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本文阐述了开式模锻变形过程阶段的划分、各阶段变形特点、变形力大小,着重分析了什么是合理的模锻变形过程,指出了设计制坯工步和予成形工步的重要性。 相似文献
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提出带肋板齿轮坯开式模锻和闭式模锻两种热精锻成形工艺方案,借助有限元分析软件模拟了两种工艺方案下齿轮坯的成形过程,分析比较了两种方案中的金属流动规律。仿真结果显示:采用开式模锻,肋板充填不饱满,成形载荷大;采用闭式模锻,零件成形质量较高,成形载荷较小。导致开式模锻成形载荷大并且肋板充填不饱满的原因为:成形中后期充填肋板的金属流动阻力增加,金属径向流动加剧并形成较大飞边,随着上模下压,飞边变形消耗滑块能量,并增加了与模具的接触面积,导致成形力急剧增加而模具型腔充填不饱满。工艺实验表明,其结果与数值模拟相吻合。 相似文献
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根据对开式模锻变形过程的理论分析,论述了几种主要工艺参数对开式模锻锻靠力的影响,提出降低开式模锻锻靠力的主要工艺措施。实践证明,这些工艺措施是行之有效的。 相似文献
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分析了厚壁管件有芯棒开式冷挤压成形特点及影响成形的参数,将此工艺分为外缩径内径不变、内扩径外径不变、外缩径内扩径3种形式,视前两种变形形式为外缩径内扩径变形的特殊形式。引入流函数,建立包含3种变形形式的统一连续速度场;根据速度场与应变速率场之间关系,确定了应变速率场;利用上限原理,得到了挤压功率、挤压力的理论模型。通过编程计算,得到了不同工况下的力-行程曲线,并与实验结果进行了对比,误差小于8%,满足工程需要。此模型可计算不同工况下的挤压力,用于厚壁管件有芯棒开式冷挤压成形工艺的制定及设备选择。 相似文献
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锥形凸台体积成形的一种合成力学模型 总被引:1,自引:0,他引:1
锥形凸台成形是金属体积成形工艺中一种典型的局部成形。该文通过分析锥形凸台在不同体积成形工艺中的成形机理,基于模块化思想,将其成形过程划分为挤压成形与角部充满两个特征时段,并将两个特征时段的滑移线场力学模型有机联结,构建了锥形凸台成形过程的一种滑移线力学模型,并介绍了应力场与变形力的求解方法。该模型丰富了金属体积成形过程的特征单元库,可套用于局部成形的应力场与变形力求解,实现局部成形的模具优化设计。 相似文献
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一阶回转曲线(first order reversal curve 简称FORC)图谱法被视为研究滞后效应领域中的“指纹鉴定”,受到了地质学界和物理学界的科学家极大的关注。在磁滞后系统中,FORC图谱可以相当敏感地表征磁性颗粒间的交换作用和矫顽力的分布情况,并且能够对磁化过程中的动态问题如不同的磁场变化速率等情况做出精确的分析。FORC图谱法也可应用到其它有滞后效应的领域如铁电滞后、热滞后、弹性滞后等。文章将从磁性领域入手,通过比较Preisach模型引入FORC图谱法,利用Takacs模型验证FORC图谱的计算过程,并列举出FORC图谱在纳米双相磁性材料的应用。 相似文献
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Kyung Seok Oh 《Journal of Materials Processing Technology》2011,211(4):695-707
A new test method including the tool shape and test procedure was developed to evaluate sheet metal formability using the finite element method (FEM). This method is intended to generate the various modes of deformation and to control the onset of failure independently under each mode so that the forming limit diagram (FLD) achieves a good representation of a wide range of strains.A blank holder force-punch stroke diagram with three failure loci is introduced to define the optimum process condition and the formability index by which each material is quantitatively evaluated. The test procedure of this method consists of three steps: drawing a blank holder force (BHF)-punch stroke diagram, measuring strains from the part stamped at the optimum process condition, and grading the test materials using the formability index. In numerical simulations under optimum process conditions, sheet metals can fail due to multi-mode rupture; this failure leads to a widely balanced strain distribution in the FLD such that strains are developed near the forming limit over a wide range of forming modes.Experiments were conducted on three grades of steel sheets to validate the proposed method. Stamping results yield well-defined strain signatures having a wide range of strain distribution in the FLD in all materials tested. The outcomes of the shape and strain behaviors agree well with the numerical results. 相似文献
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分析了极爪零件的成形工艺 ,建立了该零件温锻精密成形的三维塑性有限元模型 ,模拟了其温锻成形关键工步 ,得出变形过程中材料的流动情况、变形载荷及模具的受力分布 ,模拟结果可以为该零件的成形工艺和模具设计提供依据。 相似文献
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Mingqi Li Zhichao Sun Minghui Li He Yang 《Journal of Materials Processing Technology》2005,160(3):396-400
Tube inversion by the axial drawing is an advanced forming process for manufacturing double-walled tubes with high quality, high efficiency, and low consumption. However, to realize forming process depends on producing the tearing in deforming zone, which has a close relationship with forming load. So in this paper, the influence of forming condition parameters on the deforming force and the process is investigated by rigid-plastic FEM numerical simulation. The results show that: (1) during the whole forming process, the shape of the tube remains unchanged when the radius of the core die is larger than a certain value, so a precision forming can be easily realized; (2) for a given r/d0 or t0/d0, the deforming force depends mainly on the value of r/t0, and there is a critical parameter k, when r/t0 < k, the steady forming force decreases with an increase of r/t0; on the contrary, when r/t0 > k, the steady forming force increases with an increase of r/t0; (3) the material hardening exponent n of the tube and the friction coefficient μ have a remarkable influence on the deforming force. The smaller the value of n and the larger the value of μ the larger the forming force. 相似文献
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基于塑性理论建立了比例加载条件下双向拉伸应力应变关系,结合Swift分散性失稳准则,提出了一种建立板料成形极限应力图的方法。分别应用Hill 48和Hosford屈服准则以及单向拉伸性能参数,建立了铝合金板(r<1)和薄钢板(r>1)两种材料的成形极限应力图(FLSD),分析表明,不同的屈服准则的选取对于成形极限应力曲线有不同的影响,对于不同类型的材料屈服准则的影响程度也不同。与由通常的成形极限图(FLD)转换所得到的成形极限应力图(FLSD)进行了对比分析,结果表明,所提出的方法计算过程更为简便,并能较为准确地建立成形极限应力图,可以作为复杂加载路径下的成形极限破裂判据。 相似文献
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Huang Shangyu Chang Zhihua Wang Zhongren Wang Lifeng Yang Mei School of Materials Engineering Wuhan Automotive Polytechnic University Wuhan P. R. China School of Materials Science Engineering Harbin Institute of Technology 《中国有色金属学会会刊》1998,(3)
1INTRODUCTIONElectromagneticforming,esentialybeingakindofapplicationofimpulseintensivecurenttechniqueinmetalworking,dealswith... 相似文献