TC1Mδ2.37钛板平底压窝形状畸变现象

针对TC1M钛合金板料,用ADINA软件对平底压窝成形及回弹过程进行了有限元数值模拟,对因各向异性而引起的制件形状变化给予描述,并进行了一系列室温下的压窝成形工艺试验,试验结果与有限元模拟预测结果吻合良好。研究结果表明,制件回弹后将产生两种形状畸变现象,一是凸缘底面翘曲,不再保持为平面,翘曲形式为两高两低,在TD方向上的凸缘外沿两点为翘曲最高点,在RD方向上的外沿两点为翘曲最低点;二是制件上顶面产生翘曲,翘曲高度亦遵循两高两低的变化规律,高低点位置与凸缘部分相似。     

钛及钛合金板材拉深成形的影响因素与技术进步

钛及钛合金相对铝、钢等金属材料塑性差、极限变形量小、成形时回弹大,拉深成形相对困难。介绍了钛及钛合金拉深成形的影响因素及其对成形的影响,综述了钛及钛合金拉深成形在各向异性控制、压边力控制、计算机模拟以及加热方法等方面的技术进步,指出了未来研究人员应充分利用计算机模拟技术,对影响钛及钛合金冲压成形的各种因素及其之间的相互关联建立详尽的数据库,以便该成形工艺在钛及钛合金零部件的成形得到更广泛的应用。     

TC1Mδ2.5钛板圆孔翻边成形极限与翘曲的研究

室温下用厚度为2．5mm、中心有预制底孔的TC1M钛合金圆板坯料进行圆孔翻边成形试验,结果表明：除翻边底孔尺寸小于极限值时在唇口边缘发生破裂的正常失效方式之外,卸载后翻边制件还会出现突缘平面翘曲、翻边孔口部椭圆化、口部收缩等形状翘曲现象,这些都造成钛合金薄板翻边零件无法满足尺寸和位置精度要求。在给出极限翻边系数的同时,对这种形状非轴对称化程度进行了定量描述,并给出了理论上的解释。     

TC1Mδ1·5mm钛板圆孔冷翻边极限与翘曲变形的研究

室温条件下采用有预制底孔的TC1Mδ1.5mm钛合金坯料进行圆孔翻边成形试验,结果表明,除底孔尺寸小于极限值时在唇口边缘发生破裂的正常失效方式之外,卸载后翻边制件还会出现突缘平面翘曲、翻边孔口部椭圆化、口部收缩等形状翘曲现象,这些都造成钛合金薄板翻边零件无法满足尺寸和位置精度要求。在给出极限翻边系数的同时,对这种形状非轴对称化程度进行了定量描述,并解释了此类现象产生的原因。     

合金材料的板材冲压（4）

(5)一次反拉深成形带非平面凸缘的锥形零件模具一次成形图38所示带非平面凸缘反拉深件的基本方法由和设计的模具实现的。零件材料是厚度为1.2mm 的 OT4—1钛合金钢板。     

盘形件中心区域冲锻增厚工艺

提出一种通过拉深-压平两个工步使圆形板坯中心区域增厚的工艺,基于控制变量法设计了有限元模拟方案,研究了成形过程,分析了成形中各参数对最大增厚和厚度波动的影响规律,并进行了实验验证。有限元模拟和实验结果表明,随着凸模半径R0与凸凹模间隙D的减小,凸模行程H增加,板料增厚后的最大厚度和厚度波动均显著增加。凸模头部半径R1对增厚效果影响不显著。在不同的工艺参数下,第1步拉深时拉深件侧壁倾角、局部减薄量不同,导致了第2步压平时径向应力和材料硬化的差别,最终形成了板料的均匀增厚和不均匀环形区增厚两种成形方式。     

TC2M2δ.5钛板冷热翻边成形极限及非对称化研究

TC2Mδ2.5mm钛板室温圆孔翻边成形试验结果表明,除翻边底孔尺寸小于极限值时在唇口边缘发生破裂的正常失效方式之外,冷翻边卸载后制件还出现凸缘平面翘曲、翻边孔口部椭圆化、唇口边缘高度不一致、壁厚分布不均匀等非对称化现象。600℃高温热翻边成形可以有效地提高成形极限,并消除了凸缘平面翘曲和口部椭圆化,但口部高度差以及壁厚不均等非对称化现象依然存在。本文在给出极限翻边系数的同时,对这种非轴对称化程度进行了定量描述,并给出了理论上的分析与解释。     

TC2M δ2.5钛板冷热翻边成形极限及非对称化研究

TC2M δ2．5mm钛板室温圆孔翻边成形试验结果表明，除翻边底孔尺寸小于极限值时在唇口边缘发生破裂的正常失效方式之外，冷翻边卸载后制件还出现凸缘平面翘曲、翻边孔口部椭圆化、唇口边缘高度不一致、壁厚分布不均匀等非对称化现象。600℃高温热翻边成形可以有效地提高成形极限，并消除了凸缘平面翘曲和口部椭圆化，但口部高度差以及壁厚不均等非对称化现象依然存在。本文在给出极限翻边系数的同时，对这种非轴对称化程度进行了定量描述，并给出了理论上的分析与解释。     

汽车油底壳一次拉深成形减薄率控制研究

运用Dynaform数值模拟软件,对汽车油底壳拉深成形过程中的拉深筋、压边力、毛坯形状、摩擦因数等多种工艺约束参数进行综合数值模拟,获得油底壳制件塑性成形的优化工艺方案。汽车油底壳最终拉深成形方案为不设置拉深筋,压边力取600 k N,摩擦因数取0.1,毛坯形状为圆弧化八角形,制件一次拉深成形后减薄、起皱、破裂等缺陷明显减少,生产的制件成形质量良好。     

980MPa超高强钢前纵梁冲压成形分析

研究通过显微组织、拉伸性能及成形极限对HC550/980DP和HC600/980QP两种材料的成形性进行比较,说明HC550/980DP材料的拉深成形特点,并对某车型纵梁应用HC550/980DP材料进行开发,通过优化工艺排布、改善拉深变形条件和增设侧整形工序实现超高强度制件的开发,成形制件质量减轻20%以上,在超高强钢制件设计中应充分考虑强度提升带来的板料成形性降低和回弹增大的影响,以提高制件可制造性。     

The numerical analysis of anisotropic sheet metals in deep-drawing processes

Flange earing of strong anisotropic sheet metals in the deep-drawing process is analyzed numerically by the elastic–plastic large deformation finite element formulation based on the discrete Kirchhoff triangle plate shell element model. A Barlat–Lian anisotropy yield function and a quasi-flow corner theory are introduced in the present formulation. The numerical results are compared with the experimental results of the cylindrical cup drawing process. The focus of the present research is on the numerical analysis and the constraining scheme of the flange earing of circular sheets with strong anisotropy in the square cup drawing process.     

筒形件拉深CAPP中模糊信息优化技术的应用

分析筒形件极限拉深的影响因素，运用模糊信息优化技术得出了模糊优化的工艺设计方案，使用塑性成形仿真软件模拟工件实例验证方案，用验证结果导筒形件拉深CAPP程序的内核设计。增强了CAPP软件的灵活性和实用性。     

Deep drawing of square cups with magnesium alloy AZ31 sheets

The square cup drawing of magnesium alloy AZ31 (aluminum 3%, zinc 1%) sheets was studied by both the experimental approach and the finite element analysis. The mechanical properties of AZ31 sheets at various forming temperatures were first obtained from the tensile tests and the forming limit tests. The test results indicate that AZ31 sheets exhibit poor formability at room temperature, but the formability could be improved significantly at elevated temperatures up to 200 °C. The test results were then employed in the finite element simulations to investigate the effects of process parameters, such as punch and die corner radii, and forming temperature, on the formability of square cup drawing with AZ31 sheets. In order to validate the finite element analysis, the deep drawing of square cups of AZ31 sheets at elevated temperatures was also performed. The experimental data show a good agreement with the simulation results, and the optimal forming temperature, punch radius and die corner radius were then determined for the square cup drawing of AZ31 sheets.     

Textures in high purity aluminum foils and AA3004 sheets

1　INTRODUCTIONWithincreasingdemandsofhighmaterials properties ,thetexturesinAlandAlalloysplaymoreandmoreimportantrole .Highpurityaluminumfoilsneedverystrongcubetexture ,whichwillfavorthe“channeletching”effectforhighvoltageelectrolyticcapacitors ,andAA30 0 4aluminumalloysheetsneedcertaincubetexturetosuppressthe 4 5°earingbehav iorresultingfromstrongrollingtexturecompo nents[1] .InAlandAlalloys ,heavycoldrollingwillresultinstrongβ fibertexturescomposedofthewellknownCu ({ 112 }〈111〉…     

Improvement of the drawability based on the surface friction stir process of AA5052-H32 automotive sheets

Based on the imperative social demand for lighter vehicles, lightweight materials such as aluminum alloys are expected to replace conventional steels in many automotive applications. In automotive parts manufacturing, most of the components produced in conventional stamping operations are geometrically complex as the blanks are subjected to both stretching and drawing deformations. However, aluminum alloys have intrinsic drawbacks, such as the inferior formability of these materials, although the effects of the weight reduction in terms of performance are highly promising. In an effort to improve the formability of aluminum alloy sheets, the surface friction stir process is proposed in this study. This process locally modifies the surface of automotive aluminum alloy sheets via stirring and advancing on the surface of the sheet, similar to the Friction Stir Welding (FSW) process that utilizes a probe without a pin. When the surface of the sheet is modified locally by stirring, dynamic recrystallization due to the severe shear deformation along with heat resulting from the friction occur due to changes in the micro-structure and mechanical properties in the stirred zone, while the dislocation density and grain size refinement are curtailed. In this work, the drawability performance of AA5052-H32 sheets (thickness 1.5 mm) that were welded using the surface friction stir process was experimentally and numerically investigated in cylindrical cup drawing tests. When applied to AA5052-H32 automotive sheets, the surface friction stir process improved the drawability of the entire aluminum alloy sheet. For numerical simulations, the non-quadratic anisotropic yield function Yld2000-2d was employed along with isotropic hardening, while the formability was evaluated by utilizing theoretical forming limit diagrams (FLD) based on Hill's bifurcation and M-K theories.     

A developed process for deep drawing of metal foil square cups

Deep drawing of non-axisymmetric cross-section cups from thin sheets or metal foils has become increasingly important, especially for miniaturization of mechanical components. However, with a thin sheet thickness, conventional deep drawing processes are not able to offer reasonable drawing ratios due to early formations of localized wrinkling and fractures at cup corners. In this paper, a friction aided deep drawing process has been developed to increase the deep drawability of thin sheets and metal foils. Productions of square cups have been chosen to verify the current proposed process since the shape provides recognizable non-homogeneous deformation, which can then be compared to conventional processes. In the proposed process, a circular blank holder of a square hole is divided into eight identical segments of 45°. During the deep drawing process, four of the eight segments will move radially inward while the other four segments will move radially outwards cyclically under a pre-determined blank holding pressure. A finite element model of the technique was used to simulate virtual experiments to evaluate and optimize the controlling parameters that influence the cup height and forming process. Taguchi and Pareto ANOVA statistical methods were subsequently used to determine the optimum conditions for best cup height. The results have shown that the new technique is capable of producing deep square cups from soft aluminum sheet (Al-O) of 0.5 mm thickness with a high drawing ratio of 3.3. In addition, it was also observed that the radial displacement was the most significant parameter in influencing the cup height.     

Two-stage cold stamping of magnesium alloy cups having small corner radius

A two-stage cold stamping process for forming magnesium alloy cups having a small corner radius from commercial magnesium alloy sheets was developed. In the 1st stage, a cup having large corner radius was formed by deep drawing using a punch having large corner radius, and the corner radius of the cup was decreased by compressing the side wall in the 2nd stage. In the deep drawing of the 1st stage, fracture was prevented by decreasing the concentration of deformation with the punch having large corner radius. The magnesium alloy sheets were annealed at 500 °C to increase the cold formability. Circular and square cups having small corner radii were formed by the two-stage cold stamping. For the circular cup, the height of the cup was increased by ironing the side wall in the 1st stage. The radii of the bottom and side corners of the square cup were reduced by a rubber punch for applying pressure at these corners in the 2nd stage. It was found that comparatively shallow magnesium alloy square cups used as cases of laptop computers and mobile phones can be satisfactorily formed at room temperature without heating by the two-stage stamping.     

Simulation of earing during deep drawing of magnesium alloy AZ31

Magnesium alloys develop pronounced crystallographic texture and plastic anisotropy during rolling, which leads to earing during deep drawing of the rolled sheets. This phenomenon is modelled for the magnesium alloy AZ31 using the finite-element method in conjunction with a viscoplastic self-consistent texture model. To determine the model parameters the model is adjusted to measured stress–strain curves in tension and compression. The predicted earing pattern is found to depend not only on the initial texture at the beginning of the drawing process, but to a large extent also on the evolution of texture during drawing.     

Mg sheet metal forming: Lessons learned from deep drawing Li and Y solid-solution alloys

The sheet formability of current magnesium alloys at ambient temperatures is poor; however, the formability at moderately elevated temperatures can be excellent. Cylindrical cup drawing tests are used to compare the warm forming characteristics of conventional alloy AZ31B with alloys containing lithium oryttrium solid solutions. While both types of experimental alloy can have better room-temperature ductility (ε_f∼25–30%) than AZ31B, only the lithium alloy has comparable or better deep-drawing capacity. The results are discussed in terms of the sheet anisotropy. Particular attention is drawn to the fact that magnesium alloys exhibit poor bending ductility due to their anisotropy and mechanical twinning-induced tension-compression strength asymmetry.     

Prediction of forming limit in deep drawing of Fe/Al laminated composite sheets using ductile fracture criterion

Axisymmetric deep drawing processes of laminates composed of mild steel and various aluminium alloy sheets are simulated by FEM. From the calculated stress and strain histories of elements in each layer, the fracture initiation site and the forming limit are predicted by using the ductile fracture criterion. The predictions so obtained are compared with experimental observations. The results exhibit that various types of fracture initiations in deep drawing of the laminated composite sheets are successfully predicted. Furthermore it is found that the drawability is improved by setting the mild steel sheet on the punch side for the case of aluminium alloy sheet with comparatively high ductility, and by sandwiching the aluminium alloy sheet with the mild steel sheets for the case of low ductility.