共查询到19条相似文献,搜索用时 125 毫秒
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不锈钢外板对5A06铝合金板材液压胀形行为的影响 总被引:1,自引:0,他引:1
薄壁曲面铝合金零件整体液压成形时,易发生起皱和破裂缺陷,探讨通过施加外层板能抑制缺陷发生的机理。采用5A06铝合金内层板材和1Cr18Ni9Ti不锈钢外层板材,对双层板液压胀形行为进行研究。通过塑性理论分析板材液压胀形屈服半径,讨论经向摩擦力及法向压力对板材应力大小的影响;利用数值模拟给出内层板的应力、应变分布;通过双层板液压胀形试验,对比单层板和双层板条件下,铝合金内层板极限胀形高度、极限应变,分析双层板的变形协调性。结果表明:通过施加不锈钢外层板,减小了5A06铝合金内层板顶部位置面内的双向拉应力,减小了内层板变形区应力、应变梯度,使胀形变形更加均匀,胀形高度提高32%,顶部极限应变提高51.7%,极限应变显著提高。 相似文献
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研究不同塑性变形硬化模型对汽车5182-O铝合金板材冲压成形模拟结果的影响。采用材料单向拉伸试验得到应力应变关系曲线,基于Hollomom、Krupskowsky与Power方程对曲线进行拟合,建立材料室温下塑性变形硬化模型,对厚度为1.5 mm和0.85 mm的5182板材进行冲压试验和有限元模拟分析,对比分析冲压试验与模拟结果。试验与模拟结果显示,当板料厚度为1.5 mm时,板料冲压试验的成形力最大为42.95 kN,板料拉深深度为30.58 mm,基于Power方程计算得到的最大成形力为41.5kN与试验结果比较接近,Hollomom方程计算得到的拉深深度为30.546 mm,板材成形厚度分布与试验结果比较接近;当板料厚度为0.85 mm时,板料冲压试验的成形力最大为34.47kN,板料拉深深度为33.792 mm,基于Power方程计算得到的最大成形力为34.27 kN与试验结果比较接近,Hollomom方程计算得到的拉深深度为33.636 mm,板材成形厚度分布与试验结果比较接近。基于三种硬化模型铝合金冲压成形过程的计算模拟分析结果,并通过与试验对比得到不同硬化模型对铝合金板材冲压成形计算模拟的影响,进一步为汽车铝合金覆盖件在成形工艺的研究分析提供理论指导。 相似文献
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板材充液拉深(hydromechanical deep drawing,HDD)是在拉深凹模中以一定压力液体作为传力介质代替刚性凹模传递载荷,使坯料在液体压力作用下贴靠凸模拟实现金属板材零件的成形。与传统拉深工艺相比,板料成形性显著提高,成形表面质量好,模具寿命长。随着成形设备和相关技术的发展,充液拉深工艺被广泛应用于汽车、飞机制造业。 相似文献
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针对两直臂间距较小、展平时发生干涉的等厚板材磁力支架零件,提出磁力支架零件步进式等厚冲锻成形新工艺,该工艺首先使用冲压制造出两直臂间距较大的板材零件,再分几个工步拉深两直臂的连接载体,逐步缩短两直臂间距直到目标间距为止,每个工步通过等厚冲锻工艺将局部增厚的材料减薄到原板材厚度。运用理论分析和试验方法,分析及优化拉深两直臂连接载体的形状,建立两直臂连接载体的流线型拉深的数学模型,基于该数学模型,以磁力支架零件无工艺缺陷为目标,采用数值模拟优化流线型拉深工艺参数且得到磁力支架等厚冲锻成形的步进系数。研究结果表明,运用步进式等厚冲锻新工艺三个工步可以制造出无工艺缺陷的磁力支架零件,试验结果同数值模拟结果吻合。 相似文献
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基于DEFORM-3D仿真软件,分析了7075铝合金带筋杯形件反挤压成形过程,研究了挤压速度、扭转速度、坯料初始温度对成形过程的影响,通过正交试验获得最佳成形工艺参数,并将传统的挤压成形与扭转挤压成形进行对比。结果表明,在传统反挤压的基础上,扭转作用使得坯料成形所需载荷降低,金属内部等效应变分布更均匀,通过正交试验最终得到了优化后的成形工艺参数,为铝合金杯形件反挤压成形提供理论基础。 相似文献
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针对小批量、复杂形状的薄壁聚醚酰亚胺(PEI)制件提出了采用粘性介质温热成形的方法进行此类零件的成形,以达到降低生产成本、缩短产品研制周期的目的。通过PEI板材的拉伸实验和粘性介质温热胀形试验,研究了不同温度条件下的PEI板材力学性能及其变形规律。研究结果表明:PEI板材在(20~150)℃范围内,随着温度的升高,成形性能逐渐提高;PEI粘性介质温热胀形试件的最大壁厚减薄率在胀形试件中心呈现区域性分布,最大壁厚减薄率区域面积随着变形温度的升高而增大;此外,相比于单向应力状态,PEI板材在双向应力状态下具有更好的成形性能,并且PEI板材的形变没有对零件表面光泽和透光率造成影响。 相似文献
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微拉深成形以其高效率、低成本、高质量等优点成为一种可行的制造开口、空心、薄壁微型零件的微细加工方法。然而,由于微型化的影响,使得微拉深要比宏观拉深更加困难。研制精密微型落料-拉深复合模,成形出内径仅为1 mm的微杯形件。试验材料采用厚度为50 μm的1060纯铝,在真空氛围下经300 ℃分别退火1 h和8 h。微拉深试验在SANS CMT-5504电子万能试验机上进行,试验速度为0.05 mm/s,润滑剂为聚乙烯薄膜。研究退火工艺和压边力对拉深力、拉深比、制耳和起皱的影响。试验结果表明,顺利成形出质量良好、拉深比为2.1的微杯形件;经退火处理的坯料,拉深力降低,拉深比增大,制耳减弱;随着压边力的增加,起皱减弱,但当压边力超过一定数值后则导致拉裂。 相似文献
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卢险峰 《机械工人(热加工)》1997,(6):18-19
曲面形状零件是指那些非平底、非直壁零件,包括有:球面形状零件、抛物面形状零件、锥形零件以及诸如汽车覆盖件一类的零件。这类零件在拉深成形时,整个坯料都是变形区,因为它不仅要求其外法兰部分产生拉深时相同的变形,而且还要求其中间部分由平面变成曲面或斜面,也成为了变形区,因此,可以说曲面零件成形是拉深和胀形两种变形方式的复合。 曲面形状零件拉深成形后实测变形数值如图1所示。图1a是电动喇叭罩变形分布示意(材料为08 相似文献
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Earing predictions for strongly textured aluminum sheets 总被引:1,自引:0,他引:1
Jong-Hun Yoon Oana Cazacu Jeong Whan Yoon Robert E. Dick 《International Journal of Mechanical Sciences》2010,52(12):1563-1578
Metallic alloy sheets develop crystallographic texture and plastic anisotropy during rolling. Deep drawing of a cylindrical cup from a rolled sheet is one of the typical forming operations where the effect of this anisotropy is most evident. Generally, in the finite element analyses of this process, the evolution of anisotropy during forming is neglected. In this paper, results of an experimental program carried out to quantify the anisotropy of aluminum alloy AA5042-H2 are reported. In addition to tensile tests along seven directions in the plane of the sheet, cup-drawing tests were conducted. It was observed that the material displays eight ears. The effects of the evolution in anisotropy and the directionality in hardening on the predictions of the earing profile for this material are investigated using a new methodology that incorporates multiple hardening curves corresponding to uniaxial tension along several orientations with respect to the rolling direction, and to biaxial tension. Yielding is described using the anisotropic yield function Yld2000-2D [1] and a form of CPB06ex2 yield function [2], which is tailored for metals with no tension–compression asymmetry. It is shown that even if distortional hardening is neglected, the latter yield function predicts a cup with eight ears as was observed experimentally. Consideration of distortional only leads to improved accuracy in prediction of the non-uniformity of the cup height profile. 相似文献
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Daeyong Kim Junehyung Kim Kwansoo Chung 《International Journal of Mechanical Sciences》2010,52(4):612-625
In order to evaluate the formability of friction stir welded (FSW) automotive TWB (tailor-welded blank) sheets with respect to base material direction, the aluminum alloy 6111-T4 sheet was joined with three different types of combination: RD||RD, TD||RD, TD||TD (Here, RD and TD mean the rolling direction and transverse direction, respectively). Formability performance was experimentally and numerically studied in three applications including the simple tension tests, hemisphere dome stretching and cylindrical cup drawing tests. For numerical simulations, the non-quadratic orthogonal anisotropic yield function, Yld2004-18p and the isotropic hardening law were implemented into the material constitutive model. As for the failure criterion, the forming limit diagram (FLD) was utilized to determine the failure strain. 相似文献
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耦合温度和应变率的铝合金板成形极限预测方法 总被引:3,自引:1,他引:2
为了提高铝合金板成形能力,一些先进成形工艺已经被开发。温成形是实现铝合金高成形能力和高成形精度的一种有效方法。温度和成形速度是影响铝合金板温成形工艺的重要参数,对其成形性能影响十分显著。提出一种综合考虑温度和应变率影响的铝合金板成形极限预测方法。采用响应面法建立铝合金板应变硬化指数n、应变率敏感度指数m与成形温度、应变率条件之间的力学性能函数关系;基于M-K理论,并结合Logan-Hosford屈服函数,推导出耦合温度和应变率的铝合金板成形极限图计算模型。模型检验表明力学性能响应面方程具有较高精度。成形极限的计算结果与已有的试验值对比表明,二者吻合较好,这证实耦合温度和应变率的铝板成形极限预测方法是正确和可靠的。 相似文献
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AA6061铝合金挤压管材在常温下强度高但塑性差,难以成形复杂形状零件。基于此,提出了固溶处理+固体颗粒介质胀形+人工时效的工艺流程,通过固溶、淬火和时效等热处理工艺调整铝合金变形前后的力学性能,应用固体颗粒介质胀形技术实现管件塑性成形。以AA6061挤压铝合金管为研究对象,分析了固溶处理工艺参数对合金力学性能的影响,发现管材经固溶温度560℃且保温120min处理后,其延伸率提高3倍以上,强度和硬度也大幅降低,使合金管材的成形性能指标显著提高,具备了固体颗粒介质胀形管件的条件;对合金固溶处理后再人工时效处理的试验研究表明,人工时效温度180℃且保温360min时合金塑性下降,强度和硬度等性能指标均可恢复至初始状态。基于铝合金热处理工艺特征的研究,采用固溶处理+固体颗粒介质胀形+时效处理的工艺流程,成功试制了AA6061铝合金典型的正方形截面管件,其环向最大展长率可达34%。 相似文献
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Prediction of sheet forming limits with Marciniak and Kuczynski analysis using combined isotropic-nonlinear kinematic hardening 总被引:1,自引:0,他引:1
Morteza Nurcheshmeh Daniel E. Green 《International Journal of Mechanical Sciences》2011,53(2):145-153
The forming limit curve (FLC), a plot of the limiting principal surface strains that can be sustained by sheet metals prior to the onset of localized necking, is useful for characterizing the formability of sheet metal and assessing the forming severity of a drawing or stamping process. Both experimental and theoretical work reported in the literature has shown that the FLC is significantly strain-path dependent. In this paper, a modified Marciniak and Kuczynski (MK) approach was used to compute the FLC in conjunction with two different work-hardening models: an isotropic hardening model and a mixed isotropic-nonlinear kinematic hardening model, which is capable of describing the Bauschinger effect. Predictions of the FLC using the MK analysis have been shown to be dependent on the shape of the initial yield locus and on its evolution during work hardening; therefore the hardening model has an influence on the predicted FLC. In this investigation, published experimental FLCs of AISI-1012 low carbon steel and 2008-T4 aluminum alloy sheets that were subjected to various nonlinear loading paths were compared to predictions using both hardening models. The predicted FLCs were found to correlate quite well with experimental data and the effects of strain path changes and of the hardening model on predicted FLCs are discussed. 相似文献
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