Monitoring of high-power laser welding using high-speed photographing and image processing

“…High-speed imaging spatter detection contributed to distinguish the welding defects in case of laser welding of stainless steel, by identifying the spatter diameter together with the plume features and ejection direction [18,20]. The presence of spontaneous high amounts of spatter in the image sequences confirmed that a weld seam width reduction occurred.…”

Section: Introductionmentioning

confidence: 95%

“…One cause of spatter formation is the vertical movement of liquid in the groove during irradiation caused by the vapor flow that expands in the keyhole. You et al [18] attributed this type of spatter formation to the shockwave generated by the expanding vaporized matter from the laser molten pool. In order to understand and avoid this drawback, several research groups monitored in real time the laser welding of metals and alloys by fast imaging [16][17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%

“…You et al [18] attributed this type of spatter formation to the shockwave generated by the expanding vaporized matter from the laser molten pool. In order to understand and avoid this drawback, several research groups monitored in real time the laser welding of metals and alloys by fast imaging [16][17][18][19][20]. Thus, it was possible to extract relevant information about the keyhole (shape, size, liquid movement, pore formation), plume expansion (plume length, expansion speed, particles expulsion) and its effects over the molten pool (liquid spatter).…”

Section: Introductionmentioning

confidence: 99%

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Control of Porosity and Spatter in Laser Welding of Thick AlMg5 Parts Using High-Speed Imaging and Optical Microscopy

Popescu

Delval

Leparoux

2017

Metals

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Abstract:We report on a feedback mechanism for rapid identification of optimal laser parameters during welding of AlMg5 coupons using real-time monitoring by high-speed imaging. The purpose was to constrain the liquid movement in the groove in order to obtain pore-free welds in this otherwise difficult-to-weld alloy. High-speed imaging of the welding process via an optical microscope allowed for recording at millimeter level, providing new information on liquid-metal dynamics during laser irradiation as well as plausible explanations for spatter occurrence and pores formation. The pore formation and especially the position of these pores had to be controlled in order to weld 3 mm thick samples. By tuning both laser power and pulse duration, pores were aligned on a single line, at the bottom of the weld. A laser pass of reduced power on that side was then sufficient for removing all pores and providing a suitable weld.

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“…34 To overcome this restriction, a high-speed vision system with 1000 frames per second (fps) or even higher has been developed and applied in practice. 35 In the present paper, a high-speed camera sensor system composed of a zoom optical lens, a high-speed camera body with a CCD receiver, and a notebook computer. A USB 3.0 interface is used to ensure stable data transfer between the camera body and the computer.…”

Section: Introductionmentioning

confidence: 99%

Vision-based displacement measurement sensor using modified Taylor approximation approach

et al. 2016

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, "Vision-based displacement measurement sensor using modified Taylor approximation approach," Opt. Eng. 55 (11) Abstract. The development of image sensors and optics lenses has contributed to the rapidly increasing use of vision-based methods as noncontact measurement methods in many areas. A high-speed camera system is developed to realize the displacement measurement in real time. Conventional visual measurement algorithms are commonly subjected to various shortcomings, such as complex processes, multiparameter adjustments, or integer-pixel accuracy. Inspired from the combination of block-matching algorithm and simplified optical flow, a motion estimation algorithm that uses modified Taylor approximation is proposed and applied to the vision sensor system. Simplifying integer-pixel searching with a rounding-iterative operation enables the modified algorithm to rapidly accomplish one displacement extraction within 1 ms and yield satisfactory subpixel accuracy. The performance of the vision sensor is evaluated through a simulation test and two experiments on a grating ruler motion platform and a steering wheel system of a forklift. Experimental results show that the developed vision sensor can extract accurate displacement signals and accomplish the vibration measurement of engineering structures.

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Monitoring of high-power laser welding using high-speed photographing and image processing

Cited by 74 publications

References 24 publications

Dynamic displacement measurement of large-scale structures based on the Lucas–Kanade template tracking algorithm

Dynamic displacement measurement of large-scale structures based on the Lucas–Kanade template tracking algorithm

Control of Porosity and Spatter in Laser Welding of Thick AlMg5 Parts Using High-Speed Imaging and Optical Microscopy

Vision-based displacement measurement sensor using modified Taylor approximation approach

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