筒形件拉深压边力研究与变压边力装置设计

发布时间：2018-05-24 03:11

本文选题：筒形件 + 拉深　；参考：《济南大学》2017年硕士论文

【摘要】：筒形件拉深是指在压力机上利用模具将圆形板料加工成圆筒形状的一种金属板料加工方法,在机械加工中有着十分广泛的应用。在拉深成形过程中,起皱、破裂以及减薄是评价成形件质量的重要指标。同时,压边力是影响拉深件成形质量指标的一个重要因素,通过加载不同形式的压边力,可以影响成形质量。因此,随着对拉深件质量要求不断提高,对变压边力和变压边力加载装置的研究成为拉深工艺中的一个热点。本文以筒形件拉深为研究对象,推导随拉深行程变化的临界起皱和破裂压边力,运用数值模拟软件,分析不同压边力对厚度减薄的影响规律,提出更加合理的压边力变化形式,并设计一套变压边力加载装置。主要研究内容与结果如下:(1)通过建立筒形件的起皱模型以及数学表达式,根据能量法,推导出抑制筒形件起皱的下临界压边力;通过建立筒形件破裂模型,根据拉深过程中材料的拉应力承受极限和所受拉应力,推导出防止筒形件破裂的上临界压边力。结合具体案列,推导出预防起皱和破裂的压边力具体区间。(2)通过建立有限元分析模型,利用壳单元对模型进行网格划分,采用面面接触,施加载荷和约束,施加按照理论分析获得的最大、最小临界压边力载荷,分析总结壁厚的变化规律。(3)通过分析施加不同恒压边力时筒形件壁厚变化情况,给定模拟区间,在此区间内模拟传统压边力加载形式(递增型、递减型、指数型),分析其拉深过程中壁厚减薄状况和材料的流动情况,讨论其对于拉深成形的影响,在此基础上提出新型的压边力加载方式,并进行仿真验证,总结新型压边力相对与其它传统型压边力的优势。(4)根据提出的新型压边力曲线,设计出一套可以实现新型压边力曲线的机械式拉深模具装置,并对装置的部件进行设计,建立装置的二维和三维模型,进行可行性分析。综上所述,本文建立了筒形件拉深力学分析模型,推导出起皱与拉裂状态下对应的上、下临界压边力计算公式;建立了筒形件拉深有限元分析模型,获得了加载上、下临界压边力下,零件壁厚的变化情况;分析了常用压边力加载方式对壁厚减薄的影响,基于合理壁厚减薄假设,提出了合理的压边力曲线,并设计了相应的机械式变压边力装置。上述研究结果对提高筒形件拉深质量具有一定的理论及应用价值。
[Abstract]:Deep drawing of cylindrical parts is a kind of metal sheet machining method which uses die to make circular sheet into cylindrical shape on press. It is widely used in mechanical machining. In the process of drawing, wrinkling, cracking and thinning are important indexes to evaluate the quality of forming parts. At the same time, the blank holder force is an important factor that affects the forming quality of deep drawing parts. By loading different forms of blank holder force, the forming quality can be affected. Therefore, with the continuous improvement of the quality of drawing parts, the research of variable blank holder force and variable blank holder loading device has become a hot spot in drawing process. In this paper, the critical wrinkling and fracture blank holder forces varying with drawing stroke are deduced, and the influence of different blank holder forces on thickness thinning is analyzed by using numerical simulation software, and a more reasonable change form of blank holder force is put forward. And a set of variable blank holder loading device is designed. The main research contents and results are as follows: (1) by establishing the wrinkling model and mathematical expression of the cylindrical part, according to the energy method, the lower critical blank holder force is derived to suppress the wrinkling of the cylindrical part, and the fracture model of the cylindrical part is established. According to the limit of the tensile stress and the tensile stress in the drawing process, the upper critical blank holder force to prevent the cylinder from breaking is deduced. Combined with the specific case list, the concrete interval of blank holding force to prevent wrinkling and fracture is derived. By establishing the finite element analysis model, the model is meshed by shell element, the surface contact is adopted, and the load and constraint are imposed. Applying the maximum and minimum critical blank holder force load obtained according to the theoretical analysis, and analyzing and summarizing the variation law of wall thickness. (3) by analyzing the variation of wall thickness of cylindrical parts with different constant blank holder forces, a given simulation interval is given. In this region, the traditional blank holder loading forms (incremental, decreasing and exponential) are simulated. The wall thickness reduction and material flow in the drawing process are analyzed, and the influence on the drawing forming is discussed. On this basis, a new loading method of blank holder force is put forward and verified by simulation. The advantages of new blank holder force compared with other traditional blank holder forces are summarized. (4) according to the proposed new blank holder force curve, A set of mechanical drawing die device which can realize a new type of blank holder force curve is designed, and the components of the device are designed, the two dimensional and three dimensional models of the device are established, and the feasibility analysis is carried out. To sum up, this paper establishes the mechanics analysis model of cylinder drawing, deduces the calculation formula of upper and lower critical blank holder force corresponding to wrinkle and tension state, establishes the finite element analysis model of cylindrical drawing, and obtains the loading upper, Under the lower critical blank holder force, the change of the wall thickness of the part is analyzed, and the influence of the normal load mode on the wall thickness reduction is analyzed. Based on the assumption of reasonable wall thickness thinning, a reasonable blank holder force curve is proposed. The corresponding mechanical variable blank holder is designed. The above results have certain theoretical and practical value for improving the drawing quality of cylindrical parts.
【学位授予单位】：济南大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG386

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