Abstract
A new spectroscopic parameter is used in this paper for on-line arc-welding quality monitoring. Plasma spectroscopy applied to welding diagnostics has typically relied on the estimation of the plasma electronic temperature, as there is a known correlation between this parameter and the quality of the seams. However, the practical use of this parameter gives rise to some uncertainties that could provoke ambiguous results. For an efficient on-line welding monitoring system, it is essential to prevent the appearance of false alarms, as well as to detect all the possible defects. In this regard, we propose the use of the root mean square signal of the welding plasma spectra, as this parameter will be proven to exhibit a good correlation with the quality of the resulting seams. Results corresponding to several arc-welding field tests performed on Inconel and titanium specimens will be discussed and compared to non-destructive evaluation techniques.
Highlights
The on-line monitoring of both laser and arc-welding processes is nowadays, an active area of research, and a hot topic in terms of the interest of the industry in its possible implementation for different specific applications
In this paper we propose the use of the plasma spectrum root mean square RMS signal as an alternative on-line monitoring parameter
The tests with titanium were performed without filler wire, and in both cases the shielding gas was guided to the bottom side of the plates with a flow rate of 30 L/min
Summary
The on-line monitoring of both laser and arc-welding processes is nowadays, an active area of research, and a hot topic in terms of the interest of the industry in its possible implementation for different specific applications. There are sophisticated models dealing with the different process taking place within the welding plasma, most of these solutions cannot be used for real-time analysis, as they imply a significant computational cost [7] It is precisely this complexity, in addition to the various external variables that can have an effect upon the process, what makes it impossible to theoretically relate the process input parameters to the final seam quality. In our system a CCD spectrometer is employed, and the plasma spectrum RMS signal is calculated by considering the intensity associated with all the pixels in the sensor With this approach it is possible to provide in real-time different spectroscopic monitoring parameters and, depending on the particular process, to use only one or to combine some of them under specific logic rules. Results of visual and X-ray inspection of the seams and the possibility of classifying the different weld defects in terms of the spectroscopic parameters will be discussed
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