The Experts below are selected from a list of 273 Experts worldwide ranked by ideXlab platform
De Xu - One of the best experts on this subject based on the ideXlab platform.
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compact visual control system for aligning and tracking narrow butt seams with co2 gas shielded arc Welding
The International Journal of Advanced Manufacturing Technology, 2012Co-Authors: De Xu, Zaojun Fang, Haiyong ChenAbstract:In this paper, a visual control system is proposed to locate the start Welding Position and track the narrow butt Welding seam in container manufacturing. It estimates the error between the Welding torch and the Welding seam with a camera and a panel computer. It adjusts the torch's Position via a stepper motor to eliminate the error. A decision controller with three gates is designed to decide the working procedure. Feature extraction algorithms are designed according to the seams and pre-weld spots. The seam line and the Position of the pre-weld spot are detected to locate the start Welding Position in initial aligning. Then the torch is aligned to the seam. In the Welding stage, the reference feature is determined with many frames of images based on their statistical property. The current estimated feature is checked to ensure only normal features to be used for Welding seam tracking. Experiments are well conducted to verify the effectiveness of the proposed system and methods.
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a visual servoing system for the torch alignment to initial Welding Position
International Conference on Intelligent Robotics and Applications, 2008Co-Authors: De Xu, Yuan LiAbstract:It is an important aspect to locate the initial Welding Position automatically. In this paper, a visual servoing system is proposed. Two CCD cameras are employed as the senseors to get the information of the Welding seam. The designed visual servoing controller, which is based on Takigi-Sugeno (T-S) fuzzy model, is applied to the stepper motors to adjust the Welding torch in the up-down and left-right direction. Experimental results are provided to demonstrate the validity of the proposed system.
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ICIRA (2) - A Visual Servoing System for the Torch Alignment to Initial Welding Position
Intelligent Robotics and Applications, 2008Co-Authors: De Xu, Yuan LiAbstract:It is an important aspect to locate the initial Welding Position automatically. In this paper, a visual servoing system is proposed. Two CCD cameras are employed as the senseors to get the information of the Welding seam. The designed visual servoing controller, which is based on Takigi-Sugeno (T-S) fuzzy model, is applied to the stepper motors to adjust the Welding torch in the up-down and left-right direction. Experimental results are provided to demonstrate the validity of the proposed system.
Yuan Li - One of the best experts on this subject based on the ideXlab platform.
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a visual servoing system for the torch alignment to initial Welding Position
International Conference on Intelligent Robotics and Applications, 2008Co-Authors: De Xu, Yuan LiAbstract:It is an important aspect to locate the initial Welding Position automatically. In this paper, a visual servoing system is proposed. Two CCD cameras are employed as the senseors to get the information of the Welding seam. The designed visual servoing controller, which is based on Takigi-Sugeno (T-S) fuzzy model, is applied to the stepper motors to adjust the Welding torch in the up-down and left-right direction. Experimental results are provided to demonstrate the validity of the proposed system.
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ICIRA (2) - A Visual Servoing System for the Torch Alignment to Initial Welding Position
Intelligent Robotics and Applications, 2008Co-Authors: De Xu, Yuan LiAbstract:It is an important aspect to locate the initial Welding Position automatically. In this paper, a visual servoing system is proposed. Two CCD cameras are employed as the senseors to get the information of the Welding seam. The designed visual servoing controller, which is based on Takigi-Sugeno (T-S) fuzzy model, is applied to the stepper motors to adjust the Welding torch in the up-down and left-right direction. Experimental results are provided to demonstrate the validity of the proposed system.
K.-C. Ahn - One of the best experts on this subject based on the ideXlab platform.
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An optical sensing system for seam tracking and weld pool control in gas metal arc Welding of steel pipe
Journal of Materials Processing Technology, 2002Co-Authors: K.y. Bae, T.h. Lee, K.-C. AhnAbstract:A visual sensing system was developed for automatic gas metal arc Welding (GMAW) of the root pass of steel pipe. The system consisted of a vision sensor that consisted of a charge-coupled device (CCD) camera and lenses, a frame grabber, image processing algorithms, and a computer controller. A specially designed five-axis manipulator was used to Position the Welding torch and to provide the vision sensor with automatic access to view the Welding Position. During the root pass Welding, an image of the weld pool and its vicinity was captured using the camera without interference of the intensive arc light by viewing at the instance of a short-circuit of the Welding power. The captured image was then processed to recognize the weld pool shape. For seam tracking, the manipulator was used to adjust the torch Position based upon the pool image to the groove center. The measured gap size was used to determine the appropriate Welding conditions to obtain sound penetration. The Welding speed was chosen using fuzzy logic with the knowledge of a skilled welder and measured gap. The automatic Welding equipment demonstrated that both Welding conditions and torch Position could be appropriately controlled to obtain a sound weldment and a good seam tracking capability. ?? 2002 Elsevier Science B.V. All rights reserved.
Lin Li - One of the best experts on this subject based on the ideXlab platform.
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Laser Welding of high strength steels (S960 and S700) with medium thickness
Journal of Laser Applications, 2016Co-Authors: Wei Guo, John A. Francis, Dave Crowther, Shiyun Dong, Lin Li, Alan ThompsonAbstract:© 2016 Laser Institute of America. S960 and S700 are two types of new high strength low alloy (HSLA) steels recently developed by Tata Steel, which are used for heavy lifting equipment. Little is known on their Welding characteristics with high-energy beams. In this study, single pass autogenous laser Welding (ALW) and multipass ultranarrow gap laser Welding (NGLW) were carried out using a 16 kW IPG fiber laser to examine the weldability of these HSLA steels up to 13 mm in thickness. It was found that cracking in the welded joints could be avoided. It is beneficial to use horizontal (2G) Welding Position to avoid melt sagging when Welding thick section S700 steel plates in a single pass ALW process. The fast cooling rate for the ALW of 8 mm thick S960 steel and ultra-NGLW of both the 8 mm thick S960 and 13 mm thick S700 steels causes the generation of hard martensite in the fusion zone (FZ) and heat affected zone (HAZ). This could strengthen the laser welded HSLA steel joints, but would deteriorate the toughness of the welded joints. A relatively higher heat input was used to weld the 13 mm thick S700 steel using a single pass ALW process, which causes the formation of bainite in the FZ, while hard martensite and bainie were formed in the HAZ. All the ALW and ultra-NGLW S960 and S700 steels presented almost the same tensile strengths as the base materials and also retained the elongation of the laser welded specimens, quite unexpected.
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Comparison of processing window and porosity distribution in laser Welding of 10 mm thick 30CrMnSiA ultrahigh strength between flat (1G) and horizontal (2G) Positions
Journal of Laser Applications, 2016Co-Authors: Xianfeng Shen, Wenhua Teng, Wei Guo, Lin Li, Wenpei HeAbstract:© 2016 Laser Institute of America. With the development of high brightness and high power laser, it is possible to weld thick sections using single pass autogenous laser Welding. However, it often suffers from very narrow processing parameter windows when Welding thick sections. Furthermore, porosity, back sagging, and undercut are the main defects for laser Welding of thick section high strength steel plates. A comparison of flat Welding Position (1G) and horizontal Welding Position (2G) in laser welded 10 mm thick 30CrMnSiA high strength steel plates was investigated in this paper. The results show that the 1G Position has a very narrow processing window, while the 2G Position has a much wider processing window. The porosity in the 2G Position laser welded joint distributed in the upper part of welds, while that in the 1G Position laser welded joint was distributed along the weld center. Welded joints with acceptable porosity in the 2G Position laser Welding can be obtained for an X-shaped weld profile and wider weld bead. The peak longitudinal residual stresses of the 2G Position laser welded 30CrMnSiA steel were located in the heat-affected zone (HAZ), and the lower residual stresses were presented in the weld center. The peak transverse residual stress was presented in the weld center with the lower stresses located in the two sides HAZ.
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Comparison of laser welds in thick section S700 high-strength steel manufactured in flat (1G) and horizontal (2G) Positions
CIRP Annals - Manufacturing Technology, 2015Co-Authors: Wei Guo, Zhu Liu, John A. Francis, Dave Crowther, Qiang Liu, Alan Thompson, Lin LiAbstract:Lack of penetration, undercut and melt sagging are common Welding defects for single-pass laser welds in thick plates, particularly when using a traditional 1G Welding Position (laser directed towards ground). This investigation shows, for the first time, that Welding 13 mm thick high-strength S700 steel plates in the 2G Position (laser beam perpendicular to the direction of gravity) can mitigate some of the common Welding defects including undercut and sagging. A computational fluid dynamic analysis indicates that the 2G Welding Position can assist in achieving an appropriate balance between surface tension, hydrostatic pressure (gravity) and recoil-pressure from the metal vapour.
Wei Guo - One of the best experts on this subject based on the ideXlab platform.
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Laser Welding of high strength steels (S960 and S700) with medium thickness
Journal of Laser Applications, 2016Co-Authors: Wei Guo, John A. Francis, Dave Crowther, Shiyun Dong, Lin Li, Alan ThompsonAbstract:© 2016 Laser Institute of America. S960 and S700 are two types of new high strength low alloy (HSLA) steels recently developed by Tata Steel, which are used for heavy lifting equipment. Little is known on their Welding characteristics with high-energy beams. In this study, single pass autogenous laser Welding (ALW) and multipass ultranarrow gap laser Welding (NGLW) were carried out using a 16 kW IPG fiber laser to examine the weldability of these HSLA steels up to 13 mm in thickness. It was found that cracking in the welded joints could be avoided. It is beneficial to use horizontal (2G) Welding Position to avoid melt sagging when Welding thick section S700 steel plates in a single pass ALW process. The fast cooling rate for the ALW of 8 mm thick S960 steel and ultra-NGLW of both the 8 mm thick S960 and 13 mm thick S700 steels causes the generation of hard martensite in the fusion zone (FZ) and heat affected zone (HAZ). This could strengthen the laser welded HSLA steel joints, but would deteriorate the toughness of the welded joints. A relatively higher heat input was used to weld the 13 mm thick S700 steel using a single pass ALW process, which causes the formation of bainite in the FZ, while hard martensite and bainie were formed in the HAZ. All the ALW and ultra-NGLW S960 and S700 steels presented almost the same tensile strengths as the base materials and also retained the elongation of the laser welded specimens, quite unexpected.
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Comparison of processing window and porosity distribution in laser Welding of 10 mm thick 30CrMnSiA ultrahigh strength between flat (1G) and horizontal (2G) Positions
Journal of Laser Applications, 2016Co-Authors: Xianfeng Shen, Wenhua Teng, Wei Guo, Lin Li, Wenpei HeAbstract:© 2016 Laser Institute of America. With the development of high brightness and high power laser, it is possible to weld thick sections using single pass autogenous laser Welding. However, it often suffers from very narrow processing parameter windows when Welding thick sections. Furthermore, porosity, back sagging, and undercut are the main defects for laser Welding of thick section high strength steel plates. A comparison of flat Welding Position (1G) and horizontal Welding Position (2G) in laser welded 10 mm thick 30CrMnSiA high strength steel plates was investigated in this paper. The results show that the 1G Position has a very narrow processing window, while the 2G Position has a much wider processing window. The porosity in the 2G Position laser welded joint distributed in the upper part of welds, while that in the 1G Position laser welded joint was distributed along the weld center. Welded joints with acceptable porosity in the 2G Position laser Welding can be obtained for an X-shaped weld profile and wider weld bead. The peak longitudinal residual stresses of the 2G Position laser welded 30CrMnSiA steel were located in the heat-affected zone (HAZ), and the lower residual stresses were presented in the weld center. The peak transverse residual stress was presented in the weld center with the lower stresses located in the two sides HAZ.
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Comparison of laser welds in thick section S700 high-strength steel manufactured in flat (1G) and horizontal (2G) Positions
CIRP Annals - Manufacturing Technology, 2015Co-Authors: Wei Guo, Zhu Liu, John A. Francis, Dave Crowther, Qiang Liu, Alan Thompson, Lin LiAbstract:Lack of penetration, undercut and melt sagging are common Welding defects for single-pass laser welds in thick plates, particularly when using a traditional 1G Welding Position (laser directed towards ground). This investigation shows, for the first time, that Welding 13 mm thick high-strength S700 steel plates in the 2G Position (laser beam perpendicular to the direction of gravity) can mitigate some of the common Welding defects including undercut and sagging. A computational fluid dynamic analysis indicates that the 2G Welding Position can assist in achieving an appropriate balance between surface tension, hydrostatic pressure (gravity) and recoil-pressure from the metal vapour.
