金属板材数控单点渐进成形回弹的实验研究

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。     

板材成形回弹数值分析的静力隐式方法

给出了板材成形加载过程，卸载过程数值模拟的静力隐式有限元方法，通过平衡迭代求解有限元方程，并采用隐式算法进行应力积分及接触压力计算，这种方法应力计算准确，因而回弹计算结果具有较高的精度，数值计算表明，纯弹性板大变形卸载后能够完全恢复到原始形状，说明该方法对几何非线性问题的分析是非常准确的，最后对板材柱面、球面成形的回弹进行了分析。     

CuZn37黄铜板料微塑性成形中的尺寸效应研究

为研究金属微塑性成形特点,对厚度不同及粗细两种晶粒尺寸的黄铜箔试样进行了单向拉伸和微弯曲实验,并采用经典塑性理论和应变梯度理论对弯曲回弹角进行了预测.粗晶粒板料试样单向拉伸实验表明,CuZn37黄铜的硬化曲线存在一种明显的尺寸效应,即板料厚度越小,屈服强度越高.弯曲回弹实验结果也存在另一种明显的尺寸效应现象,即板料厚度...     

大型管件管端过弯矫圆三步法控制策略

管端过弯矫圆工艺是保证大型管件产品质量的重要工序之一.管端矫圆是一个局部弹塑性变形过程,采用传统的弹塑性理论对其变形本质的精确解析存在一定困难,而合理的矫圆控制策略是提高生产效率的有效手段.本文首先采用物理实验的方法验证了管端矫圆与压扁之间的等价关系,进而通过分析管端压扁过程的弹复规律建立了"三步法"控制策略,从而为后续的过弯矫圆智能化控制系统的奠定了基础.最终的验证实验表明,该控制策略可有效地将管件的管端椭圆度控制在0.5%以下.     

橡皮囊模具快速回弹补偿系统关键算法研究

为了解决钣金成形后的回弹问题,提出一种基于模具型面的快速回弹补偿算法,能够直接在模具型面上完成回弹补偿。首先,对模具型面上的回弹曲线进行自动识别,并根据型面的回弹规律对曲线进行回弹补偿;其次,对补偿后曲线进行拟合,完成新的回弹补偿曲面;最后,通过对模具胎体的分割,完成模具胎体的回弹补偿。利用CATIA提供的 API接口,开发出橡皮囊模具快速回弹补偿系统,大幅提高了模具的设计效率。     

轿车后横梁冲压回弹问题分析和成形工艺改进

轿车后横梁型面复杂、拉深深度大且在成形时应力集中严重,导致成形后制件有回弹和型面扭曲等现象。通过对轿车地板外侧后横梁所产生的扭曲和回弹等缺陷进行应力分析,针对原方案出现的翻边回弹补偿量设计不足、未能准确计算压料力、成形工艺未能充分考虑大尺寸、高强度钢板件的成形特点等问题,制定了合理的冲压工艺方案为:下料拉深修边整形翻边冲孔冲孔侧翻。在优化工艺的基础之上,根据梁类冲压成形特点,提出了增加随形压边、拉延筋和薄膜润滑等措施,可以有效改善回弹,提高了成形件质量。     

汽车连接板成形工艺分析与模具设计

分析了汽车连接板的成形工艺,对连接板的热压成形和冷压成形2种方案做出了详尽的对比,介绍了冷压成形的模具结构、成形部分材料的选用以及对产品回弹的控制方法.结果表明,模具结构紧凑、可靠,节约了成本,且满足生产要求.     

家电产品“U形件”弯曲回弹有限元分析

对家电产品中常用的碳素结构钢Q215A"U形件"弯曲回弹进行有限元数值模拟,分析出凹模圆角半径,凸、凹模间隙,摩擦因数和凸模速度等与弯曲回弹量的关系,为模具制造和冲压生产从业人员提供有益的参考。     

Rapid springback compensation for age forming based on quasi Newton method

Iterative methods based on finite element simulation are effective approaches to design mold shape to compensate springback in sheet metal forming. However, convergence rate of iterative methods is difficult to improve greatly. To increase the springback compensate speed of designing age forming mold, process of calculating springback for a certain mold with finite element method is analyzed. Springback compensation is abstracted as finding a solution for a set of nonlinear functions and a springback compensation algorithm is presented on the basis of quasi Newton method. The accuracy of algorithm is verified by developing an ABAQUS secondary development program with MATLAB. Three rectangular integrated panels of dimensions 710 mmx750 mm integrated panels with intersected ribs of 10 mm are selected to perform case studies. The algorithm is used to compute mold contours for the panels with cylinder, sphere and saddle contours respectively and it takes 57%, 22% and 33% iterations as compared to that of displacement adjustment （DA） method. At the end of iterations, maximum deviations on the three panels are 0.618 4 mm, 0.624 1 mm and 0.342 0 mm that are smaller than the deviations determined by DA method （0.740 8 mm, 0.740 8 mm and 0.713 7 mm respectively）. In following experimental verification, mold contour for another integrated panel with 400 ram~380 mm size is designed by the algorithm. Then the panel is age formed in an autoclave and measured by a three dimensional digital measurement devise. Deviation between measuring results and the panel＇s design contour is less than 1 mm. Finally, the iterations with different mesh sizes （40 mm, 35 mm, 30 mm, 25 mm, 20 mm） in finite element models are compared and found no considerable difference. Another possible compensation method, Broyden-Fletcher-Shanmo method, is also presented based on the solving nonlinear fimctions idea. The Broyden-Fletcher-Shanmo method is employed to compute mold contour for the second panel. It only takes 50% iterations compared to that of DA. The proposed method can serve a faster mold contour compensation method for sheet metal forming.     

前盖外板成形尺寸控制方法研究

以某车型前盖外板为研究对象,利用AutoForm软件对成形制件的回弹进行模拟预测,通过优化工艺补充面及拉深筋以改善制件的回弹,基于工艺优化后的回弹制定相应的补偿方案。结果表明,实际成形制件的尺寸与理论结果一致,在工艺优化基础上对制件进行局部回弹补偿能有效控制成形制件的回弹。