铝材长方形空心管挤压过程数值模拟与模具结构优化设计

对AA1100铝材长方形空心管的挤压过程使用数值分析软件SuperForge进行数值模拟。在挤压生产中,金属流出工作带时的流速均匀性是得到高质量型材的关键。在挤压生产中通常采用几种方法修改模具,消除流速不均,例如修改分流孔的大小、形状和位置分布,修改工作带长度和焊合室形状尺寸等。本文通过数值模拟发现在长方形空心管挤压的初始模具设计中型材截面流速不均匀,造成端面不平。对此,提出了三种模具修改方案,并分别对其进行了数值模拟,经过分析比较确定了最佳模具设计方案,由此方案可以生产出合格的挤压件。     

分流组合模挤压铝合金口琴管的数值模拟

采用刚粘塑性有限元法,在DEFORM-3D有限元商业软件上成功实现了铝合金口琴管分流组合模挤压过程的三维数值模拟,获得了分流组合模挤压过程中材料的流动规律,挤压力、应力场、应变场和温度场的分布,以及模具出口处金属流速的分布情况。通过数值模拟发现,型材出口流速不均匀,造成端面不齐,对此,提出了模具修改方案,通过调节模具工作带的长度,实现了型材挤压出口流速均匀的目的,从而保障了型材的产品质量。模拟结果为模具的优化设计及工艺参数的选取提供了理论参考。     

Optimal extrusion die design to achieve flow balance

The design of a plane strain two-hole extrusion die is presented. This design example can be considered as a test case to judge the usefulness of the present method in the design of extrusion dies for uniform exit flow. Bearings for this die are to be designed so that the material exits both holes with parallel balanced flow. The finite-element method combined with techniques of mathematical programming is adopted. Derivatives of the objective function used during the optimization phase are efficiently computed using analytical sensitivity analysis and an optimal bearing length is reached after few iterations of the optimization procedure. Available experimental data for a two-out extrusion die with bearings have been used to validate the numerical results.     

Non-steady FE analysis on porthole dies extrusion of aluminum harmonica-shaped tube

According to the rigid-viscoplasticity finite element method, the porthole die extrusion process of an aluminum harmonica-shaped tube was successfully simulated based on software Deform-3D. The distribution of stress field, effective strain field, velocity field and temperature field during the extrusion process were discussed and the metal flow in welding extrusion was analyzed. The simulation results show that the material flow velocities in the bearing exit are non-uniform with the originally designed die and the forepart of the profile is not neat or even. Aiming at solving this problem, the modification method of die structure was improved. The result shows that the uniform material flow velocities in the die exit and a perfect extruded are obtained by modification bearing length.     

A general methodology for bearing design in non-symmetric T-shaped sections in extrusion process

In this study, a general methodology has been developed to design the proper bearing in order to eliminate the curvature of the final product in extrusion process. Three smooth curved (advanced-surface) dies with non-symmetric T-shaped sections and different off-centricities have been studied. For each die, the proper bearing has been designed and physical and numerical modeling have been performed to validate the design. The design procedure is as follows: A formulation, based on Bezier curves, has been used to determine the exit velocity profile. Since the result of Bezier method is different from the actual velocity profile, the Chitkara corrective function has been modified and applied to improve the velocity field. A deviation function has been developed to measure the curvature of the final product in terms of the exit velocity field. Considering the obtained velocity field, the friction effects, and the geometry of the dies, the proper bearing for each die has been designed. Finally, numerical and physical modeling have been performed on the die-bearing combination. According to the results, the curvature of the final product was eliminated to a great extent.     

CPU散热片挤压过程的数值模拟及模具优化

采用刚粘塑性有限元法,利用Deform-3D有限元软件实现了铝合金CPU散热片导流模挤压过程的数值模拟。获得了挤压过程中材料的流动规律、挤压力、模具应力以及模具出口处流速的分布。通过数值模拟发现,型材出口流速很不均匀,远离型材中心的散热片齿部流速过慢。通过对导流模结构的调节,使得型材出口流速基本均匀,模具应力降低,提高了模具的使用寿命。模拟结果为导流模优化设计提供了依据。     

散热器铝型材挤压的数值模拟

采用基于A-L-E算法的HyperXtrude软件,建立有限元分析模型,对散热器铝合金型材挤压过程进行了稳态流动仿真,获得了型材的位移分布和速度分布图,模拟结果与生产实际吻合较好;针对试模出现的问题,对出口速度分布和应力分布进行分析,提出在下模增加阻流台和修改工作带方案,有效地解决了初始模具设计中速度分布不均的问题;最后针对装配后型材平面度达不到要求这一缺陷,对模具工作带进行调整优化,用优化后的模其生产的型材可以装配使用.     

Mathematical model of determination of die bearing length in design of aluminum profile extrusion die

Based on the finite element simulation of profile extrusion process, the effect of local extrusion ratio, die bearing area and the distance between extrusion cylindrical center and local die orfice center on mental flow velocity was investigated. The laws of deformed metal flow on profile extrusion process were obtained. The smaller the local extrusion ratio, the faster the metal flow velocity； the smaller the area of die bearing, the faster the metal flow velocity； the smaller the distance of position of local die orifice(the closer the distance of position of local die orifice from extrusion cylindrical axis), the faster the metal flow velocity. The effect of main parameters of die structure on metal flow velocity was integrated and the mathematical model of determination of die bearing length in design of aluminum profile extrusion die was proposed. The calculated results with proposed model were well compared withthe experimental results. The proposed model can be applied to determine die bearing length in design of aluminum profile extrusion die.     

导流室设计对薄壁铝型材挤压出口速度的影响

采用基于ALE算法的HyperXtrude软件,模拟薄壁铝合金型材挤压模具导流室各种设计的金属流动情况,分析了各设计参数对金属流速的影响规律,并统计挤出型材断面上挤出方向的流速均方差S.D.作为衡量流速均匀程度的指标。分析结果表明,在设计断面不对称、壁厚不等型材模具时,有时需将型材的质心相对于模具的中心做一定距离的调整。型材断面上各处的壁厚差异和局部质心偏离都对流速有影响,但壁厚差异对于流速均匀程度的影响更大。在模具的型腔内添加阻流块结构,流速均匀程度可大为改善。调节阻流块的宽度、高度、形状、位置等参数,能够完全消除流速不均匀,但如果尺寸调整超过最佳点,流速均匀程度将迅速恶化。根据最优模拟结果对应的设计生产模具,并进行挤压实验,所得型材的尺寸质检合格,模具达到"零试模"要求。     

铝型材挤出速度对模具工作带的影响

铝型材挤出速度对模具工作带的失效有着重要影响。本文利用数值模拟实验,分析了不同出口速度下的模具应力、模具温度和模具工作带尺寸的变化规律。实验表明,随着挤出速度的提高,模具内应力增大,模具温升相对变慢。由于模具工作带附近的应力和温度均较其它部位大,从而使得模具工作带成为挤出模具失效的主要区域。     

铝型材挤压模工作带的计算机辅助设计

本文提出了一个铝型材挤压模工作带的数学模型，该模型不仅反映了模孔形状对金属流动的影响，而且考虑了模孔位置的影响，根据该模型作者在ＣＡＤＤＳ５上开发了铝型材挤压模工作带的计算机辅助设计系统。实践表明，该系统设计的挤压模工作带能较好地平衡金属流出模孔的速度，减轻型材的歪扭，弯曲，波浪，裂纹等缺陷。     

铝型材出口速度分布的数值模拟

铝型材挤压过程中的出口速度,是模具优化设计的重要参数之一,型材出口速度不均的原因之一是模具设计不当。为了获得高质量的挤压制品,对模具出口区域速度分布的研究是必须的。本文采用DEFORM3D对铝型材进行了3D模拟,获得了在模具制造之间铝型材的出口速度。数值模拟的结果得到了实验的验证,这对优化模具过程是非常重要的。     

铝合金挤压材“麻面”缺陷产生机制的研究

“麻面”是影响铝合金挤压材表面质量的主要缺陷之一。研究了铝合金挤压材,特别是铝型材在挤压过程中出现的“麻面”缺陷产生的机制、规律及影响因素。结果表明,“麻面”缺陷的产生与合金的本性、挤压工艺参数、模子工作带的表面状况、工作带的形状,特别是模孔出口直径及工作带出口方向的圆角大有关。提出了预防或消除这一缺陷的主要措施。     

铝型材挤压模工作带优化

基于MATLAB平台，将BP神经网络、遗传算法和数值模拟技术应用于铝型材挤压模具参数优化设计。采用三层BP神经网络建立型材挤压模具的数学模型，由正交实验法安排模拟实验组合，采用有限元软件进行挤压过程的数值模拟，并以具有不同工作带尺寸的挤压模具中金属流出模口平面上的Z向质点流速均方差作为模型目标值，将模拟结果作为神经网络的输人样本对训练网络并建立网络知识源，通过遗传算法求得模型的全局优化解；最后通过有限元数值模拟技术验证并比较优化所得工作带与经验法确定的工作带对金属流动均匀性的影响。数值模拟结果表明，本研究对挤压模具工作带的优化是有效的。     

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.     

分流组合模挤压过程数值模拟及模具优化设计

文章利用刚粘塑性有限元软件DEFORM-3D对分流组合模挤压小直径薄壁纯铝圆管过程进行了三维有限元模拟,得出了模具焊合室深度以及工作带长度对挤压力、应力应变、模具应力等物理场量的影响规律,从而对模具结构参数进行优化。模拟结果表明,分流模上模应力集中主要分布在分流桥和模芯部位,下模应力集中分布在工作带附近和焊合室圆角过渡区,焊合室深度和工作带长度对产品质量有很大影响。通过试验得知,加大焊合室深度和工作带长度,可提高产品焊缝强度和表面质量。     

基于BP神经网络的铝型材挤压模具优化设计

采用三层BP神经网络建立挤压模具的数学模型,利用三维刚塑性有限元模拟获得神经网络的样本信号,对神经网络模型进行训练。利用神经网络函数逼近功能,以U形铝型材在挤压工作带出口处具有最均衡的轴向挤压速度为目标,最终对U形铝型材挤压模具合理模孔位置进行了优化设计,并采用计算机模拟仿真对优化结果进行验证,表明优化结果是有效的。     

铝型材挤压成型数值模拟与模具优化设计

采用HyperXtrude专业铝型材挤压成型有限元软件系统,以多边型空心铝型材为研究对象,对其稳态挤压成型过程进行数值模拟,计算结果发现初始模具结构中金属材料流速严重不均匀.通过增设导流槽、合理布置分流孔和调整工作带长度等措施,获得了较为理想的模具结构,同时提高了模具的寿命.     

聚晶金刚石拉丝模具孔型结构分析

本文介绍了聚晶金刚石的特点及拉丝模具的结构,其结构由模套、烧结金属、硬质合金环、聚晶金刚石组成,分析了采用该结构的原因。聚晶金刚石拉丝模的孔型结构分为入口区,润滑区,压缩区,定径区,安全角,出口区六部分,对各个区域的角度、长度及其功能特点进行了分析,说明了各区域对其使用性能的影响,特别对压缩区,定径区两部分进行了重点叙述,最后给出各部分参数值。     

FEM simulation of aluminum extrusion process in porthole die with pockets

In order to investigate the effects of pockets in the porthole die on the metal flow, temperature at the die bearing exit and the extrusion load were contrasted with the traditional die design without the pockets in the lower die. Two different multi-hole porthole dies with and without pockets in lower die were designed. And the extrusion process was simulated based on the commercial software DEFORM-3D. The simulation results show that the pockets could be used to effectively adjust the metal flow and especially benefit to the metal flow under the legs. In addition, the maximum temperature at the die bearing and the peak extrusion load decrease, which indicates the possibility of increasing the extrusion speed and productivity.