楔块锁模空心枝形件闭式挤压模具设计

因空心枝形件形状所致,其挤压成形无法采用上模插入下模的闭式锻模结构.本文论述了空心枝形件闭式挤压工艺,给出了空心枝形件闭式挤压新型模具结构和设计要点.该模具采用楔块锁紧上凹模与下凹模对合结构,锻件在两个凹模和两个凸模形成的封闭模腔中挤压成形,生产的锻件无飞边.     

锥面锁紧两半凹模双侧枝件闭式挤压模设计

因双侧枝件的形状所致,采用传统的整体凹模结构不能实现无飞边模锻,给出了双侧枝件闭式挤压模结构,该模具纵向对合凹模依靠锥面锁紧。锻件在两半凹模和凸模形成的封闭模腔中挤压成形,生产的锻件无飞边。     

射孔弹壳体冷挤压工艺分析及有限元模拟

针对射孔弹壳体挤压件进行了工艺分析。对比了一次性成形和预挤压-变薄拉深加顶镦两种工艺方案,并比较了整体式凹模和预应力组合凹模两种不同模具结构对成形的影响。采用有限元软件Deform2D对不同工艺方案和模具结构进行了模拟验证。结果表明,采用两次挤压成形工艺方案,同时选用预应力组合凹模结构,可显著提高挤压凹模的承载能力,使凹模内壁所受等效应力降低到安全范围内。     

万向节轴承套热挤压模具设计

介绍了万向节轴承套热挤压件图的设计和热挤压模的结构,对反挤压凹模和反挤压凸模的主要尺寸进行了计算。     

万向节轴承套热压模具设计

介绍了万向节轴承套热挤压件图的设计和热挤压模的结构,对反挤压凹模和反挤压凸模的主要尺寸进行了计算。     

套筒热挤压工艺与模具设计

给出了套筒零件实用的热挤压工艺和模具结构,论述了模具的工作过程及凹模与凸模设计。该模具通过更换凸、凹模,便可生产不同规格的反挤压杯形挤压件,提高了模具利用率,降低了生产成本。     

深孔变壁厚锥形件冷挤压工艺与模具设计

深孔变壁厚锥形件需要3次挤压成形,给出了该零件冷挤压工艺和实用的模具结构,论述了反挤压工序件与成品正挤压模腔的关系,以及凸模和凹模设计。该模具采用伸缩式双级卸料装置,实现较大行程的卸料。     

综合多因素的等温挤压成形模具型腔尺寸计算方法

为提高等温挤压成形件的尺寸精度和减少试模次数,利用弹性力学厚壁圆筒理论拉美(Lame)方程、塑性力学应力-应变本构方程,针对轴对称结构的整体凹模和二层组合凹模,建立了等温挤压成形过程中模具变形、热膨胀和材料回弹等各因素对成形件尺寸偏差影响的数学模型,确定了对等温挤压成形模具型腔尺寸修正的总偏差。对具体零件的等温挤压成形进行实验验证,采用所提出的模具型腔尺寸修正方法设计出的等温挤压成形凹模获得的成形件的尺寸相对偏差小于0.2%,为等温成形模具型腔尺寸的设计提供了参考和一种较为实用的修正方法。     

T形锻件挤压模设计

T形锻件因形状所致,其挤压成形无法采用传统的整体凹模结构。现给出了T形锻件无飞边挤压模具结构。该模具采用斜面自锁纵向对合凹模结构,侧面设有凹模顶出装置,锻件在两半凹模和凸模形成的封闭模腔中挤压成形,生产的锻件无飞边。     

汽车液压减振器外壳热挤压模设计

针对汽车减振器外壳结构特点,通过工艺分析提出通过正向挤压和侧向挤压复合工艺实现热挤压一次成形的新工艺的解决方案和设计路线,设计了减振器外壳热挤压模具。凸模头部采用平底锥形设计,可以降低单位挤压力;凹模采用挤压筒和挤压凹模的组合结构,可以解决凹模加工工艺性问题及便于零件的退卸料;并论述了模具的结构原理和工作原理。为确保模具符合热挤压实验的要求,对模具的关键部件进行了理论分析和计算,并通过实验方法成形出了表面光滑无缺陷、尺寸精度和力学性能均符合要求的筒形件,实验结果表明了该工艺方案和模具结构设计的可行性和实用性。     

等温反挤压中挤压件抱模的防治方法

分析了等温反挤压时产生抱模现象的原因 ,并从工艺和模具结构方面探讨了排除抱模的措施和防止抱模方法 ,对反挤压模的设计有一定的参考价值     

Extrusion of 7075 aluminium alloy through double-pocket dies to manufacture a complex profile

Low-temperature incipient melting and high deformation resistance of aluminium alloy AA7075 place extraordinary demands on extrusion die design and process optimization, especially when the shape of the extrudate is complex. The present case study was aimed at combining the considerations on die design and process optimization for the alloy to manufacture a complex solid profile with large differences in wall thickness, by means of 3D FEM simulation and experimentation instead of the traditional trial and error approach. The effects of die bearing length and extrusion speed on extrudate temperature and extrusion pressure were predicted. The results of the simulations clearly indicate that for AA7075 extrusion speed has a strong effect on extrudate temperature and the latter largely determines the surface quality of the extruded profile. A longer die bearing allows more heat to dissipate from the extrudate to the colder die and leads to a greater extrudate dimensional accuracy. The effects of die bearing length and extrusion speed on extrusion pressure are however insignificant. Thus, the extrusion throughput is mainly limited by the extrudate temperature rather than extrusion pressure. The case study demonstrates that 3D FEM simulation is a viable predictive tool for both die design and process optimization and the approach is applicable to the extrusion of other alloys for any other extrudate shapes.     

The effect of die shape on the hot extrudability and mechanical properties of 6061 Al/Al2O3 composites

Metal matrix composites (MMCs) fabricated by the compocasting process show a homogeneous distribution of the reinforcing fiber in the matrix. Microstructural observation of hot extruded MMCs reveals that as the extrusion ratio increases, the fiber alignment becomes improved, but fiber fracture occurs more severely.The mechanical properties of hot extruded MMCs are better than those of the matrix metal, with the exception of the elongation at failure, and are not influenced significantly by the extrusion temperature. The tensile strength and hardness of MMCs are improved to a greater degree by hot extrusion using a constant-strain-rate die. Also, there exists a critical extrusion ratio that gives maximum strength, which is 5.44 in this study. Additionally, fractograph of the tensile specimen of extruded MMC indicates the ductile fracture behavior of the matrix.     

挤压成形制备多孔氮化硅陶瓷

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.     

Examining the Effect of the Die Angle on Tool Load and Wear in the Extrusion Process

The tool durability is a crucial factor in each manufacturing process, and this also includes the extrusion process. Striving to achieve the higher product quality should be accompanied by a long-term tool life and production cost reduction. This article presents the comparative research of load and wear of die at various angles of working cone during the concurrent extrusion. The numerical calculations of a tool load during the concurrent extrusion were performed using the MSC MARC software using the finite element method (FEM). Archard model was used to determine and compare die wear. This model was implemented in the software using the FEM. The examined tool deformations and stress distribution were determined based on the performed analyses. The die wear depth at various working cone angles was determined. Properly shaped die has an effect on the extruded material properties, but also controls loads, elastic deformation, and the tool life.     

Extrusion of spray-formed Al–25Si–X composites and their evaluation

A comprehensive methodology to fabricate an Al–25Si–X composite via spray-forming and extrusion was investigated to judge the potential of this alloy for applications requiring high strength as well as high wear resistance and/or high elastic modulus. Billets were spray-formed with a low gas/metal ratio of about 0.8 m³/kg to reduce the consumption of nitrogen gas. The billets, having considerable porosity, were then extruded into sub-scale bars using various extrusion parameters, such as extrusion ratio, die temperature, and die configuration to optimize the extrusion conditions and eliminate the pores in the preform. Based on results obtained from the preliminary sub-scale extrusion tests, the spray-formed billets were then hot extruded into a tubular shape with outer and inner diameters of 97 mm × 77 mm, respectively, at an extrusion temperature of 500 °C. Various material properties of the extruded tubes were measured and compared with other candidate materials for these applications.     

硬铝主动轮冷挤压及精推挤成形工艺

对硬铝主动轮的冷挤压工艺进行分析,确定了冷挤压零件图和冷挤压方案及毛坯尺寸,对零件冷挤压的变形程度进行了校核,计算了挤压吨位,拟定了挤压前的毛坯处理规范,并对模具结构进行了介绍。     

双孔模型材挤压过程的有限元分析

本文采用大变形弹塑性有限元理论 ,对双孔模型材挤压成形过程进行了有限元分析。模拟了双孔模非对称角铝型材挤压变形过程 ,获得了挤压变形时网格畸变、流速、应力和应变分布 ,展示了型材挤压件变形不均匀细节。并与单孔模型材挤压过程进行了比较 ,发现双孔模[1] 挤压时 ,变形体内存在两个互为相反方向的涡流场 ,它们相互抵消 ,从而可以消除型材挤压过程中产生的扭拧、波浪、弯曲等缺陷。为提高挤压件质量 ,优化设计多孔型材挤压模以及制定合理的工艺 ,提供了理论依据