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工艺参数对楔横轧特大型轧件内部应力影响分析 总被引:4,自引:0,他引:4
楔横轧成形特大型轧件为复杂的三维变形,其内部应力变化规律复杂,至今缺乏深入研究与本质理解,严重影响楔横轧的应用与发展。采用有限元先进数值方法模拟楔横轧特大型轧件成形过程,详细分析成形过程中轧件内部中心点的应力变化规律,阐明成形角、展宽角和断面收缩率三个主要工艺参数对特大型轧件内部应力的影响关系,为合理选取楔横轧特大型轧件模具工艺参数、开发设计特大型楔横轧机提供重要的理论依据。 相似文献
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机械结构轻量化的主要途径是在结构上采用空心轴.近年来, 采用楔横轧带芯棒轧制空心轴类件的工艺得到了较广泛的关注.厚壁空心轴类件在楔横轧轧制过程中易发生“失圆”现象.本文通过热压缩实验研究了25CrMo4合金钢在楔横轧变形条件下热变形行为, 获得其真应力-应变曲线.在此基础上, 基于Deform-3D有限元软件, 建立25CrMo4厚壁空心轴楔横轧有限元仿真模型, 分析厚壁空心轴楔横轧成形机理, 研究得出断面收缩率、成形角、展宽角对轧件不圆度的影响规律: 断面收缩率增大, 不圆度减小; 成形角增大不圆度减小, 轧制温度越高减小趋势越明显; 展宽角增大不圆度增大, 提高轧制温度抑制增大趋势.选取部分工艺参数进行楔横轧验证实验, 对比了有限元仿真结果和实验结果, 表明有限元仿真模型预测精度较高. 相似文献
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轧件内部横向应力和剪应力是影响楔横轧多楔同步轧制铁道车轴质量关键因素之一。本文基于多楔轧制旋转条件理论,采用Ansys/Ls-Dyna有限元软件,对多楔同步楔横轧轧制铁道车轴成形过程中,工艺参数对横向应力和剪应力影响规律进行了系统的研究,并对计算模型进行了实验验证,获得了工艺参数对楔横轧多楔同步轧制铁道车轴应力影响规律。研究结果为推广楔横轧多楔同步轧制技术成形铁道车轴、实现铁道车轴的高效节材化生产、提高车轴轧制质量提供了理论依据。 相似文献
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R. H. Wagoner S. Latreille J. L. Siles Yong H. Kim 《Metallurgical and Materials Transactions A》1991,22(12):3003-3011
In order to investigate the role of thermal effects in punch stretching, a simple nonisothermal forming operation was carried
out and was simulated using finite element modeling (FEM). A heated hemispherical punch deformed a steel sheet which was fully
clamped between room-temperature circular dies. Strains were measured at standard punch heights for comparison with FEM-simulated
ones. The strain distributions were in reasonable agreement, and the qualitative changes in the distributions with punch temperature
were predicted very well by the simulations. The form of the nonisothermal FEM formulation was verified by these agreements.
Increased punch temperature improves formability by lowering the peak strain in the punch-sheet contact region. Nonisothermality
can play a significant role in distributing strains throughout a deforming sheet under conditions similar to these.
S. LATREILLE, formerly Granduate Student, The Ohio State Univerity 相似文献
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A simulation model for two-roll cross wedge rolling (CWR) was presented by using three-dimensional rigid-plastic finite element method (FEM).The whole forming process of CWR,including knifing zone,guiding zone,stretching zone,and sizing zone,was simulated using the model in which dynamic adaptive remeshing technology for tetrahedral solid elements was used to fix element distortion.Based on the simulation results,the distributions of metal flow field,strain field,and damage field,and the geometry of the workpiece's end were analyzed.These results could provide theoretical guidance for realizing net shaping and reasonable design of tools. 相似文献
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Seokmin Hong Junghoon Lee Sunghak Lee Wanchuck Woo Sung-Kyu Kim Hyoung Seop Kim 《Metallurgical and Materials Transactions A》2014,45(4):1953-1961
In Twinning Induced Plasticity (TWIP) steels, delayed fracture occurs due to residual stresses induced during deep drawing. In order to investigate the relation between residual stresses and delayed fracture, in the present study, residual stresses of deep drawn TWIP steels (22Mn-0.6C and 18Mn-2Al-0.6C steels) were investigated using the finite element method (FEM) and neutron diffraction measurements. In addition, the delayed fracture properties were examined by dipping tests of cup specimens in the boiled water. In the FEM analysis, the hoop direction residual stress was highly tensile at cup edge, and the delayed fracture was initiated by the separation of hoop direction and propagated in an axial direction. According to the neutron diffraction analysis, residual stresses in 18Mn-2Al-0.6C steel were about half the residual stresses in 22Mn-0.6C steel. From the residual strain measurement using electron back-scatter diffraction, formation of deformation twins caused a lot of grain rotation and local strain at the grain boundaries and twin boundaries. These local residual strains induce residual stress at boundaries. Al addition in TWIP steels restrained the formation of deformation twins and dynamic strain aging, resulting in more homogeneous stress and strain distributions in cup specimens. Thus, in Al-added TWIP steels, residual stress of cup specimen considerably decreased, and delayed fracture resistance was remarkably improved by the addition of Al in TWIP steels. 相似文献
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Hemispherical stretching experiments and corresponding finite element modeling (FEM) were performed on three aluminum-killed
(AK) steels. Strain distributions measured from photogrids on the specimen surface were compared to those predicted by a three-dimensional
(3-D), membrane, rigid-viscoplastic FEM program. The material model uses Hill's nonquadratic theory for normal anisotropy
and Coulomb friction. The new anisotropy coefficient,M, and friction coefficient, μ, have opposite effects on the strain distribution. Balanced, biaxial simulations of highM materials required unrealistically high friction coefficients to produce agreement with measured strains. The discrepancies
call into question the validity of Hill's nonquadratic yield surface and the method of measuringM.
J.R. KNIBLOE, formerly Graduate Student, Department of Materials Science and Engineering, The Ohio State University 相似文献
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借助刚塑性有限元DEFORM-3D对4Cr9Si2马氏体耐热钢楔横轧成形过程进行了数值模拟,分析了展宽角对楔横轧轧件成形缺陷的影响规律.在楔横轧轧制刚楔入时,轧件的心部受到三向拉应力的作用;展宽角减小,轧件在楔入段时三向拉应力最大值和持续时间增大,使心部缺陷产生的可能性增加;而展宽角减小,金属轴向流动速度加快,使得对称中心在楔入段完成后的直径减小,而轴向力则随着展宽角减小,其数值还有一定的增大,最终将导致对称中心横截面拉细状况的产生;随着展宽角增大,表面螺旋痕将会增加,但展宽角对表面螺旋痕的影响不明显.通过实验验证了有限元的正确性和模拟结果的可靠性. 相似文献