Process control in laser manufacturing–dream or reality?

Schmidt, Michael; Albert, Florian; Frick, Thomas; Grimm, Alexander; Kägeler, Christian; Rank, Matthias; Tangermann-Gerk, Katja

doi:10.2351/1.5061045

Cited by 10 publications

(5 citation statements)

References 6 publications

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“…36 Schmidt and his research staff have pointed out that in the case of a 3?6 kW laser lap welding of zinc coated steel sheets, with the material thickness being 1?3-2?5 mm and the welding speed being 4-6 m min , the frequency of weld pool oscillations is within the range of 300-500 Hz, while that of the keyhole oscillations is within the range of 2000-2500 Hz. 37,38 As shown in Fig. 4, external frequency missing is related to some welded defects.…”

Section: Photodiode Sensormentioning

confidence: 96%

Review of laser welding monitoring

You

Gao

Katayama

2014

Science and Technology of Welding and Joining

187

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Laser welding, as a highly efficient processing technology, has been widely applied to manufacturing industry. This paper makes an overview on real time monitoring of laser welding. It begins with a detailed introduction to six typical sensors (photodiode, visual, spectrometer, acoustical sensor, pyrometer, plasma charge sensor) in laser welding detection. Then it makes a review on multi-sensor fusion technology in both laser welding monitoring and adaptive control. Last, subjects for future research concerning welding monitoring and control have been proposed. The paper concludes that the real-time monitoring of laser welding can provide a great amount of valid information about welding status to help effectively identify weld defects and realize adaptive control.

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Section: Photodiode Sensormentioning

confidence: 96%

Review of laser welding monitoring

You

Gao

Katayama

2014

Science and Technology of Welding and Joining

187

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“…The specified correlation helps to further identify frequency characteristics of the characteristic signals when weld defects occur. It has been proved that under particular welding conditions (zinc coated steel sheets, 3.6 kW, 4 m min −1 -6 m min −1 ) the frequency of molten pool oscillations is within the range of 300 Hz-500 Hz, and that of the keyhole oscillations is within the range of 2000 Hz-2500 Hz [14,15]. External frequency missing occurred with the presence of some weld defects.…”

Section: Introductionmentioning

confidence: 97%

The high frequency characteristics of laser reflection and visible light during solid state disk laser welding

2015

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Optical properties are related to weld quality during laser welding. Visible light radiation generated from optical-induced plasma and laser reflection is considered a key element reflecting weld quality. An in-depth analysis of the high-frequency component of optical signals is conducted. A combination of a photoelectric sensor and an optical filter helped to obtain visible light reflection and laser reflection in the welding process. Two groups of optical signals were sampled at a high sampling rate (250 kHz) using an oscilloscope. Frequencies in the ranges 1-10 kHz and 10-125 kHz were investigated respectively. Experimental results showed that there was an obvious correlation between the high-frequency signal and the laser power, while the high-frequency signal was not sensitive to changes in welding speed. In particular, when the defocus position was changed, only a high frequency of the visible light signal was observed, while the high frequency of the laser reflection signal remained unchanged. The basic correlation between optical features and welding status during the laser welding process is specified, which helps to provide a new research focus for investigating the stability of welding status.

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“…Even though such systems are absolutely suitable for monitoring purposes, their capabilities are insufficient to fulfill the requirement of a robust and adaptive on-line closedloop control system [3]. Concerning the latter, typical frame rates of camera-based systems should be in the multi kHz range [8].…”

Section: Introductionmentioning

confidence: 99%

Multi-feature detection for quality assessment in laser beam welding: Experimental results

Nicolosi

Tetzlaff

Abt³

et al. 2012

2012 13th International Workshop on Cellular Nanoscale Networks and Their Applications

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Laser beam welding (LBW) has been largely used in manufacturing processes ranging from automobile production to precision mechanics. The complexity of LBW requires the development of strategies for the real-time control of the process. Most of the available feedback systems lack of temporal and/or spatial resolution and, therefore, they hardly allow observing more than one characteristic of the process. In the last years, we proposed some high-speed visual algorithms for image feature extraction from process images. The detection of the full penetration hole (FPH) allowed controlling the laser power at rates of up to 14 kHz. Another strategy enables observing the occurrence of spatters at monitoring rates of 15 kHz. The achievement of these results was made possible by the adoption of a visual system including a focal plane processor programmable by typical Cellular Neural Network (CNN) operations. This paper is focused on a new visual algorithm for the simultaneous detection of FPH and spatters, which led to real-time control rates of about 8 kHz. Besides the algorithm description, some interesting experimental results will be presented

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Process control in laser manufacturing–dream or reality?

Cited by 10 publications

References 6 publications

Review of laser welding monitoring

Review of laser welding monitoring

The high frequency characteristics of laser reflection and visible light during solid state disk laser welding

Multi-feature detection for quality assessment in laser beam welding: Experimental results

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