车架薄壁小管“H”型接头电阻对焊工艺

自行车车架后三角平立叉与平立叉小管的焊接,如图1所示,国内普遍采用传统的焊接工艺,焊接表面常出现高低不平的焊疤,产品质量不稳定、生产效率低、劳动强度高、且污染环境、生产成本高等缺点。针对这些情况,我们试验研究了薄壁管“H”型接头各种接触焊工艺及小管端部型式对焊的性能,实现了车架平立叉薄壁小管“H”型接头电阻对焊,经济效益显著,对类似“H”型的结构件也具有一定的推广意义。一、“H”型接头电阻对焊工艺在电阻对焊中,加热和塑性变形是形成焊接接头的主要条件,为获得优质的对焊接头,焊接区必须产生足够的塑性变形,焊接端面必须加热到适当均匀的温度并尽可能减少接口中的氧化夹杂物,而自行车平     

自行车接头的连续闪光对焊法

连续闪光对焊和电阻对焊都属于电阻焊范围,由于电阻对焊有时也产生闪光和飞溅,故有些工厂误把电阻对焊当成闪光对焊。其实这两者的工艺过程有明显差别,就焊接质量来说,连续闪光对焊优于电阻对焊。我厂从生产自行车接头以来,一直采用电阻对焊。后因焊接质量太差,焊接强度不够而     

高强铝合金板轧制过程中应力分布规律的有限元分析

采用ANSYS软件进行高强铝合金板轧制过程数值模拟,分析了等效应和剪切应力沿合金板材的分布规律,探究了轧制工艺及板材厚度对应力分布的影响.研究表明,随着轧制温度的升高,等效应力和剪切应力减小,且温度较高时,等效应力和剪切应力的分布均匀;增加轧制道次有效提高应力分布的均匀性;板材厚度较小时,等效应力由心部到表面分布不均匀...     

名词解释

重力焊将重力焊条的引弧端对准焊件接缝,另一端夹持在可滑动夹具上,引燃电弧后,随着电弧的燃烧,焊条靠重力下降进行自动焊接的一种高效率焊接法。热剂焊将留有适当间隙的焊件接头装配在特制的铸型内,当接头预热到一定温度后,采用经热剂反应形成的高温液态金属注入铸型内,使接头金属熔化实现焊接的方法。闪光对焊电阻焊件装配成对接接头,接通电源,并使其端面逐渐移近达到局部接触,利用电阻热加热这些接触点(产生闪光),使端面金属熔化,直至端部在一定深度范围内达到预定温度时,迅速施加顶锻力完成焊接的方法。     

压焊温度场微计算机测试与分析

微计算机图象法测量焊接温度场是一项新技术。本文介绍该方法的原理和特点,继弧焊温度场的测量之后,又对几种压焊动态温度分布进行了测试试验与分析。经微计算机处理,通过伪彩色图象处理机及自动绘图机做实际温度分布图的绘制,形象、直观地描述电阻对焊,连续闪光对焊、预热闪光对焊以及点焊过程中的温度分布情况。     

对焊

<正>对焊是利用电阻热使对接接头的焊件在整个接触面上形成焊接头的电阻焊方法,可分为电阻对焊和闪光对焊两种。电阻对焊适用于形状简单、小断面的金属型材的对接。闪光对焊接头质量高,焊前清理工作要求低,目前应用比电阻对焊广泛。它适用于受力要求高的重要对焊件。焊件可以是同种金属,也可以是异种金属;焊件截面可以小至0.01mm2(如金属丝),也可以大至1×105mm2(如金属棒和金属板)。     

400 Mpa超细晶粒钢直流电阻闪光对焊接头组织的数值模拟

对超细晶粒钢直流闪光对焊过程进行了有限元分析.根据计算的焊接温度场和基于EDB模型的Monte Carlo (MC)模拟时间与实际焊接时间的关系,建立了直流闪光对焊过程显微组织的演化模型,对超细晶粒钢筋焊接接头的奥氏体晶粒长大进行了模拟研究,同时考虑了温度梯度对热影响区晶粒长大的热钉轧作用.结果表明,MC模拟技术能预测闪光对焊接头的晶粒大小、尺寸分布,为合理地制定焊接规范、提高接头质量提供有效的分析手段.     

闪光对焊技术

众所周知,电阻焊的主要特性是利用电流在工件自身电阻上产生的焦耳热作为焊接热源。电阻焊有点焊、缝焊和对焊等三种基本形式,其中的对焊方法是将细长的工件以端面相对,一次实现全面积的焊合。对焊方法也具有各种电阻焊方法所共有的无需填加焊接材料、成本低、生产率高、易于操作的优点,在汽车制造、建筑和机械制造等行业中得到广泛应用。     

竖向钢筋电渣压力对焊工艺在施工中的应用

针对竖向钢筋传统焊接工艺质量差、工效低、浪费多等问题．公司在施工中采用竖向钢筋电渣压力对焊工艺，即：利用电流通过渣池产生的电阻热将钢筋端部熔化．然后施加压力，使钢筋焊合的工艺．摸索出外观检查、力学性能试验等一整套焊接接头质量检验方法．并提出了在操作中应注意对焊接钢筋端面要平、端部要直，焊剂使用前必须经过烘焙处理，钢筋必须夹紧、上下钢筋之间要压紧时正等关键问题。通过采用竖向钢筋电碴压力对焊工艺．提高了焊接质量，取得了较好的经济效益。     

激光焊接在汽车车体制造中的应用

用激光焊接件取代车人板整体下料毛坯，材料利用率提高９．２％。该激光焊接车门内板冲压件毛坯生产系统已投入批量生产。着重分析切边板材端面精度对接缝间隙量的影响，探讨焦点位置，激光功率，焊接速度与焊缝宽度的关系及其对焊接质量的影响。     

Prediction of the Interface Temperature Rise in Tribochemical Polishing of CVD Diamond

Tribochemcial polishing is one of the most efficient methods for polishing CVD (Chemical Vapor Deposition) diamond film due to the use of catalytic metal. However the difficulty to control the interface temperature during polishing process often results in low material removal because of the unstable contact process. So this research investigates the contact process in the tribochemical polishing of CVD diamond film and proposes a dynamic contact model for predicting the actual contact area, the actual contact pressure, and the interface temperature in the polishing process. This model has been verified by characterizing surface metrology of the CVD diamond with Talysurf CLI2000 3D Surface Topography and measuring the polishing temperature. The theoretical and experimental results shows that the height distribution of asperities on diamond film surface in the polishing process is well evaluated by combining the height distribution of original and polished asperities. The modeled surface asperity height distribution of diamond film agrees with the actual surface metrology in polishing process. The actual contact pressure is very large due to the small actual contact area. The predicted interface temperature can reach the catalytic reaction temperature between diamond and polishing plate when the lowest rotation speed and load are 10 000 r/min and 50 N, respectively, and diamond material is significantly removed. The model may provide effective process theory for tribochemcial polishing.     

基于权重粒子群算法的工件铣削温度研究

为研究铣削加工中工件的温度分布规律,推导其热传导数学模型,提出应用权重粒子群算法(Weighted particle swarm optimization, WPSO)开展时变热流密度辨识的方法,并结合试验数据对AISI1045钢在特定工况下的温度分布情况进行分析。结果表明,铣削过程中的界面热流密度呈3个阶段的非线性变化;切削初期存在缓慢温升的平台期,渡过平台期后,工件与刀具相接触部分的温度急剧上升,最高温度可达到860 ℃左右;从试验结果与解析结果的对比来看,两者误差的最大值约为11.06%,结果基本吻合。研究表明所提出的方法可以较为准确研究铣削加工过程中工件的温度分布情况。     

换档离合器摩擦片温升分析

本文通过对换档离合器摩擦片温度场分析，建立了离合器接合过程中的热传导物理模型，运用有限元求解出了摩擦片的温度分布情况及温升情况，对于离合器使用、设计具有一定的指导作用。     

基于ABAQUS的PDC钻头切削齿温度场分析与仿真

基于有限元分析软件ABAQUS的Drucker-Prager材料模型以及破坏准则,模拟PDC钻头切削齿在切削过程中的温度场,并讨论在切削过程中摩擦产生的热在切削齿后倾角的温度分布和磨损平面的温度分布情况。仿真分析结果能真实地表明在切削齿与岩石作用过程中的温度场、应力场的分布情况,为以后PDC钻头的设计提供有效的依据。     

钢塑共挤模具导入角变化对聚合物熔体流动行为影响的数值模拟分析

以聚合物挤出过程有限元模型为基础,采用自主开发的有限元分析软件对幂律型流体在钢塑共挤模具分流段的流动过程进行了非等温模拟,获得了聚合物熔体在模具分流段内的速度场和温度场分布;分析了导入角变化对聚合物熔体流动行为影响的一般规律。结果表明:仅考虑导入角变化对流动行为的影响时,速度场和温度场的分布趋势基本不变;在垂直于流动方向的截面上的速度分布和在流动区域内的最大温升会略有改变。给出的如何合理选择导入角度的建议,对模具设计与优化具有一定的指导意义。     

Temperature uniformity of the glass panel heated in the infrared heating chamber

An analysis has been carried out to investigate the effect of the reflectivity on the temperature distribution of a glass panel by infrared radiant heating. Halogen lamps are used to heat the panel, located near the top and bottom of the rectangular chamber. The thermal energy is transferred from the lamps to the panel only by radiation and it is considered by using view factor. The conductive transfer is limited inside the panel. The results show that the uniformity of the temperature distribution of the panel is improved and, at the same time, the time for heating increases as the wall reflectivity increases. The temperature difference between the center and the corner reaches a maximum in the early stage of the heating process and then decreases until it reaches a uniform steady-state value.     

Tool edge radius effect on cutting temperature in micro-end-milling process

The cutting temperature plays an important role in micro-scale cutting process due to the fact that the dimension of the micro-cutter is small and the value of micro-cutter wear is sensitive to temperature. In this paper, the temperature distribution of the micro-cutter in the micro-end-milling process has been investigated by numerical simulations and experimental approach. Micro-end-milling processes are modeled by the three-dimensional finite element method coupling thermal?Cmechanical effects. The micro-cutter cutting temperature distribution, the effect of various tool edge radii on cutting force, and the effective stress during micro-end-milling of aluminum alloy Al2024-T6 using a tungsten-carbide micro-cutter are investigated on. The simulation results show that with increase of tool edge radius the cutting force increases, while the effective stress and mean cutting temperature decreases slightly. In increasing the tool edge radius, the maximum effective stress and cutting temperature region of the micro-cutter occur from the rake face to the corner on the tool edge and the flank face. The tool edge radius has been found to be the major factor affecting micro-cutter temperature distribution. The experimental verification of the simulation model is carried out on a micro-end-milling process of aluminum alloy 2024-T6 with a high-precision infrared camera. The influence of tool edge radius on cutting temperature distribution was verified in experiments.     

面向RPST的氩氮等离子射流温度分布的测量

在假定等离子体处于局域热力学平衡与光学薄条件下 ,用谱线绝对强度法测量了在等离子熔射快速制模(RPST)过程中氩氮等离子射流的温度分布。实验由CCD装置采集等离子射流图像 ,通过标定实验建立射流图像灰度和辐射强度之间的函数关系并应用Abel变换最终得到射流的温度场分布。获取的温度场将为RPST熔射工艺的合理设计提供科学依据     

熔锥型光纤耦合器流变成形的工艺敏感性研究

基于理论与实验研究,建立了光纤耦合器熔融拉锥过程的粘弹流变力学模型,并给出了光纤耦合器非均匀温度场条件下的流变过程数值分析,获得了拉锥速度、熔融温度等流变工艺参数对器件应力分布与器件性能的影响规律。特别是熔融温度对器件应力分布的影响极为突出,熔融温度变化5℃可导致最大应力变化30%,同截面的应力差值改变20%,温度梯度变化3%可以导致锥区截面的应力差值改变90%。并发现在目前的流变工艺条件下,光纤耦合器易产生耦合区析晶、锥区微裂纹等流变缺陷,目前的流变制造技术与设备难以实现器件的微观结构与折射率均匀分布。该研究为光纤耦合器流变制造工艺与设备的改进、优化提供了基础。     

Multi-field coupling finite element analysis for determining the influence of temperature field on die service life during precision-forming process of steel synchronizer ring

Failure analysis shows that increased die temperature caused by severe plastic deformation of material and heat conduction between hot billet and cavity significantly affects the distortion of gear cavity in steel synchronizer ring forging process. The forging process of steel synchronizer ring and die temperature distribution under different forging conditions are analyzed through finite element method. Simulation results show that severe plastic deformation occurs in the gear cavity. The improvement of lubrication condition results in decreased die temperature. When the initial billet temperature is high, the die temperature is also high. Increasing forging speed in a certain range facilitates the die temperature decrease. The distribution of die temperature in synthetic forming technology is more reasonable than that of one step forging. The synthetic forming technology is adopted in production to reduce the effects of severe plastic deformation caused by die temperature. The ejection mechanism and control system of the double disc friction press are improved to reduce the contact time between the hot billet and cavity. Experimental results show that synthetic forming technology is reasonable, and that the die service life is prolonged.