| With the rapidly development of automobile industry in recent years, competition among automobile enterprises become increasingly fierce. Reducing product cost, improving product quality and shorting the development cycle has become the key to the survival and development of automobile enterprises. However, the quality of automobile body assembly is the bottleneck of improving the quality of vehicle at present. It not only directly affect the overall visual evaluation of customers, but also limits the ability of the independent research and development to a great extent. Domestic car enterprises used to reduce the body assembly deviation from the angle of the mold, material or forming process, to produce higher precision parts. However, this cannot solve the problem from fundamental. At the same time, it will reduce the production efficiency, so that the manufacturing cost will be improved.The advent of the computer age has injected vigor and vitality into the automotive industry, and one of the most important is the dimensional engineering. Body dimensional engineering is one of the key technologies to improve the quality of self-brand products. Beginning from the pre research stage, continued to products listed, each stage were strictly management control through the dimensional engineering, so as to improve the quality and reliability of automotive products.This paper is supported by the project of “3D tolerance analysis and optimization of U stampings of B-Pillar”, describing the work of the various stages of the project with the combination of theory and practice. The application of dimensional engineering technology in the optimization of assembly deviation was studied in detail. The main contents of this paper were as follows:(1)The difficulty of the assembly of B-pillar and the purpose of optimizing the assembly deviation are defined. The dimensional engineering was applied to the analysis and optimization process, and the mathematical method is combined with dimensional engineering to realize optimization of assembly deviation for the first time. Compared with the former, the assembly deviation generally decreased more than 30% and the production efficiency improved by more than twice in the production practice, which effectively improve the assembly precision and reduces the manufacturing cost.(2) The assembly process of B-pillar was analyzed according to dimensional engineering process, and the original assembly feature and tolerance information were determined. The 3DCS simulation software was used to analyze the assembly deviation. The specific optimization method is proposed in view of the reasons influencing assembly deviation to prove that dimensional engineering is significant to reduce assembly deviation.(3)Considering the proposed optimization method cannot achieve satisfactory optimization effect, this paper deeply studied the locating mode of B-pillar. A multiobjective optimization method for locating layout is proposed, through simulation analysis of the locating coordinate factors affecting assembly quality. Combined with response surface methodology and 3DCS numerical simulation, the mathematical model between the locating layout parameters and assembly quality were established. Optimizing the locating layout parameters by means of Design-Expert8. 0 software, finally the optimal combination of coordinate parameters was obtained, that is, L1x=1360 mm, L2x= 1538 mm,L3z= 241 mm,L4z=250 mm.(4)The above optimal parameters were verified by numerical simulation, and the size deviation and quality fluctuation of the assembly are analyzed. Factory practice has proved the feasibility of the method.The research improves the dimensional engineering design of B Pillar and provides a new solution for the low cost and high quality production of B-pillar. Researchers can make robust design on this basis to further improve the quality stability. |
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