汽车前梁多道次内高压成形

基于动力显示有限元软件eta/DYNAFORM,以汽车前梁为例,开展了回转拉伸弯曲和模具压弯多道次内高压成形工艺过程数值模拟。结合各种成形工艺下汽车前梁内高压成形极限图,分析其成形质量。在此基础上进行管坯回转拉伸预弯曲和内高压成形试验,给出了典型截面的壁厚分布,并与模拟结果进行了比较。研究结果表明,模拟结果与实验结果相一致。预弯曲成形后,管坯壁厚分布对内高压成形结果中壁厚分布具有一定的影响。多道次内高压成形模拟能够提高内高压成形模拟精度。管坯模具压弯的壁厚分布较回转拉伸弯曲的壁厚分布好,利于汽车前梁内高压成形性能提高。     

浅谈内高压成形工艺及设备

管件内高压成形技术作为汽车结构轻量化的重要应用领域之一,近几年来发展迅速,国外众多汽车公司已将其应用于空心轻体零件的生产.介绍了内高压技术的工艺特点及其应用,叙述了内高压成形设备的基本结构及关键技术.     

双拐曲轴内高压成形过程的有限元分析

在分析目前曲轴制造工艺现状的基础上,指出了现有工艺方法的缺陷。介绍了国内外曲轴内高压成形技术及其模拟技术的发展,给出了双拐曲轴内高压成形工艺的有限元分析结果,指出内高压成形技术作为一种先进的成形工艺,可以用来制造空心曲轴等具有较大膨胀量的非对称结构零件并具有广泛的应用前景。     

浅谈某车型纵管梁的内高压成形工艺

介绍了内高压成形原理,并以某车型前副车架纵管梁为例,分析了制件的结构特点和截面变化,重点介绍了该零件的内高压成形工艺方案的确定过程。     

内高压成形工艺与设备的新进展

阐述了内高压成形的工艺特点、工业应用、关键技术以及近年来取得的新进展，分析了专用成形设备的基本形式、结构和原理，介绍了国际上主要的设备制造商。     

内高压成形技术现状与发展趋势

介绍了内高压成形原理，工艺分类、优点、应用范围和适用材料，综述了国外内高压成形在工业领域尤其汽车工业的应用情况，给出了用内高压成形制造的典型结构件、枝杈管件、异形管件和空心轴类件。详细介绍了国内研制的400MPa内高压成形机参数及在该设备上试制的铝合金管件、不锈钢管件、空心阶梯轴和轿车后轴纵臂等内高压成形件。最后指出内高压成形需要深入研究的课题和发展趋势。     

不规则四边形截面管件内高压成形数值模拟

以不规则四边形截面管件为研究对象,作内高压成形.基于dynaform软件平台,建立了内高压成形有限元模型,利用该模型研究了内压和轴向进给对不规则四边形管材内高压成形的成形形状、角充填情况及壁厚减薄情况的影响规律,分析了管材破裂和起皱缺陷产生的原因.模拟结果显示,适当减小内压力,同时增大轴向进给量,可以有效地防止破裂的发...     

转向节预成形工艺优化设计

提出了转向节预成形优化设计新工艺.针对某转向节半封闭式锻造成形过程,利用有限元法进行了数值模拟分析,研究了坯料四个关键部位尺寸对成形质量的影响;通过模拟转向节成形过程,预测成形缺陷,确定了预成形优化工艺参数.结果表明,通过预成形优化设计,成功解决了成形过程中的缺陷,有效地降低了最大成形载荷,提高了模具寿命,在很大程度上减少了试模时间和生产成本,提高了生产效率.     

汽车前梁内高压成形工艺分析

传统汽车前梁的制造一般是板料冲压成形,它的缺点是成形工序多,模具结构复杂。内高压成形汽车前梁具有工艺简单,生产费用低,成形零件强度与刚度高的优点。采用有限元分析方法对汽车前梁内高压成形过程进行了模拟分析,研究了预弯曲形状和内高压压力对零件成形质量的影响。结果表明:坯料形状对零件胀形质量有重要影响,完全预弯成形后零件胀形质量较好;内高压压力过大会使零件破裂,过小会造成胀形不足;当内高压压力为70 MPa时,可成形出质量较好的零件。     

内高压成形工艺及其在汽车轻量化中的应用

对内高压成形工艺的发展现状和趋势、工艺过程、技术特点、生产线组成进行了分析研究。通过某副车架内高压成形项目,分析研究了内高压成形工艺技术在汽车轻量化中的应用。     

Analysis and design of hydroforming process for automobile rear axle housing by FEM

An FEM program, HydroFORM-3D, for the analysis and design of tube hydroforming processes, has been developed by modifying and adding some subroutines to the previous rigid-plastic finite element program, and then applied to the hydroforming process for an automobile rear axle housing. This paper includes the theoretical background of the program development. Through a numerical simulation, an optimum process is proposed to meet the practical requirements, which shows the efficiency of the numerical simulation. Two types of hydroforming dies are analyzed by numerical simulation. The sliding-type die has the drawback of a possibility of buckling, whereas the fixed-type die causes bursting failure. The thickness distribution of the final product is affected not only by the types of die, but also by the loading paths. The potential failure site for rear axle housing predicted by the numerical simulation is consistent with the experimental results. The values of maximum axial compression force for the first and second hydroforming processes are also in good agreement with experimental data. To manufacture a sound automobile rear axle housing without failure, it is better to use the sliding-type die and it is also critical to maintain a suitable hydraulic pressure level.     

Loading path optimization of tube hydroforming process

Optimization methods along with finite element simulations were utilized to determine the optimum loading paths for closed-die and T-joint tube hydroforming processes. The objective was to produce a part with minimum thickness variation while keeping the maximum effective stress below the material ultimate stress during the forming process. In the closed-die hydroforming, the intent was also to conform the tube to the die shape whereas in the T-joint design, maximum T-branch height was sought. It is shown that utilization of optimized loading paths yields a better conformance of the part to the die shape or leads to a higher bulge height. Finite element simulations also revealed that, in an optimized loading path, the majority of the axial feed needs to be provided after the tube material yields under the applied internal pressure. These results were validated by conducting experiments on aluminum tubes where a good correlation between the experimental results and simulations were obtained.     

直管液压成形工艺模拟及缺陷分析

通过简单例子解释了液压成形工艺的基本原理,并通过塑性有限元模拟了在直管成形过程中会出现的缺陷及成形极限．为今后应用液压成形技术提供基础数据与指导。     

A simple experimental tooling with internal pressure source used for evaluation of material formability in tube hydroforming

Material properties have powerful impact on the tube hydroforming (THF) process and the quality of the deformed tube, so it is important to select proper materials and evaluate the material formability prior to conducting the process. A simplified and applied tooling, which has no use for any external hydraulic pressure source but internal one, was designed for charactering the material formability in THF. A pressurized-fluid supplier is automatically established to provide the internal pressure and axial load synchronously required for THF, and the ratio of the two loads is achieved by proper design of the supplier. As a stand-alone hydraulic bulging fixture, the tooling can be worked on a conventional press, even on a single action press. Free bulge forming (FBF), bulge forming with axial loading (BFAL), free and restrained bulge forming (free and fixed ends) can be fulfilled by the tooling, and furthermore, bulge forming with proportional loading to some extend can be realized. Comparative bulge forming experiments under various forming conditions were carried out with the tooling to validate this project and the results suggest that restrained conditions on the tube ends highly affect the FBF, while the ratio of the two loads dominates the BFAL.     

Improvement of Formability by Oscillation of Internal Pressure in Pulsating Hydroforming of Tube

A new history of internal pressure in the hydroforming processes of tubes is developed to attain high formability. The effect of improvement of formability by the oscillation of internal pressure in a pulsating hydroforming process of tubes is examined using both finite element simulation and experiment. The deformation behaviour during the hydroforming is greatly affected by the oscillation of internal pressure. For a monotonic history of small internal pressure, the wrinkling was caused by insufficient bulging, whereas the necking and bursting occurred for a monotonic history of large internal pressure. The occurrence of these defects can be avoided by oscillating the internal pressure in the pulsating hydroforming. The improvement of formability in the pulsating hydroforming is due to both low pressure and oscillation of pressure. The effects of the amplitude and cycle number of pressure in the pulsating hydroforming on the deformation behaviour are investigated. It is found the oscillation of internal pressure is effective in preventing the occurrence of defects.     

Optimization of loading conditions for tube hydroforming

Tube hydroforming is a developing technology with advanced features of lightness and unified part. This study investigates the best possible regulation for loading conditions between the internal pressure and the axial feeding by hydroforming of a T-shape metal tube. Using conjugate gradient method with finite element method, a program module is generated to check the hydroformed tube quality about its thickness uniformity and the geometry accuracy. Thereby, a batch mode and a sequential mode to optimize the loading conditions of the tube hydroforming process are created and investigated. Regarding the tube quality from the simulation results, the hydroforming process, which follows the loading curve generated by the sequential mode, is better than by the batch mode. The optimal loading procedure generated by this article can offer another possibility for engineer by determining the internal pressure and the axial feeding in tube hydroforming.     

Prediction of forming limits and parameters in the tube hydroforming process

Determination of process limits and parameters for hydroforming was conducted applying widely known plasticity, membrane and thin-thick walled tube theories. Analytical predictions were compared with experimental findings. Simple but useful analytical models to predict buckling, wrinkling and bursting as well as axial force, internal pressure, counter force and thinning in tube hydroforming were verified with experimental results.     

Application of two dimensional (2D) FEA for the tube hydroforming process

Use of FEM in the metal forming process has been a proven analysis tool. Two-dimensional FEA for simplified sections can help to reduce time and cost in part, tooling and process design in tube hydroforming technology as it is a relatively new process, and the existing experience and knowledge base is not as broad as with other forming processes. Some case studies are presented to demonstrate the use of two-dimensional FEA in the hydroforming process. Upon verification through comparison of FEA predictions with experimental results, further planned simulations are conducted to generate simple design rules on geometrical and process parameters.     

内高压成形技术研究与应用新进展

介绍近年来在内高压成形机理、工艺、设备和应用方面的最新进展。针对大截面差管件,弯曲轴线异型截面构件和枝杈管3类工艺,给出典型零件缺陷形式、形状精度、壁厚分布和工艺参数的影响。详细介绍了皱纹控制与利用,降低整形压力的方法和内压与轴向力耦合作用下管材的塑性失稳起皱分析。最后给出了研制的典型内高压成形件及在汽车、航天、航空中的应用。     

A fast algorithm for strain prediction in tube hydroforming based on one-step inverse approach

This paper presents recent developments of a simplified finite element method called the inverse approach (IA) for the estimation of large elastoplastic strains and thickness distribution in tube hydroforming. The basic formulation of the IA, proposed by Guo et al. (1990), has been modified and adapted for the modeling of three-dimensional tube hydroforming problems in which the initial geometry is a circular tube expanded by internal pressure and submitted to axial feed at the tube ends. The application of the IA is illustrated through the analyses of numerical applications concerning the hydroforming of axisymmetric bulge, made from aluminum alloy 6061-T6 tubing, the hydroforming of square section hollow component and the hydroforming of a free Tee extrusion from welded low carbon steel LCS-1008 tubing. Verifications of the obtained results have been carried out using experimental results together with the classical explicit dynamic incremental approach using ABAQUS^® commercial code to show the effectiveness of our approach.