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针对方盒形体在拉深成形过程中易出现起皱、破裂等缺陷的问题,对其产生机理进行了分析研究。利用Dynaform对方盒件拉深过程进行了数值模拟研究,验证了理论分析的正确性,最后提出了起皱与破裂的预防措施。 相似文献
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金属薄壁盒形件在拉深成形过程中,由于模具结构和工艺条件的影响,成形过程中法兰区常发生起皱现象,在生产实践中消除这些问题能够显著降低生产成本和提高产品质量。以NUMISHEET’93国际会议的标准考题之一薄壁方盒形件为例,使用有限元软件ABAQUS模拟研究了模具圆角、润滑条件、压边力,以及板坯形状等因素对法兰区起皱的影响规律,得到了一些改善方盒形件成形质量的工艺措施。 相似文献
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方盒形件分区压边方式拉深压边力的数值模拟 总被引:1,自引:0,他引:1
板料拉深成形是冲压生产中的一种少、无切削的先进加工方法,拉深成形的重要工艺参数之一是压边力,是保证零件成形质量的关键.根据方盒形件的拉深成形特点,将压边圈设计为直边区域、法兰转角区域及直边与转角交界区域的十六块分区压边方式,并对分区压边圈在不同压边力加载模式下进行了模拟分析.分析结果表明:对于方盒形件的拉深,将压边圈设计为适当的分区结构、各分区压边圈采取合理的变压边力加载模式可以充分改善板料的成形性能、达到抑制板料起皱和延缓破裂以及提高板料拉深成形质量. 相似文献
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数值模拟的双层金属板拉深成形工艺研究 总被引:1,自引:0,他引:1
某轿车排气歧管保护罩采用双层镀铝钢板同步拉深工艺制成,为获得最佳成形工艺参数,避免拉深时产生严重减薄及起皱现象,采用Dynaform软件对双层金属板同步拉深成形过程进行了有限元数值模拟,分析了压边力对拉深成形过程的影响,获得了不同压边力下保护罩内、外层板的壁厚减薄与增厚分布规律。结果表明,与单层板拉深成形相似,对于复杂型面双层金属板拉深件而言,单纯增加压边力并不能完全避免拉深过程中的起皱现象;采用压边力及合理布置拉深筋,可以保证内、外层板材料塑性流动均匀,有效抑制起皱、拉裂等缺陷。根据数值模拟结果进行了产品试制,获得了质量合格的拉深件。 相似文献
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在分析经典资料介绍的盒件拉深成形极限和毛坯制定法的基础上进行了方盒件的拉深研究,实验得出了方盒件单工序成形的更高极限值,提出了一种较为合理的新的毛坯制定法———“三参数法”,对于生产中进一步提高方盒件一次成形极限具有指导作用 相似文献
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在分析经典资料介绍的盒件拉深成形极限和毛坯制定法的基础上进行了方盒件的拉深研究,实验得出了方盒件单工序成形的更高极限值,提出了一种较为合理的新的毛坯制定法-“三参数法”,对于生产中进一步提高方盒件一次成形极限具有指导作用。 相似文献
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以某半球形TA1钛合金拉深成形件为例,通过ABAQUS有限元软件建立了拉深成形三位模型和数值模拟正交试验方案。以是否破裂和起皱为衡量指标,探究凹凸模间隙、拉深速度和压边力对拉深成形件质量的影响,结果表明:起皱现象主要出现在压边区域不影响成形件质量,对底部最小厚度的影响从大到小依次为拉深速度、压边力以及凹凸模间隙。基于正交试验结果设计优化方案,得到最优工艺参数组合并将其应用于实际生产得到表面质量较好的拉深成形件,结果表明:基于正交试验对拉深成形工艺参数优化的方案可行,可以为企业生产提供指导,具有一定的工程应用价值。 相似文献
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This paper analyses the elastic wrinkling of an annular plate subjected to in-plane uniform tensile stress on its inner edge with the combined use of the Kantorovich method and Galerkin method, and discusses the appearance of wrinkles on the flange of a metal circular sheet during its axisymmetric deep-drawing operation. 相似文献
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板料成形时极限拉深系数的确定 总被引:2,自引:1,他引:1
以金属板料拉深成形时凸模圆角处和凸缘区金属的变形为基础,提出了一个确定板料成形时极限拉深系数的判据。该判据可用于定量研究材质和成形工艺参数对极限拉深系数m k值的影响。并且,在金属板料拉深成形时凸模圆角处金属的变形分析的基础上,应用本文判据导出了平底杯型件拉深时极限拉深系数的计算式。同时,从计算结果的分析中,进一步阐明了板料拉深时合理工艺参数的选择依据。试验结果表明:该判据确定的极限拉深系数m k值准确,且其适用性强。 相似文献
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圆杯无压边锥模拉深皱曲强度与拉深极限预测 总被引:1,自引:0,他引:1
采用能量法导出圆杯无压边锥模拉深的皱曲强度,考虑了材料性 能,径向和周向弯曲作用,厚度变化及加工硬化效应。应用该强度预测无皱极限拉深比,与 Sowerby等人使用3种材料3种板厚作的无压边锥模拉深试验结果完全一致,最大相对误差不 超过8%。提出的研究方法同样适用于轴对称非直壁零件拉深凸凹模间悬空区的切向压缩失稳 分析。 相似文献
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A new kinematically admissible velocity field is suggested for the upper-bound solution of hydroforming of longitudinally curved boxes with regular polygonal cross-section. In order to maintain the uniform wall thickness the back-up fluid pressure is controlled to vary with respect to the punch position during the hydroforming process. The pressure vs punch stroke curves for various process conditions are determined from theoretical analysis. The effects of punch shape, work-hardening exponent, drawing ratio and friction are then analysed and discussed. Experiments are carried out in a hydroforming press according to the computed pressure vs punch stroke curves. The hydroformed specimens have shown very little thickness variation within a 5% range. Thus, the validity of the assumption of uniform wall thickness has been confirmed. The flange deformation from the computation is found to be in good agreement with the experimental observation. When the computed reference curve of pressure vs punch stroke relation has been used, no defect, i.e. no necking or no wrinkling has been observed in the experimental specimens. It has been shown that the present method of analysis can be effectively used for the hydroforming process design of longitudinally curved boxes with regular polygonal cross-section. 相似文献
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J. P. De Magalhes Correia G. Ferron L. P. Moreira 《International Journal of Mechanical Sciences》2003,45(6-7):1167-1180
An analysis of the onset of wrinkling is first developed for a doubly curved, elastic–plastic shell element submitted to a biaxial plane stress loading. Plastic yielding is described using a criterion recently proposed for anisotropic sheet metals. The wrinkling limit curves obtained with this analysis are compared with previous results based on different yield criteria. Finite element (FE) simulations of a deep-drawing experiment are also performed using the Abaqus/Explicit code with the aim of comparing the FE results relating to the initiation of wrinkling with the predictions of the analytical model and with experiments from the literature. 相似文献
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Optimization of the design parameters of modified die in hydro-mechanical deep drawing using LS-DYNA 总被引:1,自引:1,他引:0
Swadesh Kumar Singh Amrit Dixit D. Ravi Kumar 《The International Journal of Advanced Manufacturing Technology》2008,38(1-2):32-37
The use of a modified die enhances the limiting draw ratio compared to that obtainable in a conventional deep drawing operation. Application of these dies, in conventional deep drawing, eliminated the use of blank holder but enhances the tendency of wrinkling in drawn products. In hydro-mechanical deep drawing process, the punch deforms the blank to its final shape by moving against a controlled pressurized fluid. In this paper, a new concept of the application of modified dies in hydro-mechanical deep drawing is presented. The finite element (FE) simulations of a deep-drawing process using modified dies are performed using the 2-D explicit finite element code LS-DYNA, with the aim of optimization of design parameters and the results are compared with the experimental values. The initial design steps in the design of modified die in finite element simulation were taken from the concept of Tractrix die. The use of Tractrix die enhances the draw ratio but simultaneously increases the tendency of wrinkling. In this paper the design parameters of modified Tractrix die for hydro-mechanical deep drawing are optimized for the successful drawing of cups. It is also experimentally verified that by using such modified dies in hydro-mechanical deep drawing, deeper cups are drawn without wrinkling. 相似文献
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A Barlat–Lian anisotropy yield function is introduced into a quasi-flow corner theory of elastic–plastic finite deformation and the elastic–plastic large deformation finite element formulation based on the principle of virtual velocity and the discrete Kirchhoff triangle plate shell element model. The focus of the present researches is on the numerical simulation of the flange earring of deep-drawing process of circular sheets with stronger anisotropy, based on which, the schemes for controlling the flange earring are proposed. 相似文献
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Wrinkling control in aluminum sheet hydroforming 总被引:4,自引:0,他引:4
Nader Abedrabbo Michael A. Zampaloni Farhang Pourboghrat 《International Journal of Mechanical Sciences》2005,47(3):333-358
In this paper, the wrinkling behavior of 6111-T4 aluminum alloys during sheet hydroforming process was numerically and experimentally investigated. In sheet hydroforming, one or both surfaces of the sheet metal are supported with a pressurized viscous fluid, while a punch forms the part. In sheet hydroforming the use of a matching female die is not needed. The use of the pressurized fluid delays the onset of material rupture (International Journal of Mechanical Science 2003;45:1815–48) and also acts as an active blank-holding force to control wrinkling in the flange area. To form a wrinkle-free deep-drawn hemispherical cup with sheet hydroforming, a theoretical analysis based on the work of Lo et al. (Journal of Materials Processing Technology 1993;37:225–39) was initially used to predict the optimum fluid pressure profile. Simplifying geometrical assumptions and Tresca material model used in the theoretical analysis provided a fluid pressure profile that resulted in premature rupture of the sheet metal. However, an optimum fluid pressure profile generated by the finite element method, using Barlat's anisotropic yield function (Journal of Mechanical Physics and Solids 1997;45(11/12):1727–63), was successfully applied in sheet hydroforming to make the deep-drawn hemispherical cup without tearing and with minimal wrinkling in the flange area. The finite element model was also capable of accurately predicting the location of the material rupture in pure stretch, and wrinkling characteristics of the aluminum alloy sheet in the draw-in process. 相似文献
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依据作者建立的数学模型,编制了计算机模拟拉深试验软件.该软件全面反映了影响拉深性能的各种因素,有足够的精度供冲模设计师确定生产条件下的圆简及带突缘圆筒的极限拉深系数;也可作为冲压工艺课程的教学工具,帮助学生研究拉深性能的变化规律. 相似文献