共查询到18条相似文献,搜索用时 46 毫秒
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氮化硅陶瓷超塑性研究 总被引:1,自引:0,他引:1
以非晶氮化硅纳米陶瓷粉体为起始材料,以纳米氧化钇和氧化铝为添加剂液相烧结获得超塑性陶瓷块体材料,实现氮化硅陶瓷的超塑性拉伸和超塑性成形。氮化硅陶瓷的平均晶粒直径为280nm,在1550℃的较低温度,4.7×10-4/s的相对较高应变速率下,延伸率可达到110%,在成形速率0.2mm/min的条件下,可拉深成形出完好的球形和锥形零件。在室温断口上存在大量的细小的白色氮化硅晶粒;而高温断口上却几乎不存在这样的晶粒,这种不同可以用氮化硅陶瓷材料的超塑性变形机理来解释,也可以证明超塑性变形过程中晶界玻璃相的存在。 相似文献
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多次拉深成形有限元建模关键技术研究 总被引:5,自引:0,他引:5
研究了多次拉深成形有限元建模中的几何建模、网格划分、材料和边界条件处理等关键技术。本文所阐述的技术对于多次拉深这一比较复杂的板料盛开有工艺的数值模拟研究有较大的参考价值。 相似文献
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针对飞机翼尖航行灯深腔整流蒙皮壁薄、尺寸大、拉深过程起皱的问题,以有限元模拟为指导结合模具结构优化展开拉深成形技术研究。在展开毛坯合理、摩擦系数设置较大的情况下,压边间隙控制在1.35~1.45 mm时零件最大减薄率可以控制在10%左右,此时其余拉深成形工艺参数在一定范围内波动对零件成形影响小,可生产高质量合格零件。尖端起皱区抬高不仅可缓解起皱,而且可将严重起皱区转移到工艺补偿区域,通过优化毛坯形状改善压边阻力分布可以达到消除起皱效果。经过对比,工艺方案模拟防起皱与实际拉深防起皱结果吻合,通过模具结构优化与数值模拟技术相结合,可以预测并避免板料成形过程中出现的起皱、开裂现象。 相似文献
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以甲基纤维素作粘结剂配制氮化硅泥料,利用柱塞式挤压模具通过挤压成形法制备多孔氮化硅陶瓷.研究了挤压、干燥、排胶、烧结等各个工艺阶段坯体的开气孔率、体积密度、弯曲强度、显微结构及相转变等的变化规律.结果表明:挤压成形是制备多孔氮化硅陶瓷的一种有效而实用的方法.最后利用蜂窝陶瓷模具,首次成功挤出具有广泛应用前景的氮化硅蜂窝陶瓷.在未来的汽车尾气处理领域,有望取代当前广泛使用的堇青石材质蜂窝陶瓷. 相似文献
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壁厚分布对薄壁构件的结构性能有重要影响。本文研究超塑成形件壁厚分布的预测技术,实现了超塑成形过程的有限元数值模拟的成形件厚度分布曲线的自动预测,以半球壳和矩形盒成形为例,为自由胀形和约束胀表两种情形形件厚度变化进行了分析,预测结果与实验数据吻合。 相似文献
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纳米陶瓷的热压烧结及超塑成形(英文) 总被引:2,自引:0,他引:2
纳米陶瓷具有优良的室温和高温力学性能 ,如较高的抗弯强度、断裂韧性、耐磨性等 ,使其在切削刀具、轴承、高温发动机部件等诸多方面都有广泛的应用。利用纳米陶瓷的超塑性进行成形加工是实现复杂形状零件近净成形的重要手段。本文采用化学沉淀法制备了平均粒径 10nm ,且无硬团聚的 3Y TZP (3%摩尔氧化钇稳定的四方相氧化锆多晶体 )粉体 ,研究了不同密度素坯的热压烧结行为。 3Y TZP毛坯的超塑性拉深试验表明在 14 5 0℃压头速率为 0 2mm·min-1时可以实现半球形件的成形 ,其成形高度达到 5 7mm ;Al2 O3 ZrO2 纳米复相陶瓷的正挤压试验表明 ,这种典型的晶间 /晶内型纳米陶瓷在很高的温度下可以 0 . 5mm·min-1的压头速率进行挤压成形 ,在某种程度上可以满足工业成形的需求 ;Si3 N4 Si2 N2 O复合陶瓷通过烧结锻造可以成形陶瓷齿轮 ,其烧结温度为 16 0 0℃ ,超塑性锻造温度为 15 5 0℃。 相似文献
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Overview of superplastic forming research at ford motor company 总被引:1,自引:0,他引:1
Friedman P. A. Luckey S. G. Copple W. B. Allor R. Miller C. E. Young C. 《Journal of Materials Engineering and Performance》2004,13(6):670-677
In an effort to reduce vehicle weight, the automotive industry has switched to aluminum sheet for many closure panels. Although
the application of aluminum is compatible with existing manufacturing processes and has attractive qualities such as low density,
good mechanical properties, and high corrosion resistance, it has less room-temperature formability than steel. The expanded
forming limits that are possible with superplastic forming can significantly improve the ability to manufacture complex shapes
from materials with limited formability. Aluminum closure panels produced by superplastic forming have been used by Ford Motor
Company for over a decade. However, applications have been limited to low-volume, specialty vehicles due to the relatively
slow cycle time and the cost penalty associated with the specially processed sheet alloys. While there has been substantial
research on the superplastic characteristics of aluminum alloys, the bulk of this work has focused on the development of aerospace
alloys, which are often too costly and perhaps inappropriate for automotive applications. Additionally, there has been a limited
amount of work done to develop the technologies required to support the higher production volumes of the automotive industry.
This work presents an automotive perspective on superplastic forming and an overview of the research being performed at Ford
Motor Company to increase the production volume so superplastic forming can be cost competitive with more traditional forming
technologies.
This paper was presented at the International Symposium on Superplasticity and Superplastic Forming, sponsored by the Manufacturing
Critical Sector at the ASM International AeroMat 2004 Conference and Exposition, June 8–9, 2004, in Seattle, WA. The symposium
was organized by Daniel G. Sanders, The Boeing Company. 相似文献
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超塑性材料的镦粗变形力的研究 总被引:1,自引:3,他引:1
通过采用主应力法导出考虑纵向变形速度和横向加速度的镦粗变形力的计算公式,并用算例讨论了超塑性材料变形力的计算方法、变形力随时间的变化规律,以及纵向变形速度和横向加速度对变形力的影响大小。由于主应力方法适合于a/h不太小的情况,因此导出的公式也应该满足这一条件。变形力可以分成qj,qy,qd3项,其中qd在ρV2/k极小于1时,可以忽略不计;但是当ρV2/k接近于1时就不可忽略。接触面的分布压力的最大和最小值的位置和一般率无关的塑性材料镦粗时的位置一样,分别在x=0和x=±a/2处。 相似文献
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A review of the numerical analysis of superplastic forming 总被引:1,自引:0,他引:1
This paper reviews the literature on the numerical simulation of superplastic forming (SPF). After introducing the phenomena of superplasticity and superplastic constitutive equations, non finite element analyses are reviewed. The finite element method of solution to SPF simulation is then examined within the context of the standard flow formulation. However non steady state SPF is not ideally suited to a standard flow formulation and an alternative, incremental flow formulation is discussed. 相似文献
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大块非晶合金超塑性变形的研究现状与发展 总被引:1,自引:0,他引:1
文章对国内外非晶合金超塑性基本性能的研究工作进行了介绍和评述。根据材料成形工艺的要求,提出了非晶合金超塑性成形研究的内容。介绍了非晶合金超塑性拉伸实验和压缩实验的研究进展,分析了温度和成形速率对变形的影响,介绍了粘度的影响因素,对这些研究内容和热点问题进行了评述。展望了非晶合金超塑性研究的发展趋势,提出应加强非晶合金超塑性流动过程的理论研究。 相似文献
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Reinforced ceramic dies for superplastic forming operations 总被引:2,自引:0,他引:2
Daniel G. Sanders 《Journal of Materials Engineering and Performance》2004,13(6):753-757
Ceramic dies have been developed to meet the need for a dimensionally stable tool, which can withstand the temperatures (425
to 950 °C) and high forming pressures (up to 7 MPa) that are required for superplastic forming (SPF), superplastic forming
with diffusion bonding (SPF/DB), and hot sizing of metal parts. With the improvements that have been made to strengthen fused
silica based ceramics, the performance of ceramic tools is slowly closing in on meeting the same forming complexity as corrosion-resistant
steel (CRES) dies can achieve. Boeing has successfully superplastically formed jet engine wide chord fan blades using ceramic
dies, and many production aircraft parts are being built with Boeing’s patented ceramic die technology.
This paper was presented at the International Symposium on Superplasticity and Superplastic Forming, sponsored by the Manufacturing
Critical Sector at the ASM International AeroMat 2004 Conference and Exposition, June 8–9, 2004, in Seattle WA. The symposium
was organized by Daniel G. Sanders, The Boeing Company. 相似文献