深盒形件液压拉深成形工艺研究

用DYNAFORM有限元仿真软件对深盒形件液压拉深成形过程进行了模拟,分析了压边力和液体压力对盒形件成形质量的影响。研究结果表明,合适的压边力和液体压力能控制盒形件拉深缺陷的发生,采用液压拉深盒形件可获得更好的壁厚分布。     

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     

Technology of sheet hydroforming with a movable female die

An improved sheet hydroforming process is proposed and investigated experimentally and numerically. A movable female die keeps in contact with the deformed area of the sheet blank so that further deformation of the deformed area is restricted. Under the sealing, the sheet blank under the flange can be drawn in. So the hydroformed part has less thinning than the hydrobulge formed part only, and the limit drawing ratio of the sheet can be remarkably improved. This process is especially suitable for forming of small batch production of sheet metal parts with complicated shapes. The female die can be replaced with other female die of various shapes, and can also be made of very cheap materials such as plaster and hard wood instead of metal when the part number is very small. Thus complex-shaped sheet parts can be formed with less expensive tool systems.In this paper, the hydroforming processes of part A (without a movable die) and part B (with a movable die) were investigated by experiment and by elastoplastic FEM. The effects of various process parameters on the deformation of the sheet blanks were investigated. The forming conditions affecting wrinkling and rupture have been analyzed. The effects of friction and contacting force acting on the experimental results are also discussed.     

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.     

Study on hydromechanical deep drawing with uniform pressure onto the blank

Sheet hydroforming has many virtues and has gained increasing interest in industries recently. In this paper, hydromechanical deep drawing (HDD) with uniform pressure onto the blank is proposed and investigated in detail both primarily in experiments and simulation. Final cups with drawing ratios of 2.46 and 3.11 were, respectively, obtained using Al–Mg–Si alloy (Al6016-T4) and soft aluminum (Al1050-H0) that have the strong anisotropic properties. The influence of process parameters on the sheet deformation was studied and the typical failure types including fracture and wrinkling were discussed. Finally, FEM was used to analyze the forming process, and the results from the FEM simulations were in good agreement with those from the experiments.     

先进板材液压成形技术及其进展

文章立足于板液压成形这种先进成形技术,面向创新,介绍了其原理及特点,并分类探讨了板液压成形技术最新进展,指出了今后的发展趋势。     

支叉管零件充液成形工艺

针对某军机支叉管类零件的结构型面复杂、曲率变化大的特点,其传统的成形方式主要采用落压成形,在成形过程中易产生起皱、破裂和表面质量差等问题.因此,提出采用被动式充液成形来加工支叉管零件,并利用有限元软件ANSYS/LS-DYNA建立有限元分析模型,对其充液成形过程进行有限元仿真模拟,研究不同压边力对充液成形的影响,从模拟...     

充液成形装置及锥形件充液拉深成形研究

介绍了作者研制的充液成形装置 ;使用此装置研究了充液成形过程中压边力和液池压力对圆锥形零件成形结果的影响并实现了此种零件的大拉深比单工步成形     

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。     

均匀设计法、神经网络和遗传算法结合在内高压成形工艺参数优化中的应用

内高压成形技术是以轻量化和一体化为特征的一种空心变截面轻体构件的先进制造技术。目前,内高压成形技术越来越受到人们的关注,特别是汽车制造企业。管材的内高压成形过程与很多因素有关,其中施加在管件内部的压力与轴向进给量之间的配比关系尤为重要,对两者的匹配关系进行优化是内高压成形面临的重要课题。传统的优化方法需要大量的模拟计算,耗时多且不易掌握。针对这一问题,该文提出了将均匀设计法、神经网络和遗传算法相结合进行参数优化,既利用了均匀设计试验的均匀可靠性,又运用神经网络的非线性映射、网络推理和预测功能,最后发挥遗传算法的全局优化特性,得出了最优结果,并直接为实际生产提供了可靠的参数依据。     

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。     

我国内高压成形技术现状与进展

综述了近年来国内内高压成形机理、数值模拟、设备和工艺研究情况。详细介绍了轴向失稳应力、开裂内压、起皱控制与利用。设备关键技术和影响数值模拟结果的主要因素,以及研制的典型汽车结构件、复杂管件和组合式凸轮轴。最后指出内高压成形的发展趋势。     

内高压成形起皱行为的研究

对内高压成形起皱过程进行了理论分析、数值模拟和实验研究．分析了加载路径、成形区长径比等因素对皱纹数量和工件成形效果的影响．结果表明：不是所有的皱纹都是失效形式，在某些情况下，管料起皱后仍然可以成形，关键是获得有益皱而不是死皱，通过起皱在成形区聚料是一种有效的预成形方法，该方法拓宽了内高压成形区间．     

铝合金曲面斜法兰罩盖成形工艺的数值模拟与试验研究

研究了铝合金罩盖刚性模拉深预成形-新淬火-充液拉深终成形的多道次成形工艺。通过分析零件的几何特征,确定预成形中间构型的几何形状以及确定合理的冲压方向。基于有限元分析软件Dynaform对成形工艺进行模拟分析,优化成形过程的关键工艺参数,并进行试验验证与优化。研究表明:液室压力及加载路径对充液拉深成形零件质量影响较大,成形所需最大液室压力为15 MPa,充液拉深终成形后的零件壁厚最大减薄率为11.424%,侧壁与法兰没有明显的起皱趋势。试验证明对于该铝合金罩盖零件,采用刚性模拉深预成形-新淬火-充液拉深终成形的多道次成形工艺较传统多道次拉深工艺有明显的优势,可得到表面质量良好的合格零件。     

Discrete layer hydroforming of three-layered tubes

Discrete layer forming proposed in this study is a hydroforming process which can selectively deform the outer tube to a desired shape without any deformation of the inner tube by piercing small holes in the inner tube. A three-layered tube is assembled from inner, middle, and outer tubes, from either similar or dissimilar materials, and deforms simultaneously when internal pressure and axial feed are applied to the tube. In special working environments, multi-layered tubes with combined material properties, high strength, and corrosion resistance are required to satisfy conflicting performance requirements. The feasibility of proposed discrete layer forming process of three-layered tube was evaluated by a tube hydroforming experiment and process analysis was performed. An optimal loading path to prevent wrinkling around holes was developed by an analytical model and was experimentally verified. The results show that the proposed discrete layer forming process can be successfully applicable to hollow forming of non-axisymmetric multilayered tubes for structural purposes.     

圆角结构对新型金属桥塞密封件液压成形性能的影响

针对新型金属桥塞密封件的成形工艺开展研究,探究圆角结构对密封件液压成形性的影响。采用有限元模拟(MSC.Marc软件)和实验相结合的方法,选取零件的形状和中间薄壁弧形段壁厚作为调控对象。通过比较不同圆角半径对零件等效塑性应变分布和大小以及对液压成形力的影响作用,得出合理的圆角结构尺寸。结果表明,随着圆角半径增大,零件中间弧形薄壁段等效塑性应变更加均匀,数值也逐渐减小,液压成形力逐渐增大。模拟和实验结果基本一致,圆角半径为2.5 mm时,对密封件的成形效果最佳,圆角部位不仅未开裂,且外形尺寸满足要求,因此,利用液压成形工艺加工该类金属桥塞密封件可行且高效。     

基于DYNAFORM的内高压成形中预成形工艺改进

对复杂形状空心构件内高压成形工艺进行了数字模拟研究。采用有限元模拟,对矩形截面空心零件弯曲部位在内高压成形过程中产生起皱、破裂等缺陷进行了分析;针对矩形截面空心件弯曲部位,提出采用椭圆截面充液预成形的方法,控制起皱、破裂缺陷的产生,成形质量较理想。并通过试验进行了验证,采用较低压力可以改善内高压成形过程中材料的分布、提高材料的成形极限、控制缺陷产生并提高产品质量。     

空心双拐曲轴内高压成形数值模拟

应用动态显式有限元法对空心双拐曲轴的内高压成形过程进行了模拟分析,研究了加载路径对内高压成形的影响,指出了在加载曲线中存在着最佳成形区间,成形压力小于20MPa时,管坯产生起皱,成形压力大于32MPa时,管坯发生开裂,只有合理的应用加载路径,成形压力介于20MPa与30MPa之间,使轴向进给量可以正好补偿径向的变形量才能获得壁厚较为均匀的合格零件。     

板材零件局部体积成形技术研究

板材局部体积成形技术,或称为板材热冲锻成形技术,为近年来提出的一种板材零件成形方法,其特点是板材冲压成形时不但完成板材零件形状的成形,还兼有局部结构的体积成形,例如局部凸柱、凸台、凸筋等结构的成形,适合于成形镁合金、铝合金等金属的成形,尤其适于替代一些电子器件外壳的铸造加工产品。文章介绍了板材热冲锻成形技术的原理、主要工艺控制参数,并对镁合金盒形件的热冲锻成形过程进行了实验研究和计算机模拟分析。针对带有螺丝柱的典型AZ31B镁合金方盒件,通过实验和有限元模拟,研究了其热冲锻成形工艺。实验表明,在再结晶温度以上冲锻2mm或3mm厚的镁合金板材有很好的成形能力,盒形件的周边和内部凸柱都能同时成形。研究结果表明,合理的模具结构、摩擦润滑条件和加热温度等参数,可以获得侧壁高度均匀、凸柱高度合适、无吸孔和凸柱断裂等缺陷的工件。     

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。