Jeong Suh

Quality monitoring of laser welding

In this paper, a study of quality monitoring technology for the laser welding was conducted. The laser welding and the industrial robotic systems were used with robot-based laser welding systems. Over the past years, Trumpfs 4kW Nd:YAG laser (HL4006D) and ABBs IRB6400R robot system (payload:120kg) were used. The new laser source, robot and laser scanner system are used to increase the processing speed and to improve the efficiency of processes. The laser system used in this study was IPGs 1.6kW Fiber laser (YLR-1600), while the robot system was Hyundai Heavy Industrys HX130-02 (payload : 130kg). The robot-based laser welding system was equipped with a laser scanner system for remote laser welding. The welding joints of steel plate and steel plate coated with zinc were butt and lapped joints. The quality testing of the laser welding was conducted by observing the shape of the beads on the plate and the cross-section of the welded parts, analyzing the results of mechanical tension test, and monitoring the plasma intensity by using UV and IR sensor. This paper proposes the quality monitoring method and the robot-based remote laser welding system as a means of resolving the limited welding speed and accuracy of conventional laser welding systems.

Development of Welding Profile Sensor and Its Application

This paper describes the development of a welding profile sensor for the laser welding robot application. The sensor consists of a PC based vision camera and a stripe-type laser diode. All components are assembled into a compact module which can be attached to the end-effector of welding robots. The laser-stripe sensor can measure the profile of the welding object and obtain the seam line. Moreover, the working distance of the sensor can be varied. The robot, the seam tracking system, and CW Nd:YAG laser are used for the laser welding robot system. The simple control scheme of the whole system is also presented. The profile measurement and the seam tracking experiments were carried out to validate the operation of the system.

Study on Robot Application Technology for Laser Welding

The laser welding technology for manufacturing light car body is studied. A industrial robot, a seam tracking system and 4 kW CW Nd:YAG laser are used for robot based laser welding system. The laser system is used 4 kW Nd: YAG laser(HL4006D) of Trumpf and the robot system is used IRB6400R of ABB. The monitoring method of welding quality and seam tracking technology along the butt-joint are studied. The robot laser welding system is equipped with a seam tracker and plasma sensor. The precise positioning (<200 mum) of the laser beam on the welding joint to be welded is obtained by seam tracker. The seam tracking system is SMART-20LS and RAPAL of Servo-Robot and MVS-5 sensor of MVS. The welding joints of steel plate are butt and lap joint. We investigate the parameters which have influence on the welding quality through the plasma intensity signals measuring method. The artificial defects (<o1 mm) in joint are well observed by using the plasma intensity signals measured by the plasma sensor of UV and IR. The laser welding tests for non-linear tailored blank are performed after the observation experiments of bead on plate. Finally, the welding process for non-linear tailored blank and front side member is studied. In this study, the robot based laser welding system is developed for the precision seam tracking and the real-time monitoring of welding quality.

Intelligent vision sensor for the robotic laser welding

The intelligent sensory system is required to ensure the accurate welding performance. This paper describes the development of an intelligent vision sensor for the robotic laser welding. The sensor system includes a PC based vision camera and a stripe-type laser diode. A set of robust image processing algorithms are implemented. The laser-stripe sensor can measure the profile of the welding object and obtain the seam line. Moreover, the working distance of the sensor can be changed and other configuration is adjusted accordingly. The robot, the seam tracking system, and CW Nd:YAG laser are used for the laser welding robot system. The simple and efficient control scheme of the whole system is also presented. The profile measurement and the seam tracking experiments were carried out to validate the operation of the system.

Finite Element Analysis of Nd:YAG Pulse Laser Welding for AISI 304 Stainless Steel Plate

Pulse laser welding of AISI 304 stainless steel plate was simulated to find optimal welding conditions by using commercial finite element code MARC. Due to geometric symmetry, a half model of AISI 304 stainless steel plate was considered and user subroutines were applied to boundary condition for the heat transfer. Material properties such as conductivity, specific heat, mass density and latent heat were given as a function of temperature. A moving heat source was designed on the basis of experimental data. As a result, Nd:YAG laser welding for AISI 304 stainless steel was successfully simulated and it should be useful to determine optimal welding condition.

Nutrient Removal Using BauxsolTM for Treated Wastewater Reuse

Urban areas consume huge amounts of water and produce much wastewater, which deteriorate the aquatic environment and exhaust the country’s freshwater resources. Water reuse from sewage and wastewater is recognized as a good option for securing water. There are several kinds of processes for improving the water quality. Nutrient removal is very important for water reuse, especially in water supply for outdoor use, to prevent water quality deterioration via eutrophication. Moreover, low cost and easy maintenance should be considered for nutrient removal. In this study, red mud and BauxsolTM, a mixed mineral powder made of physicochemically modified red mud residue generated by the Bayer process for alumina refineries, was used for the removal of nitrate and heavy metals in artificial solution, and of phosphate in final effluent, from a sewage treatment plant in Dae-gu, Republic of Korea. Nitrate removal by red mud showed little efficiency while heavy metal removal showed high efficiency. The concentrations of the total phosphate in the effluent and treated water were 1.51 and 0.14 mg/L, respectively, which represent about 90.7% removal. Before and after the treatment, the pH was maintained at a neutral range of 6.5-7.2. BauxsolTM also showed a high heavy metal removal capacity. Therefore, BauxsolTM in powder and pellet form can be applied individually or mixed with soil to improve water quality for water reuse.

Study on quality monitoring of laser welding

For the purposes of this paper, a study of quality monitoring technology for the laser welding was conducted. Laser welding and industrial robotic systems are used with robot-based laser welding systems. The laser system used in this study was IPGs 1.6kW fiber laser (YLR-1600), while the robot system was Hyundai Heavy Industrys HX130-02 (payload:130kg). The robot-based laser welding system was equipped with a laser scanner system for remote laser welding. The welding joints of steel plate and steel plate coated with zinc were butt and lapped joints. The quality testing of the laser welding was conducted by observing the shape of the beads on the plate and the cross-section of the welded parts, analyzing the results of mechanical tension test, and monitoring the plasma intensity by using plasma detector. Over the past three years, Trumpfs 4kW Nd:YAG laser (HL4006D) and ABBs IRB6400R robot system (payload:120kg) was used. The new laser source, robot and laser scanner system are used to increase the processing speed and to improve the efficiency of processes. This paper proposes the robot-based remote laser welding system as a means of resolving the limited welding speed and accuracy of conventional laser welding systems.

Robot Based Laser Welding Technology

In order to obtain a good result in the laser welding process, the laser welding technology for manufacturing an automobile body is studied in this research. The monitoring of the welding quality and the seam tracking are studied to improve the productivity. The robot, the seam tracking system and CW Nd:YAG laser are used for the robot laser welding system. The laser system is 4kW Nd:YAG laser_(HL4006D) of Trumpf and the robot system is IRB6400R of ABB. The robot laser welding system is equipped with the seam tracker and plasma sensor. The seam tracking system is composed of SMART-20LS and RAPAL of Servo-Robot and MVS-5 sensor of MVS. The precise positioning of the laser beam on the joint to be assembled is obtained by seam tracker. The welding joints of steel plate are butt and lap joint. The three dimensional welding for non-linear tailored blank is performed after the fundamental experiments of bead-on-plate. Finally, the welding process for non-linear tailored blank and front side member is studied. The monitoring method of welding quality and seam tracking along the butt-joint are studied. The artificial defects in joint are well observed by the plasma intensity signal from the plasma sensor of UV and IR. The robot based laser welding system is developed for the precision seam tracking and the real-time monitoring of welding quality.

Sensor Guided Laser Welding Robot System

In order to obtain a good result in the laser welding process, the laser welding technology for manufacturing an automobile body is studied in this research. The robot, the seam tracking system, and CW Nd:YAG laser are used for the laser welding robot system. Especially, the development of the laser-stripe sensor is highlighted. The laser-stripe sensor can measure the profile of the welding object and obtain the gap and seam line. Moreover, the working distance of the sensor can be varied. The control scheme of the whole system is also presented. The profile and gap measurement and the seam tracking experiments were carried out to validate the operation of the system.

Finite Element Analysis for Prediction of Bead Shape of Nd:YAG Laser Fillet Welding

Nd:YAG pulse laser fillet welding of stainless steel plate was simulated to find welding condition by using commercial finite element code MARC. Full model of AISI 304 stainless steel plate was considered and user subroutines were applied to boundary condition for the heat transfer. Material properties such as conductivity, specific heat, mass density and latent heat were given as a function of temperature. As results, Three dimensional heat source model for pulse laser beam conditions of fillet welding has been designed by the comparison between the finite element analysis results and experimental data on AISI 304 stainless steel plate. Nd:YAG laser welding for AISI 304 stainless steel was successfully simulated and it should be useful to determine optimal welding condition.