Application Research On The Assembly Quality For The Automobile B-pillar Based On The Dimensional Engineering

The assemble quality of Body in White(BIW) restricts the vehicle quality for the own-brand cars. BIW quality directly affects the appearance of the vehicle, i.e. wind noise, abnormal noise and driving experience. In the design of the body size, the domestic auto companies mainly using past experience or other reference benchmarking models, and continue to debug in the trial process, which resulting in long product development cycles and high production costs. Due to lack of the dimensional management system, the sources of deviations that occurred during the assembly process can't be accurately located, only a compromise by reducing the appearance of standard or relaxed tolerance requirements.B-pillar is an important part of the BIW, which extending from the roof to the bottom of the vehicle. The assembly quality for B-pillar directly affects the leakproofness, wind noise, aesthetics and some parts' interference capability. Due to the complex shape and enormous amounts of matching surfaces for the B-pillar parts, the gap deviations and via holes interference will appear in the actual assembly process. To solve these problems, based on the “Three-Dimensional Tolerance Design and Optimization for the Automobile B-pillar U-shaped Parts” project, this article using the dimensional engineering to analyze the assembly deviations for B-pillar parts.In the assembly process, every step will cause a certain impact on assembly quality, resulting in the generation of deviations. The main factors affecting the deviations are location strategy, assembly process and tolerance design. This article makes an accurate analysis for the size deviations based on the dimensional engineering and 3DCS. According to the structure of the B-pillar, a new assembly process was proposed to decrease the size deviations effectively; besides, based on the tolerance contribution analysis, the critical tolerances were found to make a further improvement for the B-pillar parts. The main contents for this article are as follows:(1)The background and the development for the dimensional engineering in recent years were introduced. The specific problems occurred during the assembly process were verified and the necessity of using dimensional engineering was pointed out.(2)The specific concept of dimensional engineering and CAT was explained(3)The dimensional engineering for B-pillar was analyzed.(4)The B-pillar assembly model was established, and the simulation process was built to analyze the size deviations.(5)According to the simulation results, the quality of the B-pillar was improved by the change of the assembly sequence and the optimization of the key tolerances.