State of the Art and Perspectives of Hydroforming of Tubes and Sheets

Hollow parts of high accuracy and high strength can be produced by forming methods using liquid media. Hydroforming of tubes has reached a high standard for small parts (volume some 1000 cm3) and is further developed for larger parts (volume some 10.000 cm3). Processes for hydraulic sheet metal forming are sometimes used for small parts from single sheets These pro-cesses are currently under intensive investigation, which is also true for the processing of double layered sheets Single sheets can be formed using membranes which separate the workpiece and the liquid. This results in interesting possibilities for a part and process integration in one step The forming performance of aluminum alloys can be enhanced by using a heated liquid media when forming without membranes.

Study on the Deformation Characteristics of the Sheet Hydroforming with a Movable Die

An improved sheet hydroforming process with a movable die is proposed and investigated by elastoplastic FEM. The effects of varied process parameters on the deformation of the sheet blanks were investigated. The effects of the movable die on the FLD were also analyzed. Using a movable die may increase the forming limit of the blank and improve the forming performance. Moreover, the drawing ratio of the blank may be increased by changing the process conditions such as blank holder force and the counterforce of the movable die on the blank.

Process and Equipment of Double-Sided Sheet Hydroforming for Large-Sized Al-Alloy Tailored Shell

In the industrial field,tailored blank forming with aluminum alloy(Al-alloy)has developed fast to meet the demands for large size integrated components with curved surfaces of high precision and with uniform mechanical properties.Traditional forming methods for tailored blank components faced challenges with uneven deformation behaviors and coexistence of rupture and wrinkling defects occuring during the forming process.In this paper,a new manufacturing procedure is proposed with advanced welding and forming technologies for forming integrated shell components.Friction stir welding with post-weld heat treatment was employed to prepare the tailor welded blank and improve its formability prior to forming.A double-sided pressure sheet hydroforming process was introduced to fabricate the Al-alloy tailored blank into a curved surface shell.Finite element modeling was established to analyze the effect of the weld line position and loading paths of stress distributions during the double-sided sheet hydroforming(DSHF)process.A large double-action CNC sheet hydroforming press with tonnage of 150 MN and high pressure liquid volume of 5 m~3 was developed in China.As an application case of the proposed process and equipment,a full-scale tank dome with a diameter of 3 m was successfully hydroformed with a large size Al-alloy tailored blank.It was shown that the DSHF process has the advantages in controlling rupture and wrinkling defects with an Al-alloy tailored blank,and the novel manufacturing procedure enables the production of integrated thin-walled component more competitively than traditional methods.

3003铝合金双层盒形壳体液压成形工艺及壁厚控制

为解决铝合金双层盒形壳体拉深成形开裂难题,提出了盒形件充液拉深与液压胀形复合成形工艺。通过工艺仿真研究了压边力、液室压力及胀形压力对双层板盒形件成形起皱和开裂的影响,并对关键工艺参数进行了优化。结果表明:充液拉深工艺有助于改善壁厚分布,合理的液室压力能够减少内外层板壁厚减薄,但液室压力过大会导致板料初期反胀过度引发减薄甚至破裂,在一定的胀形压力下外板能够实现贴模成形。通过实验研究了复合工艺对铝合金双层盒形壳体成形的影响,最大壁厚减薄率小于15%。该复合工艺为铝合金双层壳体零件成形提供了新方法。

航空发动机高温合金环形罩壳充液拉深成形缺陷控制

针对航空发动机环形罩壳零件整体成形时产生起皱和开裂的问题,提出环形罩壳零件一道次充液拉深成形工艺。在分析计算和有限元仿真基础上实现了工艺参数优化,并开展了成形工艺实验研究。随液室压力的增大,环形罩壳零件侧壁起皱趋势降低;同时,在合理的压边力下局部凸包的减薄率逐渐降低,充液拉深成形能够显著抑制曲面起皱与底部开裂,解决环形罩壳零件整体成形制造难题。

航空发动机大高径比高温合金筒形件充液拉深缺陷形成规律分析

针对航空发动机大高径比高温合金筒形件无法整体成形的难题,开展了一道次充液拉深成形工艺研究。研究了GH3536高温合金板材的力学性能,基于有限元数值分析软件对筒形件充液拉深成形进行数值模拟,分析不同工艺参数对筒形件壁厚和成形缺陷的影响。根据模拟结果进行筒形件充液拉深成形实验,优化了压边力和液压加载工艺窗口,成形出合格的深筒形件,分析了该零件的缺陷形成规律。

高能率冲击液压成形设备设计及复杂铝合金零件成形

通过结合液压成形柔性介质优势和高速成形高应变速率优势,提出了一种新型高能率冲击液压成形技术和装备,该技术能够提高材料的塑性成形能力,同时具有回弹小,无需密封,良好的表面质量,非常好的小特征填充能力等特点,能够解决传统落压成形技术制造铝合金复杂航空钣金零件过程中存在的起皱、开裂和需要大量人工辅助的问题。首先对单冲击体和双冲击体2种冲击形式的冲击传载特性进行了深入研究。研究发现,大质量单冲击体液室压力保持效果好、液固界面压力倍增系数高、能量利用率高。在此基础上研制了新型冲击液压成形设备,通过采用气液组合驱动方法实现了高压高速驱动,设备冲击能量为225 kJ,液室直径250 mm,液室峰值压力可达1000 MPa以上。不同于以往设备主要用于实验研究,该设备能够实现高能率冲击液压成形技术的工业化生产。最后进行了工艺验证,通过两道次成形获得了完好的5A06铝合金航空复杂薄壁口框零件,解决了落压成形存在的问题,加工效率提高了4倍以上。

Mechanics analysis of axisymmetric thin-walled part in warm sheet hydroforming

To obtain the influence of fluid pressure and temperature on warm hydroforming of 5A06-O aluminum alloy sheet, the unified mechanics equilibrium equations, which take through- thickness normal stress and friction into account, were established in spherical coordinate system. The distribution of through-thickness normal stress in the thickness direction was determined. The relation between through-thickness normal stress and fluid pressure was also analyzed in different regions of cylindrical cup. Based on the method of subtracting one increasing function from another, the constitutive equation of 5A06-O applied to warm hydroforming was established and in a good agreement with uniaxial tensile data. Based on whether the thickness variation was taken into account, two mechanic models were established to do the comparative study. The results for the studied case show that the calculated stress values are pretty close according to the two models and consistent with results of finite element analysis; the thickness distribution in flange computed by the second model conforms to the experimental data. Finally, the influences of fluid pressure on the flange thickness and radial stress were analyzed.

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。

镁合金板件温热成形技术的几个新进展

介绍了镁合金薄壁板材的温热冲压成形技术、温热液压成形技术和局部热冲锻成形技术。与传统镁合金冲压成形在250℃以上温度不同,温热成形可以在105～170℃之间进行,筒形件温热成形时其极限拉深比可达1.4～2.6,可以满足大多数镁合金薄板件的成形需要。镁合金薄板温热成形工艺在电子器件外壳和汽车薄板件的生产方面具有很好的发展前景,可以取代压铸技术生产新一代优质的镁合金产品。温热液压成形技术适合生产数码相机壳等复杂形面的镁合金板件,有很好的应用前景。局部热冲锻成形技术可以成形局部带有凸台的镁合金薄板件,该技术使镁合金板件具有替代压铸件的技术优势。

复杂薄壁零件板多级充液成形及过程数值模拟

板充液成形已被证明是制造复杂零件一种有效的方法.采用板多级充液成形方法对难成形复杂薄壁结构的飞行器零件进行了研究,利用有限元数值模拟的方法,分析了预成形凸模形状、预成形深度,以及液室压力等关键工艺参数对成形的影响.对成形中出现的诸如破裂、起皱等失效形式进行了探讨,给出了终成形时实现成功成形的最高液室压力区域范围.提出了控制成形质量的措施,优化了工艺参数,并根据数值模拟的结果进行了试验验证.结果表明,模拟结果和试验结果达到了较好的一致.

航空铝合金复杂构件充液柔性成形过程及质量控制研究

针对某型号飞机铝合金复杂构件充液成形的失效形式,采用有限元数值模拟和试验的手段,研究了毛坯形状、液室压力等关键工艺参数对成形失效的影响,给出了铝合金复杂构件充液成形质量控制的措施,为此类型航空复杂构件的充液成形提供了技术指导。

薄板液压成形起皱预测及控制研究进展

板材拉深成形广泛应用于航空航天、汽车制造、船舶工业等领域,是金属塑性加工领域的研究热点。随着工业生产向整体化、轻量化、高精度、低成本不断发展,以火箭燃料贮箱箱底为代表的大型曲面封头厚径比小于0.3%,起皱成为制约其拉深成形的主要缺陷之一,严重影响零件质量、模具使用寿命和工业生产的稳定性。综述板材拉深成形起皱理论预测、数值模拟和工艺试验的最新研究现状,重点介绍板材液压成形技术对于起皱控制的研究进展,表明通过合适的液压成形可以成形出无起皱缺陷、厚径比较小的零件。提出现有问题并对未来研究方向进行展望。

板材零件成对液压成形新技术

板材成对液压成形技术是一种新的板材成形技术 ,具有成形性好、制造工期短、费用低等优点 ,特别适用于批量小、形状复杂板材零件的生产 .介绍了板材成对液压成形技术的成形原理、成形过程、分类及研究现状 .

基于YX28-400/650C双动液压机的板材液压成形装备的研制

板材液压成形技术以其工艺柔性高、制件质量好、成本低等优点在汽车、航空航天等领域得到应用,应用前景十分广阔.针对基于YX28-400/650C型双动压力机的充液拉深装备进行研究,介绍了它的总体方案设计、模具结构特点、液压系统和自控系统及使用情况.

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。

铝合金不等高盒形件充液成形过程预胀形效应(英文)

利用数值模拟和实验方法研究预胀形对不等高平底异形盒形件充液成形过程的影响,探讨预胀高度和预胀压力对成形结果的影响规律,优化压力加载路径。结果表明:预胀形对成形结果影响较大。过高的预胀高度会导致不等高盒形件最低拐角区凸模圆角处的裂纹和折痕,过低的预胀高度会导致最高拐角区凸模圆角处的破裂。当预胀高度在合理范围时,预胀压力对筒壁最高拐角区凸模圆角处的破裂影响较小。但是,过大的预胀压力会导致筒壁最低拐角区凸模圆角附近产生裂纹及褶皱。合理预胀高度和预胀压力可有效控制失效形式的发生。

板材零件成对液压成形的分析与试验研究

板材成对液压成形技术是一种新的板材成形技术 ,具有成形性好、制造工期短、费用低等优点 ,特别适用于批量小、形状复杂板材零件的生产。本文对板材成对液胀成形技术进行了理论分析和试验研究 ,介绍了该技术的技术原理和特点 ,提出了提高其成形极限的措施。结果表明 :理论分析结果和实验结果是一致的。

板金液压柔性技术及其产品设计

板金液压柔性成形具有诸多的优点,受到了汽车、航空航天等领域设计和研究者的普遍重视。文章主要介绍了板金液压柔性成形技术的内涵和外延,针对所提出的无模液压柔性成形技术和复合液压柔性成形技术,从不同的工艺方法入手,基于所研制的液压柔性成形设备,介绍了相关的飞机等领域产品特点以及设计要点,并对其中的关键工艺参数进行了描述。

异种板材成对液压成形的材料变形行为研究

通过应力分析了异种板材配对液压成形过程板材的变形行为和相互作用,采用DC04、DP450两种板材组成3种配对方案,通过数值模拟和实验获得了3组配对方案中板材的法兰流入量、试件高度和壁厚分布.研究发现,强度低的板材先发生变形,并带动强度高的板材变形,而后者阻碍前者变形,两个板材总体上趋于协同变形,数值模拟和实验结果证明了力学分析结论的正确性.