共查询到19条相似文献,搜索用时 78 毫秒
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主要研究了金属板材数控单点渐进成形过程中的回弹问题 ,分析了影响板材渐进成形回弹的主要因素和变化规律 ,提出了一种通过增大成形角度控制回弹的方法。 相似文献
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基于量纲分析法的金属板材折弯回弹数学模型 总被引:11,自引:1,他引:11
回弹是影响金属板材工件成形精度的一个非常重要因素。准确控制回弹是工件精密成形和模具设计的关键所在。针对用于修正回弹的传统试错法的不足,提出一种基于量纲分析和正交试验相结合的方法来建立金属板材折弯回弹半径数学模型。并讨论回弹数学模型的适用范围。该模型定量求解了板料回弹半径与凸模半径、板材厚度、屈服强度、弹性模量之间的非线性关系。将此应用于折弯凸模的设计制造,且用该凸模多道次渐进成形了一半椭圆形工件,它的平均误差是+0.63/-0.65mm。该制造结果表明,基于量纲分析法和正交试验法建立的板料回弹半径数学模型是合理有效的,该建模方法有助于加快模具设计进程,降低生产成本,为金属板料折弯成形及模具设计提供了一条新的途径。 相似文献
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给出了直接计算双向曲率冲压模具补偿回弹所需预弯尺寸的逆解公式.通过计算两个方向上的塑性弯矩来建立算法的数学模型.为验证合理性,用有限元软件对不同厚度、期望成形半径为200mm的具有等向曲率的工件进行模拟.结果显示,回弹后的最大法向误差由未补偿的1.96mm降至补偿后的0.52mm,并且板厚越厚,回弹越小,模拟结果与计算值基本相符.因此,计算方法可以为初始模具型面尺寸设计提供参考. 相似文献
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板料卸载后回弹变形对钣金件的成形精度影响很大。基于Numisheet1993的U形弯曲标准考题,考虑板材与模具间的接触演变过程,建立了一个有限元模型来预测铝合金板材弯曲过程的回弹。模拟中板材本构方程基于更新拉格朗日弹塑性材料模型,压边力采用凸缘边界的等效力表示,卸载过程采用模具反向运动方法。对有限元敏感度分析发现,回弹大小和整体精度受到元素大小、积分点和屈服准则的很大影响。有限元模型通过Numisheet1993和2005的考题进行验证,发现精度达90%以上。通过有限元分析得到了一个优化的模型,提供了一个更加精确的方法,该方法还可减少计算时间。 相似文献
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在分析理想弹塑性材料弯曲回弹的基础上,提出了一种板料弯曲回弹的计算方法,推导出根据板料强度、厚度和最终成形半径直接计算弯曲半径的逆解公式.这一公式对板料成形中模具修正有一定的借鉴作用. 相似文献
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针对板材非圆弧弯曲回弹补偿模具型面的求解问题,提出了定弧长离散法,在此基础上,结合经典圆弧弯曲回弹理论建立三次多项式插值,迭代计算出模具形状曲线,并在MATLAB中进行数值模拟,经验证该理论解析法具有良好的计算精度. 相似文献
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研究了忽略薄板厚度变化对有限元仿真计算时间和计算结果的影响 ,得到薄板冲压成形过程中压边力和材料特性与薄板回弹量的关系曲线 相似文献
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板料成形数值模拟的准确性在很大程度上取决于回弹模拟的精度。本文就 DYNAFORM软件中单元尺寸与回弹模拟计算的关系进行了研究 ,得出了相应的结论。 相似文献
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A method to design tooling in sheet metal forming using springback calculations is presented. The designed tooling produces a part which matches the desired shape, thereby compensating for springback. To design the appropriate tooling, traction distributions on the sheet in the fully loaded deformed state are computed using the finite element method. The calculated tractions are then used to numerically reproduce springback of the desired part shape by elastic unloading of the part in a reverse manner. The method is examined for materials covering a range of steel strength and hardening, and is found to produce parts with negligible shape error. The success of the tooling design algorithm leads to a proposal for an experimental method to design tooling based on traction distribution measurements. 相似文献
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Zhong-Yi Cai Ming-Zhe Li Xi-Di Chen 《The International Journal of Advanced Manufacturing Technology》2006,27(11-12):1089-1096
The design of the runner and gating systems is of great importance to achieving a successful injection moulding process. The subjects of this study are the finite element and abductive neural network methods applied to the analysis of a multi-cavity injection mould. In order to select the optimal runner system parameters to minimize the warp of an injection mould, FEM, Taguchi’s method and an abductive network are used. These methods are applied to train the abductive neural network. Once the runner and gate system parameters are developed, this network can be used to accurately predict the warp of the multi-injection mould. A simulated annealing (SA) optimization algorithm with a performance index is then applied to the neural network in order to search the gate and runner system parameters. This method obtains a satisfactory result as compared with the corresponding finite element verification. 相似文献
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Zemin Fu Jianhua Mo Wenxian Zhang 《The International Journal of Advanced Manufacturing Technology》2009,45(5-6):448-458
A mathematical model of springback radius was developed with dimensional analysis and orthogonal test. With this model, the punch radius could be solved for forming high-precision semiellipse-shaped workpieces. With the punch radius and other geometrical parameters of a tool, a 2D ABAQUS finite-element model (FEM) was established. Then, the forming process of sheet metal multiple-step incremental air bending was simulated with the FEM. The result showed that average errors of the simulated workpiece were +0.68/?0.65 mm, and provided the process data consisting of sheet feed rate, punch displacement and springback angle in each step. A semiellipse-shaped workpiece, whose average errors are +0.68/?0.69 mm, was made with the simulation data. These results indicate that the punch design method is feasible with the mathematical model, and the means of FEM simulation is effective. It can be taken as a new approach for sheet metal multiple-step incremental air-bending forming and tool design. 相似文献