平行流铝管连续挤压金属流动的数值模拟研究

针对平行流多孔铝管连续挤压成形过程,基于Deform-3D软件平台,通过对挤压模型采取适当的简化措施,实现了挤压过程的三维有限元数值模拟;揭示了金属的变形流动特点,为平面分流组合模的设计提供理论依据,初步得到了模具结构的改进方案。     

生产汽车换热器平行流铝扁管的硬质合金镶嵌挤压模

分析了汽车换热器平行流铝扁管的结构和传统挤压模具结构的特点。提出采用硬质合金镶嵌挤压模的结构。介绍了上模模芯采用硬质合金镶嵌的原理,利用斜面结构具有自动补偿和自锁的特点,并对传统的模具结构进行改进,增设前置分流保护板,同时在上模开设工艺槽,其结果是降低了硬质合金镶件的受力,提高了硬质合金镶件的稳定性以及上下模配合间隙的准确性。还介绍了下模的硬质合金镶嵌方法,利用硬质合金与钢材线膨胀系数的差异,采用销子定位的方式,可以使销子与硬质合金镶件的配合由常温下的间隙配合变成高温工作下的过盈配合,结果是硬质合金的镶嵌更加牢固可靠。实践表明效果良好,挤压模具的寿命大大提高。     

微型微通道管的连续挤压成形工艺

微型微通道管产品具有孔道数量多、孔道尺寸小、壁厚薄、尺寸精度要求高等特点,制备加工难度很大。采用连续挤压制备方法,通过采取双槽挤压方式、增加金属导流板等措施,对模具结构与加工方法、挤压工艺进行优化设计,明显改善了微型微通道管产品挤压成形时金属在产品宽度方向的流动均匀性、孔道部位的有效填充及焊合质量,解决了挤压过程中模具模芯强度不足导致的尺寸超差与失效问题和溢料过多导致产品无法挤出等问题。最终成功试制了厚度为2.2 mm、宽度为45 mm的52孔微型微通道管产品,产品外形尺寸和组织结构均满足设计要求。     

复杂空心铝型材的挤压缺陷仿真分析及材料在分流模中的流动行为优化（英文）

为了解决复杂空心铝型材在挤压试验中出现的截面内凹缺陷,基于Arbitrary Lagrangian-Eulerian(ALE)算法,利用HyperXtrude软件平台建立型材在多孔分流挤压模具挤压过程中的三维稳态有限元模型。定量分析型材挤压出口不同方向的金属流速及焊合室内不同高度的压力分布。为实现出模口型材横截面材料流速的均匀性,采用增加阻流块方法对模具结构进行优化。优化后进行挤压试验,型材底面Y方向的最大位移由1.1mm减小到0.15 mm,内凹缺陷得到显著改善。研究方法为复杂空心铝型材分流模挤压缺陷的改善和材料流动行为的优化提供理论指导。     

CONFORM连续挤压的模具

ＣＯＮＦＯＲＭ连续挤压的送料方式决定了连续挤压模具的结构形式，主要有桥式分流模和双沟槽挤压模。叙述了连续挤压圆管的模具结构设计，着重讨论了双沟槽挤压模的结构设计。     

多孔薄壁扁管连续挤压模的研制

介绍了连续挤压模的生产工艺过程 ,模具主要结构及设计参数 ,分析了生产中存在的问题以及采取的措施 ,充分发挥了连续挤压设备的潜力 ,扩大了产品品种     

多孔管、棒挤压模加工工艺的改进

采用微调镗刀和专用磨头，在铣床上加工多孔管、棒挤压模工作带，代替了传统的电加工和钳工手工抛光方法，使模具工作带的尺寸精度和表面光洁度得以显著提高。     

基于FEM的铝型材分流焊合挤压过程数值模拟

铝型材的分流焊合挤压相对于其它传统的挤压方法,在生产中空型的管类型材时具有非常大的优势.本文基于FEM方法,利用DEORM-3D对薄壁铝合金圆管型材进行了从分流-焊合-挤出成形的全过程模拟.得到了挤压过程中的网格变形图和行程载荷曲线.同时针对分流模变形抗力大的特点,进行了模具的受力变形分析,对挤压过程中模具可能出现的失效进行预测.模具应力分析结果表明,分流孔及其模芯处变形量大,应力集中明显,容易磨损,设计模具时应重点考虑这些部分,以提高模具寿命.其模拟结果为模具设计和工艺参数选择提供理论依据.     

新型太阳能边框挤压模具设计

为提高企业生产效率,通过采用一模多孔模具设计思路,对太阳能边框进行一模三孔挤压模具设计,在传统设计思路上不断创新改进,并从模具加工工艺、挤压工艺两方面严格管控。通过改进单孔模的传统设计方案并经过生产检验,成功研发出一模三孔挤压模具,实现了铝型材挤压生产率和成品率大幅度提升,同时满足了企业快速生产需求和客户质量的要求。     

球面滑履冷挤压模脱模装置的改进设计研究

介绍一种高精度球面滑履零件冷成形模具,在实际应用中该模具能实现滑履成形,但模芯经常断裂,而且滑履挤压件的薄壁端口发生微塑变形.通过对模芯断裂和顶出变形分析,将模芯由台阶配合改作锥面配合,并将模具脱模机构改成梯度脱模,从而很好地解决了模芯断裂和挤压件顶出变形的问题.有效保护模具和保证挤压件尺寸精度,具有较高的应用价值.     

连续挤压多通道铝扁管用硬质合金模具的研制

分析了连续挤压多通道铝扁管用硬质合金模具的结构及加工工艺性,对该种模具的加工方法和加工电参数进行了介绍。     

Effect of geometry on void formation in commercial electroplating of thin strips to copper

Three plating trials comprised of six samples were performed to evaluate the ability to attach thin strips of varying cross section to a copper substrate via commercial nickel electroplating in a nickel sulfamate bath. Nickel plated to the top, bottom, and sides of the nickel strips, as well as to the substrate. A significant void formed beneath rectangular nickel strips for all geometries studied, including strip widths of 500 µm to 5000 µm and gap thicknesses from 100 µm to 1500 µm. This is due to the starvation of ions when two regions of growing grains impinge and entrap a volume of electrolyte, surrounding it completely by deposited nickel. Impingement often occurs just past the edge of the strip which causes the void width to be greater than the strip width and form seams at the edge of the void. The rate of plating is greatest in areas where sharp corners exist, due to higher current density. More plating reaches under the strip as the width decreases and/or gap thickness increases. Thus, the void size decreases with decreasing aspect ratio, defined as the strip width over gap thickness. The use of a cylindrical strip produces sound plating with no voids. This is because the lack of corners allows impingement to occur first beneath the center of the circular cross section, so liquid is never surrounded. The results of this study demonstrate how to minimize or avoid void formation in commercial electroplating of suspended strips which is of great importance in the installation of sensor strips in the coating layer of continuous casting molds.     

Ductile damage and simulation of fine-blanking process by FEM

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换热管耐CaCl2溶液腐蚀性能研究

通过建立模拟试验装置,测试三种铜换热管(黄铜、B10、B30,其中黄铜管和B10管分带螺纹和光管两种)在CaCl2溶液(质量浓度20%)中的耐冲刷腐蚀性能.试验过程中定期测量管路的腐蚀电位变化.试验结束后,解剖管状构件,从宏观和微观方面观察试验后换热管表面状态,综合对比分析三种换热管的耐CaCl2溶液腐蚀性的优劣.     

微小齿轮模具的微细电火花线切割加工研究

介绍了微细电火花线切割加工微小齿轮模具的方法，其关键技术包括：晶体管可控微能量RC脉冲电源、间隙放电状态检测系统、基于压电陶瓷电机驱动的精密伺服机构和偏开路加工控制策略。使用微细电火花线切割加工机可一次切割出厚度为1mm、模数为0．04和厚度为3、5mm、模数为0．1的微小齿轮模具，表明由微细电火花线切割加工出的微小齿轮模具能满足微成形加工的技术要求。     

AM30 porthole die extrusions—A comparison with circular seamless extruded tubes

One of the prospective applications of wrought AM30 magnesium alloy is in the form of hollow circular extrusions. They can either be fabricated by employing a conventional conical die and mandrel that produce seamless extrudates, or by using a porthole die employing a welding chamber technique. The latter has become popular due to several advantages and has been adopted commercially for aluminium and magnesium alloy extrusions. In the present investigation, cast billets of AM30 magnesium alloy were extruded under similar conditions, using two different dies, i.e., a conventional conical die and a commercially used porthole die. The extruded circular tubes produced by the two methods were characterized for their microstructure as well as physical and mechanical properties. The tubes fabricated using porthole die showed significant refinement in microstructure with improved mechanical properties, outside the seam-joint portion, compared to the tubes fabricated using conical die. The extrusion loads using porthole die, were, however, higher compared to the conventional method. Processing issues, structure and properties of magnesium extrusions, produced by the two methods, are discussed in details in this paper.     

Internal void closure during the forging of large cast ingots using a simulation approach

Large cast ingots often contain defects or undesirable microstructural features, such as voids and zones related to casting. Some of these features can remain after hot open die forging, which is an important process for converting large cast ingots into wrought components. During the initial cogging and deformation steps prior to the detailed open-die-forging operations, any internal voids should be eliminated. The present work focuses on the closure of internal voids during open die forging so as to produce a sound component. Hot compression tests were conducted to obtain the flow strength of the cast microstructure at different temperatures and strain rates. The measured flow strength data together with other appropriate material properties were used to simulate the forging steps for a large cast ingot. The numerical simulations for the forging deformation and for the internal void behavior were performed using DEFORM-3D™. Actual defects were measured in commercial ingots with an X-ray scanner. The simulation results for the void deformation behavior are compared with voids measured before and after forging. Through the comparison of experimental results and numerical simulation, a criterion for void closure is proposed. The criterion is that a local effective strain value of 0.6 or greater must be achieved for void closure during forging. Such a criterion can be used in conjunction with simulations to insure that a sound component is produced during the hot open die forging of large cast ingots.     

新型弯管综合测量检具设计

设计了一种新型弯管检具,对检具的设计作了详细说明。该检具适用于多基准、高精度的弯管件检验,在检验过程中收到了很好的效果,为控制弯管质量提供了保障。     

基于微细电火花加工技术的微冲裁模具在线制备

针对微冲裁异形截面的微小模具难以制备及安装对准的问题,利用微细电火花三维铣削加工技术加工反拷贝电极及凹模,利用所加工的反拷贝电极通过电火花反拷贝加工技术加工凸模,整个工艺过程在线制作,避免了凸凹模具二次装夹产生的位置误差。该工艺分别在线制作凸凹模具,实现了复杂截面形状微型模具制备和在线对准。通过设计试加工实验确定加工参数,并利用该工艺成功制作了一套截面形状复杂的具有微小特征结构的高精度微冲裁模具。     

空洞敏感材料超塑性胀形过程的有限元模拟

基于刚粘塑性有限元技术采用最大应变速率恒定的压力控制策略和超塑性成形空洞损伤演变模型对空洞敏感材料的超塑性胀形过程进行了数值模拟。分别以半球壳和圆筒形零件为例 ,给出了优化后自由胀形和充模胀形的加压曲线 ,预测了成形零件的壁厚分布及空洞体积损伤情况。本文分析结果对指导超塑性胀形工艺设计具有实际意义。