Assembly Error Stack-up Analysis on Assembly Dimension-Chain for Mechanical Product

摘要

In the process of mechanical assembly, there would be assembly error stack-up because of the manufacturing error of the parts and the deformation error of the fixtures. The stack-up error finally comes into being on the Closing Link of Assembly Dimension-Chain (ADC). It may cause over-tolerance on the closing-link and make assembly quality of mechanical product go down or not be fulfilled. At the time, product assembly has to do poorly done work over again. So it is very important to analysis assembly error stack-up of mechanical product to fulfill assembly tolerance. This paper presents an approach analyzing assembly error stack-up based on Graph Theory. Firstly, assembly tolerance model is made based on Graph Theory. The model includes dimension tolerance, shape tolerance, location tolerance and assembly mating tolerance. Secondly, on the basis of assembly tolerance model, this paper applies Breadth-First Search (BSF) Algorithm to generating ADC. And ADC is represented based on vector. Thirdly, the approach of assembly error stack-up analysis based on Monte Carlo method is presented. It includes two steps: 1) achieve errors of all composing-links of ADC; 2) Define error stack-up route of ADC and calculate stack-up error. Finally, changing some tolerances is to satisfy tolerance of the closing-link of ADC. We apply the approach successfully to analyze assembly error stack-up on a component of an aircraft.