板材充液拉深动态加载系统开发与应用

液室压力和压边力加载路径是充液拉深工艺中决定零件成形质量的关键工艺参数。针对传统被动加压方式加载路径单一,液室压力较低,不能满足复杂结构零件和高强度材料的成形要求,提出采用闭环控制技术实时调节液室压力和压边力的动态加载方式。设计可控压边和高压增压系统,并应用基于上、下位机的检测控制系统实时调节凸模速度、压边力和液室压力满足设定的工艺参数。在动态加载系统上进行异型结构不锈钢零件的充液拉深试验,动态加载路径下试验件一次整体成形,且表面质量好,贴模精度高。结果表明,充液拉深动态加载系统能够实现复杂加载轨迹和局部高压,适用于复杂结构和高强度材料零件的成形制造。     

先进充液柔性成形技术及其关键参数研究

基于所提出的具有均匀压边力并轴向加压的板材充液柔性成形技术,面向板材液压柔性成形技术的普遍规律,成形出拉深比较高的铝合金筒形件以及其他复杂形状的零件如方锥盒形件、方盒形件、轴对称锥形件等,对其中的关键技术如初始液压加载状态、液压加载最优路径、破裂控制等一些关键参数进行了研究和优化;考虑板平面方向性系数的影响,利用数值模拟的手段对其成形过程进行了分析,指导实验研究,得出了有益的结论。     

盒形件充液拉深成形工艺优化及试验研究

本文主要研究充液拉深成形技术在复杂异形长法兰类盒形件成形过程中的应用,首先对该类零件的材料进行了力学性能和成形性能测试分析,获取材料的成形极限,确定了充液拉深成形方案;建立了盒形件的有限元仿真模型,模拟了盒形件在充液拉深成形过程中材料的壁厚变化情况,通过成形缺陷分析对关键工艺参数低压充液时间TLP、整形时间TIP、最大压边力Fmax、液体流速Vel％,最大成形力Pmax及时效时间Tw等进行了重新设计,并通过数值模拟和试验验证相结合的方法优化了工艺参数;最终,完成了盒形件充液拉深成形流程再造,确定出最优的工艺参数,并成功实现盒形件的充液拉深成形,使其制造效率和产品质量大幅提升,为低塑性、难变形材料盒形件的批量制造奠定了工艺基础.     

双曲度蒙皮零件主动式充液成形技术研究

双曲度蒙皮零件在航空制造领域应用广泛,基于截面尺寸变化较大,具有局部特征的复杂蒙皮类零件提出了主动式充液成形技术。液室压力的加载是主动式充液成形的关键参数之一,通过数值模拟分析了不同液体加载速率条件下2A12-O铝合金双曲度蒙皮零件底部破裂危险点与两端起皱危险点的应变轨迹的变化规律,同时讨论了不同液体加载速率下对壁厚分布的影响。结果表明:合理的液体压力加载速率可以明显的改善应变路径,有效的降低纵向应变,抑制双曲度蒙皮零件底部的过渡减薄,改善了零件的表面质量。     

混合器壳体充液成形研究

分析了火焰筒混合器壳体充液成形过程中存在的问题,利用数值模拟技术并结合新材料的应用,提出了火焰筒混合器壳体充液成形模具的改进方案及模具液压室压力快速准确调节的方法,实现了在普通液压机上进行稳定、快速充液成形。     

2024铝合金长半管类零件充液成形技术研究

针对国内某支线飞机上2024铝合金弧形挡板零件在传统落压成形中容易产生的回弹、扭曲、贴模度差和表面质量差等问题,利用有限元软件建立有限元模型,对2024铝合金长半管零件采用主动式充液胀形进行数值模拟。通过模拟分析,主动式充液胀形工艺可以显著增大零件的变形量,而变形量的增加使材料超出弹性变形阶段达到塑性变形,从而固定住所需型面形状。模拟得出合理的合模吨位为4 000 t,液室压力为17 MPa。最后对模拟结果进行试验验证,试制出了合格的弧形挡板零件,为弧形挡板成形提供了一套符合工业生产的工艺方法,对此类零件成形具有重大借鉴意义。     

充液拉伸

本文系统分析了充液拉伸的成形原理和特点，介绍了瑞典ＡＰ＆Ｔ公司开发的充液拉伸装置，液压机和工艺。     

抛物面零件充液拉深工艺参数优化分析及成形装置改进

充液拉深是一种先进的板材成形方法.结合装饰零件的实际需求,通过数值模拟的方法对抛物面灯罩的充液拉深成形过程进行了研究,应用显式有限元分析软件DYNAFORM,分析了变压边力和液体介质压力对零件成形质量的影响,得到了变压边力和液体压力匹配的加载曲线.并对充液拉深成形系统进行了合理改造.分析结果表明,采用优化的变压边力和液...     

火箭贮箱箱底充液拉深成形工艺的多目标优化

充液拉深成形技术能实现大型贮箱箱底的整体成形,然而成形件的质量受到许多工艺参数的影响。针对大型贮箱整体箱底构件充液拉深成形的起皱和破裂缺陷,以预胀压力、液室压力、压边力、压边圈圆角半径等工艺参数为研究对象,建立多目标优化模型。对贮箱箱底成形过程进行模拟,在此基础上,使用拉丁超立方采样法获得样本数据。采用克里金插值法(Kriging)和径向基函数(Radial basis function, RBF)建立工艺参数和质量指标之间的代理模型。利用NSGA-III算法和粒子群算法(Particle swarm optimization, PSO)确定了贮箱箱底达到目标(壁厚减薄率最小、破裂趋势最小、法兰边起皱最小、起皱趋势最小)时的最优工艺参数。最后通过实验验证了方法的有效性和结果的准确性。     

板材液压成形技术与装备新进展

随着板材零件向大尺寸、薄壁、深腔、复杂曲面以及难变形材料方向发展,具有低成本、高柔性的板材液压成形技术在航空、航天、汽车等制造业受到高度重视,并面临新的机遇和挑战。介绍板材液压成形技术的发展现状,重点介绍近年发展的径向主动加压充液拉深、预胀充液拉深、正反向加压充液拉深、双板成对液压成形和热态液压成形技术。分析国内外板材液压成形技术在汽车、航空航天等领域的应用现状,综述板材液压成形装备的研制进展,介绍正在研制的世界最大的吨位为150 MN、液体容积为5 m3的液压成形装备,对板材液压成形技术的发展趋势进行展望。     

Experimental and numerical study of stamp hydroforming of sheet metals

The objectives of this research was to experimentally and numerically study the stamp hydroforming process as a means for shaping aluminum alloy sheets. In stamp hydroforming, one or both surfaces of the sheet metal are supported with a pressurized viscous fluid to assist with the stamping of the part thereby eliminating the need for a female die. The pressurized fluid serves several purposes: (1) supports the sheet metal from the start to the end of the forming process, thus yielding a better formed part, (2) delays the onset of material failure and (3) reduces wrinkle formation. This paper focuses on the experimental and numerical results of the stamp hydroforming process utilizing a fluid pressure applied to one surface of the sheet metal. The effects of applying a constant, varying and localized pressure to the surface of 3003-H14-aluminum sheet alloy were evaluated. Experiments demonstrated draw depths improvements up to 31% before the material failed. A failure prediction analysis by Hsu was also carried out to predict an optimal fluid pressure path for the varying fluid pressure case. The commercial finite element analysis code Ls-Dyna3D was used to numerically simulate the stamp hydroforming process. Both isotropic and anisotropic material models were used and their predictions compared against the experimental results. The numerical simulations utilizing Barlat's anisotropic yield function accurately predicted the location of the material failure and the wrinkling characteristics of the aluminum sheet.     

基于组态软件的板市才液压成形监控系统

板材液压成形是一种先进的板材成形技术,广泛应用于汽车、航空航天、厨卫用具等制造领域。在板材液压成形工艺理论与实验研究成果的基础上,提出了将现代最新的组态软件技术应用于板材液压成形计算机监控系统的设计思想,研发了一套以PC机作为上位机、三菱FX2N系列PLC作为下位机的板材液压成形集成监控系统。     

Development of a hydroforming setup for deep drawing of square cups with variable blank holding force technique

Sheet hydroforming is a process that uses fluid pressure for deformation of a blank into a die cavity of desired shape. This process has high potential to manufacture complex auto body and other sheet metal parts. Successful production of parts using hydroforming mainly depends on design aspects of tooling as well as control of important process parameters such as closing force or blank holding force (BHF) and variation of fluid pressure with time. An experimental setup has been designed and developed for hydroforming of square cups from thin sheet materials. Square cups have been deep drawn using constant and variable BHF techniques. A methodology has been established to determine the variable BHF path for successful hydroforming of the cups with the assistance of programmable logic controller and data acquisition system. Finite element (FE) simulations have also been carried out to predict formability with both of these techniques. It has been found that it is possible to achieve better formability in terms of minimum corner radius and thinning in the case of variable BHF technique than in the case of constant BHF technique (constant force during forming and calibration). The results of FE analysis have been found to be in good agreement with experimental data.     

The effect of upper sheet on wrinkling and thickness distribution of formed sheet part using double-layer sheet hydroforming

In the hydroforming of curved sheet parts with a small thickness-diameter ratio, qualified parts are difficult to be manufactured when using the traditional hydroforming process. To solve this problem, double-layer sheet hydroforming was proposed and the wrinkle-free sheet parts were obtained in the authors’ previous study, but the inhibition mechanism of forming defects is far from perfection. Therefore, in this paper, the inhibition mechanism of forming defects is investigated by the combination of FE simulations and technological experiments. Different from the previous research, 2198 Al-Li alloy sheet was selected as the lower sheet. Other conditions such as heat treatment status and thickness are the same as before. The principle of wrinkle elimination can be concluded into the following two aspects. On the one hand, the upper sheet cannot be wrinkled during hydroforming, On the other hand, the surface blank holder pressure is applied in the suspending area. In addition, the beneficial friction between this two sheets changes the radial stress state of the lower sheet and makes the radial strain at some specific area (punch contact area and die corner area) decreased. In conclusion, qualified sheet parts can be manufactured by double-layer sheet hydroforming.     

Numerical analysis and design for tubular hydroforming

To get an optimum deformation path for tubular hydroforming, the hydroforming limit of isotropic and anisotropic tubes subjected to internal hydraulic pressure, independent axial load or torque is firstly proposed based on the Hill's general theory for the uniqueness to the boundary value problem and compared with those of the conventional sheet forming. The influences of the deformation path, the material properties and the active length–diameter ratio on the nucleation and the development of wrinkling during the free tubular hydroforming are also investigated. The above theory is used as a criterion and implemented with some new functions in our ITAS3D, an in-house finite element code for simulating the sheet forming, to control the materials flow and to prevent the final failure modes from occurring. Finally, the tubular hydroforming of an automobile differential gear box is taken as an example to show the efficiency and usefulness of the algorithm.     

板液力成形技术及其应用

针对板液力成形原理、特点及其最新技术进行了讨探.从不同的工艺方法入手,介绍了无模液力柔性成形技术、温介质液力成形技术、成对液力成形技术等几种先进的成形工艺,并对其中的关键技术问题进行了分析.该技术在汽车行业的应用可有效地控制变截面板的成形过程,为大幅度降低车身重量、减少能耗,提供了有力的技术支持.     

基于PMAC的钣料渐进成形机数控系统设计与开发

钣料渐进成形技术是国际上一种新型的钣料数字化制造技术,具有能快速成形复杂形状金属钣件的特点.在分析钣料渐进成形原理的基础上,根据渐进成形过程中成形工具在金属钣料表面的运动与普通铣削运动相似的特点,研制了一种基于PMAC运动控制卡的钣料渐进成形数控系统,它以通用的Windows操作系统作为开发平台,同时具有良好的硬件和软...     

采用可移动凹模的板材液压成形技术

提出一种改进的板材液压成形新工艺,即采用可移动凹模,实现拉深与胀形的复合液压成形。在整个变形过程中,板材初始变形部分始终与可移动凹模接触,从而抑制已变形区进一步变形,使变形更加均匀,实现变形的顺序控制,板材成形极限得到提高。从试验和数值模拟两方面对可移动凹模板材液压成形技术进行了研究,分析各种工艺参数,如摩擦因数等对板材成形性的影响,并且分析了可移动凹模对板材成形极限的影响。     

薄壁半球件无模液压胀形的实验研究

对薄壁半球形件的无模液压胀形工艺进行了研究，并对壳体成形过程中的变形规律进行了分析，实验证明，采用无模液压胀形工艺形半球件是完全可行的，为大型薄壁半球形零件的加工制作提供了一种全新的成形方法。