筒形件底部实心凸起板锻造成形工艺及缺陷研究

发布时间：2018-08-17 10:13

【摘要】：近年来,随着制造业水平的提高,高精密、低能耗、安全环保的产品生产已成为塑性成形领域创新研究的热点课题,不断推动着新型工艺的发展。板锻造是以板料或其半成品为毛坯在冲压成形过程中控制材料流动成形局部具有三维特征结构金属件的精密塑性成形方法,成形板材上带凸起结构特征的薄板零件具有明显的优越性。本文以筒形件底部实心凸起结构板锻造成形为例,基于主应力法,分析了筒形件底部实心凸起成形过程中拉深区域、凸模圆角区域及凸模底部区域的力学特征,重点研究了凸起底部和凸模圆角底部应力分布及金属流动规律,建立了凸起底部缩孔力学模型,推导出了凸起底部极限板材厚度的理论预测公式,提出了弯矩作用成形实心凸起的概念。基于DEFORM有限元软件平台,开发了Swift本构模型的子程序模块,从而对筒形件底部实心凸起板锻造成形过程进行模拟分析,对比了反挤压和板锻造成形实心凸起应力分布和材料流动速度分布情况。模拟结果发现,两种成形工艺在实心凸起底部挤压区应力具有沿厚度方向和半径方向呈线性增加分布;当成形同一实心凸起高度时,反挤压成形载荷仅是板锻造成形载荷的两倍左右,且在挤压区径向流动速度是板锻造成形的几十倍。同时,探讨了摩擦条件、凸起几何结构及毛坯厚度对实心凸起底部缺陷形成的影响规律,建立了实心凸起板锻造成形失效机制图。研究结果表明,板材凸起一侧润滑条件越差,凸起半径越大、凸起圆角越小、毛坯越薄越容易形成缩孔;当凸起圆角半径过大,一次缩孔深度随凸起底部厚度减薄一直增加。此外,通过板锻造成形实心凸起结构工艺试验,验证了理论结果与模拟结果的可靠性。最后文章提出了货车摇动座板锻造成形工艺,并对模具和毛坯结构进行了优化,显著减少了成形工序,节约了材料,提高了摇动座成形性能。
[Abstract]:In recent years, with the improvement of manufacturing level, the production of high precision, low energy consumption, safety and environmental protection products has become a hot topic in the field of plastic forming innovation, and has been promoting the development of new technology. Plate forging is a kind of precision plastic forming method in which sheet metal or its semi-finished product is used as blank in stamping process to control material flow forming with three dimensional characteristic structure metal parts. Sheet parts with protruding structural features have obvious advantages. In this paper, based on the principal stress method, the mechanical characteristics of the drawing region, the corner region of the die and the bottom region of the convex die are analyzed based on the principal stress method, taking the forging forming of the solid bulge structure plate at the bottom of the cylindrical part as an example. The stress distribution and metal flow law at the bottom of the convex bottom and the corner of the die are studied emphatically, the mechanical model of the shrinkage hole at the bottom of the convex is established, and the theoretical prediction formula of the thickness of the ultimate plate at the bottom of the convex is derived. The concept of solid bulge formed by bending moment is proposed. Based on the DEFORM finite element software platform, the subroutine module of Swift constitutive model is developed, and the forging process of solid raised plate at the bottom of cylindrical part is simulated and analyzed. The distribution of solid protruding stress and material flow velocity in reverse extrusion and plate forging were compared. The simulation results show that the stress of the two forming processes increases linearly along the direction of thickness and radius in the extrusion zone at the bottom of the solid bulge, and when the forming is at the same height of the solid bulge, The forming load of back extrusion is only twice as much as that of plate forging, and the radial velocity of flow in the extrusion zone is tens of times that of plate forging. At the same time, the influence of friction conditions, geometric structure of bulge and thickness of blank on the formation of defects at the bottom of solid bulge is discussed, and the failure mechanism diagram of forging forming of solid convex plate is established. The results show that the worse the lubrication condition is, the larger the raised radius is, and the smaller the raised rounded angle is, the thinner the blank is, and when the radius of the raised corner is too large, the depth of the first shrinkage hole increases with the thickness of the bottom of the bulge. In addition, the reliability of the theoretical and simulation results is verified by the experimental results of solid bulge structure formed by plate forging. In the end, the forging process of truck rocker seat plate is put forward, the die and blank structure are optimized, the forming procedure is reduced, the material is saved, and the forming property of rocker seat is improved.
【学位授予单位】：湘潭大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG316

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