汽车铝合金后背门外板成形工艺优化及回弹控制

发布时间：2018-08-12 19:02

【摘要】：随着环境污染加剧、能源紧张和汽车配置的增多,汽车轻量化成为研究热点。轻质材料铝合金取代钢材在车身上大面积使用,可以大大的减轻汽车重量。铝合金板冲压成形性能比普通钢板差,尤其应用于大型的汽车覆盖件冲压成形过程中,更易出现破裂、起皱、回弹和表面损伤等质量缺陷,所以铝合金板冲压成形工艺的设计不能简单地套用普通钢板的经验和标准。同时,相比于国外铝合金在车身上的广泛应用,国内在这方面正处于研究和尝试阶段,所以需要对铝合金覆盖件的冲压成形工艺进行深入研究。本文将以某款汽车的铝合金后背门外板为研究对象,运用有限元数值模拟和数学优化等手段,探究如何高效准确地对铝合金板进行合理的成形工艺设计、成形质量优化及影响因素分析,回弹控制。研究成果和方法对于研究和制定其他铝合金件成形工艺具有一定的指导意义。本文的主要研究内容有以下几个方面:(1)分析零件的结构和成形特点,并根据铝合金板成形性能,安排合理的冲压工序;然后借助UG造型设计和Autofrom有限元数值模拟技术相结合的方法,制定出合理的成形工艺模面,包括拉延方向、工艺补充面、压料面;然后,选取三种拉延筋布置方案进行成形过程数值模拟,结果表明非封闭式双筋方案可以较好的控制板料均匀流动,成形质量较好;比较三种铝合金材料AA6009-T4、AA6016-T4和AA6111-T4在此零件成形时成形性差异,结果显示:AA6016-T4板塑性变形较充分、但易局部破裂,AA6111-T4成形性相对差,但不要破裂,AA6009-T4板成形性居中。(2)针对零件成形过程容易产生破裂和起皱缺陷,选取压边力、摩擦系数、模具间隙和凹模圆角半径这四个工艺参数作为优化变量,以最大减薄率和最大增厚率为优化目标,利用Box-Beheken试验和二阶响应面法建立了优化变量与目标之间的非线性映射关系,并预测了单因素及多因素交互作用对优化目标影响规律。然后,用NSGA-II遗传优化算法进行多目标寻优,找到了有效控制破裂和起皱的工艺参数组合。(3)铝合金弹性模量易回弹,同时,零件卸载和修边后的回弹计算结果显示其回弹大且分布不均匀。所以采取模面修正补偿技术对成形工艺模面进行了四次迭代补偿,将修边后回弹控制在公差允许范围±0.50mm内。
[Abstract]:As environmental pollution intensifies, energy stress and vehicle configuration increase, vehicle lightweight has become a research hotspot. Light-weight aluminum alloy to replace steel in the body of large-area use, can greatly reduce the weight of cars. The forming performance of aluminum alloy sheet is worse than that of common steel plate, especially in the process of stamping forming of large automobile panels, it is more likely to appear quality defects such as rupture, wrinkle, springback and surface damage, etc. Therefore, the design of aluminum alloy sheet stamping process can not simply apply the experience and standard of common steel plate. At the same time, compared with the extensive application of aluminum alloy in the body of foreign countries, this aspect is in the research and try stage in our country, so it is necessary to deeply study the stamping forming process of aluminum alloy panel. In this paper, the aluminum alloy back door plate of a certain automobile is taken as the research object, the finite element numerical simulation and mathematical optimization are used to explore how to carry out the reasonable forming process design of the aluminum alloy plate efficiently and accurately. Forming quality optimization and influencing factors analysis, springback control. The research results and methods have a certain guiding significance for the study and development of other aluminum alloy forming process. The main research contents of this paper are as follows: (1) analyzing the structure and forming characteristics of the parts and arranging the reasonable stamping procedure according to the forming properties of the aluminum alloy sheet; Then with the help of UG modeling design and Autofrom finite element numerical simulation technology, the reasonable forming process die surface, including drawing direction, process supplement surface, compaction surface, is worked out. Three kinds of drawing bars are selected to simulate the forming process. The results show that the non-closed double reinforcement scheme can better control the uniform flow of sheet metal and the forming quality is better. The formability differences of three aluminum alloy materials AA6009-T4, AA6016-T4 and AA6111-T4 in forming process were compared. The results showed that the plastic deformation of 10% AA6016-T4 sheet was sufficient, but the formability of AA6111-T4 was relatively poor. However, the formability of AA6009-T4 plate should not be ruptured in the middle. (2) in view of the fracture and wrinkling defects in the forming process of the parts, four technological parameters, namely, the blank holder force, the friction coefficient, the die clearance and the corner radius of the die, are selected as the optimization variables. With the maximum thinning rate and the maximum thickening rate as the optimization targets, the nonlinear mapping relationship between the optimization variables and the target is established by using the Box-Beheken test and the second-order response surface method, and the law of the influence of single factor and multi-factor interaction on the optimization target is predicted. Then, the NSGA-II genetic optimization algorithm is used for multi-objective optimization, and the combination of process parameters to effectively control the rupture and wrinkle is found. (3) the elastic modulus of aluminum alloy is easy to rebound, and at the same time, The results of springback calculation after unloading and trimming show that the springback is large and the distribution is uneven. So the die surface compensation technology is used to compensate the die surface for four times, and the springback after trimming is controlled within the allowable range of tolerance 卤0.50mm.
【学位授予单位】：江苏大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U466;TG386

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