拉深筋成形二维弹塑性有限元数值模拟

利用开发的拉深筋二维弹塑性有限元数值模拟软件 ,对圆形筋和矩形筋就压筋和成形的连续过程进行了数值模拟 ;分析了拉深筋主要几何参数对压筋力和拉深筋阻力的影响 ,研究了压筋和成形两个阶段板料在拉深筋作用下的变形规律与受力特点。模拟结果与实验结果吻合良好 ,为建立一种实用的等效拉深筋模型及进一步的三维拉深筋成形模拟奠定了基础。     

基于有限元分析的覆盖件拉延筋设计与优化

结合等效拉延筋模型，采用基于有限元逆算法的三维有限元分析软件，对汽车后窗内板的拉延成形进行模拟。在确定合理的等效拉延筋阻力后，通过适当的优化算法对拉延筋的真实几何结构进行优化设计。并通过UG二次开发技术，获取优化的拉延筋几何参数和位置，在拉延件上生成真实的拉延筋模型。     

基于数值模拟的拉延筋约束阻力计算方法研究

在汽车覆盖件拉深成形中,拉延筋可以在较大范围内调节和控制板料的变形程度和变形分布,抑制多种成形质量问题的产生.其中,拉延筋几何参数起着重要的作用.本文以矩形拉延筋为例,建立了拉延筋约束阻力计算有限元模型,对拉延筋几何参数与约束阻力之间的关系进行分析研究.结果表明:拉延筋约束阻力与凹槽圆角半径和凸筋圆角半径成反比,与筋高成正比.结合某轿车B柱加强板实例,通过优化其拉延筋结构参数,得到当1号等效拉延筋高8mm、凸筋和凹槽圆弧半径3mm;2号等效拉延筋高4 mm、凸筋和凹槽圆弧半径6mm时,该制件成形质量达到最佳.     

汽车覆盖件成形拉深筋的有限元模拟与优化

利用有限元法模拟某汽车高强钢横梁的成形过程,通过设置拉深筋作为材料流动控制手段。拉深筋的参数设置对成形结果影响很大,首先通过对简单形状零件拉深成形过程的模拟得出一些拉深筋参数对模拟结果的影响规律,然后对横梁拉深筋模型进行多次模拟和修改。通过比较采用等效拉深筋与真实拉深筋模型所得模拟结果,最终得出对于复杂冲压件,应该采用真实拉深筋模型进行模拟的建议。     

平行刃剪切机剪切过程的有限元仿真模拟分析

金属剪切过程是一种复杂的弹塑性大变形过程,同时还存在着应力与应变之间的物理非线性、位移与应变之间的几何非线性以及工具与试件之间的接触边界非线性等多重非线性关系。本文用计算机辅助工程(CAE)软件——高度非线性结构有限元分析软件MARC对平等刃剪切机的剪切过程进行了三维弹塑性大变形仿真模拟,探索出一种求平行刃剪切机力能参数的数值仿真模拟方法。     

十字形钢管拉拔成形的三维有限元模拟

异型钢管拉拔成形是一种高质量、高效率和低消耗的管材成形加工工艺.以十字形钢管为研究对象,采用有限元技术对拉拔成形过程进行数值模拟,得到了成形过程中管料的变形规律.研究发现：在应力分布上,轴向、周向和径向应力随管料在模具中位移增加而增大,三者最大值均出现在减径带与定径带连接处;沿壁厚方向,中心层应力分布较均匀.在应变分布上,塑性变形主要发生在管料与模具初始接触处及减径带与定径带连接处,周向应变沿拉拔轴向分布有较大变化,在模具入口端部分数值为负,在出口端部分数值为正.同时,模拟讨论了周向压缩系数η、拉拔速度v和摩擦系数μ对拉拔过程的影响,当η在1.05～1.14之间变化时,拉拔过程较稳定,应力-应变曲线分布平稳;拉拔应力随着μ的增加而增大;当v=250mm/s时,拉拔应力取得最小值.     

拉延筋/摩擦试验机测控系统设计与实践

随着汽车工业的迅猛发展 ,冲压制件的复杂程度和难度不断增加 ,拉延筋的设计选择已经成为冲压模具设计中的关键技术。本文介绍了拉延筋 /摩擦试验的原理和方法 ,针对上海宝钢从国外引进的拉延筋 /摩擦试验机在测控等方面的不足 ,提出了一套切实可行的改进设计方案 ,并成功的得到了实现。使试验机在试验参数的控制功能方面得到了改进和提高 ,并具备了高温拉延试验功能。为进行规范、统一的拉延筋 /摩擦试验提供了可靠的保证。     

汽车侧围内补板拉深成形数值模拟分析

借助板料成形数值模拟软件Autoform对汽车侧围内补板进行拉深过程的数值模拟,确定工艺补充方法,结合成形极限图,针对产生开裂和起皱区域进行分析,从坯料几何形状、拉深筋、压边力等方面进行调整,经多次模拟得出产品的优化参数,从而缩短产品的开发周期,提高产品开发的成功率和产品的质量。     

3D FE simulation for temperature evolution in the selective laser sintering process

A thermal model of selective laser sintering (SLS) has been developed. The model allows for the non-linear behavior of thermal conductivity and of specific heat due to temperature changes and phase transformations. The temperature evolution and the formation of the sintered part are simulated by a 3D finite element analysis based on continuous media theory. It is shown that the effect of sintering has a strong influence on thermal evolution through changing the thermal properties of the material. The results of the model were experimentally tested and confirmed by temperature measurements.     

大型船用卷板机卷板成形过程的数值模拟

首先对卷板成形过程进行了理论分析;然后用有限元分析软件ABAQUS对某大型船用卷板机板料滚弯成形及回弹的过程进行模拟,得到了成形件的应力分布与应变分布;研究了上辊不同下压量对其成形过程的影响,分析了滚弯过程中辊子和板料间的法向接触正压力,并将仿真值和理论计算值进行了比较,分析了产生误差的原因.同时,分析了辊子对板料的切...     

Enhancing formability in hydromechanical deep drawing process adding a shallow drawbead to the blank holder

In this paper, a new method was proposed in order to enhance the limiting drawing ratio (LDR) of AA5754-O in the hydromechanical deep drawing process (HDD). In the proposed method, a shallow drawbead was added to the blank holder to increase LDR so as to provide strain hardening of a large region on the flange of the sheet material in addition to pre-bulging process which affects particularly only the initial stage but not the later ongoing process. So the LDR of the AA5754-O was increased from 2.65 to 2.787 by enlarging the region of strain hardening in the flange and partially reducing wrinkling tendency due to occurred tensile stresses using the convenient pressure and blank holder force profiles. The importance levels and their convenient values for height of drawbead, pre-bulge height and pressure, surface roughness of the punch were determined with analysis of variance (ANOVA) is a statistical method. ANOVA analysis illustrated that adding a shallow drawbead to the blank holder is the most effective factor between the investigated factors for the HDD process. While the effects of the pre-bulging pressure and pre-bulging height were determined as quite small, the surface roughness of the punch was found unimportant compared to the effect of the shallow drawbead. The highest LDR value was obtained with 1 mm drawbead height, 5 mm pre-bulging height, 10 MPa pre-bulging pressure and 2.8 μm surface roughness of the punch.     

变薄拉深过程的数值模拟

利用上限元法对变薄拉深过程进行了数值模拟。在考虑加工硬化的基础上分析了凹模、芯轴与制件之间的摩擦因子以及变形比对变薄拉深工艺过程的影响。     

FE simulation and process analysis on forming of aluminum alloy multi-layer cylinder parts with flow control forming

The aluminum alloy parts used in airbag of car were studied with flow control forming(FCF) method,which was a good way to low forming force and better mechanical properties. The key technology of FCF was the design of control chamber to divide metal flow. So, the design method of FCF was analyzed and two type of control chamber were put forward. According to divisional principle, calculation model of forming force and approximate formula were given. Then forming process of aluminum alloy multi-layer cylinder parts was simulated. The effect of friction factor, die radius and punch velocity on metal flow and forming force was obtained. Finally, the experiment was preformed under the direction of theory and finite element(FE) simulation results. And the qualified parts were manufactured. The simulation data and experimental results show that the forming sequence of inner wall and outer wall, and then the force step, can be controlled by adjusting the process parameters. And the FCF technology proposed has very important application value in precision forging.     

考虑内禀长度的纯铝L2微拉深过程模拟

结合传统拉深成形工艺过程,采用材料的内禀长度来表征微塑性成形过程中的尺度效应,并在建立的三维有限元分析模型的基础上,对纯铝L2的微拉深工艺过程进行数值模拟与分析,研究了纯铝微拉深的塑性成形过程.试验成形出的微拉深件直径在1.4～1.6 mm之间,纵向深度在1.2～1.4 mm之间,拉深力为2.67 N,微拉深试验结果与模拟结果基本吻合.通过试验结果和模拟结果的对比,说明含内禀长度的微塑性本构方程能够用于微拉深成形过程的有限元数值模拟.     

工艺参数对薄壁铜管游动芯头振动拉拔过程拉拔力影响分析

在金属塑性成形中加入振动,可以有效降低材料变形抗力并提高产品质量。以薄壁铜管游动芯头拉拔为研究对象,分析了振动对铜管拉拔过程中拉拔力的影响,并通过有限元分析软件MARC,对不同的工艺参数(拉拔速度、外模模角和芯头锥角)进行数值模拟。研究结果表明:针对本模型,存在一个最佳外模半锥角和芯头锥角组合(外模半锥角α为12°,芯头锥角β为9°),使得薄壁铜管游动芯头振动拉拔过程中的拉拔力最小,而拉拔速度对拉拔力的影响较小。     

Analysis of an equivalent drawbead model for the finite element simulation of a stamping process

In order to facilitate the three-dimensional finite element analysis for the stamping process, an equivalent drawbead model was adopted to simulate the restraining effects produced by the real drawbead. In the present study, the restraining force exerted by the real drawbead was first computed by the finite element simulation, and the optimum pseudo drawing speed and mesh sizes for both the drawbead and sheet metal employed in the computation were determined through a systematic approach. The computed restraining force was then assigned to a regular mesh which replaced the mesh of the real drawbead. This constitutes the equivalent drawbead model, which avoids the extremely fine mesh required to describe the deformation of sheet blank in the drawbead area. In consequence, a huge amount of computation time can be saved. The accuracy of the finite element simulations using the equivalent drawbead model was validated by both the experimental data and the theoretical predictions.     

FEM numerical simulation of tube axial drawing process

Tube inversion by the axial drawing is an advanced forming process for manufacturing double-walled tubes with high quality, high efficiency, and low consumption. However, to realize forming process depends on producing the tearing in deforming zone, which has a close relationship with forming load. So in this paper, the influence of forming condition parameters on the deforming force and the process is investigated by rigid-plastic FEM numerical simulation. The results show that: (1) during the whole forming process, the shape of the tube remains unchanged when the radius of the core die is larger than a certain value, so a precision forming can be easily realized; (2) for a given r/d₀ or t₀/d₀, the deforming force depends mainly on the value of r/t₀, and there is a critical parameter k, when r/t₀ < k, the steady forming force decreases with an increase of r/t₀; on the contrary, when r/t₀ > k, the steady forming force increases with an increase of r/t₀; (3) the material hardening exponent n of the tube and the friction coefficient μ have a remarkable influence on the deforming force. The smaller the value of n and the larger the value of μ the larger the forming force.     

拔制方式对冷拔钢管拔制效果影响的显式动力分析

借助ANSYS软件显式动力模块建立了空拔钢管和短芯棒拔制三维有限元模型,动态模拟了两种拔制方式的整个过程,从钢管定径和轴向、周向应力分布规律角度分析了实际生产中产生问题的不同机理,并就两种拔制方式中工艺参数对拔制力的影响进行了深入研究,所得结果可为选取冷拔拔制方式提供参考,可为优化模具结构和工艺设计提供依据。     

空心件镦扁镦挤过程数值模拟

运用Deform软件对空心扁法兰件镦扁镦挤过程中的缺陷进行数值模拟。根据模拟结果，改进了工艺方案，优化了模具结构。生产实践验证，这一改进能有效克服缺陷。     

薄壁铜管游动芯头拉拔过程拉拔力影响因素分析

为准确把握薄壁铜管游动芯头拉拔过程的拉拔力,该文应用非线性有限元分析软件ABAQUS建立了薄壁铜管游动芯头拉拔过程的弹塑性有限元模型,分析了内外模具锥角、游动芯头定径段长度、延伸率、摩擦因素以及拉拔速度等工艺参数对薄壁铜管拉拔过程中拉拔力的影响规律。研究表明,芯头或外模的锥角存在一个最佳组合范围,芯头定径段长度和拉拔速度对拉拔力的影响作用非常小,延伸率和摩擦系数的增加将引起拉拔力的明显增加。研究结果为实际生产中的工艺改进提供了科学依据。