薄壁空心铝型材挤压过程数值模拟及模具优化

挤压模具在铝型材挤压生产中起到至关重要的作用,直接影响挤压产品的质量.然而在实际生产中,挤压模具的设计更多依赖设计师的经验,模具设计质量难以保证,需要多次试模和修模.采用基于ALE算法的HyperXtrude软件针对某一复杂薄壁空心型材的挤压过程进行数值模拟,分析模具型腔内材料的流动规律及成形机理;根据初始模具设计的不足,提出在下模开设二级焊合室和增设阻流坎两种优化设计方案,有效地解决了初始模具设计中速度分布不均的问题.在优化方案中,型材截面上的温度分布和应力分布更加均匀,焊缝质量相比初始模具设计有较大改善.利用数值方法可对模具结构进行优化,提出的开设二级焊合室和增设阻流坎的模具设计结构可为同类铝型材挤压模具设计提供指导.     

铝型材挤压模具的3D优化设计

详细分析了铝型材挤压模具设计的特点和铝型材挤压分流模具和平模的结构特征,根据铝型材挤压模具的制造加工工艺技术和铝型才挤压模具设计步骤,用Ｃ语言编写了铝型材挤压模具参数设计的程序,以流程图的形式详细引导铝型材挤模具的设计过程;以人机对话的形式实现铝型材挤压模具参数的优化设计。     

空心铝型材分流模挤压的复合数值模拟

针对有限元模拟空心铝型材分流模挤压成形中的困难与局限性,通过有限体积法和有限元复合数值模拟法,对典型大挤压比空心型材的分流模挤压过程进行了模拟,详细研究了型材挤压成形过程中金属的流动规律及焊合过程,为分流模设计、优化提供了依据。采用数值模拟优化的结果进行了实验研究,成功地挤出了合格的空心铝型材。     

基于DEFORM的热锻挤压模具结构优化

对空心工业铝材进行热锻挤压模具设计和3D造型,基于DEFORM软件对挤压过程进行数值模拟。模具设计时优化分流孔入口形状并提出金属流速判据。通过分析模拟结果,采用调整模具工作带长度的方法,改善挤压模出口流速的均匀性,保证了型材质量,有效减少模具开发周期和成本,达到试模、修模的快速响应。     

重型车半轴套管镦挤过程中凸模磨损问题的分析

对重型车半轴套管镦挤成形过程中凸模磨损进行了研究。利用DEFORM-3D软件对重型车半轴套管镦挤成形过程进行了数值模拟,分析了不同模具初始硬度和坯料的预热温度对凸模磨损深度的影响。得到了不同硬度与预热温度对模具磨损情况的影响规律。不仅优化了工艺参数,也使锻件缺陷不同程度地减小,为半轴套管的模具设计以及挤压生产提供了指导。     

基于磨损正交试验的温挤压模具优化设计

以汽车转向螺杆的杯-杆件温热挤压凹模为例,通过对温挤压成形工序的分析,得到影响温挤压凹模磨损寿命的4个主要因素,即凹模入口处圆角大小、模具初始硬度、模具初始温度、摩擦因子。设计四因素四水平标准正交实验表,通过Deform-3D数值模拟软件,基于Archard磨损理论进行温挤压凹模型腔磨损正交试验。以凹模磨损量最小为目标获得凹模模具的最优四因素组合,并得出在温挤压内孔工序中模具初始硬度对凹模磨损影响最大,对实际生产中模具材料的选择和热处理有一定指导作用。在最优参数组合下,通过数值模拟计算得到凹模在温挤内孔中稳定阶段的磨损量,并预测出模具的使用寿命。     

基于正交试验的温挤压模具磨损优化设计

以汽车转向螺杆的杯-杆件温热挤压凹模为例,通过对温挤压成形工序的分析,得到影响温挤压凹模磨损寿命的4个主要因素,即凹模入口处圆角大小、模具初始硬度、模具初始温度、摩擦因子。设计四因素四水平标准正交实验表,通过Deform 3D数值模拟软件,基于Archard磨损理论进行温挤压凹模型腔磨损正交试验。以凹模磨损量最小为目标获得凹模模具的最优四因素组合,并得出在温挤压内孔工序中模具初始硬度对凹模磨损影响最大,对实际生产中模具材料的选择和热处理有一定指导作用。在最优参数组合下,通过数值模拟计算得到凹模在温挤内孔中稳定阶段的磨损量,并预测出模具的使用寿命。     

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.     

铝合金轴固定件热挤压成形的有限体积法模拟研究

由于变形剧烈，复杂铝型材挤压成形有限元模拟会因网格不断重划分而精度欠佳。文中基于可以有效避免网格重划分难题的有限体积法，对铝合金门轴固定产品的热挤压过程进行数值模拟，详细分析挤压成形中各个阶段金属流动情况以及应力、应变、温度、速度等场量的分布变化情况。棒料进人模口至完全流出工作带这段时间是型材挤压最为困难的阶段，材料在工作带处的应力、应变最大，温度最高，因而对模具工作带处造成的磨损也最为严重。进人到最终稳定挤压阶段时挤压方向金属流速计算值与理论挤出速度吻合很好。模拟结果表明所用有限体积法是有效的，可以为铝型材挤压的模具设计与工艺参数的选择提供理论指导。     

型材挤压过程工艺参数优化模型

提出了一种集数值仿真、人工神经网络和遗传算法为一体的工艺参数优化模型,用于型材挤压成形过程工艺参数优化,合理配置了非对称角铝型材模模孔位置。通过现场试验,验证了提出的工艺参数优化模型是行之有效和正确的。并在模孔位置优化配置结果基础上对其挤压成形过程进行数值仿真,分析了挤压成形过程中各阶段网格畸变情况,给出了挤压变形时应力和应变分布,对指导型材挤压工艺和模具优化设计具有重要意义。     

Die optimization design and experimental study of a large wallboard aluminum alloy profile used for high-speed train

The extrusion die plays a crucial role in the quality control of aluminum alloy profile production. But in practice, the design of extrusion die is mainly dependent on the experience and intuition of die designers; thus, many times of modifications and experiments should be undergone until an acceptable product is gained. In this paper, the extrusion process of a large wallboard aluminum alloy profile used for high-speed train was simulated by means of HyperXtrude software, and the flow behavior of material and deformation mechanism in the die cavity were investigated. With the simulation results of the initial die design scheme, a nonuniform velocity distribution in cross-section of the extrudate was observed. For optimizing the die design scheme, two optimal schemes (adoption of double-step welding chamber and introduction of baffle plate) were proposed. Through optimization, the velocity differences in the extrudate for optimal schemes are decreased from 39.9 to 12.2 and 10.8 mm/s, respectively. Thus, the uniformity of velocity distribution was improved in optimal schemes. The extrusion die design methods for large wallboard profiles were summarized and proposed, including the design methods of baffle plate and double-step welding chamber. Through trial production, a sound wallboard aluminum profile with good geometric shape and high dimensional accuracy was gained. Additionally, the mechanical properties of the extrudate were examined by means of experimental method. It is found that the test results stratified the practical engineering requirements.     

基于特征矩阵和神经网络的铝型材整体壁板外形识别

针对铝型材整体壁板的外形特征和设计要求，提取出9种典型壁板并构建出对应的壁板特征矩阵和目标矩阵。采用神经网络分别对带与不带噪声的整体壁板特征识别进行了研究、训练和测试，测试结果显示，采用矩阵构造的神经网络对壁板特征识别继承了神经网络的优点，可扩充性好，解决了整体壁板挤压模具CAD专家系统关于特征识别的前处理瓶颈问题。     

Multiobjective optimization design of porthole extrusion die using Pareto-based genetic algorithm

The extrusion die plays a crucial role in aluminum alloy profile production, which influences product quality and service life of extrusion die directly. In this paper, a profile with irregular shape was taken as an analysis example, and multiobjective optimization for porthole extrusion die based on modern intelligence algorithm was carried out. Aiming at achieving the uniform velocity distribution in the cross-section of the profile as well as decreasing the maximum stress on the extrusion die and the deflection of the mandrel, the angle between port bridges, the position of die orifice, and the height of welding chamber were considered as the design variables. Then Kriging model was established on the basis of Latin hypercube samplings, and above design variables were optimized using Pareto-based genetic algorithm. Finally, an optimal die structure is gained. Compared with the initial scheme, the velocity distribution in the extrudate was more even, and the stress on the die and the deflection of the mandrel were decreased obviously in the optimal scheme. The optimal design method for porthole die has strong commonality, thus, it could give useful guidelines for practical production of the same kind of aluminum profile.     

铝型材挤压模具CAD中型材截面的实体信息处理

铝型材挤压模具中，工作带起着非常重要的作用。本文开发了铝型材挤压模具CAD工作带的实体信息处理程序，对铝型材截面信息进行提取，从而根据这些信息进行模孔工作带的设计计算，并传到到UG／OPEN进行工作带图形绘制。本文中实体信息的提取主要包括实体元素信息的读取、轮廓分类和排序；信息的传递主要指从型材截面传递到所需格式的数据文件和数据文件与UG／OPEN之间的传递。     

Evaluation of a pyramid die extrusion for a hollow aluminum profile using FE simulation

The pyramid die extrusion for a hollow aluminum profile was analyzed to investigate the potential of such innovative dies. For this purpose, the pyramid and conventional porthole dies were respectively designed for a given hollow aluminum profile. And the extrusion process was comprehensively studied by performing different types of finite element simulation, such as the analysis of steady state, transient state and billet skin tracking. The effects of pyramid angle on the evaluation parameters of extrusion, such as extrusion load, material flow, exit temperature, length of transverse weld, quality of longitudinal weld, back end defect and die stress were overall analyzed and compared with the conventional porthole die. Through this study, the advantages and shortcomings of pyramid die were well concluded, which should be important information for die designers and makers.

     

Numerical and experimental study on the three-dimensional extrusion of square section from square billet through a polynomial shaped curved die

The geometry of die profile plays a major role in reducing the extrusion pressure and ensuring the smooth flow of material. In general, the extrusion process is mostly affected by billet geometry, die geometry, and interface frictional force at the die billet geometry. In the present investigation, an analysis using three-dimensional upper bound method using fifth-order die profile function has been carried out for extrusion of square sections from square billet. The extrusion pressure and optimum die length have been computed by multivariable optimization technique. The present die shape profile is found to be superior to many other profiles. The results obtained will help in design of optimum die profile and investigation of its performance.     

Numerical simulation and metal flow analysis of hot extrusion process for a complex hollow aluminum profile

The most important way to improve the quality of aluminum profiles is to assure the material flow through die land exit with the same velocity. In this paper, a numerical model was developed to investigate metal flow behavior during aluminum profile extrusion. Firstly, the numerical model for a complex hollow aluminum profile was built based on the arbitrary Lagrangian–Eulerian program HyperXtrude. Then, with the numerical model, metal flow behavior at each stage during the whole extrusion process was analyzed and dead zones in the die cavity were also investigated by means of the particle tracking method. Finally, the numerical results were validated by comparing with the nose ends of two extrudates in practice, and the comparison showed that the numerical model developed in this work could provide the effective guidance for practical production.     

连续挤压机负载扭矩的模拟确定及实验研究

建立了铝合金扁铝线连续挤压成形的有限元模拟模型,并应用有限元分析软件DE-FORM-3D对铝合金挤压的变形过程进行了三维模拟,获得了铝扁线挤压过程中的挤压轮的负载扭矩的行程曲线,该行程曲线一方面为传动系统、主轴系统的设计及电机选择提供依据,另一方面也是挤压轮预应力设计的基础。