Prediction and Control of both Wrinkle Limit and Fracture Limiton Cylindrical Cup Deep-drawing(Ⅱ)

The prediction and control criterion of both the wrinkle limit and fracture limit on the cylindrical cup deep-drawing are given, and the prediction and control diagram of both the wrinkle limit and fracture limit are also given. The results show that it is suitable for no-flange cylindrical cup deep-drawing, narrow-flange cylindrical cup deep-drawing, wide-flange cylindrical cup deep-drawing/expanding compound forming and rigid punch expanding forming.

Prediction and Control of Both Wrinkle Limit and Fracture Limit on Cylindrical Cup Deep-Drawing

hased on both the wrinkle model and fracturc model, the wrinkle critical tangent pressure and the fractureon critical radial tensile stress are calculated respectively. The maximum tangent pressure formula in the flange deformation zone and the maximum radial tensile stress formula in the cylinder-wall pass force zone are given, and both theno-wrinkle limitl criterion and no-fracture limit criterion are put froward. The prediction and control criterion anddiagram of both the wrinkle limit and fracture limit on cylindrical cup deep-drawing, the most suitable formingzone and the limit deep-drawing coefficient are obtained. Comparing with present experience formulae and actualproduct's production, this prediction and control are quite accurate.

Theoretical and Experimental Analysis of Deep Drawing Cylindrical Cup

There are mainly two methods of deep drawing analysis: experimental and analytical/numerical. Experimental analysis can be useful in analyzing the process to determine the process parameters that produce a defect free product, and the analytical/numerical modeling can be used to model and analyze the process through all stages of deformation. This approach is less time consuming and more economical. Sheet metal forming often includes biaxial in-plane deformation with non-proportional strain paths. In deep drawing of cylindrical cup, the deformation in the flange is dominated by pure shear deformation, while it changes to plane strain when the material is drawn into the die. This paper deals with the analysis of deep drawing of circular blanks into axi-symmetric cylindrical cup using numerical modeling. The blank drawability has been related both theoretically and experimentally with the initial diameter of the blank and deep drawing parameters. The strains in the radial and circumferential directions have been measured. A correlation on the flange thickness variation by taking into account the work hardening with the analytical and experimental values also has been searched.

PREDICTION AND CONTROL OF BOTH WRINKLE AND FRACTURE LIMITS ON CYLINDRICAL CUP MULTI DEEP DRAWING

Based on the superfluous triangle material wrinkle model,the no wrinkle limit criterion of cylindrical cup multi deep drawing is calculated as the prediction and control of the wrinkle limit.According to fracture model,the no fracture limit criterion of cylindrical cup multi deep drawing is calculated as the prediction and control of the fracture limit.Combining the no wrinkle limit criterion with the no fracture limit criterion,the no wrinkle and no fracture limit criterion and diagram on cylindrecal cup multi deep drawing are given as the prediction and control of both wrinkle and fracture limits.In accordance with this can determine the limit deep drawing coefficient and minimum deep drawing coefficient,and can choose the deep drawing coefficient of multi deep drawing,blank holder force and deformation force by optimization choice method.Theory calculation and test data are highly consistent,and suitable for no flange multi deep drawing,flange multi deep drawing and rigid punch expanding

An Approach to Determine Tool Speed for Cylindrical Part Drawing

In order t o evaluate inertial effect on sheet deformation in the simulation of stamping pr ocesses by dynamic explicit FEM, an analytic model is established for analyzing cylindrical cup drawing process. The main factors governing the extent of inerti al effect on sheet deformation pattern are investigated by energy method, and th e approach to the selection of reasonable tool speed for dynamic analysis of sta mping processes is proposed. The effectiveness of the present approach is furthe r demonstrated and justified by the numerical result herewith provided.

基于均匀性的模具表面复合织构

通过ABAQUS软件对筒形件拉深过程进行了数值模拟,揭示了筒形件模具表面摩擦特性对成形件的厚度、应变及其回弹具有重要影响,且模具表面存在最优的摩擦特性分布;以板厚的均匀度为优化目标,得出模具表面最优的摩擦系数组合为μA=μC=μF=0.12,μB=0.26,μD=0.09,μE=0.03,此时板厚的变化幅度最小,仅为27.99%.基于此,采用激光毛化和激光微织构复合造型技术,对筒形件模具表面的摩擦特性进行设计制造,并进行拉深成形对比试验.试验结果表明:复合造型后,拉深得到的成形件筒底圆角部分最大减薄率降低了46.56%,凸缘区最大增厚率降低了30.71%;成形件的厚度分布更加均匀,均匀度提高了39.89%.

变间隙拉深对圆筒形件拉深制耳影响的试验研究

分析了制耳产生的原因并通过各向异性板料的单向拉伸实验,获得了材料屈服强度沿不同方向的变化规律;采用变间隙模具对DC04、DC05圆坯进行拉深试验,并与等间隙模具的试验结果比较。结果表明,沿屈服强度较小的方向配置较大间隙,沿屈服强度较大的方向配置较小间隙,可以使拉深制耳率显著降低。因此采用变间隙拉深是抑制圆筒件拉深制耳高度的新途径。

筒形件新型充液拉深的数值模拟及工艺机理分析

在简要回顾和分析充液拉深装置特点的基础上 ,提出了一种新型的筒形件充液拉深装置 ,该装置除了具有传统的充液拉深装置的优点外 ,还具有三大优点。在商用软件DYNAFORM PC中构建了合理的筒形件新型充液拉深有限元模型 ,分析了新型充液拉深中凹模圆角对成形工艺的影响 ,通过大量模拟进一步明确了新型充液拉深的成形机理 。

筒形件液压拉深过程最优压边力的研究

结合筒形件液压拉深新装置的基本工作原理 ,提出了筒形件拉深法兰部分切向应变更为精确的简化计算公式 ,进一步获得了该法兰区域板料径向及切向应力的新的数学表达式。应用能量法重新建立了筒形件拉深时法兰区板料不起皱的最小压边力的数学表达式。明确指出液压拉深时拉深中的危险断面在板料凹模圆角区和筒壁区相交处 ,建立了相应的拉深力的计算公式 ,并获得了拉深破裂临界状态时极限拉深力及径向应力表达式。推导出了拉深破裂最大压边力的公式 ,指出实际拉深时最佳压边力应在防皱最小压边力和拉破最大压边力之间选取 ,同时根据该结果也能计算液体压力与最小拉深系数的关系。计算结果表明 ,该液压拉深方法可大幅度提高拉深变形程度 。

筒形件拉深CAPP中模糊信息优化技术的应用

分析筒形件极限拉深的影响因素 ,运用模糊信息优化技术得出了模糊优化的工艺设计方案。使用塑性成形仿真软件模拟工件实例验证方案 ,用验证结果指导筒形件拉深CAPP程序的内核设计。

板料成形模拟中惯性效应的探讨

为了研究冲压成形过程动力显式有限元分析中惯性效应对板材变形的影响 ,针对圆筒件拉深建立了一个力学模型 ,采用能量法对该模型进行了分析 ,探讨了决定惯性效应对板材变形影响程度的主要因素 ,提出了合理选择模具运动速度的方法。

球底直筒形拉深件成形极限理论及模拟分析

将球底直筒形零件的受力分析分成2个阶段,即材料悬空阶段和直筒贴模阶段,并从理论上分析了其成形过程中各个部位的应力状态以及成形条件对成形极限的影响;用Dynaform数值分析软件模拟了球底直筒形零件的成形过程,分析了压边力和润滑条件等对球底直筒拉深形件成形极限的影响。

防锈铝的充液拉深

根据模具几何特征 ,通过建立流体力学模型描述液体对板料单元的动态影响 ,结合有限元数值模拟技术对塑性差、难成形材料防锈铝LF6的充液拉深进行数值模拟 ,并进行实验研究 ,得到了防锈铝充液拉深合理工艺参数。结果表明 ,充液拉深流体压力作用与板料成形相结合进行数值模拟分析的方法是正确的 ,采用充液拉深工艺可以有效提高塑性差、难成形材料LF6的成形极限 ,拉深比可达到 2 .4。

铝合金球底筒形件挤压成形力学分析

通过对铝合金带法兰球底筒形件挤压成形工艺的分析,绘制了挤压应力计算图,确定了球端面凸模变形力的平衡方程和运动方程。推出了应力计算公式和单位变形力计算公式,并与实验结果作了比较,两者偏差在25%范围内。

1060纯铝微杯形件微拉深成形研究

微拉深成形以其高效率、低成本、高质量等优点成为一种可行的制造开口、空心、薄壁微型零件的微细加工方法。然而,由于微型化的影响,使得微拉深要比宏观拉深更加困难。研制精密微型落料-拉深复合模,成形出内径仅为1 mm的微杯形件。试验材料采用厚度为50μm的1060纯铝,在真空氛围下经300℃分别退火1 h和8 h。微拉深试验在SANS CMT-5504电子万能试验机上进行,试验速度为0.05 mm/s,润滑剂为聚乙烯薄膜。研究退火工艺和压边力对拉深力、拉深比、制耳和起皱的影响。试验结果表明,顺利成形出质量良好、拉深比为2.1的微杯形件;经退火处理的坯料,拉深力降低,拉深比增大,制耳减弱;随着压边力的增加,起皱减弱,但当压边力超过一定数值后则导致拉裂。

模糊信息优化技术在筒形件拉深CAPP中的应用

分析筒形件极限拉深系数的影响因素 ,运用模糊信息化技术优化工艺设计方案。使用塑性成形仿真软件模拟工件实例验证方案 ,用验证结果指导筒形件拉深CAPP程序的内核设计。增强了CAPP软件的灵活性和实用性。经实验验证 ,该项技术节省了人力、物力和财力 ,缩短了模具开发周期和降低了生产成本 ,开拓了一条仿真软件模拟。

环筒件扩挤复合成形新技术的试验研究

本文提出了一种可用于生产环筒类锻件的新工艺———扩挤复合成形技术。并采用模拟试验方法研究了该工艺中金属的流动规律和主要工艺参数对成形的影响。优化出合理的冲头工作角和扩挤变形比例，为该工艺应用于实际生产提供了科学依据。

筒形件拉深过程的数值模拟

本文研究了板料成形模拟中减速系数选取和压边圈简化模型，编制了相应的有限元数值模拟程序ＳＰＩＤ。并模拟研究了筒形件拉深过程中板厚变化规律及摩擦系数的影响，计算结果与试验值比较吻合，表明该分析程序的可靠性。

关于宽凸缘圆筒件首次拉深极限变形程度的讨论

对宽凸缘工件首次拉深最大相对高度表中(dt/d1)的排序作了修正,并对最大相对高度(h1/d1)和极限拉深系数m1这两种极限变形程度的实验数据的相容性进行了推算与验证。结果表明二者有较好的一致性。

带缺口筒形件毛坯展开的数值模拟分析

以一个带4格矩形缺口的圆筒形拉深件为对象,分析了其成形规律和毛坯展开件形状和尺寸的特点,并用有限元分析软件DYNAFORM-PC对其成形过程进行了数值分析。模拟过程更直观地再现了该零件的冲压成形过程。模拟结果与试模样件基本一致,表明用数值模拟的方法确定大型、复杂冲件的毛坯较试模方法确定毛坯有着明显的优越性。