传动轴凸缘叉精密成形研究

建立了传动轴凸缘叉热成形工艺的刚粘塑性有限元模型，采用三维有限元法对凸缘叉成形工艺进行了模拟分析，针对原有工艺出现的问题进行了改进及优化。基于模拟分析的结果，设计出结构合理、寿命较长的预成形及终成形模具，生产出的锻件尺寸精度和力学性能都有较大的提高。     

Effect of extrusion wheel angular velocity on continuous extrusion forming process of copper concave bus bar

The continuous extrusion forming process for producing large section copper concave bus bar under different extrusion wheel angular velocities was studied by three-dimensional finite element technology based on software DEFORM-3D. The rigid-viscoplastic constitutive equation was employed in the model. The numerical simulation results show that the deformation body flow velocity in the die orifice increases gradually with the increase of the extrusion wheel angular velocity. But slippage between the rod and extrusion wheel occurs when the extrusion wheel angular velocity is high. The effective stress near the die orifice enhances gradually with increasing extrusion wheel angular velocity. High stress is concentrated in adjacent regions of the flash gap. The effective strain gradient is greater near the abutment than that near the die orifice. The effective strain of the product increases gradually with increasing extrusion wheel angular velocity. In the deformation process, the deformation body temperature increases remarkably due to friction and deformation. So the cooling is necessary in the region of the die and tools.     

液压锁缸体挤压过程的数值模拟

利用Deform软件，对液压锁缸体的成形过程进行模拟，研究变形过程中的金属流动速度场与应力应变情况，分析了挤压过程的压力行程曲线，为工艺改进和优化模具设计提供理论依据。总结出液压锁缸体挤压变形过程规律，并与相关工艺试验结果进行了对比。     

双金属固相结合的有限元分析

双金属是由两种不同性能的金属结合而成的，经过恰当组合的两种金属结合以后，可以获得高强度、耐腐蚀以及导电、导热等综合性能，使材料在某些特殊的环境下发挥良好的作用。固相结合法是制造双金属的有效方法。本文基于刚粘塑性有限元理论，在两组元金属相互接触的表面之间引入摩擦单元，对Ｃｕ／Ａｌ双金属挤压固相结合的非稳态过程进行了有限元分析，得到了两组元金属之间的相对滑动量以及成形过程中的载荷－行程曲线，计算结果与试验结果比较接近。同时获得了变形体内的应力、应变分布，揭示了组元金属在成形过程中的流动规律。     

内转子的冷挤压成形工艺及模具设计

介绍了内转子零件的冷挤压成形工艺及其模具设计。     

Rapidly solidified hypereutectic Al-Si alloys prepared by powder hot extrusion

Rapidly solidified hypereutectic Al-Si alloys were prepared by powder hot extrusion.By eliminating vacuum degassing procedure.the fabrication routine was simplified.The tensile fracture mechanisms at room temperature and elevated temperature were investigated by SEM fractography.Compared with KS282 casting material,the tensile strength of rapidly solidified Al-Si alloy is greatly improved due to silicon particles refining while its density and coefficient of thermal expansion are lower.than those of KS282.The wear resistance of RS AlSi is better than that of KS282.     

TiAl ALLOYS PREPARED BY THERMAL EXTRUSION OF ELEMENTAL POWDER MIXTURES

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Zr基非晶合金在过冷液相区静液挤压的变形行为及结构

研究了Zr41.2Ti13.8Cu12.5Ni10Be22.5非晶合金在过冷液相区内静液挤压的变形行为以及结构变化。结果表明:非晶合金在高应变速率下产生了明显的塑性变形,直径从16 mm变为12 mm,断裂为4段,且样品断口上随机分布着充分发展与未充分发展的脉纹式切变带,由此可看出非晶合金的变形为非牛顿体变形行为;挤压后的样品约有3%的非晶相发生晶化,在非晶基体上析出10~20 nm的纳米晶粒,导致挤压后非晶合金的热稳定性降低;静液挤压高应变速率变形条件使非晶合金产生非均匀流变,是造成非晶合金断裂的主要原因。     

Hole flanging with cold extrusion on sheet metals by FE simulation

Flange height and lip thickness are generally restricted by the formability of sheet metals in the conventional hole flanging operation. In the current work, cold extrusion was applied and a special forming die set was designed with a stripper subjected to counter-pressure with an aim to obtain a more substantial flange. FEM software DEFORM was utilized to simulate this flange extrusion process with two forming conditions: forming with a fixed die cavity and forming with the stripper subjected to counter-pressure. The results showed the cup preform tended to buckle on its bottom with insufficient counter-pressure. The cup preform would start extruding a flange when critical counter-pressure was reached. The magnitude of the critical counter-pressure increased in flange extrusion of smaller inner diameters. The corresponding overall forming load was greatly reduced as compared to flange extrusion with a fixed die cavity.     

圆柱直齿轮超塑挤压的试验研究

对圆柱直齿轮的超塑性挤压进行了试验研究，其中挤压方式为径向挤压，试验材料为铅锡合金。试验中为降低成形力，采用了孔分流法。试验结果表明，用超塑挤压的方法加工圆柱直齿轮是可行的。孔分流方法在降低成形载荷与改善充填性方面具有优点，对生产实践具有指导意义。