特定形状焊缝MAG焊成形工艺在转向架生产中的应用

针对转向架构架结构的复杂特点,分析焊缝成形的工艺难点,通过设计分析和试验验证,得出一种特定形状或尺寸焊缝的成形工艺,通过采用与特定形状焊缝外形相同的陶瓷垫板,实现了特定形状焊缝的MAG焊直接成形,既减少了焊接填充量,显著减少焊后打磨工作量,又避免了堆焊特定形状焊缝时频繁的起弧、收弧作业,从而提高了焊缝质量,显著提升转向架构架焊接生产效率.此项技术已在部分转向架构架生产中得到了应用和推广,具有重要意义.     

弧焊机器人焊接工艺参数设计系统研究

设计了基于BP神经网络的弧焊机器人焊接工艺参数设计系统,该系统可以由表征焊接形状的焊缝几何尺寸值映射出具体的焊接工艺参数.通过正交设计法采集样本数据,建立了对应的神经网络模型.利用已建立的网络模型,设计了焊接工艺参数.通过焊接实验,分析了焊缝几何参数理论值和焊接实测值的误差,结果表明所设计的网络具有一定的工艺参数设计能力,几何参数误差在允许范围内,焊缝成形效果良好.     

基于线激光扫描的工业焊缝外观检测系统

文中针对表面带有鱼鳞纹的焊缝提出了工业焊缝外观检测算法:采用高维最小二乘法来拟合焊缝轮廓线,求取拟合轮廓线的二阶导数来确定焊趾范围;并基于拟合轮廓与实际轮廓间的位置偏差提取特征点,进而得到工业焊缝的形状参数.基于上述算法,开发和调试工业焊缝检测的软硬件系统.试结果表明,针对表面有鱼鳞纹的焊缝该算法可以稳定、准确、快速的进行检测.工业应用表明,该系统可稳定实现焊缝轮廓数据的快速采集.通过该系统实现对采样数据的处理计算,最后得到准确的检测结果.     

机器人多层多道焊缝激光视觉焊道的识别

厚板多层多道焊缝形状特征的自动识别,对保证焊接质量和实现机器人自动化焊接生产具有重要意义.文中建立了基于条形激光源CCD视觉传感多道焊缝自动检测系统,通过对多道焊缝激光条纹图像特征的分析,提出了合理的图形处理识别流程,即经过图像平滑处理、纵向灰度梯度法识别条纹中心、再经过二重斜率平滑处理、多个峰值搜索等处理流程,可获得焊缝形状的四个拐点,为焊缝跟踪、弧长控制和焊枪位姿调整提供了重要的信息,其图像处理结果与试验结果相吻合.     

焊缝含Ⅰ型单边裂纹低匹配平余高对接接头形状参数对形状因子的影响

基于有限单元法针对焊缝含Ⅰ型单边裂纹的低匹配平余高对接接头形状设计,以最大限度提高接头的承载能力以及更准确地对其进行安全评定为目标,从断裂力学角度出发,考察了焊缝含Ⅰ型单边裂纹的低匹配平余高对接接头各形状参数,即焊缝余高高度、余高宽度和焊趾圆弧过渡半径,对其形状因子的影响.结果表明,焊缝余高高度对焊缝含Ⅰ型单边裂纹的低匹配平余高对接接头形状因子影响最为显著,余高宽度和焊趾圆弧过渡半径的影响较小.采用传统的不考虑余高高度时的形状因子指导焊缝含Ⅰ型单边裂纹低匹配平余高对接接头的形状设计是不合理的.选择合适的形状参数可以提高焊缝含Ⅰ型单边裂纹低匹配平余高对接接头的承载能力.     

螺旋缝焊管焊缝形状预测

以生产现场收集的试样数据为依据,利用回归分析与神经网络研究螺旋缝焊管焊缝形状参数(余高、熔深及熔宽)与焊接工艺参数(焊接电流、电弧电压与焊速)之间的关系,从而达到预测焊缝形状的目的。最终成功地利用BP神经网络创建了单丝焊准559mm×8.8mm与双丝焊准1219mm×17.2mm这2种规格焊管外焊缝形状预测模型,并且创建了螺旋缝焊管焊缝形状预测系统。     

三维焊缝图像传感技术

介绍一种采用光栅莫尔条纹技术的三维焊缝图像传感系统,它由交角很小的两块黑白透射光栅和CCD摄像机镜头等元件构成,根据系统的光路结构找出变形的莫尔条纹相对焊缝的上表面相对偏移量与焊缝形貌的函数关系,得到焊缝的三维信息.阐述了实现方法以及图像处理过程,并进行了获取焊缝三维图像的试验.结果表明,这种光栅莫尔条纹三维测量技术提取图像信息简单,可以获得焊缝的边缘形状和焊缝坡口的大致形貌,适用于焊缝图像的精确特征识别和提取.     

家电压缩机智能开箱设备及其工艺研究

针对家电压缩机箱体形状不规则的特点,设计了一种专用的压缩机箱体智能拆解设备,拟定了一套可行的拆解工艺,搭建了开箱设备的测控系统。利用图像智能识别技术确定压缩机箱体环形焊缝的高度位置,并控制刀具自动寻找切入点;利用激光测距传感器控制切割刀具在周长方向自动跟踪压缩机箱体焊缝,保证切深恒定,不会伤及内部零件,从而实现智能控制、跟踪切割。该设备实现了家电压缩机的高效、自动化、批量化拆解,体现了家电产品的绿色回收理念。     

焊缝截面形态的数学模型、预测与焊接规范参数的设计

采用正交试验设计和数理统计的方法,建立了焊缝截面形态的多项式回归模型,同时获得了焊缝截面几何形状参数与焊接规范参数的多元回归模型。为焊缝截面形态的预测及焊接规范参数的设计提供了依据。     

大型构件水下焊接机器人系统

针对水下焊接环境要求,设计了一种履带式水下焊接机器人系统,该系统由机器人本体机构、激光视觉传感器、控制系统和焊接系统组成. 机器人本体机构由履带式移动平台和焊枪调节机构构成,运动灵活可靠,满足水下焊接焊缝跟踪要求. 完成了视觉传感器部件选型及光路设计,实现水下环境的焊缝自动识别. 设计了基于PLC机器人控制系统和协调控制方法,实现水下环境的焊缝跟踪控制. 同时在水下焊接试验平台完成焊接跟踪试验. 结果表明,机器人运行稳定,焊缝成形较好,焊接质量满足要求.     

CMT工艺及其热输入对Al-Cu合金焊缝成形和气孔的影响

采用四种冷金属过渡焊接工艺(CMT)分别在不同热输入水平下,使用ER2319焊丝进行AA2219-T851高强铝合金的平板堆焊成形,全面分析其焊缝成形和气孔分布特征。结果表明,常规CMT焊缝具有明显指状熔深特征,气孔缺陷严重并呈全焊缝分布状态;CMT-P焊缝母材熔化面积明显增加,气孔数量显著减少且在适当控制热输入时有助于消除气孔;CMT-ADV焊缝也具有指状熔深特征但熔深显著减小;CMT-PADV焊缝具有显著球形熔滴成形特征且熔深最小,两工艺低热输入和对焊丝表面氧化膜的清理作用有助于消除气孔。     

Effect of tool geometry on hook formation and static strength of friction stir spot welded aluminum 5754-O sheets

Friction stir spot welding is performed on 5754 Al alloy to investigate the effect of tool geometry on hook formation. Partial metallurgical bond (called as ‘hook’) is formed in the weld region between the overlapped metal sheets. The tool geometry is found to significantly affect the hook formation. First, welds are made to compare the effect of three shoulder profiles: concave, convex and flat (all having threaded cylindrical pins) on the hook geometry and static strength. The inherent concave profile resulted in a higher effective top sheet thickness that produced the highest weld strength. Next, with the concave shoulder profile selected, the effects of two different pin profiles: cylindrical and triangular are evaluated. Under the same process condition, welds made with the cylindrical pin have a continuous hook which bypasses the stir zone and terminates close to the keyhole. By contrast, for welds made with the triangular pin, the hook is directed upwards and then arrested at the periphery of the stir zone. The difference in the hook shape can be attributed to the material flow. Prior study shows that the static strength of welds made with the triangular pin is twice that of welds made with the cylindrical pin.     

Effect of shielding gas and activating flux on weld bead geometry in tungsten inert gas welding of austenitic stainless steels

Abstract

The aim of this study was to investigate the influence of three shielding gases (argon and argon–hydrogen and argon–helium mixtures) and two activating fluxes (a commercial flux and a TiO₂ based flux) on the geometry of welds produced by the tungsten inert gas (TIG) welding process on several casts of austenitic stainless steel AISI 316, using currents ranging from 100 to 300 A. Penetration depth increases with increasing current for all shielding gases, but weld depth to width ratio is higher for argon than for argon–hydrogen shielded welds. Both activating fluxes produce a substantial increase in penetration depth and in depth to width ratio of the welds. No correlation was found between penetration depth and oxygen content in the melted material. Some interaction exists between activating fluxes and shielding gases, which can affect the weld geometry and/or the defect formation in the welds.     

Modeling, optimization and classification of weld quality in tungsten inert gas welding

In this paper, a neural network is used to construct the relationships between welding process parameters and weld pool geometry in tungsten inert gas (TIG) welding. An optimization algorithm called simulated annealing (SA) is then applied to the network for searching the process parameters with an optimal weld pool geometry. Finally, the quality of aluminum welds based on the weld pool geometry is classified and verified by a fuzzy clustering technique. Experimental results are presented to explain the proposed approach.     

激光+GMAW复合热源焊焊缝成形的数值模拟Ⅱ.组合式体积热源的作用模型

根据激光 脉冲GMAW电弧复合热源焊焊缝横断面的形状特点,从宏观的传热过程出发,提出了4类新颖的、适用的组合式体积热源的作用模式.将电弧热、熔滴热焓和激光热能分别描述为双椭圆分布,双椭球体分布和峰值热流递增-曲面旋转体分布.将适用的组合式体积热源作用模式应用于复合焊的温度场数值分析,计算出了不同工艺条件下的复合焊焊缝形状尺寸,与实测结果进行了对比,两者吻合情况良好.所建立的4类组合式体积热源充分考虑了复合焊的工艺特点,对焊缝形状尺寸的数值模拟精度较高,能定量体现温度场的变化规律.     

镀锌钢板电阻点焊的多元非线性回归模型

为了研究用于家用轿车车身制造的镀锌钢板电阻点焊工艺,采用多元非线性回归正交组合的方法设计试验.试验将电阻点焊熔核形状参数和焊接接头抗剪强度作为考察指标,将焊接电流、电极压力、通电时间、预热电流四个参数,以及各参数之间的交互作用作为影响指标的考察因素,得到可预测熔核形状和焊接接头力学性能的四元二次回归数学模型,并通过方差分析对模型进行优化.结果表明,优化的回归数学模型可实现焊接接头熔核成形及力学性能较为准确的预测.在模型的基础上研究各参数及各交互作用对焊点质量的影响规律,从而可实现电阻点焊工艺参数的优化设计.     

Sensitivity analysis for process parameters in GMA welding processes using a factorial design method

Generally, the quality of a weld joint is strongly influenced by process parameters during the welding process. In order to achieve high quality welds, mathematical models that can predict the bead geometry and shape to accomplish the desired mechanical properties of the weldment should be developed. This paper focuses on the development of mathematical models for the selection of process parameters and the prediction of bead geometry (bead width, bead height and penetration) in robotic GMA (Gas Metal Arc) welding. Factorial design can be employed as a guide for optimization of process parameters. Three factors were incorporated into the factorial model: arc current, welding voltage and welding speed. A sensitivity analysis has been conducted and compared the relative impact of three process parameters on bead geometry in order to verify the measurement errors on the values of the uncertainty in estimated parameters. The results obtained show that developed mathematical models can be applied to estimate the effectiveness of process parameters for a given bead geometry, and a change of process parameters affects the bead width and bead height more strongly than penetration relatively.     

反应堆压力容器安全端异种金属焊缝超声检查技术

堆焊层、奥氏体粗晶材料的存在以及焊缝几何结构的复杂性使得反应堆压力容器安全端异种金属焊缝的超声检查非常具有挑战性。为提高安全端异种金属焊缝超声检查的可靠性和检查效率,利用常规双晶纵波检查技术及相控阵检查技术开展了安全端异种金属焊缝超声检查技术研究。试验结果表明,常规双晶纵波检查技术及相控阵检查技术均可有效检出安全端异种金属焊缝中的缺陷,且缺陷定量精度满足相关规范要求。其中,常规双晶纵波检查技术现已应用到核电站的役前检查及在役检查中,相控阵检查技术的缺陷定量精度及检查效率均优于常规双晶纵波检查技术。     

基于神经网络的316L不锈钢激光焊焊缝形貌预测

在316L不锈钢的激光焊接过程中,其焊接工艺参数直接影响焊缝的形貌,建立焊接工艺参数与焊缝几何形状之间的关系对于优化焊接工艺参数,降低焊接成本非常重要. 根据316L不锈钢焊缝二维不光滑轮廓形貌特点,采用分段函数思想,分别使用Hermite插值和最小二乘拟合的方法描述焊缝轮廓,构建广义回归神经网络焊缝二维形貌预测模型. 结果表明,采用Hermite插值的方法能够获得更准确的焊缝形貌,其平均相对误差为?3.49%. 该模型为316L不锈钢激光焊焊缝预测提供一种有效方法.     

Analysis of effect of tool geometry on plastic flow during friction stir spot welding using particle method

The effect of tool geometry on the plastic flow and material mixing during friction stir spot welding (FSSW) is investigated using the particle method approach. For spot welds made with a cylindrical pin tool with flat shoulder, the model predicts the material flow at the pin periphery to be in the upward direction and the material is pushed downward beneath the shoulder giving rise to the resultant hook geometry. Other pin geometries evaluated include tapered pin, inverse tapered pin, triangular pin, convex shoulder, and concave shoulder. With good correlation with experimental trials, this model is then used to predict the material flow for spot welds. The material flow, and thereby the resultant hook formation, is quantified using numerical methods and is expressed as standard deviation of the particle movement. A triangular pin with a concave shoulder is the preferred tool geometry from the current study that results in high strength spot welds.