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Contamination of Coupling Glass and Performance Evaluation of Protective System in Vacuum Laser Beam Welding
摘要： Vacuum laser beam welding enables deeper penetration depth and welding stability than atmospheric pressure laser welding. However, contaminated coupling glass caused by welding fumes in the vacuum space reduces laser transmittance, leading to inconsistent penetration depth. Therefore, a well-designed protective system is indispensable. Before designing the protective system, the contamination phenomenon was quanti?ed and represented by a contamination index, based on the coupling glass transmittance. The contamination index and penetration depth behavior were determined to be inversely proportional. A cylindrical protective system with a shielding gas supply was proposed and tested. The shielding gas jet provides pressure-driven contaminant suppression and gas momentum-driven contaminant dispersion. The in?uence of the shielding gas ?ow rate and gas nozzle diameter on the performance of the protective system was evaluated. When the shielding gas ?ow was 2.0 L/min or higher, the pressure-driven contaminant suppression dominated for all nozzle diameters. When the shielding gas ?ow was 1.0 L/min or lower, gas momentum-driven contaminant dispersion was observed. A correlation between the gas nozzle diameter and the contamination index was determined. It was con?rmed that contamination can be controlled by selecting the proper gas ?ow rate and supply nozzle diameter.
关键词： welding consistency,coupling glass,shielding gas,laser welding,vacuum,protective system,contamination
更新于2025-09-16 10:30:52
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A convolutional approach to quality monitoring for laser manufacturing
摘要： The extraction of meaningful features from the monitoring of laser processes is the foundation of new non-destructive quality inspection methods for the manufactured pieces, which has been and remains a growing interest in industry. We present ConvLBM, a novel approach to monitor Laser Based Manufacturing processes in real-time. ConvLBM uses a Convolutional Neural Network model to extract features and quality indicators from raw Medium Wavelength Infrared coaxial images. We demonstrate the ability of ConvLBM to represent process dynamics, and predict quality indicators in two scenarios: dilution estimation in Laser Metal Deposition, and location of defects in laser welding processes. Obtained results represent a breakthrough in the 3D printing of large metal parts, and in the quality control of welding processes. We are also releasing the ?rst large dataset of annotated images of laser manufacturing.
关键词： Quality-control,Laser-cladding,Laser-welding,Convolutional-neural-networks,Neural-networks
更新于2025-09-16 10:30:52
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[IEEE 2019 International Conference on Engineering, Science, and Industrial Applications (ICESI) - Tokyo, Japan (2019.8.22-2019.8.24)] 2019 International Conference on Engineering, Science, and Industrial Applications (ICESI) - Process Reliable Laser Welding of Hairpin Windings for Automotive Traction Drives
摘要： Driven by current developments the electrification of the automotive drive chain, new technologies for the production of windings for electric drives are focused in automotive industry and research institutes. Especially for the manufacturing of drives with high power density for battery electric vehicles (BEV), the application of distributed windings produced from conductors with rectangular cross-sections gains in importance. To be able to manufacture these windings, hairpin technology is pushed forward at present. The essential feature of this kind of winding is that it consists of pre-formed elements, the so called hairpins, that are assembled to the stator laminations and contacted afterwards to produce the winding. One key process within the production chain for this kind of winding is the contacting operation, because a high number of contacts needs to be realized. However, this production step poses several challenges for which in particular laser welding processes show potentials. Another complication is the fact that no established methods for the quantification of the quality of these joints are available at present. In addition, the suitability of the laser welding process for this application must be proven and error influencing variables must be identified in order to be able to advance the serial application of this process. For that reason in this paper quality criteria from the requirements contacts in electric traction drives have to face are analysed. Based on these, the achievable process capability is evaluated and the welding strategy is optimized.
关键词： laser welding,automotive traction drives,process reliability,quality criteria,hairpin windings
更新于2025-09-16 10:30:52
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Distribution of Al Element of Ti–6Al–4V Joints by Fiber Laser Welding
摘要： In the process of laser welding, the uneven distribution of solute elements caused by element burning loss and ?ow of molten pool a?ects the quality of joints. In this paper, butt welding experiments were conducted on the 3 mm thick Ti–6Al–4V specimens with di?erent preset ratios of Al and Si powders by using 4 kW ?ber laser. The distribution of Al solute element and its in?uence on the microstructure and mechanical properties of the ?nal weld joint were investigated. The results showed that the self-di?usion of Al element and the ?ow of molten pool a?ects the alloy elements distribution in laser welding. And the microhardness of the welded joint with Ti–6Al–4V and 90% Al + 10% Si powders was signi?cantly higher than that with only Ti–6Al–4V, with the di?erence of about 130HV. At the same time, in the joint with 90% Al and 10% Si powders, the acicular α’ size was ?ner, and basketweave microstructure was present as well. This research is helpful to better understand the distribution of Al solute element and its in?uence on the joint quality during laser welding of Ti–6Al–4V alloy, which provides a certain reference for improving the weld or surface properties of Ti–6Al–4V alloy during laser processing.
关键词： Ti–6Al–4V alloy,structure morphology,laser welding,elements distribution,microhardness
更新于2025-09-16 10:30:52
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Fatigue Behaviour of Laser Spot Welds in Dual Phase 780 Steel
摘要： High cycle fatigue performance was evaluated on circular shaped laser spot welds (LSW) of dual phase DP780 steels. Fibre laser with two different parameter sets were applied to produce the spot welds. The weld size growth is concomitant to laser power. The failure mechanism under fatigue loading, involving crack initiation and propagation till failure, is explained using analytical stress models and experimental data. Interrupted fatigue tests were done and the crack path was captured by observing under scanning electron microscope. Stress models show that during tensile shear loading of overlapping sheets having spot weld, there is a countering effect of shear stress and bending stress; the latter acts perpendicular to the shear stress and arises from the bending moment along the plane of contact during load transfer. The dominant stress depends on the contact area, i.e. the weld size, which largely controls the crack path route and concurrent fatigue life. Incidentally smaller welds show marginally longer life wherein the stronger axial stress component propels the crack through a longer route consuming more number of cycles. Again, with lowering of fatigue load there is a shift in the mode of failure with transition from interfacial to partial to pull-out failure. However, large welds fail in pull-out mode only irrespective of the fatigue load levels. As compared to the size effect, the weld microstructure has less influence on fatigue crack propagation.
关键词： Laser welding,Stress Intensity Factor,High Cycle Fatigue behaviour,Circular weld,Dual phase steel
更新于2025-09-16 10:30:52
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Features of Laser Welding Light Constructions from Cryogenic Austenitic Steel 316L
摘要： The publication describes the results of the research of the influence of laser welding mode parameters on geometry and quality of the formation of the welded joint of 316L steel with thickness of 1 mm. According to the results of research in the framework of pre-project works, in order to test the technology at the real objects, components of light metal structures were welded.
关键词： metal with thin thickness,light construction,austenitic steel 316L,laser welding
更新于2025-09-16 10:30:52
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Effect of Process Parameters and Heat Input on Weld Bead Geometry of Laser Welded Titanium Ti-6Al-4V Alloy
摘要： Laser beam welding is one of the most favorable welding technique and its importance in industry is demanding due to higher welding speeds and lower dimensions and distortions in the welds. Moreover, its high strength to weld geometries and minimal heat affected zones makes favorable for various industrial applications. In the present study, laser welding of titanium alloy was investigated to observe the effects of parameters on the bead geometry and metallurgical properties. The laser power and welding speeds were varied to identify their impact on the formation of weld geometry. The width and depth of the fusion zone is varied with welding conditions. The finer grains identified in weld zone and the width of heat affected zone was significantly changes with laser welding power. The mechanical properties of the weld joint are controlled by obtaining optimum weld bead geometry and width of the head affected zone in the welds.
关键词： Heat input,Fusion zone,Microstructure,Mechanical properties,Laser welding,Microhardness,Weld bead geometry,Titanium alloy
更新于2025-09-16 10:30:52
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Correlation of Process Parameters and Porosity in Laser Welding of 7A52 Aluminum Alloy using Response Surface Methodology
摘要： The article presents an experimental investigation of the effect of process parameters (i.e. laser power, welding speed and defocus distance) on porosity in laser welding of 7A52 aluminum alloy. A three-factor, three-level factorial Box–Behnken design (BBD) of response surface methodology (RSM) was used to complete the design matrix with the objective of optimizing the process parameters. Multiple regression models were established to predict the correlation between the selected process parameters and porosity, and then were tested for adequacy using analysis of variance (ANOVA). The results showed that macro pores in laser welding seam were mainly keyhole induced, and porosity susceptibility was mostly dominated by welding speed. The optimal combination of process parameters is the laser power of 3.5kW, welding speed of 10.0mm/s, and the defocus distance of +4.0mm. Under the optimal process parameters, superior weld seams without macro pore were produced. The predicted porosity area fraction with RSM models was confirmed to be in good agreement with the measured values of validation experiments.
关键词： process parameter,response surface methodology,porosity,7A52 aluminum alloy,laser welding
更新于2025-09-16 10:30:52
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Laser Welding in Different Spatial Positions of T-joints of Austenitic Steel
摘要： It has been selected the most industry perspective laser welding technological implementations of the welded T-joints made of fine-sheeted heat resisting steel AISI 321 by identifying the influence of technological parameters on formation quality, level of mechanical properties and structural peculiarities of the welded T-joints obtained by laser welding in different spatial positions.
关键词： AISI 321,T-joints,spatial positions,mechanical properties,laser welding
更新于2025-09-16 10:30:52
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Experimental design investigation of through-transmission laser welding of dissimilar polymers
摘要： In the present study, the laser weldability of several types of dissimilar polymers couples are investigated using the experimental design method. This experimental strategy allowed to quantify the influence of the operating parameters on the failure force of the welded specimens. Some preliminary tests were used in order to find the initial conditions for the design of the experimental matrices. Based on the conclusions drawn from these preliminary tests, exploratory experimental designs were used to advance towards the optimum for each couple of polymeric materials. The polymeric materials considered were: ABS and PA11 with different pigments and thickness. One could note that the laser power used is the most important parameter on the mechanical resistance and the weldability is assured in a narrow interval of power laser. An important clamping pressure and two laser passages are useful to improve the performances of the weld strength.
关键词： mechanical resistance,laser welding,weldability,dissimilar polymers,experimental design
更新于2025-09-16 10:30:52