共查询到18条相似文献,搜索用时 156 毫秒
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电磁成形是一种快速、高效的塑性成形方法。对影响电磁成形的主要因素电容和电感进行了研究,并分析了各种参数对成形的影响,从而得到较优化的工艺及参数,以达到提高成形效率的目的。 相似文献
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随着塑性微成形特征尺寸进一步缩小,材料种类不断扩大,单纯依靠模具施加载荷的方法已经越来越难以制备出满足尺寸精度和使用性能要求的微型三维构件,亟需探索新的塑性微成形新原理、新方法和新工艺。电磁微成形技术是一种利用载流导体在磁场中受到洛伦兹力而变形的高应变速率成形方法,能够有效克服微成形过程中成形性能下降、尺寸精度难以保障等问题,具有拓展塑性微成形应用领域的巨大潜力。首先从电磁成形技术的原理与特点出发,介绍了电磁成形过程中高应变速率效应对材料性能的特殊作用,然后综合分析了微成形过程中尺度效应对材料力学行为和成形性能的影响规律及相关机制,详细评述了电磁微成形技术在金属超薄板冲压以及金属表面微纳结构压印中的优势与不足,最后总结并提出了电磁微成形技术在理论和工艺方面所面临的机遇与挑战。 相似文献
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由于TA32钛合金板室温成形性差、精度难以保证,开展了电磁辅助弯曲成形方法的实验研究,通过拉伸和电磁成形实验探究了TA32钛合金的力学性能和成形性能,获得了TA32钛合金板在准静态和动态拉伸下的应力、应变关系,给出了在电磁成形状态下的成形极限应变,阐明了电磁成形作用下的TA32钛合金的增塑机制。采用匀压式电磁辅助弯曲成形的方法对TA32钛合金板开展实验研究,结果表明:电磁辅助弯曲成形方法能够有效地提高弯曲件的成形精度,并且在一定条件下,放电能量越高,贴模效果越好、成形精度越高。带压紧翼的弯曲件的变形区外层过度伸长而产生减薄并开裂,不带压紧翼的弯曲件通过合理地控制放电电压能够获得较好的成形效果。 相似文献
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Aashish Rohatgi Elizabeth V. Stephens 《Journal of Materials Processing Technology》2012,212(5):1070-1079
This work builds upon our recent advances in quantifying high-rate deformation behavior of sheet metals, during electro-hydraulic forming (EHF), using high-speed imaging and digital image correlation techniques. Aluminum alloy AA5182-O and DP600 steel sheets (1 mm thick, ∼152 mm diameter) were EHF deformed by high-energy (up to ∼34 kJ) pressure-pulse in an open die (free-forming) and inside a conical die. The deformation history (velocity, strain, strain-rate, and strain-path) at the apex of the formed domes was quantified and analyzed. The data shows that the use of a die in the EHF process resulted in an amplification, relative to free-forming conditions, of the out-of-plane normal velocity and in-plane strain-rate at the dome apex. This amplification is attributed to the focusing action of the die on account of its conical geometry. Further, while the strain-path at the dome apex was generally linear and proportional, the use of a die resulted in greater strain at the apex relative to the strain during free-forming. The sheet deformation profile in the EHF process was found to be different from that previously observed in electromagnetic forming (EMF) and, thus, the two processes are expected to result in different strain-paths and formability. It is anticipated that quantitative information of the sheet deformation history, made possible by the experimental technique developed in this work, will improve our understanding of the roles of strain-rate and sheet-die interactions in enhancing the sheet metal formability during high-rate forming. 相似文献
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电磁成形是一种高速率成形方法,它能够有效提高金属板材的成形极限。但是电磁成形过程复杂,涉及到磁场?结构场之间的耦合分析。数值模拟提供一种手段去解决耦合问题。然而,大多数的数值模拟都限于2D。建立3D有限元模型去分析电磁平板胀形。成形过程中考虑了板料与底模的接触和板料变形对磁场的影响。板料中心节点和半径20mm处节点的位移随着时间的变化与实验结果一致。分析了塑性应变能和塑性应变。 相似文献
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采用有限元法设计电磁成形的非均匀线圈(英文) 总被引:2,自引:0,他引:2
M.AHMED S.K.PANTHI N.RAMAKRISHNAN A.K.JHA A.H.YEGNESWARAN R.DASGUPTA S.AHMED 《中国有色金属学会会刊》2011,(3):618-625
电磁成形是一种使用脉冲电磁力快速成形的工艺。线圈是电磁成形系统中的一个重要组成部分,需要根据实际应用情况来设计。均匀螺旋线圈通常用在金属板材零件成形中。然而,对于这类非均匀线圈,工件中心部位的电磁力弱,从而导致变形不充分并且还有其它问题出现,如滞留气泡。因此,提出一个设计非均匀线圈的概念,以便电磁力的分布更均匀。采用有限元法对提出的非均匀线圈与传统的均匀螺旋线圈就电磁力的分布、磁场和电流密度进行比较。结果表明,非均匀线圈的电磁力分布更均匀。还计算了线圈的感应强度并进行了比较。 相似文献
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Expansion of a low conductive metal tube by an electromagnetic forming process: Finite element modeling 总被引:2,自引:0,他引:2
Chansun Shin Hyung Ha Jin Jung Gu Lee Dong-Jin Lee Chang-Kyu Rhee Jun-Hwa Hong 《Metals and Materials International》2008,14(1):91-97
The expansion of a metal tube by means of an electromagnetic forming (EMF) process is attractive because EMF has a high forming
rate and can reduce residual stress. The forming forces in EMF are Lorentz forces. They are derived from a repulsive interaction
between a transient electric current induced in a coil with the aid of a capacitor bank and an eddy current induced in a metal
tube by means of a transient current. Highly conductive metals are suitable for EMF-based tube expansion but tubes of low
conductive metals are often used for industrial purposes. We studied various methods of using EMF to increase the formability
of low conductive metals. In particular, we used a finite element method to compute an electromagnetic field coupled with
temperature and deformation of a metal tube. Our results show that a highly conductive layer can increase the formability
of a low conductive metal. 相似文献
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P. Jimbert I. EguiaI. Perez M.A. GutierrezI. Hurtado 《Journal of Materials Processing Technology》2011,211(5):916-924
Hemming is commonly one of the last operations for stamped parts. For this reason it is of critical importance on the performance and perceived quality of assembled vehicles. However, designing the hemmed union is a complicated task and is deeply influenced by the mechanical properties of the material of the bent part. Significant problems can arise in this operation when bending aluminum alloys, because cracks can appear due to the localized strain during hemming as a result of the low ductility of automotive aluminum alloys. This paper presents the development of the electromagnetic forming (EMF) technology for auto body-in-white parts hemming. A relatively simple experimental procedure to perform a hemming operation based on the principle of EMF is presented in order to compare the variation in the quality parameters of a hemmed joint. The achieved results are compared with the corresponding geometry hemmed utilizing the conventional process. At the same time, the study is completed with the development of a new simulation method for the EMF technology. The results obtained during this study prove the capability of the EMF to obtain quality hem unions simplifying the complicated conventional hemming operation. In this study a loose coupling EMF hemming simulation method has been developed using Maxwell® 3D to solve the electromagnetic field computation and Abaqus® to solve the mechanical computation. This simulation method shows good agreement with the physical experiments. Finally, the EMF hemming process is characterized by analyzing the influence of main input parameters on the quality output parameters. 相似文献
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Experimental Observations of Quasi-Static-Dynamic Formability in Biaxially Strained AA5052-O 总被引:1,自引:0,他引:1
Dahai Liu Haiping Yu Chunfeng Li 《Journal of Materials Engineering and Performance》2011,20(2):223-230
To establish the efficacy of electromagnetically assisted sheet metal stamping (EMAS), a series of combined hydraulic bulging
and electromagnetic forming (EMF) experiments are presented to evaluate the biaxial quasi-static-dynamic formability of an
aluminum alloy (AA5052-O) sheet material. Data on formability are plotted in principal strain space and show an enhanced biaxial
formability beyond the corresponding experimental results from conventional forming limit diagram. The plastic strains produced
by the combined process are a little larger than or at least similar with those obtained in the fully dynamic EMF process.
In addition, the biaxial forming limits of aluminum sheets undergoing both very low and high quasi-static prestraining are
almost similar in quasi-static-dynamic bulging process. Limit formability seems to depend largely on the high-velocity loading
condition as dictated by EMF. It appears that in quasi-static-dynamic forming, quasi-static loading is not of primary importance
to the material’s formability. Based on these observations, one may be able to develop forming operations that take advantage
of this formability improvement of quasi-static-dynamic deformation. Also, this could enable the use of a quasi-static preform
fairly close to the quasi-static material limits for the design of an EMAS process. 相似文献
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Xiao-Yang Wei Masoumeh Moradi Li-Jing Yang Zhen-Lun Song Bi-Zhang Zheng Zhan-Peng Lu 《金属学报(英文版)》2019,32(10):1287-1297
The effects of low electromagnetic field(EMF)( B = 2 mT) on the corrosion of pure copper in the absence and presence of multispecies marine aerobic bacteria were investigated in this work. The results showed that EMF has an inhibitory effect on copper metals and decreases the corrosion rate of copper metals in sterile artificial seawater. However, microbiologically influenced corrosion of Cu was increased in the presence of electromagnetic field due to its effect on the biofilm morphology and structure. EMF reduced the growth rate of bacteria and decreased bacterial attachment, thereby forming a heterogeneous and non-stable biofilm on the Cu surface in the presence of EMF. Moreover, the biofilm was dispersed throughout the surface after 7 days, whereas the scattered bacteria were observed on the surface after 10 days. Confocal laser scanning microscopy images showed large and deep pits on the surface in the presence of EMF and confirmed the acceleration of Cu corrosion in the presence of EMF and multispecies bacteria. Furthermore, XPS and FTIR results demonstrated that the corrosion products and metabolic by-products were significantly changed in the presence of EMF. 相似文献
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Analysis of Process Parameters and Forming Mechanisms within the Electromagnetic Forming Process 总被引:1,自引:0,他引:1
Electromagnetic forming (EMF) is a typical high speed forming process using the energy density of a pulsed magnetic field to form workpieces made of metals with high electrical conductivity like e.g. aluminium. In view of new lightweight constructions, special forming processes like EMF gain importance for the associated materials. For a better understanding of the working mechanisms and the process prediction a coupling of electromagnetical and structure-mechanical models, advanced simulation tools as well as detailed experimental investigations with on-line measurements of the ultra-fast deformation of significant workpiece areas is required. New results of research concerning correlations among workpiece properties, strain rate, and acting magnetic pressure are presented. 相似文献