【作者】 任莉；

【导师】 夏玉峰；

【作者基本信息】 重庆大学 ， 材料科学与工程， 2016， 硕士

【摘要】 随着近几年汽车工业的迅速发展,汽车企业之间的竞争日益激烈,降低产品成本、提高产品质量和缩短研发周期已经成为自主品牌汽车生存和长远发展的关键。然而,当前普遍存在的车身装配偏差问题使国产车面临着品质提升的瓶颈,不仅直接影响到客户的整体视觉评价,同时也在很大程度上限制了自主研发能力。国内车企过去常用的减小车身装配偏差的方式通常是从模具、材料或者成形工艺的角度进行考虑,生产出精度更高的零件,然而这并不能从根本上解决问题,同时还会降低生产效率,使制造成本随之提高。计算机时代的到来为汽车工业注入了生机和活力,其中重要的一部分就是尺寸工程。车身尺寸工程技术是提升自主品牌汽车质量的核心技术之一,从产品预研阶段开始,持续到产品的上市,每个阶段都通过尺寸工程进行严格的管理控制,从而提高汽车的品质感、质量稳定性和可靠性。本文以“B柱U形件三维公差分析及优化”项目为依托,以理论与实践相结合的方式,对尺寸工程各阶段的工作进行阐述,对尺寸工程在优化国产车车身装配偏差方面的应用进行研究。论文主要内容如下:(1)明确了B柱装配的难点及优化装配偏差的目的,将尺寸工程技术应用于装配偏差分析及优化过程,并首次提出将数学方法与尺寸工程相结合,实现对装配偏差的量化优化,在生产实践中采用该方法,装配偏差相比于优化前普遍减小30%以上,生产效率提高两倍以上,有效提高了装配精度,降低了制造成本。(2)根据尺寸工程流程进行B柱U形件的尺寸工程设计,确定公差、定位信息及装配关系,利用3DCS三维仿真软件对装配偏差进行分析,并针对影响装配偏差的因素提出具体的优化方法,证明尺寸工程对减小装配偏差的意义。(3)对定位方式优化展开深入研究,提出对定位点布局进行多目标优化的方法,结合3DCS软件和响应面法,建立了U形件侧围外板定位布局参数与装配质量之间的数学模型,并借助Design-Expert8.0软件对定位布局参数进行优化,得到最佳的坐标组合,即L1x=1360 mm,L2x=1538 mm,L3z=241 mm,L4z=250 mm。(4)通过数值模拟对上述最优参数组合进行验证,分析了装配后的尺寸偏差及质量波动情况,工厂实践也证明了该方法的可行性。本文的研究完善了B柱U形件的尺寸工程设计,为B柱的低成本高质量生产提供了一种新方案,为实际生产提供一定的指导作用,也为解决车身其他U形件的偏差问题提供了一种新的思路。更多还原

【Abstract】 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.更多还原