assembly error.(2)When the meta action assembly error exceeds the threshold,a reliability anomaly reasoning and recognition method of meta action unit assembly scenario based on Bayesian network is further proposed.Using the method of failure mode and influence analysis,the composition model of key assembly scenarios of meta action unit is established,the Bayesian network structure of meta action unit assembly scenario is given,and the intelligent reasoning of abnormal probability of meta action unit assembly scenario is realized by using evidence reasoning method.Taking the worm element action unit as an example,the abnormal assembly scenario is identified,and the assembly scenario with high abnormal probability is determined.(3)Based on the determination of key abnormal assembly scenarios,an improved spar-h(standardized nuclear power plant human factor risk analysis)method is proposed to analyze the reliability of assembly behavior.Through eight aspects of assembly operation task processing time,assembly difficulty,assembly complexity,assembly pressure,experience/training,assembly process specification,man-machine environment and working process,the determination standard of PSFs level in assembly process is improved,the assembly behavior under key abnormal assembly scenarios is studied,and detailed reliability control measures are given for human error behavior with high human error rate.(4)The assembly reliability control test verification platform of the element action unit is built,and the test scheme is designed.Based on the assembly process card of the worm element action unit,the comparative test is carried out before and after the implementation of the reliability control measures of the element action unit assembly process.The test results show that the operation reliability of the element action unit is significantly improved after the implementation of the assembly reliability control measures,The effectiveness of the reliability control method in the assembly process is verified.