大直径薄壁铝合金封头剪切旋压成形研究

应用ABAQUS/Explicit软件平台建立了大直径薄壁铝合金封头剪切旋压成形过程的有限元数值模型,通过数值模拟对大直径薄壁铝合金封头在剪切旋压过程中的应力应变分布进行了分析,获得了工艺参数对成形质量的影响规律为:随旋轮圆角半径R、旋轮进给比f及芯模转速n的增大,旋压件的不均匀变形度呈增大趋势;随旋轮圆角半径、旋轮进给比的增大,旋压件壁厚极小值逐渐减小;随芯模转速提高,壁厚极小值增大,旋压件壁厚极大值对工艺参数的变化不敏感。在此基础上确定了优化工艺参数为:R=12 mm,f=1 mm·r~(-1),n=40 r·min~(-1),并进行剪切旋压成形试验,获得了质量合格的Ф2600 mm大直径薄壁铝合金封头样件。     

2250mm薄壁封头外环约束无模旋压的壁厚精度

针对薄壁封头在传统中心约束旋压过程中出现的壁厚不均匀性问题,构建了2250mm大型薄壁封头外环约束无模旋压的1∶1三维有限元模型。研究了进给率和旋轮圆角半径对旋压件的壁厚精度影响规律。研究表明,在第一道次剪切旋压中,小的进给率和圆角半径对目标构件的壁厚精度有利,在后续扩径旋压中,进给率和圆角半径越大,壁厚均匀性越好。同时,采用通过模拟仿真得到的最优工艺参数,在外环约束无模旋压平台上成功旋制出了2250mm大型薄壁封头构件。采用超声波测厚仪测量成形件沿母线方向的壁厚,其壁厚波动规律与仿真结果基本一致,且壁厚均匀性良好。     

1060铝板两道次渐进成形外缘翻边路径优化

运用数值模拟与实体实验相结合的研究方法，设计并优化出一种两道次渐进成形外缘翻边路径，相较于单道次成形，该路径适用的加工范围更广。研究结果表明，使用圆弧直线两道次渐进成形外缘翻边路径，可以加工单道次无法成形的毛坯直径较大的翻边制件，提升制件的壁厚分布状态，在将第1道次的加工直径设置为d_m+(D-d_m)/4时制件的成形质量最好。根据有限元模拟实验，分析制件的壁厚分布曲线和平均壁厚值，拟合出扩孔两道次渐进成形圆孔翻边高度的表达式，并通过实体实验验证，实现了对两道次渐进成形外缘翻边高度的预测。     

凸模加载速度对某航空导管双翻边成形不均匀变形的影响

为解决5A02薄壁铝合金导管的不均匀变形影响其成形质量的问题,基于有限元仿真,并结合理论和实验方法,对5A02铝合金管件端头多道次双翻边的不均匀变形进行了深入研究.解决了该成形过程中有限元建模关键技术,建立了导管多道次双翻边成形有限元仿真模型,基于该模型获得了真应力-真应变规律;并提出了不均匀变形度表征方法,研究获得了...     

高压开关静触头座成形工艺

介绍了采用冲压－旋压复合工艺成形静触头座的过程。其中包括：变薄旋压成形薄壁筒体，扩口翻边成形法兰，普旋方式成形异形管口等。对主要工艺参数如主轴转速、进给率、旋轮形状、道次变形率、模板形工等作了简要介绍。该成形工艺对同类异形回转体有一定参考意义。     

6061铝合金板料圆孔翻边渐进成形

采用普通渐进成形技术研究6061铝合金圆孔的翻边性能,探究了不同预制孔直径、不同成形路径的多道次渐进成形对6061铝合金翻边高度和壁厚分布的影响规律,探讨了获取6061铝合金的极限翻边件的方法。实验结果表明:单道次渐进成形板料的成形性能较差,且中部存在减薄带,但翻边系数仍高于普通渐进成形;通过合理设计多道次渐进成形可优化成形性能。3种方案中,变高度渐近成形翻边路径相比变角度渐近成形和单道次渐近成形的翻边路径,可获得尺寸较大的制件;变角度渐近成形翻边路径相比于其他两种路径,可避免壁厚过度减薄,从而获得壁厚相对均匀的制件;3道次渐近成形相比于2道次和单道次渐近成形,所获得的翻边件的质量更好。     

双辊夹持板料旋压成形过程塑性变形行为的研究

双辊夹持式板料旋压成形是用来加工薄壁回转体法兰零件的新工艺。为了研究其旋压成形过程中的塑性变形行为,利用ABAQUS软件建立了双辊夹持旋压成形过程的三维有限元模型,并进行了薄壁回转体法兰零件的旋压成形过程的数值模拟,获得了成形过程中等效应力、应变及壁厚的分布。研究了翻边长度对成形件应力应变及壁厚减薄率的影响规律。结果表明等效应力、应变及最大壁厚减薄率均随着翻边长度的增大而增大,由此根据不同的毛坯材料可以确定相应的最大翻边长度。     

硅油减震器外壳旋压成形工艺探究

针对硅油减震器外壳成形,提出整体式四道次旋压新工艺方案,对每道次进行有限元建模并模拟,分析旋压过程中存在的失稳、塌角等问题,确定了以对称旋轮及带外缘"刚端"坯料的形式进行内筒铲旋的方案来消除缺陷。从实际生产效率及效益角度考虑,外筒壁三道次旋压翻边均采用单旋轮并以90°均布在一台机床上,减少每道次变形程度,降低成形载荷。以模拟结果为基础,开展了内筒与外筒旋压实验,验证了新工艺方案的可行性,最终得到成形良好的工件。     

2A12铝合金薄壁壳体强力旋压成形工艺

针对铝合金薄壁壳体旋压成形精度难控制以及热处理变形问题,采用强力旋压成形方法成形了2A12铝合金薄壁壳体,研究了H112态和退火态的坯料对成形的影响,分析了减薄率、进给比对成形中扩径量的影响规律,以及进给比和坯料壁厚对成形表面质量的影响。试验结果表明:H112状态的2A12铝合金经过道次减薄率为42.5%的旋压后,内表面出现裂纹;当减薄率由15.6%增大至42.5%时,扩径量由0.2 mm减小至0.03 mm;当减薄率为42.5%,进给比由0.67 mm·r~(-1)分别提高至0.8和1.0 mm·r~(-1)时,扩径量由0.12 mm分别降低0.06和0.01 mm。对H112状态的铝合金坯料采用380℃×1.5 h退火,再进行多道次旋压,旋压道次中间对坯料再进行330℃×0.5 h去应力退火,最终再对壳体进行495℃×40 min真空气冷,工件椭圆度可控制在0.12 mm以内,抗拉强度达到490～517 MPa,伸长率达到13.0%～15.5%,光洁度为1.298～2.221μm。     

薄壁锥形件旋压成型中应力、应变场的有限元分析

应用大型有限元分析软件ANSYS10.0建立了薄壁锥形工件旋压成形的有限元模型,以显式动力学求解器LS-DYNA为基础模拟了其旋压成形过程,分析了工件成形过程中的变形和应力特点,研究了应力和应变等因素对工件成形质量的影响规律。结果表明:应力、应变图显示了成形过程中工件应变和应力的分布特点与规律,为解决工件旋压成形过程中的问题提供了依据;旋压数值模拟有助于发现旋压变形中存在的旋压成形中容易产生断裂、翻边、褶皱和失稳等缺陷问题及产生的原因;旋压力振荡和减薄率过大是工件旋压断裂的主要因素;在旋压工艺中可以通过优化减薄率、转速和进给量等工艺参数有效控制锥形工件旋压成形质量;分析结果对于旋压模具的优化设计和旋压工艺参数合理选择提供了可靠的理论基础。     

Deep spinning of sheet metals

Spinning of sheet metals into cylindrical cups is an important sheet metal forming process for its advantages of flexible tooling and very small forming loads. The most challenging aspect in this process is its low formability due to wrinkling formation in the free flange. In this work, a new deep spinning process with roller set aided with blank-holder of constant clearance is proposed aiming to suppress the wrinkling formation in the deformation zone. Experimental work on annealed and hard aluminum sheet metals is carried out to assess the new process. The proposed spinning process has shown rapid increase in the formability of the sheet metals as the roller feed increases. On the other hand, significant increase in the roller feed worsens the formability of sheet metals in conventional spinning. The Limiting Spinning Ratios, LSRs; or the blank to mandrel diameters ratios, have increased from 1.75 using the conventional spinning to 2.40 using the deep spinning with annealed aluminum sheets in one pass. Also, the LSRs have increased from 1.67 using the conventional spinning to 2.24 using the deep spinning with hard aluminum sheets in one pass. New failure modes of flange jamming and wall fracture have been presented and discussed. In addition, the formability limitations, thickness strains, and spun cup form features at different process parameters are experimentally investigated and discussed. Further, a finite element model for the new process is presented and verified showing the limitation of the available shell elements offered by ANSYS Mechanical APDL in modeling the new process.     

高温合金旋压塑性变形稳定性试验研究

通过高温合金管材不同旋压变薄率的试验，探讨了常用高温合金的旋压工艺参数。在高温合金管材可旋性试验的基础上，有效控制塑性变形的稳定流动，可以旋压高精度薄壁管材。当坯料退火以后，经旋压工艺参数优化，可提高变形区金属三向塑性流动的稳定性，并有助于获取尺寸精良的管材。     

大型薄壁筒形件对轮旋压成形数值模拟及成形精度分析

为了研究对轮旋压成形机理,突破对轮旋压成形精度控制技术,采用有限元方法分析了道次减薄率、进给比、旋轮成形角以及内旋轮圆角半径等工艺参数对旋压件圆度、直线度及壁厚差的影响。结果显示:当道次减薄率Ψt=20%~30%、进给比f=1.5~2.0 mm·r-1、旋轮成形角αρ=25°、内旋轮圆角半径rρ内=10 mm时,旋压件成形精度最高。同时,分析了在总压下量为9 mm时,内、外旋轮在不同压下量下对成形精度的影响。结果表明:当外旋轮压下量为5 mm、内旋轮压下量为4 mm时,旋压件精度最高。最后,通过工艺实验验证了有限元仿真结果的准确性,结果显示两者偏差小于15%。     

Process factors influencing spinning deformation of thin-walled tubular part with longitudinal inner ribs

As a successively and locally plastic deformation process, ball backward spinning is applied for the purpose of producing thin-walled tubular parts with longitudinal inner ribs. By simplifying ball backward spinning as forward extrusion mechanics model, slab method is used in order to solve spinning force. Based on plastic mechanics, the influence of the process parameters involved on formability of inner ribs as well as the quality defects of spun parts is analyzed so as to present an approach to acquire the desired parts. The quality of inner ribs is one of the critical tasks in obtaining the desired spun workpieces and the height of inner rib depends greatly on spinning material,ball diameter, feed ratio, and wall thickness of tubular blank. The knowledge of the influence of process variables such as ball diameter, feed ratio, and wall thickness of tubular blank on the spinning process is essential to prevent the quality defects of the spun parts and obtain the desired spun parts.     

大型复杂薄壁壳体多道次旋压过程中的壁厚变化

基于ABAQUS/Explicit和Standard建立的包含回弹与退火的大型复杂薄壁壳体多道次旋压全过程模拟模型,分析了该过程中壁厚的分布与变化及工艺参数对壁厚的影响规律。结果表明,壁厚减薄经历了剪切减薄和拉薄两个阶段,壁厚剧烈减薄部位位于旋轮后方的环带并向工件口部移动,而且其值逐渐减小;壁厚沿工件母线方向分布不均匀,沿周向分布较均匀;回弹对壁厚的分布影响不大。摩擦系数在一定范围内的增大,可以有效地抑制第一道次旋压过程中壁厚过度减薄的发生,使壁厚分布更均匀;而旋轮进给比对工件壁厚的影响与摩擦系数的作用相反。在后续道次旋压过程中,工件壁厚差随着摩擦系数的增大先减小后增大,随着旋轮进给比的增大逐渐减小。这些结果可为大型复杂薄壁壳体多道次旋压成形参数的确定和优化设计提供理论依据。     

Control of wall thickness distribution by oblique shear spinning methods

A flexible method of forming circumferentially variant wall thickness distributions on the same shape is attempted using two oblique sheet spinning processes. The fundamental strategy entails the inclination of the flange plane of the workpiece during forming. In one type of synchronous dieless spinning, edge-hemmed aluminum blanks are formed for truncated cone shells, by synchronizing the motion of the spherical head roller in the axial and radial directions with the angle of the general purpose mandrel fixed on a bidirectionally rotating spindle. On the other hand, in the other type of force-controlled shear spinning, flat aluminum discs are formed by feeding perpendicularly to the flange plane of the workpiece and maintaining the thrust force along the plane via the roller tool, exerted onto the rotating truncated-cone-shaped die. The estimated wall-thickness distribution based on a simple shear deformation model nearly conformed to the measured thickness distributions of the products formed at several inclination angles of up to 15 degrees in the forming and both spinning methods. The low-cost value-added forming method seems to be practicable not only for metal spinning but also for other incremental sheet forming processes.     

Deformation history and the resultant microstructure and texture in backward tube spinning of Ti–6Al–2Zr–1Mo–1V

The correlations of microstructure and texture with deformation history in backward tube spinning were studied. Deformation history was calculated with initial and some intermediate configurations as reference configuration from FEM analysis. Microstructure and texture were investigated in the experimental workpiece of Ti–6Al–2Zr–1Mo–1V. The results show an obvious through-thickness inhomogeneity in deformation, microstructure and texture. Large material rotation occurs and plenty of grains are kinked and distorted in the outer layer, especially when thick-wall billet is spun. Deformation difference diminishes with wall thickness decreasing. The inhomogeneity of as-spun microstructure is reduced obviously in multi-pass and large deformation (for example, 85% total reduction) tube spinning. {0 0 0 2} texture develops generally without orthotropic symmetry. Textures in the outer and inner layers evolve differently because of inhomogeneous deformation histories.     

平板毛坯普旋变形方式的研究

本文通过实验研究和分析,对平板毛坯普通旋压的变形方式进行探索。实验中旋轮分别走三种不同形状的轨迹：斜直线、凹曲线和凸曲线。结果表明,在三种情况下,平板毛坯普旋（即拉深旋压第一道次）的变形和拉深变形相差甚远,而主要是剪切变薄旋压变形方式,因此第一道次的变形对普旋最终零件的壁厚具有决定性影响。