Sensitivity analysis of influencing factors on assembly accuracy of casings with interference fit rabbet

Abstract

At present, in the assembly of casings with interference fit rabbet, there is a common phenomenon that the design tolerance and machining accuracy of each group of casings are the same, but the actual assembly accuracy of the casings is different. This is due to the small differences in the geometrical error of the interference fit rabbet within the allowable tolerance range. The coupling effect of these errors directly affects the assembly accuracy of the casings and even affects the service life of the casings. In this paper, six influencing factors are selected to deal with this phenomenon. The degree of influence of each factor on the assembly accuracy is analyzed using the finite element analysis method based on the error model. The research objects are selected as a combustor casing and a compressor casing of a type of turbofan engine, and the two casings are connected by an interference fit rabbet. The evaluation index of assembly accuracy is selected as assembly coaxiality. These six influencing factors are selected as follows: rabbet coaxiality error, rabbet interference, rabbet fitting length error, flange surface perpendicularity error, flange surface flatness error and bolt pretightening force. Based on the orthogonal test method, the sensitivity values of each factor are calculated, and the degree of influence of each factor is ranked.