预胀对铝合金充液拉深影响的数值模拟研究

发布时间：2018-10-21 11:22

【摘要】：目前，汽车轻量化对节约能源，减少环境污染等方面越来越受到关注，那么铝合金汽车零部件也就越来越被广泛的应用，但铝合金板材比钢板的成形性低很多，而且汽车覆盖件的形状复杂，用传统的冷冲压成形工艺很容易出现褶皱和拉裂等质量缺陷。板材充液拉深成形是传统冲压成型工艺和液压成形工艺的结合，在成形过程中，凸模接触板料，在液室压力的作用使板料成形。板料液压拉深成形比传统的拉深工艺具备更多的优点，比如可获得更高的拉深比，更好的表面质量和较高的尺寸精度。预胀是充液拉深成形过程之前液室预先增加压力，使板料预先胀形形成软拉延筋的成形方式。软拉延筋的形成可增加板料成形的稳定性和获得更好零件质量。本文以铝合金异形底盒形件和汽车油底盒为研究对象，针对它们的零件形状进行成形工艺分析，采用预胀成形与充液拉深成形工艺相结合的新工艺进行零件的成形，并应用有限元模拟软件Dynaform5.7.1对铝合金异形底盒形件与汽车油底盒进行有限元模拟。对铝合金异形底盒形件和汽车油底盒成形结果进行分析，总结预胀压力、预胀高度、液室压力和压边间隙等参数对零件成形的影响规律。由于汽车油底盒形状复杂，，板料成形时应力应变分布极为复杂，传统的汽车油底盒都需要两次以上的拉深成形，而本文对汽车油底盒进行了一次冲压成形的可行性研究，得出以下结论：在零件成形过程中，合适的预胀压力和预胀高度对零部件形成初始软拉延筋及零件最终成形质量有很大的提高；合理的液室压力加载曲线，得到的零件表面质量较好和壁厚分布均匀；合适的压边间隙可以获得成形效果较好和壁厚分布均匀的零件；适当的增加凸模与板料的摩擦系数和选择合适的凹模圆角半径可以获得成形质量较好的零件。最后得到了合理的工艺路径，由此获得了合格的铝合金异形底盒形件和汽车车油底盒。
[Abstract]:At present, more and more attention has been paid to energy saving and environmental pollution reduction in automobile lightweight, so aluminum alloy automotive parts are more and more widely used, but aluminum alloy sheet is much less formability than steel plate. The shape of automobile panel is complex, so it is easy to appear quality defects such as wrinkle and tensile crack by traditional cold stamping process. Sheet metal forming is a combination of traditional stamping process and hydroforming process. In the process of forming, the punch contact the sheet metal, and the pressure in the liquid chamber makes the sheet metal forming. Sheet metal hydro-forming has more advantages than traditional drawing technology, such as higher drawing ratio, better surface quality and higher dimensional accuracy. Pre-expansion is a kind of forming method in which the liquid chamber increases the pressure in advance and the sheet metal bulges in advance to form a soft drawing bar before the process of liquid filling deep drawing. The forming of soft drawing bars can increase the stability of sheet metal forming and obtain better parts quality. In this paper, taking the aluminum alloy special-shaped bottom box and the automobile oil bottom box as the research object, the forming process of their parts is analyzed, and the new technology of pre-expansion forming and liquid filling deep drawing is adopted to carry out the forming of the parts. The finite element simulation software Dynaform5.7.1 is used to simulate the aluminum alloy special-shaped bottom box and automobile oil bottom box. The forming results of aluminum alloy special-shaped bottom box and automobile oil bottom box were analyzed, and the influence of pre-expansion pressure, pre-expansion height, liquid chamber pressure and blank holder clearance on the forming of parts were summarized. Because the shape of automobile oil bottom box is complex and the distribution of stress and strain in sheet metal forming is very complicated, the traditional oil bottom box needs more than two drawing forming. In this paper, the feasibility of one stamping forming of automobile oil bottom box is studied. The following conclusions are drawn: in the forming process of the parts, the proper pre-expansion pressure and the pre-expansion height can greatly improve the initial soft drawing bars and the final forming quality of the parts, and the reasonable pressure loading curve of the liquid chamber, The good surface quality and uniform wall thickness distribution can be obtained, and the parts with good forming effect and uniform wall thickness distribution can be obtained with proper blank holder clearance. The parts with good forming quality can be obtained by increasing the friction coefficient between the punch and the sheet metal and selecting the proper radius of the corner of the die. Finally, the reasonable process path is obtained, and the qualified aluminum alloy special-shaped bottom box and automobile oil bottom box are obtained.
【学位授予单位】：哈尔滨理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG389

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