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板料形状、压料筋的设置对汽车覆盖件成形中起皱和未充分拉深的影响 总被引:9,自引:0,他引:9
在汽车覆盖件成形工艺中,无论是对外观还是对功能的要求,起皱和未充分拉深问题是不允许出现的,因此对起皱和未充分拉深问题的预测和防止显得非常重要的。采用数值模拟技术可以在模具设计初期预测产品的几何形状,从而优化工艺参数以便获得高质量的成品。文章以eta/DYNAFORM有限元分析软件为平台,采用弹-塑性有限元法对DDQS钢进行数值模拟,得出相应的FLD曲线、起皱和未充分拉深区域。重点探讨了板料形状和压料筋的设置对起皱和未充分拉深区域的影响,得出了较好的解决方案。 相似文献
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板料成形性理论评价与深入研究 总被引:6,自引:1,他引:5
破裂和起皱是板料冲压成形中最主要的两种缺陷。本文对各种判断破裂的拉伸失稳理论和判断起皱的塑性屈曲理论进行了综述 ,指出现有的各种理论存在的缺点和不足。提出了基于极限分析的一般变分原理的思想和方法 ,将板材塑性屈曲时所满足的全部方程归结为一个泛函的求极值问题 ,用直接法可以方便求得金属板料塑性屈曲问题的近似解析解。最后 ,指出了发展一种能综合判断板料破裂和起皱问题的全面或广义成形性理论的必要性 ,并给出了一些研究方向和研究内容。 相似文献
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Wrinkling is one of the major defects in sheet metal products and may be also attributable to the wear of the tool. The initiation
and growth of wrinkles are influenced by many factors such as stress ratios, mechanical properties of the sheet material,
geometry of the workpiece, contact condition, etc. In the study, the bifurcation theory is introduced for the finite element
analysis of wrinkling initiation and growth. All the above mentioned factors are conveniently considered by the finite element
method. The wrinkling initiation is found by checking the determinent of the stiffness matrix at each iteration and the wrinkling
behavior is analyzed by successive iteration with the perturbed guess along the eigenvector. The effept of magnitude of perturbation
on the wrinkling behavior can be avoided by the Newton-type iteration method. The finite element formulation is based on the
incremental deformation theory and elastic-plastic material modeling. The finite element analysis is carried out using the
continuum-based resultant shell elements considering the planar anisotropy of the sheet metal. In order to investigate the
effects of geometry and stress state on the wrinkling initiation and growth, a modified Yoshida buckling test is proposed
as an effective buckling test. The finite element analysis are carried out for the modified Yoshida buckling test. The buckling
behavior of the sheet is analyzed for various modified dimensions. 相似文献
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Ti-15-3钛合金橡皮成形凸弯边起皱预测 总被引:1,自引:0,他引:1
基于ABAQUS/Explicit对Ti-15-3钛合金室温锥杯成形实验中悬空侧壁起皱现象进行分析,通过对零件边缘的皱纹波长和峰高的定量研究,获取较适合Ti-15-3钛合金室温成形侧壁起皱的模拟参数。将Ti-15—3钛合金室温锥杯成形起皱获取的模拟参数,用于Ti-15-3钛合金凸弯边橡皮成形起皱的预测,通过定量比较凸弯边边缘的皱纹波长和峰高,分析不同硬度的橡皮对Ti-15-3钛合金凸弯边橡皮成形起皱的影响。经实验验证,有限元模拟对Ti-15—3钛合金凸弯边上皱纹的模拟与实验结果有很好的一致性。 相似文献
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用动态显式有限元法对板材成形进行计算机模拟 总被引:14,自引:1,他引:13
介绍了动态显式有限元法的原理和特点 ,总结讨论了国际现有各种商用有限元软件的情况。采用显式有限元软件 L S- DYNA3D对板材零件冲压过程进行计算机模拟分析 ,预测冲压过程中可能出现的各种工艺缺陷 ,例如坯料的起皱、局部减薄和破裂 ,并以模拟结果为依据提出改进模具和工艺参数的办法 ,优化工艺参数 ,可以减少调试和修模的次数 ,以此实现降低模具费用、缩短制模时间、提高产品成品率和材料利用率 ,最终达到减少产品成本的目的。 相似文献
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利用ABAQUS/Explicit有限元分析软件对2A12 O态铝合金橡皮囊成形凸曲线弯边零件起皱现象进行分析,借助正交试验工具,进行了橡皮囊成形数值模拟试验。通过分析材料性能参数和工艺参数对凸弯边橡皮囊成形零件的影响,获取了影响凸曲线弯边零件起皱的主效应参数,并在此试验基础上建立了基于蚁群神经网络的起皱预测模型。在利用大量试验数据对其训练之后,使用该模型预测橡皮囊成形零件的起皱情况,同时对2A12 O态铝合金板材橡皮囊成形凸弯边零件进行工艺试验验证,结果表明:该模型能够在研究新零件成形过程中快速获得最佳成形参数,并且可以提高效率的工业,且预测误差控制在5%以内,且满足工业应用标准。 相似文献
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多点成形中的柔性压边技术研究 总被引:1,自引:0,他引:1
对于薄板类零件而言,无论是利用整体模具成形还是多点成形,影响成形零件质量的关键因素是起皱。为了防止薄板类零件成形过程中产生起皱,尽量提高薄板类零件的变形量,研制了一种适合于多点成形的新型柔性压边装置,依据成形件的工艺特点、变形大小、材料特性及其弹性模量和成形零件形状,可以确定压边力的大小,且与板料直接接触的柔性压边圈随成形零件的形状不同而有所变形。介绍了多点成形压力机专用的柔性压边装置的工作原理、工作过程、布置结构、力学分析、成形力及压边力的计算。阐述了实际使用过程中的压边力和成形力的调节方法及柔性压边力,实现了数字无级调压,通过调节柔性压边力,明显改善了薄板类零件的成形质量。 相似文献
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在金属板料塑性成形加工中 ,起皱是常见的 ,它影响成形件质量 ,预测与防止起皱已成为人们长期以来关注的热点问题。起皱实质上是金属板料的一种压缩不稳定现象。本文把板料塑性屈曲前后的材质状态视为刚塑性 ,板材塑性皱曲时 ,所满足的全部方程 :平衡 ,机动 ,屈服及流动定律 ,归结为一个泛函的求极值问题 ,在这个泛函中 ,内力场与速度场是彼此独立的自变函数。用直接法可以方便地求得金属板料塑性屈曲问题的近似解析解。文中以环缺在边界纵向拉压力作用下的皱曲问题为例 ,具体地给出了皱曲载荷及板的内力及速度场形态 相似文献
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Y.J. Luo S.P. Li J.F. Zheng D.N. He Y.Q. Zhang J.L. Cheng J. Y. Jiang ) National Mold & Die CAD Engineering Research Center Shanghai China ) Shanghai Volkswagen Automotive Company Ltd. 《金属学报(英文版)》2001,14(5):380-386
1. IntroductionIn the sheet metaJ fOrming process9 deep drawing is used frequently in the automotiveor packaging industry to manufacture products with comPlicated shapes and ctirvatures.In the deep drawing process, a sheet metal, the blank, is clamped between a die and a blankholder. The specific shape of the punch and the die is transferred to the blank during thedefor.atio.[1--4].In the deep drawing process, the material flow is restrained by both the friction con-dition and the blankholde… 相似文献
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F. VollertsenK. Lange 《CIRP Annals》2002,51(1):203-208
Sheet metal forming processes like the fluid form process or hydromechanical deep drawing have the potential for the manufacture of parts having high precision, large drawing ratio, and low costs especially for small and medium lot sizes. In deep drawing using a separating membrane between the liquid and the sheet the process layout for drawing of complex parts must avoid not only the typical failures of bottom fracture, first and second order wrinkles, but also an additional type of wrinkles which are maybe created at the beginning of the process. The development of these wrinkles is described using an analytical model, which was validated by experimental results. The model was used to develop the process layout for deep drawing of a complex sheet metal part. 相似文献
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Technology of sheet hydroforming with a movable female die 总被引:2,自引:0,他引:2
Shi-Hong Zhang Li-Xin Zhou Zhong-Tang Wang Yi Xu 《International Journal of Machine Tools and Manufacture》2003,43(8):781-785
An improved sheet hydroforming process is proposed and investigated experimentally and numerically. A movable female die keeps in contact with the deformed area of the sheet blank so that further deformation of the deformed area is restricted. Under the sealing, the sheet blank under the flange can be drawn in. So the hydroformed part has less thinning than the hydrobulge formed part only, and the limit drawing ratio of the sheet can be remarkably improved. This process is especially suitable for forming of small batch production of sheet metal parts with complicated shapes. The female die can be replaced with other female die of various shapes, and can also be made of very cheap materials such as plaster and hard wood instead of metal when the part number is very small. Thus complex-shaped sheet parts can be formed with less expensive tool systems.In this paper, the hydroforming processes of part A (without a movable die) and part B (with a movable die) were investigated by experiment and by elastoplastic FEM. The effects of various process parameters on the deformation of the sheet blanks were investigated. The forming conditions affecting wrinkling and rupture have been analyzed. The effects of friction and contacting force acting on the experimental results are also discussed. 相似文献
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Drawbeads in sheet metal forming 总被引:4,自引:0,他引:4
M. Y. Demeri 《Journal of Materials Engineering and Performance》1993,2(6):863-866
Drawbeads are used to control the flow of sheet metal into the die cavity during stretch-draw forming of large panels. They
prevent wrinkling in formed panels, reduce the blankholder force, and minimize the blank size needed to make a part. Drawbead
restraining forces (pulling forces) and failure locations in the formed sheets are usually evaluated by using drawbead simulation
tooling. In this article, a drawbead simulation apparatus is used to assess the influence of variation in material, bead penetration,
and fric-tion conditions on the drawbead restraining force. Results from the test can be used as input for sheet metal forming
simulation programs. 相似文献
20.
基于Autoform的汽车覆盖件拉深成形数值模拟研究 总被引:2,自引:2,他引:2
以典型覆盖件(汽车外轮罩)为研究对象,板料三维成形分析软件Autoform为平台,研究了板料与凸模、凹模的摩擦、压边力、拉深筋等因素对成形性能的影响。通过Autoform的成形仿真预测板料成形过程中减薄、拉裂、起皱等缺陷,同时分析缺陷产生的原因,进而优化板料成形工艺参数和改进模具结构。 相似文献