铝钢零件混联薄板结构焊装偏差分析建模与工艺控制研究

Aluminum-steel hybrid structure has the integrated advantages of light weight and high strength, which becomes the main development direction of lightweight auto-body. But the current variation analysis method cannot accurately calculate the aluminum-steel accumulative deformation process locally connected and the influence of deformation caused by the thermal expansion difference of dissimilar materials of aluminum and steel, which seriously restrict the design and the variation control of lightweight auto-body. Based on the influence analysis of spot welding local deformation made by welding process parameters of aluminum steel sheet and the rigid-flexible coupling repositioning analysis of sheet metal assembly, this project is proposed to study the relationship of the single welding point local deformation and multi-spot coupling deformation between dissimilar materials; the variation analysis model of the dissimilar material sheet structure is established for local deformation to the deviation of whole assembly based on an improved state space equation. The influence pattern of local deviation to the whole structure assembling deviation is revealed. The coupling mechanism of thermal expansion and contraction deformation is studied, which caused by change of operation environmental temperature and metal sheet structure assembly deviation accumulation. The aluminum-steel hybrid structure of multi-station assembly deviation forecast model is established by considering thermal expansion and contraction of aluminum-steel dissimilar material properties. On this basis, this project is to develop the joint configuration design method of aluminum-steel hybrid structure; the aluminum-steel hybrid structure assembly variation and sensitivity to multi-environment temperature are reduced through the joint configuration optimization. The theoretical and technical basis is presented for the auto-body structure lightweight design and process design.

铝钢混联薄板结构具有轻质高强综合优势,成为汽车车身轻量化的主要发展方向。但现有偏差分析方法难以精确地计算铝钢结构局部连接变形累积过程及铝钢材料热膨胀特性差异引入的变形影响，严重制约着轻量化汽车车身结构设计与偏差控制实施。本项目基于铝钢薄板点焊工艺参数对焊点局部变形的影响分析和薄板零件装配的刚柔耦合重定位分析，研究单个焊点局部变形与多焊点耦合变形间的关联关系，建立基于改进状态空间方程的异种材料薄板结构局部变形到整体装配的偏差分析模型，揭示局部误差对整体结构装配偏差的影响规律；研究薄板结构使用环境温度变化引起的热胀冷缩变形与薄板结构装配偏差累积的耦合机制，建立考虑异种材料热膨胀属性的铝钢混联薄板结构多工位装配偏差预测模型；在此基础上，发展铝钢混联薄板结构接头构型设计方法，通过接头构型优化降低铝钢混联车身结构装配偏差和对环境温度变化的敏感性，为汽车车身轻量化结构设计与工艺设计提供理论与技术基础。

铝钢混联薄板结构的应用是车身轻量化的重要发展方向，铝钢连接易产生较大的局部偏差和车身热变形，而现有车身薄板装配工艺设计方法难于对其进行分析和控制，制约着铝钢混联结构的广泛应用。本项目新建一种铝钢混联薄板结构焊装偏差分析模型，利用接头优化设计方法来降低车身装配公差。具体研究内容包括以下六个方面：（1）针对铝、钢异种薄板，进行了CMT焊接力学性能和变形分析，应用正交设计方法优化了焊接参数，减少了金属间化合物，提高了连接强度和焊缝质量，降低了焊接变形；（2）分析了多焊点偏差累积，将之加入到整体偏差分析模型上，建立了局部/整体装配偏差分析模型；（3）应用SysWeld软件进行CMT焊接过程仿真，分析了焊接过程中的传热过程，提出了双椭球模型的CMT热源分析，并通过正交设计优化降低了CMT焊接热变形；（4）以单工位装配偏差分析模型为基础，分析夹具偏差、零件偏差对装配偏差的影响，建立工位装配偏差分析模型；（5）提出了基于GAOT算法夹具定位策略优化系统，并开发了相应的软件；（6）提出了基于分总成模式和现代优化算法装配顺序规划算法，应用基于改进粒子群算法进行了接头优化和装配顺序优化。本项目的研究成果可拓展到镁钢、铝镁等多种材料混联薄板结构，具有重要的科学和工程意义。