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Study of Dynamic Features of Surface Plasma in High-Power Disk Laser Welding

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Plasma Science and Technology 2012年第3期14卷 245-251页

作者：王腾高向东 katayama seiji 金小莉 Faculty of Electromechanical Engineering Guangdong University of Technology School of Computer South China Normal University Joining and Welding Research Institute Osaka University11-1 MihogaokaIbarakiOsaka 567-0047Japan

High-speed photography was used to obtain the dynamic changes in the surface plasma during a high-power disk laser welding process. A color space clustering algorithm to extract the edge information of the surface plasma region was developed in order to improve the accuracy of image processing. With a comparative analysis of the plasma features, i.e., area and height, and the characteristics of the welded seam, the relationship between the surface plasma and the stability of the laser welding process was characterized, which provides a basic understanding for the real-time monitoring of laser welding.

关键词： plasma feature color image processing disk laser welding

Novel inspection of welded joint microstructure using magneto-optical imaging technology

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Chinese Physics B 2017年第5期26卷 209-214页

作者：高向东李正文游德勇 seiji katayama School of Electromechanical Engineering Guangdong University of Technology Joining and Welding Research Institute Osaka University 11-1 Mihogaoka

A novel method for measuring differences of microstructure by advanced use of the Faraday magneto-optical effect is proposed. Two groups of YAG laser welds on Q235 have been investigated in order to compare MO imaging and traditional methods. Microstructure images have been compared with MO images, and MO diagrams display different colors and gray scales for the base metal, the weld zone, and the heat affected zone. Experimental results indicate that the welded joint microstructure can be inspected by MO imaging without metallographic preparation.

关键词： welded inspection magneto colors welding magnetization coercivity pixel rotation captured

The mechanism of penetration increase in A-TIG welding

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Frontiers of Materials Science 2011年第2期5卷 109-118页

作者： Rui-Hua ZHANG Ji-Luan PAN seiji katayama Department of Mechanical Engineering Tsinghua University Beijing 100084 China Joining and Welding Research Institute Osaka University 11-1 Mihogaoka Ibaraki Osaka 567-0047 Japan

The mechanism of the increasing of A-TIG welding penetration is studied by using the activating flux we developed for stainless steel, The effect of fluxon the flow and temperature fields of weld pool is simulated by the PHOENICS software, It shows that without flux, the fluid flow will be outward along the surface of the weld pool and then down, resulting in a flatter weld pool shape. With the flux, the oxygen, which changes the temperature dependence of surface tehsion grads froma negative value toa positive value, can cause significant changes onthe Weld penetration. Fluid flow will be inward along the surface of the weld pool toward the center and then down. This fluid flow pattern efficiently transfers heat to the weld root and produces a relatively deep and narrow *** change is the main cause of penetration increase. Moreover, arc construction can cause the weld width to become narrower and the penetration to become deeper, but this is not the main cause of penetration increase. The effects Of flux on fluid flow of the weld pool surface and arc profiles were observed in conventiOnai TIG welding and in A-TIG welding by using high-speed video camera; The fluid flow behavior was visualized in realtime scale by micro focused X-ray transmission video observation system. The result indicated that stronger inward fluid flow patterns leading to weld beads with narrower width and deeper penetration could be apparently identified in the case of A-TIG *** flux couldchange the direction of fluid flow i-n welding pool. It has a good agreement with the simulation result.

关键词： A-TIG welding penetration increase, numerical simulation, X-ray, highspeed video camera

Online Monitoring of Welding Status Based on a DBN Model During Laser Welding

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Engineering 2019年第4期5卷 671-678页

作者： Yanxi Zhang Deyong You Xiangdong Gao seiji katayama Guangdong Provincial Welding Engineering Technology Research Center Guangdong University of TechnologyGuangzhou 510006China Joining and Welding Research Institute Osaka UniversityOsaka 567-0047Japan

In this research,an auxiliary illumination visual sensor system,an ultraviolet/visible(UVV)band visual sensor system(with a wavelength less than 780 nm),a spectrometer,and a photodiode are employed to capture insights into the high-power disc laser welding *** features of the visible optical light signal and the reflected laser light signal are extracted by decomposing the original signal captured by the photodiode via the wavelet packet decomposition(WPD)*** captured signals of the spectrometer mainly have a wavelength of 400-900 nm,and are divided into 25 sub-bands to extract the spectrum features by statistical *** features of the plume and spatters are acquired by images captured by the UVV visual sensor system,and the features of the keyhole are extracted from images captured by the auxiliary illumination visual sensor *** on these real-time quantized features of the welding process,a deep belief network(DBN)is established to monitor the welding status.A genetic algorithm is applied to optimize the parameters of the proposed DBN *** established DBN model shows higher accuracy and robustness in monitoring welding status in comparison with a traditional back-propagation neural network(BPNN)*** effectiveness and generalization ability of the proposed DBN are validated by three additional experiments with different welding parameters.

关键词： Online monitoring Multiple sensors Wavelet packet decomposition Deep belief network

Interpretation of Laser Weld Penetration and Welding Phenomena (Invited Paper)

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中国激光 2009年第12期36卷 3160-3166页

作者： seiji katayama Yousuke Kawahito Joining and Welding Research Institute Osaka UniversityOsaka 567-0047Japan

Deeply penetrated welds can be produced with high-power-density *** the factors affecting laser weld penetration,laser-induced plume behavior and the interaction between a laser beam and a plume,keyhole behavior,melt flows in the molten pool,and the generation and prevention of bubbles and porosity were ***,the effects of plasma and plume on the weld penetration were interpreted in CO2 and fiber lasers welding,*** formation of spattering,underfilled beads,and humping was *** was confirmed that porosity was easily formed at high powers and low welding speeds due to the generation of many bubbles from the tip of a keyhole.

关键词：激光焊接技术激光诱导二氧化碳激光器

Analysis of high-power disk laser welding stability based on classification of plume and spatter characteristics

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Transactions of Nonferrous Metals Society of China 2013年第12期23卷 3748-3757页

作者：高向东文茜 seiji katayama 广东工业大学机电工程学院广州510006 大阪大学接合科学研究所

Classification of plume and spatter images was studied to evaluate the welding stability. A high-speed camera was used to capture the instantaneous images of plume and spatters during high power disk laser welding. Characteristic parameters such as the area and number of spatters, the average grayscale of a spatter image, the entropy of a spatter grayscale image, the coordinate ratio of the plume centroid and the welding point, the polar coordinates of the plume centroid were defined and extracted. Karhunen-Loeve transform method was used to change the seven characteristics into three primary characteristics to reduce the dimensions. Also, K-nearest neighbor method was used to classify the plume and spatter images into two categories such as good and poor welding quality. The results show that plume and spatter have a close relationship with the welding stability, and two categories could be recognized effectively using K-nearest neighbor method based on Karhunen-Loeve transform.

关键词： high-power disk laser welding plume spatter feature classification stability

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大功率光纤激光焊焊缝跟踪偏差测量新方法

焊接学报 2011年第5期32卷 49-52,115页

作者：高向东游德勇 katayama seiji 广东工业大学机电工程学院广州510006 日本大阪大学接合科学研究所

针对大功率光纤激光焊,分析一种基于近红外图像识别的焊缝跟踪偏差测量新方法.通过高速摄像机获取动态熔池近红外图像序列,分析熔池近红外图像的灰度分布特性,利用图像灰度梯度提取熔池温度分布参数.该参数能够体现激光束偏离焊缝时熔... 详细信息

针对大功率光纤激光焊,分析一种基于近红外图像识别的焊缝跟踪偏差测量新方法.通过高速摄像机获取动态熔池近红外图像序列,分析熔池近红外图像的灰度分布特性,利用图像灰度梯度提取熔池温度分布参数.该参数能够体现激光束偏离焊缝时熔池表面温度的变化特性.以熔池温度分布参数作为特征测量值,利用最小二乘法建立焊缝路径与激光束偏离的近红外视觉模型.结果表明,该模型能够准确地反映熔池温度分布参数与焊缝跟踪偏差之间的数学关系.

关键词：大功率光纤激光焊焊缝跟踪近红外图像偏差测量

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焊缝偏差RBF神经网络预测算法

焊接学报 2012年第4期33卷 1-4,113页

作者：高向东莫玲游德勇 katayama seiji 广东工业大学机电工程学院广州510006 大阪大学接合科学研究所

以10 kW大功率光纤激光焊接304奥氏体不锈钢板为试验对象,研究一种焊缝偏差预测算法.利用红外摄像机摄取焊接过程中的熔池红外图像,提取匙孔质心、匙孔形状参数和热堆积效应参数等反映激光束与焊缝位置偏差的特征量作为径向基函数RBF神... 详细信息

以10 kW大功率光纤激光焊接304奥氏体不锈钢板为试验对象,研究一种焊缝偏差预测算法.利用红外摄像机摄取焊接过程中的熔池红外图像,提取匙孔质心、匙孔形状参数和热堆积效应参数等反映激光束与焊缝位置偏差的特征量作为径向基函数RBF神经网络预测模型的输入量,建立焊缝偏差RBF神经网络预测模型.选择焊缝偏差特征量作为训练样本并对预测模型进行训练,建立焊缝偏差预测模型.结果表明,该模型能够对大功率光纤激光焊接过程中的激光束与焊缝位置之间的偏差进行有效预测.

关键词：大功率光纤激光焊 RBF神经网络焊缝偏差预测

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色噪声下卡尔曼滤波焊缝跟踪算法与试验研究

控制理论与应用 2011年第7期28卷 931-935页

作者：高向东仲训杲游德勇 katayama seiji 广东工业大学机电工程学院广东广州510006 大阪大学接合科学研究所

精确控制激光束使其始终对中并跟踪焊缝是保证激光焊接质量的前提.以大功率光纤激光焊接Type304不锈钢为试验对象,研究一种有色噪声环境下应用卡尔曼滤波最优状态估计预测激光束与焊缝路径偏差的方法.使用高速红外视觉传感器摄取焊接区... 详细信息

精确控制激光束使其始终对中并跟踪焊缝是保证激光焊接质量的前提.以大功率光纤激光焊接Type304不锈钢为试验对象,研究一种有色噪声环境下应用卡尔曼滤波最优状态估计预测激光束与焊缝路径偏差的方法.使用高速红外视觉传感器摄取焊接区红外热像,提取焊缝位置参数并构成状态向量,建立基于焊缝位置参数的系统状态方程和焊缝位置测量方程.针对系统动态噪声为有色噪声,通过扩展状态变量的方法建立有色噪声环境下的卡尔曼滤波算法,对焊缝位置进行最优状态估计并得到最小均方差条件下的焊缝偏差最优预测值,消除系统噪声对焊缝偏差测量的影响.焊接试验结果表明新方法可有效抑制有色噪声干扰并提高焊缝跟踪精度.

关键词：焊缝跟踪色噪声卡尔曼滤波大功率光纤激光焊