薄板激光拼焊工艺研究

汽车薄板的激光拼焊可以减轻整车质量和制造成本,对提高汽车设计的灵活性具有重要意义.通过对汽车用冷扎薄钢板和镀锌板的激光拼焊的实验研究,表明虽然激光焊接接头的塑性有所下降,但其焊接强度与母材差不多,且焊接影响区小,对汽车覆盖件和地板等零件的焊接获得很好的效果.     

管材外高压成型工艺研究现状及应用

管材液压成型是一种生产中空轴类零件的成型技术,其在汽车和航空领域有广泛的应用前景.本文介绍了一种新的液压成型工艺--管材外高压成型;并综述了外高压成型(EHF)的基本原理、外高压成型优点、研究现状、应用范围、适用材料.     

曲面薄壁异形件旋压成形工艺研究

针对一种复杂曲面薄壁异形件的旋压加工，通过不同方案从强旋、普旋两方面做了工艺研究。从旋压件贴模、壁厚、旋压道次、裂纹等方面做了对比试验，结果表明：异形件旋压加工中普旋、强旋同时存在；未贴模状态下预成形以普旋为主效果良好，同时可减少模具工装，经济性好；本工艺方案综合应用普旋、强旋方式，降低了生产成本，提高了生产效率。     

深冲铝板中的再结晶织构与选择生长

利用电子显微分析（TE）和ODF织均分析，研究了纵横轧制铝板再结晶退火前后的织构和再结晶过程．直接观察到再结晶过程中的选择长大，经电子衍射分析了新晶粒的取向，并通过极图分析了各织构组分＜111＞间的关系结果表明，纵横轧制铝板再结晶过程中存在选择生长现象，并最终决定再结晶织构；面心立方金属中这种取向关系约为40°＜111＞     

板料双向加压液压胀形数值模拟

应用商用有限元软件ANSYS/LS-DYNA,对板料的双向加压液压胀形过程进行了数值模拟.并利用韧性断裂准则作为胀形高度极限的判断依据,将模拟得到的必要数据代入到准则中.对两种材料、不同初始液体压力条件下的模拟结果表明,随着初始液体压力的升高,胀形的极限高度也相应的增加,当初始压力与板料的强度相当时,极限高度提高的更明显.     

Infrared heat treatment of Ti-6Al-4V with electroplated Cu

The objective of this study is to investigate an innovative infrared (IR) technique to enhance adhesion of electroplated copper (Cu) on Ti-6Al-4V without dichromate dipping. The ultimate goal is to develop a Cu coating process on Ti-6Al-4V without hazardous hexavalent chromium (Cr) solution treatments. Cu coatings of around 50 μm were electroplated on Ti-6Al-4V specimens at a current density of 0.03 A/cm² in an acidic Cu solution. To improve adhesion of coatings, IR heat treatments were performed on the Cu-coated samples at different temperatures and durations: 860 °C for 600 s and 875 °C for 20–120 s. This process was accomplished in an attempt to replace the use of dichromate dipping before electroplating. For samples heat treated at 860 °C, no bonding existed, even after 600 s. It is believed that solid-state diffusion prevailed at 860 °C and that 600 s was not enough for sufficient diffusion to occur. Adhesion was poor when samples were heat treated at 875 °C for 20 s. Excellent adhesion was observed when the heat treatment holding time was increased to 40 s. For 90 s, the surface appearance of coatings partially changed from Cu-colored to a grayish color. There was no Cu left on the surface after a 120 s heat treatment. From optical microscopic observations on sample cross sections, an interlayer between the Cu and Ti-6Al-4V formed when heat treated at 875 °C for 40 s and longer. The interlayer thickness increased as the holding time increased, until depletion of Cu. The sheet resistivity of coated specimens was on the order of pure Cu for samples heat treated at 875 °C and less than 90 s. During the 875 °C heat treatment, the following occurred: solid-state diffusion of Cu in Ti-6Al-4V, formation of eutectic solutions, dissolution of Cu and Ti-6Al-4V into the liquid phase, and the formation of intermetallic compounds. The lowest eutectic temperature of 875 °C played a key role in this innovative process of Cu coating on Ti-6Al-4V. This paper was presented at the 2nd International Surface Engineering Congress sponsored by ASM International, on September 15–17, 2003, in Indianapolis, Indiana and appears on pp. 403–10 of the Proceedings.     

Influence of the Workpiece Stiffness on the Electromagnetic Sheet Metal Forming Process into Dies

Electromagnetic sheet metal forming is a high speed forming process using pulsed magnetic fields to form metals with high electrical conductivity such as aluminum. Thereby, workpiece velocities of more than 300 m/s are achievable, which can cause difficulties when forming into a die. The kinetic energy, which is related to the workpiece velocity, must be dissipated in a short time slot when the workpiece hits the die; otherwise undesired effects, for example rebound can occur. One possibility to handle this shortcoming is to locally increase the stiffness of the workpiece. A modal analysis is carried out in order to determine the stiffness of specific regions of the workpiece so that an estimation concerning the feasibility of the desired geometry is possible in advance without doing cost and time consuming experiments. Thereby, the desired geometry of the workpiece will be fractionized in significant sectors. This approach has to define the internal force variables acting on the cutting edge, which are required to constrain the numerical model. Finally, a method will be developed with the objective of calculating the stiffness of each sector. The numerical results will be verified by experiments. This article was presented at Materials Science & Technology 2006, Innovations in Metal Forming symposium held in Cincinnati, OH, October 15-19, 2006.     

固体颗粒介质成形新工艺及变形研究

固体颗粒介质成形新工艺,是采用固体颗粒代替刚性凸模(或弹性体、液体)的作用,对金属板料成形的工艺。固体颗粒介质成形新工艺,即可以解决流体介质、粘性介质的密封难题,又具有内压非均匀分布、便于控制成形、提高材料成形极限、降低投资成本、所得零件表面质量高、成品率高的优点,且固体颗粒无工业污染,可重复使用。该工艺为材料的加工制备提供了新的方法和手段。利用塑性增量理论,对自由变形区任意一点的应变进行了分析,得到了自由变形区任一点的应变及厚度计算公式。采用固体颗粒介质成形工艺,进行板料成形试验,成功试制出多种典型工件;对试验件壁厚分布的计算值和实测值进行了比较,证明理论正确。     

板金液压柔性技术及其产品设计

板金液压柔性成形具有诸多的优点,受到了汽车、航空航天等领域设计和研究者的普遍重视。文章主要介绍了板金液压柔性成形技术的内涵和外延,针对所提出的无模液压柔性成形技术和复合液压柔性成形技术,从不同的工艺方法入手,基于所研制的液压柔性成形设备,介绍了相关的飞机等领域产品特点以及设计要点,并对其中的关键工艺参数进行了描述。     

圆锥形零件冲压成形极限的确定

圆锥形零件极限变形程度可用极限拉深系数［ｍｚｄ］＝［ｄ２／Ｄ０］来表示。根据圆锥形零件与圆筒形零件的内在联系，经力学分析得出了便于实用的圆锥形零件极限拉深系数［ｍｚｄ］的计算表达式，并由此给出了用［ｍｚｄ］所表示的成形极限曲线和第一次拉深时的极限拉深系数。经实验验证表明所确定的成形极限是准确和可靠的。