Abstract: Taking plane assembly joint surface as the research object, the problems of assembly joint surface error modeling and tolerance optimization in the case of coupled tolerance are analyzed. Describing the tolerance by small displacement torsors theory(SDT), part plane error model is built according different tolerance design conditions, the actual change interval of assembly plane error variation bandwidth is obtained by Monte Carlo Simulation method, and the function relationship between error alteration component actual change interval bandwidth and tolerance is established by response surface method. Assembly joint surface comprehensive error model is built according to the part machining error and assembly process error. The method is expanded applied in assembly error modeling of complex assembly, and assembly accuracy prediction in the design phase is achieved. Aiming at the processing cost, and regard assembly accuracy reliability as constraint, the tolerance value of parts is optimized. At the end of the paper, the feasibility and practicability of this method in predicting the assembly precision and guiding precision design is verified by a typical engineering example.

Key words: assembly error, joint surface error, Monte Carlo simulation, reliability analysis, response surface method, tolerance optimization design