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Effect of shielding gas flow on welding process of laser-arc hybrid welding and MIG welding
摘要： The influence of shielding gas on welding process of laser-arc hybrid welding (LAHW) and metal inert-gas welding (MIG) was investigated by the computational fluid dynamics analysis (CFD) and high-speed photography. The results show that the process stability of MIG under high gas flow rate is poorer than that of LAHW. And the force of gas flow Fg can hinder the droplet transfer, whether MIG or LAHW. But the vaporization-induced recoil force Fv in LAHW helps to reduce this kind of hindrance and keep the process stability. Next, it can be found that the shielded gas flow mode in the main welding area cannot be changed significantly by increasing the shielding gas flow rate, while high gas flow rate can increase the area of high argon concentration and benefit the spread of molten metal.
关键词： Welding process,Computational fluid dynamics analysis,Laser-arc hybrid welding,MIG welding
更新于2025-11-28 14:24:20
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Process control and quality assurance in remote laser beam welding by optical coherence tomography
摘要： Remote laser beam welding significantly outperforms conventional joining techniques in terms of flexibility and productivity. This process benefits in particular from a highly focused laser radiation and thus from a well-defined heat input. The small spot sizes of high brilliance laser beam sources, however, require a highly dynamic and precise positioning of the beam. Also, the laser intensities typically applied in this context result in high process dynamics and in demand for a method to ensure a sufficient weld quality. A novel sensor concept for remote laser processing based on optical coherence tomography (OCT) was used for both quality assurance and edge tracking. The OCT sensor was integrated into a 3D scanner head equipped with an additional internal scanner to deflect the measuring beam independently of the processing beam. With this system, the surface topography of the process zone as well as the surrounding area can be recorded. Fundamental investigations on aluminum, copper, and galvanized steel were carried out. Initially, the influence of the material, the angle of incidence, the welding position within the scanning field, and the temperature on the OCT measuring signal were evaluated. Based on this, measuring strategies for edge tracking were developed and validated. It was shown that orthogonal measuring lines in the advance of the process zone can reliably track the edge of a fillet weld. By recording the topography in the trailing area of the process zone, it was possible to assess the weld seam quality. Comparing the results to microscopic measurements, it was shown that the system is capable of clearly identifying characteristic features of the weld seam. Also, it was possible to observe an influence of the welding process on the surface properties in the heat-affected zone, based on the quality of the measuring signal.
关键词： inline quality assurance,optical coherence tomography,remote laser beam welding,process control
更新于2025-11-28 14:24:20
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Green Higha??Power Disk Lasers and Industrial Applications
摘要： In the publicly-funded ProLasKu project, the laser manufacturer Trumpf has developed a high-power laser with a wavelength of 515 nm. Substantial progress in the industrial applications of green lasers has been achieved in a cooperation between the Technical University of Munich and the companies Siemens and Continental. In addition, a camera-based system for process monitoring and quality assurance in real-time based on image processing methods has been developed.
关键词： green high-power disk lasers,industrial applications,copper,laser beam welding,process efficiency
更新于2025-09-23 15:21:01
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Temperature distribution during laser based heat conduction welding of CFRP
摘要： For the implementation of carbon fiber reinforced (CFRP) parts, these need to be assembled to more complex structures. Therefore, laser transmission welding was transferred to heat conduction welding for joining thermoplastic CFRP to itself. The goal of these investigations was to determine the influence of the focal point geometry and the main fiber orientation within the CFRP on the temperature distribution at the upper joining member. A set-up was chosen consisting of two thermo cameras in order to measure the process temperatures on top and underneath the upper joining member. Furthermore, the heat affected width was determined and correlated to the process temperatures.
关键词： seam strength,carbon fiber,thermoplastic,contour welding,process temperture,heat conduction welding
更新于2025-09-12 10:27:22
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Deriving spectral information upon the laser welding process employing a hyperspectral imaging technique
摘要： In this paper we present results from process observations of deep penetration laser welding using a hyperspectral imaging (HSI) technique. For monitoring different types of laser-based material processing, we developed an appropriate high-speed camera-based HSI system. This system enables us to derive spectra of the deep penetration welding process with high time resolution. These spectra can be used for temperature determination or to extract spectral characteristics, both of which can help to further investigate process dynamics and properties of the vapor. The presented results contain particularly HSI-derived spectral information of the evolving vapor plume that is related to corresponding high-speed images and spectra acquired with a conventional VIS-spectrometer.
关键词： laser-based material processing,deep penetration laser welding,process monitoring,hyperspectral imaging
更新于2025-09-12 10:27:22
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Laser welding of hidden T-joints with lateral beam oscillation
摘要： Welded T-joints usually have one- or two-sided fillet welds which were carried out from the web-sheet side. However, accessibility to the joint from the web-sheet side is not always given for any construction. Therefore, T-joints sometimes have to be welded from the face-sheet side which can be very challenging. These so-called hidden T-joints require accurate positioning and fixing of the web-sheets. Flanges help to increase the process reliability, but they are no guarantee for defect-free welds especially in case of laser welding without filler metal. This study addresses the improvement of the process reliability for welding hidden T-joints from the face-sheet side. Therefore, two different methods were investigated: 1) lateral beam oscillation and 2) local thickening of the edge of the web-sheet. Welding experiments comprise both aluminum sheets (EN AW-1050) and uncoated DC01 steel sheets. The results demonstrate that the locally thickened edge of the web-sheet is beneficial to compensate misalignments of the travel path of the laser beam and of the positioning of the web-sheet. In contrast, beam oscillation only improved the steel weldments in terms of compensating misalignments. Best results were achieved for 1.8 mm oscillation width at 200 Hz.
关键词： laser welding,process controll,beam oscillation
更新于2025-09-12 10:27:22
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Laser welding of copper using a high power disc laser at green wavelength
摘要： The trend towards renewable energies and electromobility is increasing the demand for copper. Laser welding as a flexible and fully automatable process is being more frequently employed to join copper materials. The use of green laser radiation compared to infrared laser radiation has the advantage of a significantly higher absorption coefficient for copper materials. Therefore, high power laser sources emitting at a green wavelength promise a more stable and a more efficient process. In this paper, experimental investigations with a green continuous wave laser radiation at a maximum power of 1 kW are presented. Using design of experiments, the process limits are determined depending on the laser power and the welding velocity. Furthermore, the potential of heat conduction welding using this laser source is investigated.
关键词： Green wavelength,Laser material processing,Heat conduction welding,Process limit,Copper
更新于2025-09-12 10:27:22
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[Energy, Environment, and Sustainability] Sensors for Automotive and Aerospace Applications || Sensors in the Joining and Welding Process in Automobile Manufacturing
摘要： Welding and joining processes are one of the key processes in the automobile industries, which give the core strength to the joint and consequently to the vehicle. The complex design of the vehicle and small parts creates difficulty for the manual joining process and therefore the need for automation has increased. The manufacturing companies spend a lot of money on the equipment and processes to maintain the high quality of the vehicle. The sensors are integrated along with the equipment in the welding and joining processes to improve the quality and decrease the risk of damage associated with the process. This review starts with different types of welding methods and then focusses on the sensors and its types.
关键词： Sensors for welding and joining,Automobile manufacturing sensors,Sensors and safety in the welding process,Welding and joining
更新于2025-09-04 15:30:14