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控制厚度分布的正反向超塑胀形的有限元分析 总被引:4,自引:1,他引:4
为研究正反向超塑胀形工艺对厚度分布的影响,应用商业有限元软件MARC对带有凹槽的深盒形7475合金零件正反向超塑胀形过程进行了有限元模拟,并对不同工艺条件下成形后零件的壁厚分布结果进行了分析.研究表明:正反向超塑胀形工艺是控制成形零件壁厚的有效途径,通过优化压力-时间曲线和反向胀形模具形状,明显改善了零件的厚度分布,达到了零件的设计要求;后处理直观地显示了该零件正反向超塑胀形的全过程,为成形提供了合理的方案;零件变形各阶段的应变速率控制在7475合金的应变速率范围内,证明压力-时间曲线设计合理. 相似文献
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目的研究加载路径对空心双拐曲轴成形效果的影响。方法基于有限元分析软件,对304不锈钢双拐曲轴内高压胀形工艺进行有限元仿真,分析了加载路径对双拐曲轴胀形高度与壁厚的影响,并对开裂、起皱等缺陷产生的原因进行分析,最后,根据数值模拟结果,对双拐曲轴进行实际成形试验,并将数值模拟结果与试验结果进行对比。结果成形压力小于20 MPa时,管坯产生起皱;成形压力大于60 MPa时,管坯产生开裂。通过试验获得了壁厚分布均匀的双拐曲轴零件,并且数值模拟结果和试验结果基本一致。结论轴向进给大、内压不足容易导致过渡圆角处起皱;轴向进给小、内压过大容易导致拐部顶端开裂。只有设置合理的加载路径才能成形出壁厚均匀性好,胀形高度达到要求的双拐曲轴。 相似文献
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高压气胀成形是在内高压成形基础上发展起来的管件成形技术,采用气体介质加载,可在高温下成形钛合金构件。以Ti-3Al-2.5V钛合金管材为实验材料,开展了矩形截面构件和大截面差构件高压气胀成形工艺研究,提出了气压阶梯加载方法和气压与轴向位移匹配的加载方法。结果表明,利用Ti-3Al-2.5V钛合金在一定温度和应变速率范围的应变和应变速率双硬化机制,采用合理的加载路径,能够消除开裂缺陷,以较高的效率实现钛合金异形管件的成形制造,并且构件壁厚相对均匀,形状和组织性能均可得到有效控制。 相似文献
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以正反向超塑成形厚度均匀的TC4钛合金深筒形件为背景(厚度精度要求1.6mm±0.2mm),设计了多种预成形模形状,采用MSC.MARC有限元模拟研究了不同形状的预成形模对深筒形件侧壁厚度分布的影响, 并分析了预成形模和终成形模的表面摩擦系数分别对成形件壁厚分布的影响,提出了模具型面变摩擦控制厚度分布的方法.结果表明:预成形模对压边部分环形带区域和筒形件底部区域的局部预减薄,对最终侧壁的厚度分布有非常大的改善.同时,合理地增大预成形模的表面摩擦能显著增加预成形的局部减薄作用,对于提高工件最终壁厚分布均匀性有利.减小终成形模的摩擦,可以使板料整体变形均匀化,壁厚分布趋于均匀.根据有限元分析结果,对模具表面进行处理,并通过正反向超塑成形实验制得TC4钛合金深筒形件,其厚度分布满足1.6mm±0.2mm. 相似文献
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目的针对C919大型客机机身双曲度蒙皮进行纵向拉形的加载轨迹优化与试验研究。方法应用蒙皮拉形工艺设计制造软件,采用优化设计的方法,对机身典型蒙皮零件进行纵向拉形加载轨迹设计;进行拉形过程的有限元仿真,判断设计的加载轨迹是否满足成形要求,将优化后的加载轨迹应用于实际零件成形;进行实际零件拉形试验,对毛料伸长与局部应变进行测量,与有限元仿真进行对比,验证有限元仿真的准确性。结果实际零件的毛料伸长与轨迹设计和有限元模拟的伸长量十分接近;将优化设计后的加载轨迹应用于实际零件的成形,获得了满足零件交付要求的蒙皮零件。结论通过加载优化设计与试验,验证了有限元模拟有较好的精度;通过加载轨迹优化与有限元模拟结合的拉形工艺设计方法,可以用于零件的实际生产。 相似文献
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A series of experiments were performed by use of various forming paths during superplastic forming of an Al-Li based alloy. A fully recrystallized Al-Li-Cu-Mg-Zr alloy could be formed superplastically using paths of either a constant or a variable strain rate. The distribution of thickness along the formed sheet was confirmed by the results as being not much sensitive to the forming paths. The uniformity of the formed part affected the microstructural characteristics; the grain size was larger in regions at which the plastic deformation was larger, an effect was believed due to strain-induced grain growth. Static growth of grain showed little effect on an Al-Li based alloy during superplastic forming. The strain-induced grain growth influenced the distribution of grain size, resulting in cavitation occurring in the regions of large grain size. A two-step variable forming path could reduce cavitation in the formed part. 相似文献
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P. Ganesh 《Materials and Manufacturing Processes》2015,30(9):1080-1089
This study attempts to investigate the superplastic forming (SPF) of friction stir welded (FSW) AA6061-T6 alloy sheet at various tool rotation speeds in the range of 500 to 2000 rpm. The effect of FSW on SPF free blow forming of AA6061-T6, pole height, pole thickness, equivalent strain rate, and equivalent flow stress were investigated at constant pressure and constant temperature. Using the Cheng model the pole thickness, the equivalent strain rate, and equivalent flow stress were determined from superplastic free blow forming experiment. The finite element modeling and simulation is performed over the SPF of FSW specimens using selective superplasticity method. Experimental results indicate that tool rotation speed is the critical parameter during friction stir welding that has a greater influence on SPF. The theoretical modeling results exhibit that the SPF of friction stir welding can be practically applied to determine pole thickness, strain rate, flow stress, and strain rate sensitivity index. The finite element modeling results were found to be fairly agreeing with the experimental results. Hence, superplasticity can be significantly enhanced by friction stir welding by varying the FSW tool rotation speed. 相似文献
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Superplastic forming is a manufacturing process during which a sheet is blow formed into a die to produce lightweight and strong components. In this paper, the microstructural mechanism of grain growth during superplastic deformation is studied. A new model, which considers grain growth, is proposed and applied to conventional superplastic materials. The relationships among the strain, strain rate, test temperature, initial grain size, and grain growth in superplastic materials are discussed. According to the proposed model, theoretical predictions for superplastic forming processes are presented, and comparison with experimental data is given. The new constitutive equation of superplasticity is introduced into a finite element method program to study superplastic blow forming. The effects of the geometric shape parameters of the die on the superplastic blow forming process are investigated, and the inhomogeneity in the thickness distribution of the specimen is analyzed. 相似文献
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目的研究三维异形截面汽车纵梁充液成形过程的变形规律。方法通过数值模拟和试验研究相结合的方法,分析多工序中的充液成形过程,对影响构件成形性能的液压力加载路径关键参数进行分析。结果线性加载路径下试件最大减薄率为26.3%,试件出现了局部开裂现象。两段式线性加载条件下最大起皱指标为0.149,试件出现了起皱缺陷,最大壁厚减薄为23.2%,开裂现象并未明显缓解。分段式线性加载条件下试件的最大减薄率仅为16.8%,贴模偏移量为1.89 mm,未出现起皱叠料现象,成形质量较好,同时,试验结果与数值模拟结果有较好的一致性。结论液压力加载路径对试件壁厚分布影响较大,采用分段式线性加载,可以实现低压阶段的分段加压和有效补料,以及后期的线性高压整形,试件成形质量较高。 相似文献
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目的 利用数值模拟方法研究单点渐进成形工艺参数对制件成形区最小壁厚的影响规律,得出最优工艺参数组合,提高制件的成形质量。方法 在对2024铝合金正五边锥形件建立有模单点渐进成形数值仿真模型的基础上,对进给率、层间距、成形工具头直径和摩擦因数对制件成形区最小壁厚的影响进行单因素和正交试验分析,并通过物理试验对仿真优化后的工艺参数组合进行验证。结果 正五边锥形件单点渐进成形加工过程中,最小壁厚与进给率、层间距成反比,与成形工具头直径成正比,而摩擦因数对最小壁厚的影响较小;各工艺参数对最小壁厚的影响程度为进给率>层间距>成形工具头直径>摩擦因数;最佳工艺参数为成形头直径9 mm、进给率200 mm/min、加工层间距0.2 mm和摩擦因数0.1。结论 通过有限元仿真得出了单点渐进有模成形工艺对制件最小壁厚的影响规律,通过正交试验分析得出了正五边锥形件单点渐进有模成形最佳工艺参数组合,利用该参数组合可以得到壁厚较为均匀的正五边锥形件。 相似文献
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充液成形技术能有效解决复杂零件的成形问题.针对某飞机薄壁深腔蒙皮常规拉深成形需要多道次成形、成形质量差的问题,通过分析充液成形过程中易出现的失稳,设计了带部分阴模的一模两件充液成形的技术方案.结合数值模拟,对薄壁深腔件充液成形过程中出现的悬空区失稳形式进行了研究,优化了液室压力加载曲线、压边间隙、初始反胀压力等工艺参数.结果表明,薄壁深腔件在带部分阴模的一模两件的工艺方案下,能有效避免悬空区的起皱,同时改善了一模一件补充段的破裂问题,提高了零件成形极限和壁厚分布的均匀性. 相似文献