斜壁矩形盒件多点拉深成形的数值模拟

通过对斜壁矩形盒件多点拉深成形的有限元数值模拟,分析了成形过程中起皱与拉裂缺陷的产生,研究了四种不同压边力加载曲线即恒压边力、↘形压边力曲线、V形压边力曲线、■形压边力曲线对成形结果的影响。结果表明:斜壁矩形盒件在整个多点拉深成形过程中,在宽度方向的侧壁底部极易发生破裂缺陷,在法兰直边对称轴处起皱最严重;不同的压边力曲线对斜壁矩形盒件多点拉深最终成形结果的影响很大,其中■形状的压边力加载曲线最有利于斜壁矩形盒件的多点拉深成形。     

分区压边拉深工艺改善矩盒形件成形研究

板料拉深过程中成形性能的优化是最重要的问题之一。通过有限元分析软件DYNAFORM对矩盒形件拉深成形过程进行模拟,研究了盒形件在整体压边圈恒压边力、分块压边圈恒压边力以及分块压边圈变压边力情况下的成形性能。模拟分析结果表明,分块压边下存在最优压边力分布,对每一分区加载随凸模位置变化的压边力类V型曲线,能最大程度的提高矩盒形件的拉深成形性能,为实现矩盒形件拉深过程的最优化提供思路,并在实践生产中指导复杂工件的工艺优化,最终改进工件的成形性能。     

基于变压边力的盒形件拉深研究

利用数值模拟软件Dynaform,建立了盒形件的有限元模型,研究了盒形件在整体压边圈和分块压边圈分别在定压边力、变压边力情况下的拉深成形情况.分析结果表明,变压边力控制技术可以有效地改善盒形件的成形性能,并在此基础上找出了盒形件的最优压边力加载模式.     

矩形件拉深成形变压边力的数值模拟研究

利用有限元软件ANSYS/LS-DYNA研究变压边力对矩形件拉深成形性能的影响.模拟结果表明,合适的变压边力能够提高矩形件的拉深极限,改善矩形件的成形性能.     

圆锥形件拉深过程中变压边力的研究

起皱和断裂是板料成形过程的主要失效模式，合理控制成形过程中的压边力，可以消除这些缺陷，提高成形性能。本文以圆锥形件的成形为例，采用Dynaform软件对变压边力控制的成形工艺进行了数值模拟计算，得到了最佳压边力变化曲线。本文还对模拟结果进行了实验验证。结果表明，变压边力拉深工艺能够极大提高板料的极限拉深高度。     

矩形盒曲面压料的变压边力拉深数值模拟分析

运用数值模拟的方法研究了矩形盒曲面压料拉深时,采用随时间及位置变化的压边力对成形性能的影响。分析结果表明曲面整体压料时,渐增式压边力加载相应地可以提高矩形盒成形性,渐减式压边力加载不利于提高成形性。在压边圈直、曲边分块压料,并分别采用不同压边力模式进行组合加载的模拟实验中,直、曲边均采用渐增式压边力加载,在很大程度上提高了矩形盒拉深成形性。     

矩形盒变压料方式拉深中应变路径的有限元分析

利用有限元方法模拟五种不同压料方式及压料力控制的矩形盒拉深过程.其中,曲边锥面压料拉深有利于法兰曲边材料向直边扩散,沿拉-压路径变形的质点变形量有所增大.平、曲面分块变压料力拉深降低法兰曲边变形抵抗,但质点应变轨迹控制效果不明显,可相应提高拉深成形性.直边设置拉延槛的矩形盒拉深可将质点变形轨迹基本控制在拉压变形区,缓解凸模转角断裂危险区内双拉变形状态,提高拉深成形极限的效果相对显著.     

半球形件拉深压边力数值模拟与优化

针对半球形零件,利用有限元分析软件Dynaform研究了不同恒定压边力对拉深件成形质量的影响,确定了压边力的安全区域。采用6条变压边力控制曲线分别进行模拟。结果表明：采用开口向上的抛物线形变压边力控制曲线,半球形件的质量最好,厚度分布比较均匀,最大增厚率和减薄率分别为22.4%和12.2%。采用数值模拟得到的结果对半球形件拉深的实际生产有一定的指导作用。     

盒形件智能化拉深变压边力控制规律及其预测

智能化拉深过程中压边力规律的实时预测是关键技术之一。选择非轴对称件中的锥壁盒形件为研究对象,通过数值模拟和试验对成形过程中压边力随凸模行程的变化规律进行研究,得到能够提高成形质量的较优压边力变化趋势,提出破裂临界压边力控制原理,并将前馈神经网络模型引入盒形件智能化拉深压边力控制规律的预测,预测结果与试验吻合较好,实现较优压边力规律的实时预测,为实现盒形件拉深成形过程的智能化控制奠定基础。     

矩形盒分块变压料力拉深的有限元分析

作为薄板非回转对称拉深成形系统研究的一部分,针对矩形盒拉深中压料力对成形性和成形极限的影响进行相应的实验和有限元模拟分析。研究表明,矩形盒分块变压料力拉深有助于提高拉深成形性和成形极限。但如何对压料板正确分块、分块衔接方式以及实现变压料力实时控制还需要做大量深入的基础研究工作。     

A closed-loop type algorithm for determination of variable blank holder force trajectory and its application to square cup deep drawing

In deep drawing, a low blank holder force (BHF) can cause wrinkling, while a high BHF can lead to tearing. Thus, it is important to determine the appropriate BHF to be utilized in the forming process. In this study, a variable blank holder force (VBHF) approach to deep drawing is employed, and a simple closed-loop type algorithm is developed to obtain the VBHF trajectory. The proposed algorithm is divided into two phases. The objective of the first phase is to check wrinkling and tearing. In this phase, a low BHF, which is the cause of wrinkling, is used as the initial BHF; it is then increased to prevent wrinkling. The algorithm is terminated when tearing occurs. In a numerical simulation, the distance between the die and the blank holder is used to measure wrinkling. On the other hand, the thickness of the blank is used to determine the tearing. Next, in the second phase, the deviations in thickness are examined. Wrinkles are also checked in the second phase. By iterating the above two phases, the VBHF trajectory can be obtained. One of the advantages of the VBHF is that it reduces the forming energy. The validity of the proposed algorithm is examined through both a numerical simulation and experiment.     

抛物面零件充液拉深工艺参数优化分析及成形装置改进

充液拉深是一种先进的板材成形方法.结合装饰零件的实际需求,通过数值模拟的方法对抛物面灯罩的充液拉深成形过程进行了研究,应用显式有限元分析软件DYNAFORM,分析了变压边力和液体介质压力对零件成形质量的影响,得到了变压边力和液体压力匹配的加载曲线.并对充液拉深成形系统进行了合理改造.分析结果表明,采用优化的变压边力和液...     

法兰为整体拉深的矩形盒成形应力分析

为了有效预测矩形盒拉深中的成形力和压料力，在拉深试验和有限元数值模拟的基础上，将法兰直边、曲边作为变形整体进行了应力应变分析。给出极限拉深时板坯下料以及拉深力和压料力的近似计算公式，为进一步开展试验、数值模拟和理论解析提供相应的参考资料。     

圆筒形件拉深失稳及各因素影响分析

对板料成形中圆筒形件拉深的破裂失稳及产生破裂失稳的临界压边力进行研究.由于凸、凹模圆角及其间隙的存在,圆筒形件拉深的筒壁区实际为凸、凹模圆角之间的公切线部分.根据Mises-Hill屈服函数及Tresca准则求出凸缘变形区、凹模圆角区和筒壁区的应力分布,得到危险断面处的应力表达式,从而求出不产生破裂失稳的临界压边力的解析表达式,并进一步分析获得拉深比、硬化指数、厚向异性系数、摩擦因数以及径向推力等因素对临界压边力的影响规律.采用液压压边与周缘加径向推力的拉深模具对08Al板料进行拉深试验,试验结果与理论计算结果具有很好的一致性.     

基于熵权综合评价法的动力电池壳首道次拉深成形参数优化

针对某动力电池壳首道次拉深成形过程中的起皱、破裂、厚度不均匀和模具接触力大的问题,提出了一种基于熵权的综合评价法对其进行多目标工艺参数优化来提高首道次成形质量。选取压边力、凹模圆角半径、凸模圆角半径、模具间隙、摩擦因数为影响因素,以最大减薄率、最大增厚率、最大凸模接触力、最大厚度差为评价指标,进行正交试验仿真。在此基础上应用熵值法和综合评价法,获得了最优的工艺参数组合,提高了动力电池壳首道次成形质量。     

Optimization of variable blank holder force trajectory by sequential approximate optimization with RBF network

Sequential approximate optimization (SAO) is an attractive approach for design optimization. In this paper, the radial basis function (RBF) network is employed for the SAO. First, we examine the width of the Gaussian kernel, which affects the response surface. By examining the simple estimate proposed by Nakayama, four sufficient conditions are introduced. Then, a new simple estimate of the width in the Gaussian kernel is proposed. Second, a new sampling strategy with the RBF network is also proposed. In order to find the sparse region, the density function with the RBF network is developed. The proposed width and sampling strategy are examined through benchmark problems. Finally, the proposed SAO is applied to the optimal variable blank holder force (VBHF) trajectory for square cup deep drawing. The objective is taken as the minimization of the deviation of whole thickness. The constraints are quantitatively defined with the forming limit diagram in which no wrinkling and tearing can be observed. The design variables are the blank holder force. In particular, the risk of both tearing and wrinkling can be handled as the constraints separately. Numerical simulation is carried out by the optimal VBHF trajectory with SAO. It is clear from the numerical simulation that no tearing and wrinkling can be observed.     

Effects of variable blank holder forces and a controllable drawbead on the springback of shallow-drawn TA2M titanium alloy boxes

Springback, which occurs during stamping of shallow-drawn titanium alloy sheets, can negatively influence the stamping accuracy and reliability of follow-up assembly and welding of parts and restrict the application of titanium alloy sheets when high precision is a requirement. Therefore, accurate prediction and control of springback in titanium alloy sheets is an industrial problem that requires urgent attention. In this paper, a TA2M titanium alloy box formed via shallow drawing is used as the research object and springback control during stamping is attempted by varying the magnitude and mode of the blank holder force (VBHF) and height of a controllable drawbead. The influences of drawbead height, VBHF magnitude, and loading mode on the resulting sheet springback are determined by means of finite element simulation and experimentation to determine the best combination yielding the minimum springback. The results of this research provide a reliable reference for future efforts to form tough materials.     

基于径向基神经网络杯形件拉深成形变压边力预测技术研究

分析了RBF神经网络的预测策略和方法,并建立了板料拉深成形的变压边力预测神经网络模型.采用正交设计法进行样本参数的制定,利用板材成形CAE软件Dynaform获得训练数据,利用被训练好的神经网络对薄板成形过程中变压边力的预测技术进行了研究.数值模拟结果表明,此方法对拉深成形变压边力的预测是可行的.     

Determining the optimum variable blank-holder forces using adaptive response surface methodology (ARSM)

Wrinkling and fracture are main defects in sheet-metal forming. They can be reduced or eliminated by manipulating a suitable blank-holder force (BHF). But it is difficult to attain the optimum BHF during sheet-metal forming. In this article, a new optimization algorithm integrating the finite element method (FEM) and adaptive response surface methodology $(r)ARSM$(c) is presented to determinate the optimum BHF. To assure convergence, the trust region modes management strategies are used to adjust the move limit of design spaces. Finally, the optimum results of rectangular box deep drawing are given. Experiments are performed to verify the optimal result.