Research On Error Evaluation And Adjustment Strategy Of Critical Number Chain In Large Complex Assembly

Under the background of industry 4.0 and made in China 2025,large-scale equipment manufacturing industry has developed rapidly and has become a vital part of modern industry.The requirements for large-scale equipment assembly performance in various application fields are higher and higher,but the problems of low performance and low assembly quality of large-scale equipment in China have not been fundamentally solved.Therefore,in order to enhance the comprehensive strength and international competitiveness of China's large-scale equipment manufacturing industry,focusing on improving the assembly accuracy and performance of large machinery,ships,wind tunnels,aerospace and other large complex products has become an urgent problem to be solved.In order to solve the above problems,this paper studies the error evaluation and adjustment strategy of large complex assembly key dimension chain.Firstly,the assembly characteristics and functional requirements of large complex products are analyzed.Based on the small displacement screw theory,the error screw model of typical features of large complex assembly under the joint constraints of dimensional tolerance and geometric tolerance is established;According to the mechanism of transfer and accumulation of variation error between fitting surfaces of parts,the error transfer path of assembly is described based on homogeneous transformation theory.Finally,the construction method of assembly error transfer and accumulation model is proposed.Secondly,the problem of low accuracy of traditional Monte Carlo assembly error analysis method is studied.An improved assembly error analysis method is proposed by using the constraint relationship between components in the error screw model to limit the variation range of component function feature components.Compared with the traditional error analysis method,the calculation accuracy is improved;The feasibility and effectiveness of the improved assembly error analysis method are verified by simulation calculation with vis VSA assembly accuracy analysis software;For the key control objectives that do not meet the assembly function requirements in the simulation process,tolerance optimization and simulation verification are carried out based on the contribution factor report in the analysis results.Finally,the deformation information of the assembly is obtained by using the finite element analysis software,and the error transformation matrix of the deformation information of the parts is established.Then the manufacturing error and deformation error of the parts are coupled in three dimensions,and the comprehensive assembly error analysis model is obtained;Based on the integrated assembly error transfer and accumulation model,the influence of self weight on the final assembly error accumulation of large complex products is analyzed,and the necessity of taking the deformation factor into consideration in the evaluation and analysis of assembly error is explained;The error accumulation of large complex assembly dimension chain is tracked dynamically,and the analysis results provide a reference for real-time adjustment.