装载机后车架焊接顺序优化的数值仿真

利用热弹塑性有限元法和Marc对装载机后车架的焊接变形进行数值仿真.分别用壳单元和实体单元进行仿真,对比焊接角变形,结果表明两者精度比较相似.建立后车架壳单元热-力耦合模型,定性对比在相同约束条件下焊接顺序对整个后车架结构内缩变形和面外弯曲变形的影响.结果表明,在先焊接框架焊缝的条件下,整体结构刚度增大,各种变形较小;其中,当采用正/反面焊缝、立焊缝依次焊接时,大梁下挠峰值最小,为0.002 m,从而确定后车架最佳焊接顺序方案,在该顺序下的变形模拟值与实测值吻合良好.     

基于ANSYS的MV3车轮焊接变形分析

针对汽车轮辐焊接变形影响车轮精度的问题,用ANSYS仿真分析轮辐焊接变形.采用单丝MAG焊和双丝MAG焊技术,每种焊接方法又分"先外后内焊"和"先内后外焊"2种不同的焊接工艺,得到不同热输入条件下的温度梯度场、等效应力场和焊后结构变形.分析结果表明:"先内后外焊"工艺优于"先外后内焊",且单丝MAG焊产生结构变形的最大位移约为双丝MAG焊的2倍,因此采用"先内后外焊"工艺的双丝MAG焊优势明显.     

基于有限元方法的车身B柱全工序焊接变形研究及应用

为研究不同车身结构对焊接变形的影响，对欧版原型车和产品安全措施(product safety measure, PSM)项目车型的B柱区域同时建立电阻焊有限元焊接模型。应用热弹塑性有限元方法模拟B柱区域的焊接变形量，并进行B柱区域全工序链式仿真，得到整体焊接变形量。结果表明，B柱区域在电阻焊后产生最大0.85 mm的变形，与实际变形量0.90 mm吻合。利用全工序链式仿真获得的整体变形量比各个工序简单累加的结果小，实际应用中效果良好。     

基于主S-N曲线法的地铁制动箱焊接疲劳分析

为研究地铁车辆制动箱焊接接头的疲劳寿命,根据实际结构建立4节点壳单元有限元模型,给出搭接焊和T型焊的焊缝建模方法.在3种振动工况下,运用主S N曲线法计算焊缝的等效结构应力和对应损伤比.结果表明：该地铁车辆制动箱焊接结构设计合理可靠;通过与实体单元模型计算结果进行对比证明壳单元模拟焊缝的合理性;在不同尺寸单元下对比2种疲劳评估方法,结果表明名义应力法预测疲劳寿命的准确性较低.     

机器人小车焊接构架变形预测和分析

为探究焊接变形对机器人小车碰撞性能和使用寿命的影响,基于热弹塑性固有应变法,利用仿真软件VIRFAC对机器人小车焊接构架变形进行数值模拟。通过热源校核,模拟4种典型接头的热源分布,建立固有应变数据库,分析具有282条焊缝的机器人小车整体变形规律。结果表明：机器人小车焊接构架的最大变形为2.962 mm,位于顶层边框位置。研究结果为机器人小车的焊接设计、强度和稳定性分析提供支持。     

新一代计算机焊接模拟系统与应用

一、概述 焊接工艺在工业生产中扮演着重要的角色,特别是在汽车、船舶和航天航空工业中.焊接工艺在具有众多优点的同时,也存在一些缺点,例如,冶金过程中伴随金相转变导致的热膨胀和收缩、内应力和结构的扭曲与变形.这些问题都必须得到很好地控制,尽量减少其影响.从仿真的角度来说,其目的就是在焊接工艺进行之前对结构变形和内应力进行计算,通过调整焊接参数、焊接工艺、焊接顺序、焊接位置、约束条件和材料等,优化最终的焊接结果.     

基于焊件识别与位姿估计的焊接机器人视觉引导

为实现智能化柔性化焊接,并解决焊件本身立体结构遮挡焊缝影响视觉引导的问题,提出一种基于物体识别与位姿估计思想的焊接机器人视觉引导方法.首先,通过焊件的CAD模型离线建立焊接模型库;然后,在线计算焊件点云的VFH特征,与焊接模型库进行比对实现焊件识别,计算FPFH特征实现SAC-IA和ICP结合的两步位姿估计,并通过假设验证优化结果;最后,利用焊接模型库的焊接信息结合焊件位姿生成焊接轨迹,为焊接机器人提供视觉引导.实验结果表明,所提方法可以利用目标整体三维信息准确识别焊件并估计其姿态,进而引导机器人完成智能柔性的焊接操作.     

手工焊接工具和焊接技术

在业余电子制作中,电路的制作通常采取插板焊接的形式。简单说就是对照着电路图或制作好的PCB板上的编号,把元件插进板子上面的焊孔里,再用焊接工具进行焊接,最后完成整块电路的制作。这是最常见的方式,在这里,焊接既起到连接电路的作用,又起到将元件固定在电路板上的作用（不论是洞洞板还是PCB板）。     

百万机组电厂钢煤斗焊接工艺

国电泰州电厂一期工程2x1000MW机组输煤系统钢煤斗由华东电力设计院设计,每台炉设计6只煤斗,每只煤斗重133892.8kg.煤斗可分为五大部分,即锥体、环梁、方圆节、顶盖和止晃梁. 煤斗的材质为Q235B,止晃梁的材质为Q345B,内衬不锈钢为1Cr 18Ni9Ti. 煤斗的制作焊接采用手工电弧焊、CO2气体保护焊和埋弧焊.手工电弧焊主要用于煤斗的对接焊缝、顶盖的对接焊缝和不锈钢的焊接;CO2气体保护焊主要用于煤斗的加固筋焊接;埋弧焊主要用于方圆节三角形板的对接焊缝.     

五自由度激光焊接器智能控制系统设计

激光焊接装置能够焊接难焊的薄板合金材料,且具有构件变形小、接头质量高、重现性好、易于进行自动化控制实现柔性加工和智能加工等优点.为优化智能焊接系统,设计了具有五个自由度的集成激光焊接装置.该系统解决了传统激光焊接设备对工艺参数调节困难和自动化程度低等技术缺陷.仿真与试验研究表明,该系统满足了设计要求.     

基于模态瞬态法的发动机罩焊点疲劳优化

针对某车型整车耐久路试过程中发动机罩铰链加强板焊点出现开裂的问题,采用模态瞬态法对发动机罩焊点进行疲劳分析。根据发动机罩模态应变能分布情况优化铰链加强板结构和焊点分布,试验车整改后在整车耐久路试中发动机罩焊点未再出现开裂现象。发动机罩铰链加强板焊点开裂是振动疲劳问题,采用基于惯性释放的准静态法计算疲劳损伤不能预测焊点开裂问题,采用模态瞬态法疲劳计算方法才能更好地预测发动机罩焊点疲劳损伤。从模态应变能角度对结构振动疲劳开裂问题进行优化能明显提高优化效率。     

铝合金焊接熔池图象传感器

采用图象处理与模式识别的方法对铝合金的焊接质量进行智能控制还没有成功 ,因为铝合金表面不同于其它黑色金属 ,铝合金表面反射全波段的可见光 ,熔池与周围金属的灰度对比度极弱 ,在焊接电流较大时弧光强烈 ,弧光以及熔池周围金属的反射光足以掩盖熔池 ,普通的光学传感器无法在上述苛刻条件下取得铝合金焊接熔池区域的图象。通过光谱分析 ,可以设计全新的光学传感器 ,利用普通工业CCD摄像机获得清晰的铝合金焊接熔池区域图象 ,为铝合金智能化焊接打下了良好的基础     

汽车车身点焊机器人焊钳分析

本文着重介绍现阶段焊接机器人的优点和机器人焊钳的主要结构形式，并对不同的机器人焊钳的结构进行介绍和分析，指出其优缺点和适用范围。通过多方面分析，本文指出现阶段点焊机器人焊钳采用中频变压器和伺服电机驱动时，焊接质量最好。     

Effect of welding sequences on residual stresses

Accurately predicting welding residual stresses and developing an available welding sequence for a weld system are pertinent tasks since welding residual stress is inevitably produced in a welded structure. This study analyzes the thermomechanical behavior and evaluates the residual stresses with various types of welding sequence in single-pass, multi-pass butt-welded plates and circular patch welds. This is achieved by performing thermal elasto-plastic analysis using finite element techniques. Furthermore, this investigation provides an available welding sequence to enhance the fabrication process of welded structures.     

Numerical analysis on snapping induced by electromechanical interaction of shuffling actuator with nonlinear plate

When a voltage is applied between two electrodes consisting of a rigid ground and a deformable rectangular plate that has two parallel free edges, and one movable edge and one fixed edge, the plate bends under the electrostatic force generated in it. Accompanying to the bending deformation, the movable edge of the plate results in some displacement along the movable direction, which is the main clue of the MEMS actuator of shuffling movement. As the control voltage is applied up to a critical value, the phenomenon of snapping occurs at the plate electrode under the interaction of electromechanical coupling such that the shuffling displacement is obtained as possibly as large. Based on the nonlinear theory of plates with the von Karman’s type deformation and the electrostatic theory, a theoretical analysis for the snapping behavior is quantitatively displayed in this paper. For this purpose, a numerical code is proposed by associating the increment finite element methods for deformation with the moment method for electrostatic fields as well as the arc-length control approach in the quantitative calculations. The numerical results for some case studies show that the path of bending deformation from stability into instability passing through the snapping criterion can be tracked well by this numerical code, while the characteristic curves of the maximum deflection in the plate and the shuffling displacement versus the control voltage, which are mainly concerned in the design of the MEMS shuffling actuator, are obtained additionally.     

Control of human arm movement in machine-human cooperative welding process

This paper studies accurate control of human arm movement in machine-human cooperative control of GTAW process. An innovative teleoperated virtualized welding platform is utilized to conduct dynamic experiments to correlate the human welder arm movement with the visual signal input. An adaptive ANFIS model is proposed to model the intrinsic nonlinear and time-varying characteristic of the human welder response. A model based predictive control algorithm is then proposed and an analytical solution is derived. Human control experimental results verify that the proposed controller is able to track varying set-points and is robust under measurement and input disturbances.     

Effect of cold bending and welding on buckling of ring-stiffened cylinders

The BOSOR5 computer program for elastic plastic buckling of shells of revolution is used for calculation of bifurcation buckling of cold bent and welded ring-stiffened cylinders under external pressure. Residual stresses and deformations from cold bending and welding are included in the model for buckling under service loads by introduction of these manufacturing processes as functions of a time-like parameter which ensures that the material in the analytical model experiences the proper sequence of loading prior to and during application of the service loads. The cold bending process is first simulated by a thermal loading cycle in which the temperature varies linearly through the shell wall thickness, initially increasing in time to simulate cold bending around a die and then decreasing in time to simulate springback to a final somewhat larger design radius. The welding process is subsequently simulated by the assumption that the material in the immediate neighborhoods of the welds is cooled below the ambient temperature by an amount that leads to weld shrinkage amplitudes typical of those observed in tests. Buckling loads are calculated for a configuration including and neglecting the cold bending and welding processes. These predictions are compared to values obtained from tests on two nominally identical specimens, one carefully machined and the other fabricated by cold bending the shell and then welding machined ring stiffeners to it.