共查询到20条相似文献,搜索用时 593 毫秒
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拉延筋在汽车覆盖件拉深成形中起着十分重要的作用。利用拉延筋可以调节和控制板料的变形程度和变形分布,抑制破裂、起皱、面畸变等多种冲压质量问题的产生。在很多情况下,拉延筋的设置合理与否将决定覆盖件拉深的成败。较系统地总结了板料成形拉延筋技术以及拉延筋作用原理、阻力模型、影响因素等的研究现状。 相似文献
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目前角钢和型钢压弯、压凹时的变形力多根据经验确定,笔者由功的平衡原理出发,考虑其变形时的应力状态,得出型材在压弯成形时的精确变形,并对所得数学式进行试验验证,二者结果十分接近,该式有很好的推广应用价值。 相似文献
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分子动力学模拟研究金属的力学性质,需要采用合适的应变分析方法研究金属的变形特征及其演化规律.金属材料复杂变形的局部应变特征缺乏简便有效的分析手段,整体变形也没有合适的描述方法.本文提出分子动力学中应变分析的统计矩方法,通过统计矩建立了微观量和宏观应变的关联.在单晶单轴加载、纳米多晶剪切和冲击加载下的应用表明,矩应变分析方法可以很好的描述和评估材料的局部变形和整体变形特征,并通过应变不均匀度鉴别材料的局部塑性变形和弹性变形,是深入研究复杂结构材料变形机理的一种有效的通用分析方法. 相似文献
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张金锁 《安全.健康和环境》2016,16(4):12-14
针对某油库6#储罐,采用ANSYS建立有限元模型,对其罐壁板单元进行网格划分,对比分析了满载时罐体未变形及变形两种情况的应力分布,通过变形罐体的应力云图可以看出该储罐罐体已经产生变形,且局部变形比较严重。变形前后应力数据显示罐体多处已经处在材料屈服极限范围内,甚至接近于屈服极限上限290 MPa,具有一定危险。提出应及时检测其它储罐,并采取相应措施防止罐体出现较大变形。 相似文献
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介绍了 3种先进的连接管件成形技术 ,即小弯曲半径管内压推弯成形技术、球形管接头的胀形成形技术和管件的内径滚压成形技术 ,对其基本成形过程进行了描述 ,并通过铝合金、不锈钢和钛合金管件的成形试验获得了主要工艺参数对成形的影响规律 ,结果表明采用这些方法成形所需的连接管件是非常有效的 相似文献
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Surface distortions in the form of wrinkles are often observed in sheet metals during stamping and other forming operations. Because of the trend in recent years towards thinner, higher-strength sheet metals, wrinkling is increasingly becoming a more common and troublesome mode of failure in sheet metal forming. The prediction and prevention of wrinkling during a sheet forming process are important issues for the design of part geometry and processing parameters. This paper treats the phenomenon of flange wrinkling as a bifurcated solution of the equations governing the deep drawing problem when the flat position of the flange becomes unstable. Hill’s bifurcation criterion is used to predict the onset of flange wrinkling in circular and square cup drawing. In particular, the maximum cup height that can be drawn without the onset of flange wrinkling is predicted for the given set of process parameters. A parametric study of the maximum cup height is also carried out with respect to various geometric, material and process parameters. Finite element formulation, based on the updated Lagrangian approach, is employed for the analysis. The incremental logarithmic strain measure, which allows the use of a large incremental deformation, is used. The stresses are updated in a material frame. The material is assumed to be elastic–plastic, strain hardening, yielding according to an anisotropic yield criterion of Barlat et al. (2005) [23] (named as Yld2004-18p). Isotropic power law hardening is assumed. Inertia forces are neglected due to small accelerations. Modified Newton–Raphson iterative technique is used to solve the nonlinear incremental equations. 相似文献
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《Journal of Manufacturing Processes》2008,10(1):21-27
Press brake bending is a commonly used process for sheet metal part fabrication. It has been observed that the final bend angle, which is the angle achieved upon removal of the punch, is smaller than the initial bend angle. This springback is due to the elastic recovery of the sheet metal. Various theoretical models have been proposed to predict the springback using the tooling geometry and the known properties of the sheet metal. However, in a production environment, the actual properties of any given workpiece may vary from the nominal properties of the lot. This variation causes the actual springback to deviate from the theoretical predictions. This paper presents a practical incremental bending methodology to control punch displacement to achieve more accurate final bend angles. In the proposed approach, workpiece properties are estimated from measured loaded and unloaded bend angles. The estimated properties are used to determine the final punch position required to obtain the desired bend angle after springback. A series of bending experiments was performed. It was found that the proposed method can better predict springback and effectively control the bend angle variation in a production environment. 相似文献
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近些年来,面对全球化的竞争,越来越需要小批量、多样化、周期短的新的成形技术.薄板成形技术在成形工艺中占有很重要的地位,其多样化趋势已经变得越来越明显,出现了多种加工方法,它对将来的工业结构和产品的生产技术将是一场革命.文中介绍了变压边力技术、成对液压成形技术、粘介质成形技术、无模分层成形技术等几种柔性化程度高的板材成形技术及其发展趋势. 相似文献
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端头多半圆弯曲件比较常见,但质量难以保证。此文通过对成形弯曲工艺的分析,提出了改进措施,并介绍了两种典型模具结构,及其零部件的设计。 相似文献
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Zhen Cui Z. Cedric Xia Feng Ren Vijitha Kiridena Lin Gao 《Journal of Manufacturing Processes》2013,15(2):236-241
Incremental Sheet Forming (ISF) is an emerging sheet metal prototyping technology where a part is formed as one or more stylus tools are moving in a pre-determined path and deforming the sheet metal locally while the sheet blank is clamped along its periphery. A deformation analysis of incremental forming process is presented in this paper. The analysis includes the development of an analytical model for strain distributions based on part geometry and tool paths, numerical simulations of the forming process with LS-DYNA, and experimental validation of strain predictions using Digital Image Correlation (DIC) techniques. Three kinds of parts include hyperbolic cone, skew cone and elliptical cone are constructed and used as examples for the study. Analytical, numerical and experimental results are compared, and excellent correlations are found. It is demonstrated that the analytical model developed in this paper is reliable and efficient in the prediction of strain distributions for incremental forming process. 相似文献