铝合金异形件充液成形失稳控制策略

对2024-O铝合金异形件的充液成形过程进行研究,讨论充液成形过程中可能出现的失稳形式,通过数值模拟与实验分析液室压力和压边间隙对充液成形的影响,优化工艺参数,提出了控制失稳的措施。结果表明,长边法兰起皱和短边侧壁断裂是成形的主要失效形式,采用合理的压边间隙、液室压力加载路径,可以有效控制法兰起皱和侧壁破裂,实验结果与数值模拟符合较好。     

基于LS-DYNA的板材液压成形数值模拟的软件研究

采用VB6.0为开发工具,基于LS-DYNA,编写有良好人机交互界面的数值模拟软件,并建立了符合板材液压成形工艺的力学模型.以摩托车油箱为例,进行板材液压成形数值模拟试验,得到了良好的模拟结果.此软件解决了板材液压成形数值模拟中复杂边界条件的设置问题及压边力与成形力的加载问题,将使用者从繁重的反复修改参数的工作中解放出来,为进一步发展此成形工艺提供了有效工具.     

A comparative study of stamping and hydroforming processes for an automobile fuel tank using FEM

The use of sheet metal in the hydroforming process for hollow bodies is a new manufacturing technology for the automotive industry. In this paper, a comparison is made between the forming processes of sheet hydroforming and conventional stamping for production of an automobile fuel tank using a commercial explicit FEM code. A modeling methodology for correlation between stamping and hydroforming is proposed in order to obtain the optimal process parameters for producing a sound hydroformed fuel tank. The simulation model for a conventional stamping process is also verified by comparison with experiment. Finally, it is concluded that the hydroforming process can produce a fuel tank with a more uniform and sound thickness distribution than the stamping operation.     

Numerical simulation of sheet hydroforming taking into account analytical pressure and fluid flow

The paper treats the modeling and simulation of sheet metal hydroforming taking into account fluid pressure and fluid velocity effects. A hydro-mechanical model is proposed to determine the fluid flow and the pressure variation in the die cavity in case of sheet hydroforming. The hydrodynamical model for the fluid flow between the sheet and the blank holder is based on Reynold's equation. A numerical and experimental hydromechanical deep drawing of a cylindrical cup validates the predictions of the proposed approach.     

汽车中空异形板件液压成形的实验与仿真分析

为研究基于液压成形的汽车钣金件成形规律,以汽车中空异形板件为研究对象,自行设计并搭建板材液压成形实验测试系统,以此开展板件液压成形的实验研究,借助DYNAFORM有限元软件对板材液压成形进行有限元仿真分析,通过与实验测试结果的对比,验证了建立的有限元模型与数值模拟的正确性。以此为基础,探究压边力、压边力加载路径、液室压力、压边间隙和板材与凹模之间的摩擦系数等关键工艺参数对板材液压成形厚度的影响规律,提出汽车中空异形板件液压成形工艺,为板材液压成形技术在汽车钣金件成形中的应用提供参考。     

关键参数对薄壁筒形件充液成形的影响规律

为了研究初始反胀高度(IRBH)、反胀压力(IRBP)和液室压力加载路径3个工艺参数对板料充液成形的影响规律,以不锈钢321材料为研究对象,进行板材充液成形工艺过程的分析。首先,利用数值模拟的方法,在有初始反胀(IRB)的充液成形基础上,研究了初始反胀高度与初始反胀压力的组合形式以及液室压力加载路径对制件成形的影响规律,然后分别研究了有无初始反胀的充液成形过程。最后,通过实验的方法进行验证。结果表明:当初始反胀高度为3.75 mm、初始反胀压力为2 MPa时,充液结束时板料的最大减薄率为4.803%,在所有结果中最小;无初始反胀时,零件壁厚最大减薄率为5%;当在充液拉深后期继续加大液室压力时,板料底部发生波动,出现二次变形,与此同时,板料最大减薄率增大。从而验证了合适的初始反胀高度和反胀压力可以减小制件壁厚的最大减薄率,液室压力加载路径不同,零件的壁厚分布也不同。     

飞机铝合金双曲度蒙皮充液成形的数值模拟与试验

针对某型飞机上蒙皮零件,基于有限元分析软件Dynaform,对主动式充液成形和被动式充液成形两种方案进行了数值模拟对比分析。根据数值模拟结果,认为该零件较适合采用主动式充液成形,其次,通过修改工艺补充面和优化成形工艺参数,有效地控制零件的最大减薄量。同时,保证一定的减薄量,使板料达到塑性变形状态,从而有效减小回弹。再通过回弹分析,根据回弹量计算结果,运用Think Design软件对模具型面进行回弹补偿,将回弹量控制在合格范围内。最终通过实际试模,验证了数值模拟的准确性及适用性,加工出表面质量良好、精度满足要求的合格产品。     

板液压成形及无模充液拉深技术

板液压成形技术是液压成形技术中重要的一类 ,广泛地应用于宇航、汽车等工业领域。近年来由于新材料和复杂几何形状零件的不断出现 ,更加突出此种技术的关键性。本文就板液压成形技术原理、数值模拟技术和分类进行了研究 ,探讨了此种技术将来的发展 ,介绍了基于板液压成形技术的无模充液拉深技术 ,利用实验和数值模拟技术对此技术进行了分析 ,验证了此项技术的可行性 ,并取得了较好的结果     

板料液压成形的数值模拟研究

首先对板料液压成形技术相关知识进行了介绍,接着以阶梯圆筒形制件的液压拉伸数值模拟仿真为例,采用DYANFORM软件来说明应用数值模拟技术对板料液压成形过程进行有限元分析的具体步骤。最后,分析了板材液压成形数值模拟的特点并对板料液压成形数值模拟技术的发展趋势进行了展望。     

Evaluation of effect of flow stress characteristics of tubular material on forming limit in tube hydroforming process

The material properties for the analytical and numerical simulation in sheet metal processes, especially in tube hydroforming process, are generally obtained from the uniaxial tensile test of raw sheet material. However, the validation of the formability and reliability of the numerical simulation for the tube hydroforming process arises from the fact that the material characteristics of tubes are different from those of the raw sheet materials. In order to determine the most suitable material property of the tubular material for the evaluation of forming limit on the THF process, the uniaxial tensile test for the specimens of the raw sheet metal and the roll-formed tube and the free bulge test for the roll-formed tubular material are carried out in this paper. The forming limit curves are also derived using plastic instability based on three kinds of necking criteria, which are Hill’s local necking criterion for sheet and Swift’s diffuse necking criteria for sheet and tube, to describe and explain the forming limits for the roll-formed tubular material in the THF process. In order to acquire the informative data on the forming limit curves in the THF process, the loading condition of the free bulge test is controlled. The proper band from nearly necking initiation to nearly bursting initiation has been defined for the roll-formed tubular material in the THF process. It can be concluded that the flow stress of the tubular material should be determined from the actual free bulge test to find the practically valuable forming limit curve for the THF process.     

Manufacture of an automobile lower arm by hydroforming

An automobile lower arm has been fabricated in a prototype form by hydroforming with the aids of numerical analysis and experiments. For the numerical process design, a program called HydroFORM-3D developed here on the basis of a rigid–plastic model, has been applied to the lower arm hydroforming. The friction calculation between die and workpiece has been dealt with carefully by introducing a new scheme in three-dimensional surface integration. To accomplish successful hydroforming process design, thorough investigation on the proper combination of process parameters such as internal hydraulic pressure, axial feeding and tool geometry has been performed. Results obtained from numerical simulation for a lower arm in the hydroforming process are compared with a series of experiments. The comparison shows that the numerical analysis successfully provides the manufacturing information on the lower arm hydroforming, and it predicts the geometrical deformation and the thinning.     

高强钢复杂曲面件充液拉深工艺模拟研究

对某高强钢复杂曲面件的充液拉深工艺进行有限元数值模拟,分析了液室加载路径以及最高液室压力对成形结果的影响,得到该零件充液拉深成形合理的液室加载路径及最高液室压力。     

板料双向加压液压胀形数值模拟

应用商用有限元软件ANSYS/LS-DYNA,对板料的双向加压液压胀形过程进行了数值模拟.并利用韧性断裂准则作为胀形高度极限的判断依据,将模拟得到的必要数据代入到准则中.对两种材料、不同初始液体压力条件下的模拟结果表明,随着初始液体压力的升高,胀形的极限高度也相应的增加,当初始压力与板料的强度相当时,极限高度提高的更明显.     

板材成对液压成形工艺加载路径对成形性的影响(英文)

板材成对液压成形可以用于制造复杂几何截面的空腔构件,通过合理的工艺加载路径可以实现板材的流动控制。研究非焊接板材成对液压成形工艺以及两个主要工艺参数(合模力和液压力)的影响。通过理论计算研究不同合模力对应的极限液压力,得到极限液压力曲线,揭示不同工艺参数组合对变形行为的影响规律。通过有限元分析和实验研究验证了理论值,结果表明它们之间具有较好的一致性。实验采用2种线性加载路径和1种阶梯型加载路径研究加载路径对变形行为和零件成形性的影响,结果表明采用阶梯型加载路径可以得到很好的成形性。     

摩托车油箱液压成形力学分析及模具设计

板材液压成形是金属板料塑性成形的一种新工艺,非常适合于汽车覆盖件、摩托车油箱等复杂零件的生产。但是板材液压成形工艺与模具的设计目前尚无完善的理论,文章基于板材液压成形的力学分析,设计了一套摩托车油箱的液压成形模具。     

基于响应曲面法的QSTE460板料冲裁工艺参数优化

以冲压零件作为分析对象,基于响应曲面法设计板料冲裁的模拟试验,利用DEFORM-2D模拟软件对板料的冲裁变形过程进行有限元模拟,建立了冲裁工艺参数与冲裁断面光亮带长度之间的数学模型。通过模拟结果的分析得知:冲裁间隙与模具刃口圆角半径对光亮带长度的交互式影响最大。将冲裁速度、冲裁间隙以及模具刃口圆角半径作为设计变量,以光亮带长度作为优化目标,利用Design Expert软件对响应曲面模型进行优化,得到板料冲裁的优化参数:冲裁速度为14.04 mm·s-1,冲裁间隙为8.99%t(t为板料厚度),模具刃口圆角半径为1.25%t,光亮带长度的响应值为0.834 mm。此外,利用冲压模具进行试验验证,试验值与响应值之间的相对误差为11.8%,验证了响应曲面法应用于板料冲裁工艺参数优化的准确性。     

反胀压力对铝合金球底筒形件充液拉深过程的影响

充液拉深工艺是一种先进的板材柔性成形方法。结合航天部件的实际需求,通过数值模拟的方法,对5A06铝合金球底筒形零件的初始反胀充液拉深成形过程进行了研究。应用基于LS-DYNA3D内核的动力显示分析软件eta/Dynaform5.5,分析了液室初始反胀压力与液室压力对零件壁厚分布以及起皱、拉裂等缺陷的影响规律,讨论了反胀压力与液室压力的匹配关系,得到了合理的加载区间。结果表明,采用优化的初始反胀压力和液室压力耦合加载条件,可以有效的抑制零件球底部的过度减薄,控制悬空区的内皱,提高零件成形质量。     

A Modified Isotropic–Kinematic Hardening Model to Predict the Defects in Tube Hydroforming Process

Numerical simulations of tube hydroforming process of hollow crankshafts were conducted by using finite element analysis method. Moreover, the modified model involving the integration of isotropic–kinematic hardening model with ductile criteria model was used to more accurately optimize the process parameters such as internal pressure, feed distance and friction coefficient. Subsequently, hydroforming experiments were performed based on the simulation results. The comparison between experimental and simulation results indicated that the prediction of tube deformation, crack and wrinkle was quite accurate for the tube hydroforming process. Finally, hollow crankshafts with high thickness uniformity were obtained and the thickness distribution between numerical and experimental results was well consistent.     

应用JSTAMP／NV的管材液压成形案例仿真

为有效地预测管材液压成形过程中存在的问题,比如：制件在外侧过度减薄和内侧起皱,用JSTAMP／NV对汽车副车架液压成形工艺过程进行有限元模拟分析,得出各工序的仿真结果。应用逆向求解器Hystamp仅需直接指定管坯的尺寸参数、材料和弯曲工艺参数即可自动执行弯曲仿真计算并可在几秒内获取弯曲仿真的结果;应用LS—DYNA执行预成形和液压成形工序仿真的计算,需设定液压成形工序的工艺参数,包括液压加载的曲线和方向以及轴向进给位移。JSTAMP／NV能有效模拟管材液压成形工艺过程并预测成形过程中在变形区出现的屈曲、起皱和破裂等缺陷,可以为工艺试验提供指导。     

Investigation into the effect of pre-bulging during hydromechanical deep drawing with uniform pressure onto the blank

Many parameters influence the process of sheet hydroforming, but the key one is the pre-bulging. Pre-bulging includes two parameters: pre-bulging height and pre-bulging pressure, which influence the forming process significantly. In this paper, based on the proposed hydromechanical deep drawing with uniform pressure onto the blank, the effect of pre-bulging on the forming is investigated experimentally and the needed process windows for the pre-bulging pressure and the pre-bulging height are built by using pure aluminum and aluminum alloy. Finally, FEM is used to analyze the forming process to explain some results which were found in the experiment.