双向弯曲成形模的设计

分析了封闭板零件的结构及冲压工艺性。讨论了其双向弯曲(翻边)成形工序的成形模结构及工作原理,指出了该模具中关键零件的结构设计及该模具设计时的注意事项。     

钎头零件的超塑成形与超塑压接技术研究

采用超塑成形与超塑压接复合技术制出了复杂的钎头零件,使生产率提高41％,材料利用率提高34．8％,制件质量进一步提高。     

连续弯曲成形模设计

介绍了使用弹簧和斜楔功能将3道工序并在1副模具中将零件冲制成功,与传统的冲压工艺相比,降低了模具开发的成本,减少了机床及生产场地的占用率,提高了生产效率,同时也保证了零件质量。     

纳米陶瓷的热压烧结及超塑成形(英文)

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℃。     

Developing a superplastic forming application using aluminum tube

The outboard light housing on the Boeing 737 next generation aircraft was initially designed and manufactured as a cast aluminum part. Delays in delivery and other quality problems resulted in the part being redesigned as an aluminum superplastically formed (SPF) part. Advances in material use and tooling were necessary to successfully transition the part to the SPF form. The resulting part is lower in cost and lighter in weight than the original. This work summarizes the steps taken to implement the SPF outboard light housing. 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.     

超塑成形工艺对TC21合金超塑性的影响

分析对比了一步与两步超塑成形法对未经特殊细化的TC21钛合金超塑性和显微组织的影响。研究结果表明:在变形温度为870~930℃范围内,两步超塑成形伸长率明显好于一步超塑成形。在变形温度为870℃,第1步和第2步应变速率均为3.3×10-4s-1,预应变量为50%,间隙保温时间为20 min时,两步超塑成形的伸长率达到最大值为438.60%,和恒应变速率的一步超塑成形相比,伸长率提高了74.72%。真应力-应变曲线表明:两步超塑成形时,第2步开始时的应力明显小于第1步结束时的应力,第1步变形对金属产生了一定的软化作用。显微组织显示:动态再结晶一直伴随着整个两步超塑性变形过程,再结晶行为的发生为塑性变形提供了细小等轴组织,有利于该合金超塑性的提高。     

多点渐进成形工艺数值模拟及实验对比

针对成形大尺寸船板需要大设备的问题,以多点渐进成形方法为研究对象,该方法既有单点渐进成形的由局部变形累计成总体变形的特点,又有多点成形模具自由重构的特点。采用数值模拟法仿真了4种不同的成形工艺产生的成形效果,同时展开了相同工况的实验研究,将实验结果在三维扫描仪下进行测量,然后对比验证了数值模拟的仿真结果。研究结果表明:对于双曲率船板而言,两侧多点同步驱动的成形方案比一侧先调整好位置、另外一侧再依次驱动的方案要优越,成形路径对成形效果的影响不太明显,压头的驱动方式对成形力的历史变化影响显著。     

方锥形件成形模设计

介绍了一种方锥形件的成形工艺,模具利用零件本身的特点,没有采用导向装置,而是通过巧妙的设计,简化了模具结构,将切边、冲孔设计成复合模,通过2次切边、1次冲孔满足了产品质量要求。     

Superplasticity and superplastic forming of aluminum metal-matrix composites

Superplasticity hos been observed in many aluminum metal-matrix composites at extremely high strain rates (approximately 0.1–1 S^?1). These materials generally exhibited a strain-rate sensitivity value of about 0.3 and a maximum elongation of about 300%. It is believed thot the presence ofa liquid phose, or in some cases a low-melting-point region, at the reinforcement/matrix interfaces is responsible for the phenomenon. This phenomenon is not observed in all reinforced composites, despite the fact thot they contain fine grain sizes. Thus, a fine matrix grain size is a necessary but insufficient condition for the high-strain-rate superplasticity.     

尾翼超塑成形工艺方案优化

在文献「１」研究成果的基础上,通过对成形方案的分析优化和进一步试验研究,提出具有优质、高效、节能特点的铝合钓饵毛翼超塑成形工艺方案。     

The superplastic forming of bulk metallic glasses

Superplastic forming (SPF) is introduced in this article as a net-shape processing method for bulk metallic glasses (BMGs), commercially known as Liquidmetal® alloys. This method decouples fast cooling and forming of the BMG. Forming takes place in the supercooled liquid region, where the BMG exists as a highly viscous liquid and increases its fluidity with increasing temperature. The SPF method is very similar to techniques used for processing thermoplastics. In this work, a simple flow law is used to quantify the forming ability and to estimate both the potential and the limitations of the SPF method. This process is especially well suited to replicate small features and thin sections with high aspect ratios, which makes this process appropriate for microelectromechanical systems, nano- and microtechnology, jewelry, medical and optical applications, and data storage.     

超塑性材料的镦粗变形力的研究

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。     

铁路轴承保持架的超塑成形工艺参数优化及成形试验

文章对铸造状态的铝青铜进行了超塑性拉伸试验,并以试验结果为样本,借助Levenberg-Marquardt算法对样本进行学习,建立了铸态铝青铜超塑性拉伸条件与其超塑性性能的BP网络模型。基于所建模型,对铸态铝青铜的超塑性成形工艺参数进行了优化,得到最佳的超塑性成形工艺参数,并以此为依据,进行了铁路轴承保持架的超塑性挤压试验。结果表明,所建模型能够较好地反映材料超塑性拉伸条件与超塑性性能间的内在关系,网络模型的输出值和试验值间的误差较小,说明将人工神经网络用于铝青铜超塑性性能预测是可行和有效的。所预测的铝黄铜最佳超塑性条件能够满足保持架超塑成形的需要,且在最佳超塑性条件下成形保持架具有明显的经济效益。     

双层成形弯管模设计

针对一种连续短直线段水管的弯曲成形,设计了双层成形弯管模;弯管模开有成形型腔,型腔按照管子的弯曲轨迹,结合Pro/E三维造型进行设计,满足了管子夹紧、让位、换层的成形要求;同时设计了万向球头芯棒,保证了管子弯曲处成形饱满,更有利于管子夹紧;另外,配合设计了导模及防皱板,保证管子不起皱、拉裂.成形的管子走向稳定,外形饱满,无褶皱、夹伤等缺陷.     

U形固定夹成形模设计

对U形固定夹进行了工艺分析,详细介绍了各成形工序的模具结构特点、在试模过程中出现的问题、解决这些问题的方法和补救措施,充分考虑了模具结构的可调整性、易损件的更换和模具制造成本的控制。模具已投入生产达3年,经济效益好。     

电饭煲外壳成形模设计

对电饭煲外壳的成形工艺进行了分析,针对卷圆和翻边成形困难的特点,采用电饭煲外壳卷圆和翻边复合成形模进行生产,并详述其模具设计以及工艺要点,经过近千万次的使用表明:模具结构稳定可靠,对类似的成形模设计具有参考作用。     

Semi-analytical modelling with numerical and experimental validation of electromagnetic forming using a uniform pressure actuator

In this study, an electromagnetic forming process using a uniform pressure actuator is investigated through electro-magnetic-mechanically coupled numerical simulations; a simplified analytical model to predict the forming pressure and shell theory for mechanical deformation; and experimental results, which include Photon Doppler Velocimetry to measure the deformation. Velocity and the final deformed part shape are compared between the numerical, analytical, and experimental methods and reasonably good agreement is demonstrated. However, accurate comparison is affected by the energy level used with the numerical simulations matching better for the lower energy case due to less material draw-in and the analytical model providing more precise results for the higher energy case.     

纳米陶瓷超塑加工成形的研究进展

在对纳米陶瓷超塑性拉伸研究进行总结的基础上 ,综述了陶瓷超塑成形的研究进展情况。指出 :陶瓷材料由于其超塑特性 ,所以能够用各种现有的金属塑性成形方法来成形。最佳成形温度范围大约在 12 0 0℃～ 15 0 0℃之间 ,最佳晶粒平均直径为 10 0nm～ 2 0 0nm。