内齿轮冷挤压工艺参数分析及模具寿命预测

采用刚粘塑性有限元法对盲孔内齿轮冷挤压成形工艺参数进行了分析,并预测了模具寿命.运用金属塑性成形软件DEFORM-3D,以275减速轴为研究对象,成形载荷为评价指标,就影响成形工艺的模具设计参数、齿轮特征和工艺条件进行分组建模分析.结果表明:凹模芈锥角、模数、齿数对成形载荷影响较大;工艺条件中摩擦系数对载荷的影响最大;而挤压速度对载荷的影响则不显著.最后基于Archard模型预测了模具寿命.分析结果对实际生产具有重要的指导意义.     

汽车油底壳成形工艺数值模拟

采用Dynaform软件对某汽车油底壳的拉深成形过程进行了数值模拟.研究了压边力、凹模圆角半径以及有无拉延筋时对零件冲压成形的影响,通过FLD,厚薄图和成形结果对比,调整成形时压边力和凹模圆角半径,得到了优化的压边力和凹模圆角半径,为同类零件以及模具的设计提供参考.     

薄壁半球壳零件拉深成形的有限元模拟分析

通过改变凹模圆角半径、压边力等成形参数对0.5 mm厚铝合金板拉深成半球形零件的成形过程进行了仿真模拟,研究了不同成形参数下零件成形过程中的应力应变分布和零件成形后的壁厚分布,揭示成形参数对半球形零件成形质量的影响.为实际生产中提高半球形零件的成形质量和抑制成形过程中板料起皱与开裂提供了一定的参考.     

衔铁零件挤压凹模结构参数优化设计及模拟

针对衔铁零件的冷挤压模具--凹模的结构特点,采用正交试验方法,应用有限元分析软件DEFORM-3D对影响挤压力的凹模型腔结构参数进行优化设计,获得最优化的凹模结构参数,并在此基础上对优化后的结构进行数值模拟,得到挤压过程中凹模结构参数信息,为模具设计提供理论依据.     

汽车轮毂轴承套圈冷挤压数值模拟分析研究

对某型号汽车轮毂轴承内圈冷挤压模具进行三维建模,利用Deform软件,设定挤压条件后,对内圈挤压成形过程进行了数值模拟。分析了挤压过程中金属的流动与速度分布,挤压速度和摩擦因子对模具载荷的影响,并对凹模的应力进行了分析,指出应力集中导致模具容易损伤的部位。通过数值模拟分析,提出了减小摩擦因子,提高表面质量的方法,减小应力集中和载荷过大造成的模具损伤,通过优化工艺参数提高挤压成形质量。     

基于正交试验的梭床冷挤压过程数值模拟分析

基于Deform-3D对梭床的冷挤压成形过程进行数值模拟。通过正交试验的极差法和方差法,以最大成形载荷和凸模磨损量为目标变量,分析凸模材料硬度、挤压速度和润滑系数等关键参数的影响,从而获得最优工艺参数组合方案:凸模材料硬度为65HRC、润滑系数为0.1、挤压速度为30mm/s。利用最优工艺参数进行二次数值模拟,并对比了优化前后的最大成形载荷和凸模磨损量,以达到冷挤压最优效果,并通过折叠角和损伤因子分析得出满足此锻件的冷挤压成形要求,为实际的锻造生产过程提供理论指导。     

高强钢钢圈轮辐的拉深成形数值模拟

为达到减重与降耗的目的,汽车钢圈趋向采用高强度钢。其成形性能有所不同,冲压工艺参数有待重新研究。依据对轮辐结构的特点进行分析,拟定其冲压成形工艺。在建立轮辐三维模型的基础上,以Dynaform有限元分析软件为分析平台,对其关键的冲压工序:拉深、局部成形与翻边进行了数值模拟,并对影响轮辐冲压工艺的主要参数:凹模圆角半径、压边力、摩擦系数与冲压速度进行优化。模拟结果与实测结果的对比说明了有限元数值模拟的可行性和新工艺参数的合理性。     

基于Taguchi方法的镍涂层薄板冲压工艺参数研究

从厚度减薄和厚度分布角度出发,结合Taguchi实验设计方法,建立了镍涂层薄板的数值仿真模型,分析研究了凹模圆角半径、压边力、摩擦系数等工艺参数对镍涂层薄板冲压成形性能的影响,最终确定了各个工艺参数对成形质量(厚度变化)的影响及其相对影响程度。同时,通过对比仿真数据与实验结果,验证了该仿真模型的有效性。     

超大截面变化台阶轴复合成形与计算机数值模拟

分析一种应用在新能源汽车启动电动机上的超大截面变化的多台阶轴类零件的结构特点,以及其冷挤压成形工艺技术的技术难点,详细论述此类零件复合冷挤压成形的工艺流程、成形坯件和冷挤压模具的设计要点,设计出预制坯、预镦坯、以及冷挤压三道工序的冷挤压复合成形模具,并通过三维有限元数值模拟技术对其复合冷挤压成形工艺进行模拟和分析,针对性地对预制坯以及冷挤压的凹模入模角、过渡圆角、工作带等模具结构和尺寸参数进行优化与改进,并进行深入的试验研究,成形加工出的零件完全满足后续机械加工对其结构和尺寸的要求,解决了此类零件成形制坯困难的问题,达到大幅度降低生产加工的成本和节能环保的目的,为下一步大批量产业化生产打下良好的基础。     

半球底直筒形拉深件成形极限实验研究

以半球底直筒形拉深件为研究对象,用实验的方法,从压边力、摩擦系数、凹模圆角半径等几个方面对半球底直筒形件进行成形研究,得到了各工艺参数对其成形极限的影响.即压边力、摩擦系数在一定范围内的增大,半球底直筒形拉深件的胀形区域减小,成形极限有降低的趋势.     

熔融挤压快速成形支撑参数的研究

针对快速成形产品悬空部分的支撑问题,归纳出常见零件的5种悬空特征,分别为倾斜形、弧顶形、平顶形、开放式悬臂形、封闭式悬臂形。采种熔融挤压MEM(MeltedExtrusionModeling)工艺进行加工实验,得到这5种悬空特征无需添加支撑即可成形的极限悬空参数,分别为倾斜角60°、弧顶半径4mm、平顶长度8mm、开放式悬臂长度3mm、封闭式悬臂长度5mm。零件悬空部分的无支撑成形是利用成形材料自身的强度和刚性来支持丝料的悬空连续轨迹,保证后续成形。成形环境温度对悬空部分的成形质量影响较大。     

无支撑熔融挤压快速成形的参数研究

针对快速成形产品悬空部分的支撑问题,归纳出常见零件的5种悬空特征,分别为倾斜形、弧顶形、平顶形、开放式悬臂形、封闭式悬臂形。采种熔融挤压工艺进行加工试验,得到这5种悬空特征无需添加支撑即可成形的极限悬空参数,分别为倾斜角60°、弧顶半径4 mm、平顶长度8 mm、开放式悬臂长度3 mm、封闭式悬臂长度5 mm。成形环境温度对悬空部分的成形质量影响较大。     

The effect of selected parameters on temperature distribution in axisymmetric extrusion process

A numerical method was developed to simulate the transient temperature distributions during forward extrusion process. The computer program simulates the extrusion process and takes into account some extrusion variables such as extrusion velocity, extrusion ratio, die preheat temperature, and percentage reduction in area. It can be seen that the higher the percentages reduction in areas, the higher the temperature rises during the extrusion process. Also, increasing speed of deformation shows an increasing dead zone temperature rise than a more gradual die land temperature rise. It is further seen that extrusion temperature increase is a function of the container temperature.     

正交试验法的热挤压模具热处理工艺参数的改进

针对3Cr2W8V钢热挤压模具产生断裂失效致使寿命偏低的问题,分析模具制造工艺流程,找出发生断裂失效的原因,并用正交试验法确定新的热处理工艺参数,使模具寿命成倍提高,满足设计要求.     

Influence of processing parameters on wear resistance of nanostructured OFHC copper manufactured by large strain extrusion machining

The tribological behaviour of three ultra-fine grained oxygen-free high conductivity (OFHC) copper materials manufactured by large strain extrusion machining (LSEM), under variable shear strain, is studied under ball-on-flat reciprocating configuration and compared with that of conventional microstructured copper. The results are discussed as a function of microstructure and sliding direction. The lowest wear volume is obtained when the sliding takes place in the perpendicular direction to that of grain orientation. The highest wear resistance is observed for nanostructured copper material with an elongated grain structure in the extrusion direction. The wear resistance of this anisotropic material depends on the sliding direction. Wear mechanisms are discussed from scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) observations.     

Effects of extrusion variables on temperature distribution in axisymmetric extrusion process

A numerical method was developed to simulate the non-steady-state temperature distributions during forward extrusion process. The velocity, strain rates, and strain fields within the deformation zones during extrusion were obtained, using upper bound method of analysis to obtain internal heat generations coupled to the necessary heat transfer conduction equations. The computer program written in C++ language essentially simulates the extrusion process and takes into account extrusion variables such as material properties, friction conditions, extrusion velocity, extrusion ratio, die preheat temperature, billet height, percentage reduction in area, and die land length. The effects of billet height and percentage reduction in area on the temperature distributions within the dead metal zone give good agreements with experimental results. It is found that the higher the billet's heights and higher the percentages reduction in areas, the higher the temperature rises during the extrusion process. The die land zone shows increasing temperature rise with increasing friction coefficient, while increasing friction coefficient has no effect on the dead zone temperature. Also, increasing speed of deformation shows an increasing dead zone temperature rise than a more gradual die land temperature rise. It can be stated that the extrusion temperature increases proportionally to the increase of the container temperature.     

Rate-dependent transient extrusion

Plane strain slip line field solutions are developed for deformation at the edge of a cylindrical billet when this is backward extruded to form a thin-walled cup. The extrusion pressure for a perfectly plastic material is then derived assuming homogeneous compression in the centre of the billet. A geometric factor, derived from the slip line field, is identified which permits the extrusion pressure to be determined for a nonlinear viscous material.Theoretical results agree well with recent experimental data on back extrusion of highly rate-sensitive superplastic alloys. It is shown that an apparent steady state exists in the process and that extrusion pressure increases with ram speed with a rate index approximately equal to that of the material. The punch profile shape has a greater effect on extrusion pressure for viscous materials than for perfectly plastic ones. The method of analysis appears to have a generality beyond the particular process considered and may be used to optimize extrusion equipment designs.     

Ram extrusion of reactive plastics

A system is proposed for the processing of highly filled thermosetting material. That system permits orientation of the fibrous filler over the length and cross section of the part. A wood-based thermosetting composite for the production of high-strength shaped components is also considered.     

Factors influencing paste extrusion pressure and liquid content of extrudate in freeze-form extrusion fabrication

Freeze-form extrusion fabrication process extrudes an aqueous ceramic paste of high solids loading by ram extruder to fabricate 3-D ceramic green parts. An appropriate extrusion pressure is necessary to get the desired extrusion velocity, and the extrudate should be keep in the same composition during the extrusion process for fabricating uniform green parts. The ram velocity, die land geometry, and paste property are three main factors influencing paste extrusion process. In this paper, the experiments were carried out to determine the effect of the three factors on the extrusion pressure and liquid content of extrudate. The experimental results show that the ram velocity is a strong factor governing the extrusion pressure profiles and too low ram velocity can result in liquid phase migration. The die land diameter and paste viscosity have obvious impact on paste extrusion process, which is largely consistent to the Benbow–Bridgwater model but sometimes is influenced by liquid phase migration. A further analysis of paste extrusion process indicates that the varying of paste structure in different extrusion stage leads to the experimental phenomenon. The research can help to get better understanding of influence factors in paste extrusion and to give reference of controlling the process in freeze-form extrusion fabrication process.