汽车发动机罩外板拉深成形的数值模拟

以板料成形的弹塑性理论和Dynaform软件为基础,对一汽大众宝来A5发动机罩外板的拉深过程进行了研究.采用正交实验法对外板零件的拉深工艺参数和模面结构参数进行了设计,研究了压边力、冲压速度、拉深筋高度和凸凹模间隙对外板零件起皱与破裂的影响规律.结果表明,压边力及冲压速度对外板零件的局部最小厚度影响均较大,凸凹模间隙及拉深筋高度对局部最小厚度的影响却较小.具体表现为:压边力越大,外板件的局部最小厚度越小;冲压速度越快,局部最小厚度越小.分析了起皱和破裂产生的原因,提出了相应的拉深质量解决方案.将此工艺方案应用于实际的工艺设计和试模生产中,成形过程与数值模拟实验结果吻合良好.     

工艺参数对TAO半球件冷拉深成形的影响规律

以TAO薄壁半球形零件冷拉深成形为研究对象,采用数值模拟与试验研究相结合的手段,在研究该拉伸成形过程中零件的应变及壁厚分布规律及组织演变规律的基础上,对破裂、起皱缺陷位置进行了预测.同时,采用正交试验分析方法,研究了单位压边力、摩擦系数、凹模圆角半径和凸凹模间隙等工艺参数,对该拉深成形过程的影响规律.结果表明,单位压边力、摩擦系数、凹模圆角半径对拉深过程均有显著影响,其中贡献率分别为凹模圆角半径41.04%,摩擦系数30.27%,压边力24.68%.     

工艺参数对TA0半球件冷拉深成形的影响规律

以TA0薄壁半球形零件冷拉深成形为研究对象,采用数值模拟与试验研究相结合的手段,在研究该拉伸成形过程中零件的应变及壁厚分布规律及组织演变规律的基础上,对破裂、起皱缺陷位置进行了预测。同时,采用正交试验分析方法,研究了单位压边力、摩擦系数、凹模圆角半径和凸凹模间隙等工艺参数,对该拉深成形过程的影响规律。结果表明,单位压边力、摩擦系数、凹模圆角半径对拉深过程均有显著影响,其中贡献率分别为凹模圆角半径41.04%,摩擦系数30.27%,压边力24.68%。     

5A06铝合金中厚板的温热反拉深变形行为（英文）

针对铝合金中厚板室温下反拉深易破裂问题,提出了温热反拉深成形方法。以4.5 mm厚的5A06铝合金板材为研究对象,分别进行室温、280和360°C下的反拉深实验和数值模拟研究,分析温度、压边力和压边间隙对反拉深变形过程中破裂和起皱缺陷的影响规律。采用Abaqus/Explicit软件对温热反拉成形进行了热力耦合数值模拟,得到反拉深变形过程中应力及温度的分布。结果表明:弯曲效应导致凹模内圆角与直壁区过渡处在厚度方向存在径向应力梯度,当温度升高至280°C时,该应力梯度由室温下505 MPa降为72 MPa,减小了85.7%。提高成形温度能明显降低径向应力梯度,从而避免了破裂的发生。当温度高于280°C时,外侧凹模圆角处的切向应力增大,该处起皱缺陷易于发生。当温度升高至360°C时,材料由于过度软化而发生破裂。采用1.5t(t=4.5 mm)压边间隙时,能消除高温成形过程中破裂和起皱缺陷,并成功成形420 mm深的筒形件。     

杯形件冲压成形优化的研究

使用3参数Barlat-Lian屈服准则,通过有限元软件模拟杯形件的拉深成形,获得压边力、凹模圆角半径参数与破裂、起皱、厚度最大变薄率之间关系的数据;通过多元非线性回归处理,分别建立压边力、凹模圆角半径参数与破裂、起皱、最大变薄率的目标函数模型.进一步运用层次分析法求出各目标函数的权重,将多目标函数转化为单目标优化的数学模型,求出成形工艺的参数优化解.最后通过模拟和实验验证杯形件的成形,证明了该方法的可行性.     

矩形盒深拉深成形有限元模拟

针对矩形盒成形过程中各种形式的起皱和拉裂问题，采用MSC．Marc有限元分析软件对矩形盒深拉延成形过程进行模拟。建立了包括板料、凸模、凹模及压边圈在内的整体分析模型，通过对成形过程中拉深件的等效应力进行比较，分析了不同的凸模圆角半径、凹模圆角半径及凸模角半径对矩形盒拉深成形的影响。此外，还对模拟结果做了进一步的分析，得出了凸凹模圆角半径之间的相应关系，以便合理的确定矩形盒深拉延成形时二者的取值范围。考察了模拟方法的可行性和可靠性。     

基于Dynaform的凸缘圆筒件拉深工艺有限元分析

针对带凸缘圆筒件在拉深试模生产中出现的凸缘起皱、零件拉裂问题,通过Dynaform软件对圆筒件的拉深成形过程进行建模与仿真计算,根据模拟结果预测了可能出现缺陷的区域,分析了影响圆筒件成形效果的关键因素.为消除缺陷,研究了压边力、拉深速度、摩擦因数、凸凹模间隙4个因素对凸缘起皱及最大减薄率的影响.以工件最大减薄率最小为目...     

基于PAM-STAMP三通半管拉深成形工艺的模拟

针对一些航空航天三通管件毛坯料厚度薄,成形后厚度要求严格,结构复杂等难于成形特点,对三通半管拉深成形过程的进行了研究。运用PAMSTAMP模拟软件研究不同参数下半管成形后的厚度和质量,分析了凹模圆角半径、凸凹模间隙、压边力对零件成形质量的影响,并获得了最优的工艺参数。用于指导生产,降低了生产周期和成本。     

汽车顶盖前横梁拉延成形工艺数值模拟分析

汽车顶盖前横梁零件的拉延成形容易出现大面积成形不足、局部起皱和破裂。采用有限元分析软件Dynaform对零件拉延成形进行数值模拟,研究该零件拉延成形不足、起皱和破裂的原因及解决措施。研究结果表明,合理的拉延筋设置和压边力调整可以解决零件拉延成形不足、起皱和破裂的问题;汽车顶盖前横梁的拉延成形最佳模具设计参数及成形参数组合为:压边力1000 k N,并需设置半圆形拉延筋,摩擦系数取0.13,凸凹模间隙取0.88。最后通过生产实际结果验证了模拟参数组合的可行性。     

压边力对AZ31镁合金热拉深成形性能的影响——试验及有限元数值模拟研究

在AZ31镁合金板材热拉深成形过程中,压边力Pb可根据成形特点进行设计,压边力过大、过小会引起试样破裂或起皱,至使成形过程不能顺利进行.利用自行设计的拉深模具,采用加热圈与加热棒连接热电偶的方式对凹模与冲头进行控温;通过对弹簧压下量的控制分别施加固定压边力与渐变压边力来研究压边力对AZ31镁合金热拉深成形性能的影响,并采用正交各向异性屈服准则和Wagoner提出的考虑了应变速率与温度影响的应力-应变材料模型.编制用户子程序嵌入MSC.Marc软件中对拉深过程进行了数值模拟,模拟结果与试验结果具有较好的对照性.结果表明,在其它条件合适的情况下,采用浮动压边力(控制在2kN～10kN),可以成形出无破裂与起皱的合格产品.模拟结果与试验有良好的对照性,证明可以用数值模拟来指导实际成形过程.     

Effects of pre-bulging on 2024 aluminum alloy complex-shaped components

To improve the poor plasticity of 2024 aluminum alloy sheet, which causes wrinkle and fracture in conventional deep drawing of complexshaped components, hydromechanical deep drawing (HDD) with pre-bulging was investigated. The loading paths of chamber pressure and pre-bulging pressure were designed and optimized by numerical simulations and experiments, and effects of loading paths were obtained and analyzed for thickness, stress and defects. A reasonable loading path was determined. Thickness is more uniform when pre-bulging pressure is 2 MPa and chamber pressure is 15 MPa. The suspending area of a blank wrinkles easily between the punch and the die when pre-bulging pressure is smaller than 1.5 MPa; fracture occurs for the suspending area of blank between the punch and the die when pre-bulging pressure is larger than 8 MPa. The results show that a helpful friction can be generated, the stress state can be improved, and fracture and wrinkle can be avoided by a reasonable pre-bulging in the suspending area of the blank for a complex-shaped component. The uniformity of thickness and forming limit can be enhanced.     

汽车座椅外侧板单动拉延成形工艺分析及优化

以某型号汽车座椅外侧板为例,采用Auto Form软件对座椅外侧板拉延成形过程进行模拟分析,并根据分析结果预测出拉延过程中的拉裂风险。通过调整零件的圆角半径和修改局部结构,消除了开裂风险,降低了最大减薄率。为取得更好的成形效果,选取压边力、摩擦系数、冲压速度、凸凹模间隙4个重要成形工艺参数进行正交试验及参数优化,得出最优工艺方案为:压边力250 k N、摩擦系数0.13、冲压速度1000 mm·s-1和凸凹模间隙2.42 mm,最终零件的最大减薄率为24.33%,最大增厚率为6.54%。采用优化后方案进行实际拉深试模,得出零件的成形性能与有限元模拟结果一致,工件质量完全符合设计要求。     

基于Dynaform的印涂铝盖冲压拉深摩擦条件的数字化设计技术

以非线性有限元软件Dynaform为平台,保持凸模与坯料间的摩擦系数不变,分别将凹模与坯料间的摩擦系数取值为0.01,0.02,0.04,0.08和0.1,研究凹模与坯料间的摩擦系数对1716印涂铝盖冲压拉深过程中壁厚分布的影响;再将凹模与坯料间的摩擦系数保持不变,分别将凸模与坯料间的摩擦系数取值为0.1,0.125,0.15,0.17和0.18,研究凸模与坯料间的摩擦系数对1716印涂铝盖冲压拉深过程中壁厚分布的影响。结果表明:1716印涂铝盖末次拉深的相对合理摩擦条件是凸模与坯料间静摩擦系数取0.17,凹模与坯料间动摩擦系数取0.020。同时,生产试验表明,采用静摩擦系数为0.17、动摩擦系数为0.020的摩擦条件可以生产出质量合格的产品。     

基于DYNAFORM的汽车前防撞梁支撑板的拉延模具设计

汽车覆盖件是以冲压件为主的零件,而作为生产冲压件的冲压模具的设计,与汽车覆盖件的成形质量息息相关。利用DYNAFORM仿真软件对某汽车防撞梁支撑板进行了拉延仿真,并依据仿真结果对其冲压速度、拉延筋布置方案、压边力、凸凹模间隙等参数进行选取和设计。通过分析厚度变化云图,采用厚度差来评价成形结果,确定了具有较好成形效果的参数组合。仿真结果表明:在确定了拉延模具采用等效实体拉延筋的设置后,压边力为360 k N、冲压速度为4000 mm·s-1、凸凹模间隙为0.66 mm时,可获得最好的成形效果。本设计及其仿真结果为其他类型的汽车防撞梁支撑板拉延模具设计提供了有效参考。     

基于正交试验的座椅撑板冲压成形回弹研究及优化

以某汽车座椅撑板为研究对象,采用Autoform有限元软件建立拉延过程有限元模型,对其成形和回弹进行分析。针对拉延成形过程中回弹量过大的缺陷,设计正交试验,选取压边力、摩擦系数、冲压速度和凸凹模间隙4个重要工艺参数作为因素,研究工艺参数对回弹量的影响规律,得到最优的工艺参数组合为:压边力250 k N,摩擦系数0.08,凸凹模间隙1.2 mm,冲压速度4000 mm·s~(-1)。采用优化参数组合进行试模,试验结果与数值模拟结果吻合较好,工件成形效果完全符合设计要求。     

Numerical simulation and analysis on the deep drawing of LPG bottles

Deep drawing is one of the most used sheet metal forming processes in the production of automotive components, LPG bottles and household goods, among others. The formability of a blank depends on the process parameters such as blank holder force, lubrication, punch and die radii, die-punch clearance, in addition to material properties and thickness of the sheet metal. This paper presents a numerical study made on the deep drawing of LPG bottles. In particular, the application of both variable blank holder forces and contact friction conditions at specific location during deep drawing are considered. The numerical simulations were carried out with DD3IMP FE code. A variable blank holder force strategy was applied and the numerical results were compared with results from other blank holder force schemes. It is evident that the proposed variable blank holder force scheme reduces the blank thinning when compared to other schemes; the friction coefficient also has a significant influence on the stress–strain distribution.     

Finite element modeling and experimental results of brass elliptic cups using a new deep drawing process through conical dies

This paper introduces a new technique for deep drawing of elliptic cups through a conical die without blank holder or draw beads. In this technique an elliptic-cup is produced by pushing a circular blank using a flat-headed elliptic punch through a conical die with an elliptic aperture in a single stroke. A 3D parametric finite element (FE) model was built using the commercial FE-package ANSYS/APDL. Effects of die and punch geometry including, half-cone angle, die fillet radius, die aperture length and punch fillet radius on limiting drawing ratio (LDR), drawing load and thickness strain of the cup have been investigated numerically for optimal process design. A die with half cone angle of 18° has shown the best drawability for the new technique. An experimental set-up has been designed, manufactured, and used for experimental production of elliptical shaped sheet-metal cups. A total of seven punches having aspect ratios ranging from 2 to 2.25 and a die with an aspect ratio of 2 have been manufactured and used. Tensile tests were carried out to obtain the stress–strain behavior for the formed sheet metal. Experiments were conducted on blanks of brass (CuZn33) with initial thicknesses of 1.5, 1.9, 2.4 and 3 mm at different clearance ratios (c/t). Effects of blank thickness and clearance ratio on limiting drawing ratio, drawing load and thickness strain were numerically and experimentally investigated. Finite element model results showed good agreement with experimental results. An elliptic cup with a limiting drawing ratio (LDR) of 2.28 has been successfully achieved using the proposed technique and set-up.     

Optimum selection of variable punch-die clearance to improve tool life in blanking non-symmetric shapes

Punch-die clearance is a well-known parameter affecting both tool life and edge quality of parts in blanking and piercing. Selecting the optimum or best punch-die clearance can give a significantly longer tool life by minimizing tool wear. Previous studies have shown the effect of punch-die clearance on various sheet materials and thicknesses during blanking of round parts while non-round geometries are more commonly found in industrial applications. Therefore, in this study, the effect of part geometry is considered to select the ‘best’ punch-die clearance to minimize tool wear. In blanking non-round geometries, the punch and die undergo non-uniform wear, with higher wear observed in areas with sharp radii and abrupt changes in geometry. In the present study, the effect of punch-die clearance on punch stress for blanking various shapes is investigated using Finite Element (FE) analysis. The punch-die clearance that gives the lowest value of the punch stress for the different part geometries is identified. A method is developed to select a geometry dependent variable punch-die clearance to obtain more uniform wear on the punch, thereby increasing the punch and die life.     

基于综合设计的覆盖件冲压工艺优化

针对正交实验设计方法的不足,提出结合正交实验设计和响应面模型(等径设计)的综合设计方法.以汽车行李箱盖的冲压拉延过程为例,进行冲压工艺优化设计.选择拉延筋、摩擦系数(凹模与板料、凸模与板料)、压边力、凸凹模间隙、冲压速度为实验的6因素,每个因素选取3水平,以最小减薄率为质量评价标准,进行综合设计,获得了各因素对最大减薄率的影响规律,得到了最优的关键工艺参数.并利用最优值进行了数值模拟仿真,验证了方法的可行性与实用性.     

扬声器盆架拉深模设计与调试

介绍了采用加大拉深模凸、凹模过渡圆角,增大凸、凹模间隙,降低表面粗糙度值及减少拉深过程压边力变化等措施,避免扬声器盆架拉深破裂,完成了模具的设计制造,生产的产品质量优良。