铝板/塑料混合成型中铝板大塑性变形区的有限元分析

采用弹塑性大变形更新的Lagrange有限元方法研究了铝板 /塑料混合成型过程中铝板的成形过程和变形特点。结果表明 ,当塑料熔体压力从 30MPa增大到 5 0MPa时 ,铝板凸缘区已基本不再参与变形 ,铝板上两个板厚减薄较严重的大塑性变形区在此阶段形成。模底接触区与自由变形区交界处的大塑性变形区依次处于板料曲面内双向伸长变形和平面应变状态 ;模腔入口圆角区与自由变形区交界处的大塑性变形区由两部分构成 ,其中与模壁接触部分依次处于板料曲面内双向伸长变形、拉伸变形和平面应变状态 ,另一部分依次处于板料曲面内双向伸长变形和平面应变状态。     

The non-hydrostatic response of polymer melts as a pressure medium in sheet metal forming

The polymer injection forming process is a recent invention for producing plastic?Cmetal hybrids. It is a combination of injection molding and sheet metal hydroforming process in which polymer melt serves as a pressure medium. This paper presents the experimental investigations on the non-Newtonian nature of thermoplastic melt as pressure medium. The objective of this work is to identify the presence of non-hydrostatic pressure distribution within the cavity and its influence on the final shape of the formed sheet metal component. Experiments are conducted with center-gated injection mold under varying processing conditions. The development of localized cavity pressure during the process is recorded and evaluated against the final shape of formed sheet metal. It has been observed that higher injection rate, higher injection temperature, and higher melt flow index of the processed polymer is necessary for the uniform pressure distribution and subsequently uniform forming of the sheet metal.     

Finite element analysis of forming of sheet metal blank in manufacturing metal/polymer macro-composite components via injection moulding

A new approach to manufacture metal/polymer macro-composite components is presented, in which the injected polymer melt from the injection machine forces the sheet metal blank to deform according to the contour of the mould and the space between the formed sheet blank acts as the moulding cavity of the polymer melt. As the melt cools down, it adheres to the surface of the formed sheet blank. The mechanism of adhesion bonding between the polymer and the surface of the formed sheet blank is discussed briefly. The deformation characteristics and evolution of plastic strains of the sheet blank during the manufacturing process, the distribution of plastic strains and thickness of the formed sheet blank, and the effects of drawing-in of the flange on these have been analysed by the finite element method and experiment. According to deformation characteristics, the formed sheet blank can be divided into five regions. It is shown that deep drawing is the dominating process when the pressure increases from 0 to about 30 MPa; after this stage, stretch forming of the sheet blank that has already been in the mould cavity is the dominating process and two highly strained zones with severe thickness reduction are developed.     

超声振动效应对TA2钛合金板材力学及胀形性能影响

针对钛合金板材塑性变形能力差的问题,进行了超声振动辅助成形工艺的研究,分析超声振动对钛合金TA2板材力学性能及与接触面之间摩擦系数的影响。在此基础上进行了不同宽长比坯料的超声振动辅助胀形实验,分析超声振动对TA2板材胀形力、极限胀形高度的影响。同时,基于网格应变原理,通过不同宽长比坯料极限应变的测量,建立TA2板材的成形极限图。研究结果表明,选择合适的超声振动辅助成形工艺参数, 不仅可以提高TA2板材变形能力,还可以减小摩擦对板材成形性能的影响,从而有效提高了TA2板材的成形极限。     

Fracture types and thickness distribution in superplastic sheets formed with plastic injection molding

This paper investigates the fracture types and thickness ratio distribution in superplastic Zn/Al sheets formed during a hybrid process combining superplastic sheet forming with plastic injection molding. Three types of sheet fractures, edge cracking, central cracking and combined cracking, are observed. The success of forming superplastic sheets with rib features using injection molding with various parameters, including melt temperature, injection pressure and mold temperature, are investigated. They are presented in the form of a molding area with areas of various fracture types. Central cracks occur when superplastic sheets are formed with injection molding with higher melt temperature, while edge cracks occur with higher injection pressure. When the melt flow is parallel to the sheet rolling direction, the areas of edge crack are enlarged. The sheet thickness ratio distribution is obtained for various injection parameters and rib depths. Observation of the sheet thickness distribution for variation parameters, the tendency of the sheet fracture type can be generalized.     

Study on superplastic blow-forming of 8090 Al–Li sheets in an ellip-cylindrical closed-die

The purpose of this paper is to explore the plastic deformation behavior of the sheet during blow-forming of a superplastic sheet into an ellip-cylindrical closed-die by the finite element method. A finite element commercial code “DEFORM” is used to carry out the simulations and calculate the pressurization profile and sheet thickness distribution during the blow-forming process. A pressure control algorithm is proposed to keep the maximum strain rate in the deformation zone of the sheet equal to the target value, which corresponds to the highest m value of the material being superplastically formed. The effects of various forming conditions, such as the friction coefficient between the sheet and die and the aspect ratio of the die, on the forming pressure and thickness distribution of the product are discussed. Experiments using 8090 Al–Li sheets on superplastic blow-forming in an ellip-cylindrical closed-die are also carried out. The theoretical predictions of thickness distribution of the product are compared with experimental results.     

金属塑性成型过程中摩擦声发射信号特征

在金属塑性成型的过程中,在较大的正压力作用下,变形金属与模具之间存在着摩擦力,导致除了浪费能源以外,还会使金属坯料的变形不均匀。采用声发射技术,检测了模拟金属滑块和滑板在三种匀速运动及三种正压力的情况下,产生的塑性变形摩擦声发射信号的变化。试验结果表明,在特定条件下,随着正压力的增加,声发射信号的计数和幅度减少。     

铝合金板温成形过程中凸凹模圆角处摩擦的测量

在温成形过程中铝合金板与模具表面的接触和摩擦行为十分复杂,不同的接触区域摩擦状况不尽相同。本文分析了板料成形中摩擦测量的国内外发展状况,采用自行设计的新型摩擦测量装置完成了铝合金板温成形过程中凸凹模圆角处摩擦系数的测量。该测量装置的特点是可以模拟板料的真实变形过程,因而可以获得更为准确的测量结果。     

激光毛面钢板的使用性能

介绍了激光毛面钢板的表面形貌特征及其对钢板使用性能的影响。激光毛面钢板有较小的摩擦系数和较高的抗擦伤能力，有很好的冲压流动性和塑性变形能力以及表面光亮度。     

盒形件粘性介质拉深过程流动性的有限元分析

为研究工艺参数对铝合金盒形件粘性介质拉深过程材料流动性能的影响,采用ANAYS/LS-DYNA软件对其成形过程进行有限元模拟,分析了成形过程中坯料形状、摩擦系数和压边力大小对材料流动和壁厚减薄的影响。研究结果表明,使用圆形坯料可促进盒形件圆角处材料的流动,降低盒形件的最大减薄率;改善润滑条件、调节压边力大小,则可有效控制坯料的流动,提高成形性。     

塑性成形过程摩擦测试的研究进展

摩擦是影响金属塑性成形及其过程有限元模拟的重要因素 ,因此有必要对其测试方法进行研究。本文介绍塑性成形过程摩擦测试研究方法和测试技术的研究现状与进展 ,并对模拟试验法和直接测量法各自的特点进行了分析。作者设计出一种新型的探针传感器 ,开发出了铝合金板料温成形过程摩擦在线检测系统 ,并对铝合金板(5 182 )圆筒形件温成形过程进行了摩擦测试。     

FHPP单元成形过程初期阶段的热力耦合分析

摩擦液柱成形(FHPP)是摩擦叠焊的基本单元成形过程,也是影响摩擦叠焊焊接质量的关键环节.采用有限元软件MSCMarc建立了FHPP过程初期阶段的三维有限元热力耦合模型,对同质材料Q235-Q235组合进行了计算.结果表明,在焊接过程中焊棒底端摩擦面上的温度呈现沿径向由内向外逐渐升高的趋势,而接触压力的分布则是逐渐渐小.在材料未发生明显塑性变形的状态下提高转速对温度的升高作用显著,但是温度越高,效果越不明显.当材料在高温状态下发生塑性变形时,采用增大轴向力的方式更有利于温度的升高和材料大变形的产生.     

不锈钢板料塑性成形摩擦机理的研究

介绍了不锈钢板料在塑性成形时的摩擦特点以及润滑剂在不锈钢材料和模具表面的成膜原理。对不锈钢板料在中、高接触压力下的滑动摩擦机理进行了试验研究，比较了使用不同润滑剂时，不锈钢板料塑性成形的摩擦状况。     

深冲用电镀钢板的摩擦特性及表面损伤的研究

采用扳成形动卷摩擦因数测试装置对两种铡扳(热浸镀 电镀,即GA-E钢板;IF钢电镀锌钢扳,即EG钢板）以及未电镀的裸板进行摩擦特性研究,着重研究了成形模具温度对摩擦的影响,并对两种镀层钢板经拉深后的表面损伤进行了分析。研究结果表明：(1)在相同的变形条件下,与EG钢板相比,GA-E钢板的摩擦因数随温度增加的变化幅度较小;(2)两种镀层钢板的摩擦因数均随冲头速度的增加而降低;(3)GA-E钢板接触表面损伤的主要形式为微裂纹,而EG钢板的接触表面损伤为犁划痕。     

板料成形的数值模拟及其在U形法兰件中的应用

板料成形的数值模拟可以预测并显示板料在拉深过程中的起皱、拉裂、板料的厚度变化等。描述了板料成形的物理过程、力学模型与模拟典型成形过程，讨论了数值模拟的数学方法与有限元模拟及其求解步骤，并运用软件Dynaform模拟分析了U形法兰件的成形过程，分析了零件的厚度分布，预测了零件可能产生起皱的部位，提出了消除或减少起皱的工艺改进方案。     

铝合金板温成形过程摩擦在线检测系统的研究

介绍并分析了对板料成形过程摩擦问题研究的发展与现状。设计出一种用于动态测量板料成形真实过程摩擦系数的探针传感器,并在此基础上开发出铝合金板料温成形过程摩擦在线检测系统。利用该系统进行了铝镁合金板(5182)筒形件温成形过程摩擦在线检测,得到了合理的实验结果。     

板料成形过程模具圆角摩擦测试实验装置的研究

板料成形研究中的一个难点是如何采用实验方法定量测定板料成形过程中板料与模具之间的摩擦系数.通过对板料成形时的变形特点进行分析,提出一种新的板料成形过程模具圆角摩擦测试实验方法,并研制出相应的摩擦测试实验装置.该实验装置考虑了板料成形时周向收缩、厚向增厚的变形特点,能够在线测试出室温和加热状态下板料成形过程模具圆角处的摩擦系数.摩擦测试结果表明,所研制的摩擦测试装置具有灵敏度高、可重复性好、使用方便的特点,为深入研究板料成形过程中摩擦系数随工艺参数的变化规律提供了实验手段.     

锌层对电镀纯锌钢板成形性能的影响研究

分析电镀锌钢板的成形特性,包括镀层对力学性能和成形极限的影响,镀层损伤行为以及摩擦系数和润滑剂粘度的关系等。结果表明,电镀纯锌层对钢板的力学性能和成形极限影响很小。随着运动粘度的增加,电镀锌钢板的摩擦系数逐渐降低。与合金化镀层相比,电镀纯锌镀层更易随基板变形,因此表面裂纹出现较晚且数量较少。     

曲面形件拉延变形过程数值模拟

运用有限元模拟软件MSC.Marc对不锈钢带凸缘半球面形件和抛物面形件进行了数值模拟研究.首先采用拉延成形方式对半球面形件和曲面形件进行数值模拟,模拟了它们在不同工艺参数下的成形过程.从模拟结果中分析应力、应变和材料厚度的分布与变化,分析了凹模圆角半径、凸模形状对拉延成形过程的影响,得出在拉延成形方式下,凹模圆角半径R=10 mm时成形性与成形质量最佳;为了比较不同成形工艺对曲面形件成形的影响,对半球面形件进行了胀形成形模拟,采用相同的分析方法得出,胀形时的变形程度较大,胀形后的材料厚度较薄,坯料没有增厚现象.     

金属薄板冲压成形的有限元模拟研究

利用Visual Basic设计冲压成形的用户界面,结合ABAQUS建立模型并进行有限元模拟分析,获得了冲压成形仿真模拟效果,以及成形过程中的应力、应变、厚度等状态的变化。着重分析了金属薄板与凹模接触面的摩擦系数对冲压成形的影响。结果表明,接触面摩擦系数不宜过高,也不宜过低,取值适中时,既能保证金属薄板得到充分变形,又可避免产生起皱、拉裂、回弹等现象。为金属薄板的冲压成形工艺设计提供了理论参考,从而大量减少实验方案数量、降低成本、提高生产效率。