Assembly Precision And Its Reliability Assessment Method For Mechanical Products

Quality is not only the lifeline of products,but also an important theme for the transformation and upgrading of China's manufacturing.Meanwhile,assembly is a crucial section in manufacturing,and the quality of assembly has direct influence on the overall quality of the product.According to the practical requirement of mechanical products and from the view of assembly precision calculation,reliability assessment of assembly,optimization of assembly precision,as well as mechanical products' assembly precision analysis and its reliability assessment are studied.The main work of this thesis is as follows:(1)Based on the definitions of assembly precision for mechanical products,the state space method is adopted to build the assembly error propagation model,and the error transfer matrix is built to describe the transfer process between the parts.Besides,considering the measurement and adjustment of assembly process,the state space method is improved to realize the combination of theoretical calculation and actual testing.After that,the assembly error is calculated through software,and the probability distribution of assembly error in each process is described.According to the analysis,a case study of radar antenna array assembly is completed.(2)The concept of assembly precision reliability is proposed,and Monte Carlo simulation is adopted to calculate the reliability.After that,on the basis of genetic algorithm,the assembly precision optimization is carried out with the aim of minimizing comprehensive cost and constraint condition of the assembly precision reliability.The analysis of optimization process is completed in Matlab optimization toolbox.A case study of precision optimization for a radar antenna array assembly is completed.(3)The software of assembly precision assessment is developed with the assembly precision and its reliability evaluation method solidified.The software is divided into two modules,i.e.database module and assembly precision assessment module.With the software,the assembly error propagation analysis and assembly precision reliability calculation can be conducted,then the results can be output as a report.Finally,by comparing with the theoretical calculation results of a radar antenna array,the applicability of the software is therefore validated.In this thesis,assembly precision and its reliability assessment for mechanical products is proposed based on the study of assembly precision calculation,reliability assessment of assembly,and optimization of assembly precision.A case study of a radar antenna array assembly is completed.Besides,an assembly precision reliability assessment approach is developed.This research provides an effective method for mechanical product assembly reliability assessment,which has potential value of engineering application.