scholarly journals OCT Capillary Depth Measurement in Copper Micro Welding Using Green Lasers

2021 ◽  
Vol 11 (6) ◽  
pp. 2655
Author(s):  
Tobias Beck ◽  
Christoph Bantel ◽  
Meiko Boley ◽  
Jean Pierre Bergmann
Keyword(s):  
Laser Welding ◽  
Process Monitoring ◽  
Weld Seam ◽  
Welding Process ◽  
Direct Determination ◽  
Deep Penetration ◽  
Scanning System ◽  
Depth Measurement ◽  
Aspect Ratios ◽  
Deep Penetration Welding

The transition of the powertrain from combustion to electric systems increases the demand for reliable copper connections. For such applications, laser welding has become a key technology. Due to the complexity of laser welding, especially at micro welding with small weld seam dimensions and short process times, reliable in-line process monitoring has proven to be difficult. By using a green laser with a wavelength of λ=515, the welding process of copper benefits from an increased absorption, resulting in a shallow and stable deep penetration welding process. This opens up new possibilities for the process monitoring. In this contribution, the monitoring of the capillary depth in micro copper welding, with welding depth of up to 1 , was performed coaxially using an optical coherence tomography (OCT) system. By comparing the measured capillary depth and the actual welding depth, a good correlation between two measured values could be shown independently of the investigated process parameters and stability. Measuring the capillary depth allows a direct determination of the present aspect ratio in the welding process. For deep penetration welding, aspect ratios as low as 0.35 could be shown. By using an additional scanning system to superimpose the welding motion with a spacial oscillating of the OCT beam perpendicular to the welding motion, multiple information about the process could be determined. Using this method, several process information can be measured simultaneously and is shown for the weld seam width exemplarily.

scholarly journals Depth Dependence and Keyhole Stability at Threshold, for Different Laser Welding Regimes

2020 ◽  
Vol 10 (4) ◽  
pp. 1487 ◽  
Author(s):  
Remy Fabbro
Keyword(s):  
Aspect Ratio ◽  
Laser Welding ◽  
Scaling Laws ◽  
Weld Seam ◽  
Operating Parameters ◽  
Cylindrical Shape ◽  
Aspect Ratios ◽  
Stability Issues ◽  
Keyhole Behavior ◽  
Ratio Range

Depending of the laser operating parameters, several characteristic regimes of laser welding can be observed. At low welding speeds, the aspect ratio of the keyhole can be rather large with a rather vertical cylindrical shape, whereas at high welding speeds, low aspect ratios result, where only the keyhole front is mainly irradiated. For these different regimes, the dependence of the keyhole (KH) depth or the keyhole threshold, as a function of the operating parameters and material properties, is derived and their resulting scaling laws are surprisingly very similar. This approach allows us to analyze the keyhole behavior for these welding regimes, around their keyhole generation thresholds. Specific experiments confirm the occurrence and the behavior of these unstable keyholes for these conditions. Furthermore, recent experimental results can be analyzed using these approaches. Finally, this analysis allows us to define the aspect ratio range for the occurrence of this unstable behavior and to highlight the importance of laser absorptivity for this mechanism. Consequently, the use of a short wavelength laser for the reduction of these keyhole stability issues and the corresponding improvement of weld seam quality is emphasized.

Optimization for Laser Welding Fillet Joint Based on Response Surface Method

2011 ◽  
Vol 211-212 ◽  
pp. 1110-1114
Author(s):  
Xiao Yun Zhang ◽  
Yan Song Zhang
Keyword(s):  
Laser Welding ◽  
Response Surface ◽  
Weld Seam ◽  
Welding Process ◽  
Galvanized Steel ◽  
Plant Production ◽  
Welding Parameters ◽  
Technical Instructions ◽  
Fillet Joint ◽  
Laser Welding Process

The wide use of galvanized steel in automobile manufacturing brings much challenge to the roof to body-side laser welding process. Fillet joint is an effective way to solve this problem such as pore in laser welding process. However, there is little research on this type of complicated joint process. Focused on this problem, take metallographic size of weld seam as the weld quality criteria, response surface methodology (RSM) is used to study the influence of laser welding parameters on weld seam quality. Finally, the optimum welding parameters are concluded to give technical instructions for the plant production.

Processing of Keyhole Depth Measurement Data during Laser Beam Micro Welding

2020 ◽  
Vol 234 (5) ◽  
pp. 722-731
Author(s):  
Sören Hollatz ◽  
Marc Hummel ◽  
Lea Jaklen ◽  
Wiktor Lipnicki ◽  
Alexander Olowinsky ◽  
...  
Keyword(s):  
Laser Beam ◽  
Data Processing ◽  
Laser Beam Welding ◽  
Measurement Data ◽  
Welding Process ◽  
Deep Penetration ◽  
Limited Information ◽  
Depth Measurement ◽  
Interferometric Measurement ◽  
Weld Depth

Analysing the quality of weld seams is still a challenging task. An optical inspection of the surface is giving limited information about the shape and depth of the weld seam. An application for laser beam welding with high demands regarding the weld depth consistency is the electrical contacting of battery cells. The batteries themselves have a limited terminal or case thickness that must not be penetrated during the welding process to avoid leakage or damage to the cell. That leads to a minimum weld depth to ensure the electrical functionality, and a maximum weld depth indicated by the case thickness. In such applications, a destructive analysis is not suitable which leads to the demand for a non-destructive measurement during the process. Using a coaxial, interferometric measurement setup, the keyhole depth during the deep penetration welding is measureable. For a keyhole with a depth of a couple of millimetres, such a system is commercially available. In micro scale, however, these systems are facing several challenges such as scanning systems, small spot diameters of a few tens of micrometres and narrow keyholes. This study contains an investigation of an interferometric measurement of the keyhole depth and the suitability for laser micro welding. Therefore, the data processing of the achieved measurements is investigated, and the results are compared with the depth measurement of metallographic analysed samples. Stainless steel is used to investigate the behaviour and the stability of developed data processing strategy and the resulting depth values.

Extraction of Characteristic Parameters of Keyhole during High Power Fiber Laser Welding

2012 ◽  
Vol 201-202 ◽  
pp. 352-355
Author(s):  
Yong Hua Liu ◽  
Xiang Dong Gao
Keyword(s):  
Laser Welding ◽  
Fiber Laser ◽  
High Power ◽  
Continuous Wave ◽  
Welding Process ◽  
Detection Methods ◽  
Deep Penetration ◽  
Welding Quality ◽  
Characteristic Parameters ◽  
Fiber Laser Welding

During deep penetration laser welding, a keyhole is formed in the molten pool. The characteristics of keyhole are related to the welding quality and stability. Analyzing the characteristic parameters of a keyhole during high power fiber laser welding is one of effective measures to control the welding quality and improve the welding stability. This paper studies a fiber laser butt-joint welding of Type 304 austenitic stainless steel plate with a high power 10 kW continuous wave fiber laser, and an infrared sensitive high-speed video camera was used to capture the dynamic images of the molten pools. A combination filtering system with a filter length of 960-990nm in front of the vision sensor was used to obtain the near infrared image and eliminate other light disturbances. The width, the area, the leftmost point, the rightmost point, the upmost point and the bottommost point of a keyhole were defined as the keyhole characteristic parameters. By using the image preprocessing method, such as median filtering, Wiener filtering, threshold segmentation and Canny edge detection methods, the characteristic parameters of a keyhole were obtained. By analyzing the change of the keyhole characteristic parameters during welding process, it was found that these parameters could reflect the quality and stability of laser welding effectively.

Laser Welding on Material Used for Automobile Lightweight

2012 ◽  
Vol 442 ◽  
pp. 389-392
Author(s):  
Qiang Wu ◽  
Lan Ying Xu ◽  
Yu Zhong Li
Keyword(s):  
Laser Welding ◽  
Heat Affected Zone ◽  
High Strength ◽  
Deep Penetration ◽  
Technological Parameters ◽  
Welding Stability ◽  
Zinc Coated Steel ◽  
Protective Gas ◽  
Deep Penetration Welding ◽  
The Relationship

Based on a large number of welding tests to automotive lightweight material by CO2 laser, the microstructures of welded joint were tested related to performance. on the condition of welding technology, the relationship between the lower critical power of stabile deep penetration welding and welding speed and the focus position is deduced, In a coaxial and side protective gas conditions, through the optimization of technological parameters laser deep penetration welding can effectively avoid heat affected zone of high strength zinc coated steel becomes soft, welded comprehensive quality has been effectively controlled. Zinc evaporates unsteadily, which leads to expansion of heat affected zone and reduction of welding stability, so in this paper effective measures are taken to control it. Experimental results show that a qualified welding quality can be obtained by optimized process parameters of laser welding and adopting argon as shielding gas.

scholarly journals Experimental analysis of key parameters of laser fion welding of honeycomb plate heat exchanger

2019 ◽  
Vol 23 (5 Part A) ◽  
pp. 2757-2764
Author(s):  
Xinwu Du ◽  
Xin Jin ◽  
Huangzhen Lv ◽  
Shiguang Wang
Keyword(s):  
Heat Exchanger ◽  
Welding Process ◽  
Plate Heat Exchanger ◽  
Deep Penetration ◽  
Optimal Arrangement ◽  
Weld Shape ◽  
Plate Heat ◽  
Laser Deep Penetration Welding ◽  
Deep Penetration Welding ◽  
Hydraulic Bulging

The combination of laser deep penetration welding and hydraulic bulging is the most advanced production technology of honeycomb plate heat exchanger in the world. The micro-shape and heat transfer effect of the heat exchanger of honeycomb plate are mainly determined by the distribution mode of welding spot, weld shape and welding point arrangement. Therefore, the important principle of the honeycomb plate heat exchanger processing is to improve the pressure as much as possible to form turbulence while ensuring the welding quality. In the present experimental work, the effect of different weld shape and weld distribution of honeycomb plate heat exchanger produced by 06cr19n10 plate using hydraulic bulging and laser deep penetration welding on hydraulic bulging effect was studied carefully. The results showed that the optimal arrangement method is the equilateral triangle. The welding process parameters were optimized to increase the welding strength. The results showed that when the welding power was 2.1 kW, the bonding strength of the weld was the highest, at 52.70 kN. When the welding power was 2.2 kW and the gap between the welding points was 30 mm, the tensile strength of the honeycomb plate was the best, at 19.0 MPa. The results of this paper provide experimental support for industrial production of honeycomb plate heat exchanger.

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