矩形断面环形件弯曲成形过程中弹复问题的研究

采用三维弹塑性有限元方法对矩形断面环形件冷态弯曲成形过程的弹复变形问题进行分析研究 ,通过对成型过程的计算机仿真 ,分析了在一定宽度和高度工况下弯曲成型后弹复变形的规律。对确定矩形断面环形件生产过程中主要成型工具的尺寸具有指导作用     

冷弯成形实验的有限元分析中的影响因素研究

使用ANSYS/LS-DYNA有限元软件建立了模型,利用ANSYS的显式求解功能对板料冷弯成形测试实验中试件的变形进行有限元弹塑性分析,着重分析了在有限元分析过程中,求解时间、试件厚度、网格密度、模具倒角及试件翼端长度对试件内最大等效应力的影响.     

圆管二次辊弯成形过程中的大变形有限元法模拟

应用弹塑性三维大变形有限元理论，同时考虑材料和几何双重非线性，基于Ｐｒａｎｄｔｌ－Ｒｅｕｓｓ流动规律和Ｍｉｓｓ屈服准则，并采用Ｕｐｄａｔｅｄ－Ｌａｒｇｒａｎｇｉａｎ增量叠加法分析了不同压下量成形过程中金属由非稳态到稳态的流动规律，然后通过有限元程序实现了计算机模拟。模拟结果为ＣＡＤ（计算机辅助设计）及ＣＡＭ（计算机辅助制造提供了重要理论依据，同时还可以指导实际生产过程，对提高产品的质量和经济效益有     

环形件螺旋精密冷成型工艺研究

将具有一定几何断面形状的型材或条形钢板经专用成形设备卷曲成形,通过切割、焊接工艺技术,生产环形件。为减少切削加工,对原始坯料断面形状,采用有限元分析的方法确定。     

环形侏螺旋精密冷成型工艺研究

将具有一定几何断面形状的型材或条形钢板经专用成形设备卷曲成形，通过切割，焊接工艺技术，生产环形件。为减少切削加工，对原始坯料断面形状，采用有限元分析的方法确定。     

风管共板法兰辊弯成形过程的有限元仿真

利用通用非线性的ABAQUS软件对多道次辊弯成形过程进行建模以及数值模拟,对辊弯成形工艺及成形规律进行了研究,为辊弯成形的工程设计、工艺参数和辊弯设备的调整提供了科学的依据。整个辊弯成形过程基于动力显式算法,建立风管共板法兰多道次辊弯成形的有限元模型。其中涉及了辊弯成形的模型建立、单元选择、边界条件、有效速度质量放大系数的选择等辊弯成形的一般性问题解决方法。     

变压器用热轧波纹板冷弯成形过程分析

 利用实验室模拟及有限元模型两种方法模拟波纹板冷弯压靠成形过程,结果表明,该材料所能承受的最大拉应变远大于最危险点所承受的拉应变,残余压应力位置处的显微硬度高于残余拉应力位置处。变形过程中的冷弯压靠危险点未发现冷弯裂纹,热轧酸洗板能够满足变压器用波纹板冷成形要求,变压器波纹板以热代冷方案是可行的,也符合节能降耗的要求。     

冷弯型钢成型过程的实验研究

冷弯成型变形复杂,实验研究是冷弯成型研究中不可缺少的一部分,采用电阻应变片测量法和网格法对冷弯成型过程进行研究,并以直缝焊管为例,对带材的变形及弹复等进行综合测试,获得了许多有价值的实验数据,有助于工厂改进工艺,生产出高质量的产品。     

Numerical Simulation and Sensitivity Analysis of Parameters for Multistand Roll Forming of Channel Section With Outer Edge

 Cold roll forming is a high production but complex metal forming process under the conditions of coupled effects with multi factor. A new booting finite element method (FEM) model using the updated Lagrangian (UL) method for multistand roll forming process is developed and validated. Compared with most of the literatures related to roll forming simulation, the new model can take the roll rotation into account and is well suited for simulating multistand roll forming. Based on the model, the process of a channel section with outer edge formed with twelve passes is simulated and the sensitivity analysis of parameters is conducted with orthogonal design combined FEM model. It is found that the multistand roll forming process can be efficiently analyzed by the new booting model, and sensitivity analysis shows that the yield strength plays an important role in controlling the quality of the products.     

TC4钛合金负角度零件超塑成形及性能研究

在前期材料实验的基础上对TC4钛合金负角度零件超塑成形过程进行仿真,获得压力-时间曲线和壁厚分布,并根据仿真结果中接触摩擦力分布情况,预测了模具磨损。对仿真获得的压力-时间曲线进行修正,并将修正后曲线作为实际加载曲线进行超塑成形实验,获得负角度零件。比较了零件型腔底端壁厚的实际结果与仿真结果,同时,研究了成形零件的负角度壁壁厚分布、显微组织、力学性能。结果表明:取件温度为300℃时,零件外形及表面质量较好;实际零件型腔底端壁厚分布与仿真结果趋势相同,两者最大误差为4.4%;零件最小壁厚在负角度过渡圆角处,其值为0.66 mm,最大减薄率为67%;负角度壁壁厚标准差为0.186 mm,说明此部位壁厚分布比较均匀;成形后材料的晶粒尺寸长大明显,而室温屈服强度、抗拉强度、延伸率从原始材料的951,1045 MPa,13.9%下降至853,955 MPa,10.8%,说明经过超塑成形后,材料由于晶粒长大而导致力学性能下降。     

压型板辊弯成型过程数值模拟

针对压型板辊弯成型过程中带材变形复杂、成型规律难于掌握的问题，应用显式动态有限元模块ANSYS／LS-DYNA对压型板辊弯成型的全过程进行模拟分析。动态分析板带从前一架进入下一架的成型过程，板料可在两架间同时各自变形。发现应力的集中区域存在于变形过渡区和辊缝中心线下的主要变形区；横向弯曲应变大都集中于弯曲角处，应变值随成型角增大而增大。模拟结果证实通过有限元模拟探索冷弯成型规律的可行性。该方法对于分析其他复杂断面型钢的成型特点具有一定的理论和实际意义。     

板带在排辊成型过程中的仿真研究

通过采用大型非线性有限元软件Marc对板料的排辊成型过程进行了模拟,获得了板带各机架截面处和沿板带纵向的等效应力分布规律。分析了排辊对板带接触作用的成型特点,为排辊成型机组的孔型设计以及排辊调整提供了理论依据。     

Ring Rolling Research at the Dresden University of Technology – its History from the Beginning in the 70s to the Present

The paper presents a brief history of ring rolling development at the Dresden University of Technology (DUT) from the 70s to the present. The technological scope covers the techniques explored at the DUT: Tangential profile ring rolling, axial profile tube rolling/roll plunging and the TRENPRO® method to produce shaped rings. Starting from the state of the art, technological principle, range of application and machine‐oriented implementation of these techniques are described. Furthermore, other common ring rolling variants, such as axial profile ring rolling, skew‐rolling and radial‐axial ring rolling, are taken into consideration. Finally, the authors provide a summary of problems still to be solved and ways to refine and disseminate the “ring rolling” discipline, assessing the rolling methods’ potential as extremely forward‐looking.     

Experimental Study on Springback of Sheet Metal Single Point Incremental Forming

Sheet metal single point incremental forming (SPIF) is a new technology for flexible process.The spring- back phenomenon in single point incremental forming has been discussed.Effects of forming angle and shape of the part are analysed using simple experimental method.Tool diameter, sheet thickness, step size, material parameters and the interaction of them are also analysed by using orthogonal test.The results show that the primary factor af- fecting springback is forming angle.In addition, springback is decreased when the specimen has a larger forming angle.The order of the four factors that influence springback is tool diameter, sheet thickness, step size and materi- al parameters.The forming precision will increase if springabck is decreased by optimizing the forming parameters.     

Theoretical and Experimental Damage Prediction in Cold and Semi‐Hot Bulk Forming of Ductile Steels

Bulk forging is among the most important manufacturing methods in metal forming, due to its wide applicability from some ounces to several tons of steel in a high diversity of shapes and forming conditions. Economical constraints demand for further optimisation and cost‐effective production. This requires the application of suitable finite elements simulation software, in order to support the already digitalised construction processes. Ductile damage is one of the most severe problems to arise during the production sequences, not only in cold but also in semi‐hot forging operations. Mathematical approaches exist for the modelling and simulation of ductile fracture in steel. In this paper some widespread used damage models are introduced and discussed. Their damage prediction quality has been verified by experiments, the tensile test and the collar specimen upsetting with several different steels under cold and semi‐hot forging conditions. The methods for the experimental fracture detection are introduced as well. In cold forging the passive ultrasonic testing with integrated statistical filtering algorithms is used. As this method is not applicable to semi‐hot forging experiments, optical fracture detection by means of a high‐speed camera is used instead. A very interesting material behaviour of the steels tested has been identified in the semi‐hot upsetting of collar specimen. For every steel a distinct temperature crossover interval exists, in which the forging process abruptly changes from damaged to undamaged state. This interval amounts to some degrees Celsius only for each of the seven materials investigated. Among the damage models proposed, the Model of Effective Stresses by Lemaitre is chosen for the application to a cold and a semi‐hot forging operation. These industrial processes of an axle end (cold) and a journal bearing (semi‐hot) are susceptible to damage for reasons to be discussed in this paper. It will be shown that the internal fracture of the axle end (chevrons) and the surface fissures of the journal bearing can be predicted with high accuracy. Moreover, the application of the damage model in the finite element software MSC.SuperForm 2004 offers a promising approach for process optimisation. Several possibilities could be tested for their suitability of reducing the calculated damage: geometry variation of the forming tools, process annealing, different materials. The use of damage models in finite element simulation can be regarded as a further step towards an optimal process design.     

冷成型对低碳微合金钢拉伸行为及性能的影响

研究了冷成型对铁素体+珠光体组织类型低碳微合金热轧钢板拉伸行为及性能的影响。用弯曲和压平变形模拟高频直缝焊管制管及取样钢板所经历的冷成型过程。对冷成型前后材料拉伸行为和性能进行对比试验,结果表明,冷变形不同程度改变材料拉伸行为及性能,且这种变化是由冷变形方式和程度所决定;包申格效应试验分析结果表明,材料背应力随塑性应变增加而增大,且到达某一数值后当塑性应变继续增加,背应力增加幅度明显减小;有限元分析结果表明,冷成型导致的钢板性能变化是由包申格效应和加工硬化共同作用的结果,并给出了其形成机制。     

基于样条有限条法的冷弯成形全流程模拟

采用基于更新拉格朗日法（UL法）的弹塑性大变形样条有限条法，结合流动模型，分析并模拟了普通槽钢成形过程中变形带材的位移场、应变场和应力场，计算结果与相关献的实验结果相吻合，进一步证明了计算方法和所建模型的有效性，为设计工作提供了理论依据，对实际生产具有重要意义。