变径波形套复合模设计

提出利用复合缩径－胀形工艺制造变径波形套,设计了成形模具;介绍了波形套复合模的结构和工作过程,分析了波形套成形特点,计算了工艺力。     

焊接钢管管坯成型过程中鼓包的预防

简要分析了带钢在成型为待焊开口管坯的变形过程中，其边缘鼓包的形成机理。阐述了绝大部分鼓包都是材料、孔型、轧制线、设备、操作等因素综合作用引起的，提出了预防鼓包的措施     

Time distance diagram of the jet initation of covered high explosive charges

The bulging behaviour of a steel barrier in front and in contact with a high explosive charge desensitises the charge sensitivity for a shaped charge jet impact. The reasons are rampwave behaviour and pre-compression of the charge, which is explained in detail with a time distance diagram.     

Failure of Heat-Exchanger Tubes due to Localized Scaling and Microstructural Transformation

Failure of tubes in a bayonet-type high-pressure heat exchanger was caused by water interruption. The failures were accompanied by excessive plastic deformation, and cracks were found in the thick inner scale on the failed tubes. In the fractured regions, the tube inner surfaces and microstructures showed excessively thick scales and carbide networks, while the locations opposite fractures were scale free. These observations suggest the occurrence of localized heating that subsequently caused bulging and failures. Further inspection of the tube bundles also showed augmented scale thickness in sound tubes. It was recommended that the entire tube bundle be replaced.     

周边夹持大应变金属薄膜变形特性有限元分析

受侧向载荷作用的金属薄膜可作为一种功能元件用于防止装置超压或实现某些特定的工艺操作，在许多行业被大量使用。几何和材料非线性的特点使得解析计算非常困难，目前其设计和制造主要依赖于实验。文中采用MITC4(mixed interpolation of tensorial components)壳元基于T.L．(Totoal Iagrange)列式，对普通和开有透缝的二种结构形式的金属薄膜进行有限应变弹塑性有限元分析。通过与实验结果的比较，得出如下的结论，①普通膜的高应力应变区位于极顶附近约1／3口径的区域，应力梯度自周边向内不断减弱。②极顶挠曲高度随加载呈弱“S”形的规律变化。③随加载，横向塑性应变的变化过程可以划分为缓慢增加段、过渡段和快速增加段3个阶段，阶段的2个分界点为pa/so≈530MPa和880MPa。④透缝膜高应力应变区位于内圈终止小孔孔桥间的边缘局部区域。⑤存在一个重要的数群pa/(s0b)，不同d时最大等效应力相对于该数群具有十分相近的变化规律。     

半球形胀形过程的刚塑性有限元分析

以刚塑性材料模型和三维薄膜单元为基础，分析了半球形冲头的胀形过程，对变形区的变形流动特点及材料参数等因素对变形的影响进行了研究。用网格法测量了半球形冲头胀形时的应力分布，并将有限元计算结果与实验结果进行了对比，验证了有限元分析结果的可靠性。     

球阀阀芯一种新的聚氨酯胀形制造工艺的研究

在分析了球阀阀芯采用铸造工艺方法制造存在铸造缺陷多、产品合格率低、生产率低，材料消耗量大利用率低，对环境的污染大等不足的基础上，论述了球阀阀芯新的聚氨酯成形工艺。并对这两种新旧工艺方案在工艺特点、原材料消耗及成本核算三方面进行了对比分析，进一步对该新工艺方案最关键的胀形工序、模具结构进行了论述。应用结果表明，该工艺方案值得在工业实际中推广应用。     

汽车桥壳液压胀形极限成形系数及胀裂判据

利用研制的集增压器、冲液器、滑动胀形模具于一体的超高压液压胀形装置,在普通液压机上进行汽车桥壳样件的液压胀形胀裂试验,绘制出液体胀形压力与管坯压缩量不同的匹配关系时(即不同加载路径)的胀形极限图,揭示出极限胀形系数与管坯轴向应变存在线性关系kr=1 δ5-1.72εz,并与材料断后伸长率δ5有关.给出管坯胀裂时的应变判据|εn|=δ5及应力判据δθ=2σb,即胀裂时管坯壁厚方向的应变等于材料的延伸率,环向应力等于材料拉伸强度的2倍.研究成果能为理论研究及工程应用提供依据.     

方花键轴开模冷挤压的模具设计及工艺实验研究

针对１２５ｃｃ摩托车变速箱的方花键主轴,讨论了花键开模挤压的模具结构特点和影响花键成形的模具回弹问题,提出在开模挤压的可成形性范围内选择入模角,可以避免挤压时出现的入模口局部镦粗现象的发生。     

Control of Meniscus-Level Fluctuation by Optimization of Spray Cooling in an Industrial Thin Slab Casting Machine Using a Genetic Algorithm

Meniscus-level fluctuation is a common problem during thin slab casting and can lead to breakout. Because meniscus-level fluctuation increases with increase in casting speed, it restricts high-speed casting. It is now known that the meniscus-level fluctuation is caused by fluctuation in bulging and decreasing the total bulging can control it. Increasing the spray cooling reduces the total bulging and hence the meniscus-level fluctuation. However, the increase in spray cooling poses other problems. The midwide surface temperature at the slab exit may fall excessively, requiring significant reheating and thus fuel consumption in the reheating furnace. Also, the temperature at the unbending point may fall below a critical value causing crack formation. Thus, an optimization procedure was adopted to find the optimum combination of spray cooling, which will minimize the total bulging, keeping the midwide surface temperature at the slab exit more than a minimum and user-specified value. To do so, a genetic algorithm was used in conjunction with a model for estimation of temperature at different locations of strand and total bulging in the strand (thermal-bulge model). Based on the results of optimization, the casting speed in a plant could be enhanced by more than 30%.