1. Closed loop control of laser welding using an optical spectroscopic sensor for Nd:YAG and CO2 lasers
- Author
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Bert Huis in 't Veld, Teresa Sibillano, Domenico Rizzi, A.R. Konuk, Ronald G.K.M. Aarts, and Antonio Ancona
- Subjects
Weld seam ,Mechanical engineering ,Welding ,Spectroscopic analysis ,Stainless steel ,law.invention ,law ,Emission lines ,Optical spectroscopic ,Weld quality ,Laser joining ,Laser power scaling ,Plasma plumes ,Penetration depth ,Spectroscopy ,Neodymium ,TS - Technical Sciences ,Industrial Innovation ,Cross section ,Controllers ,Spectrometers ,Physics ,Welding process ,Industrial applications ,Laser beam welding ,Laser welds ,Closed-loop control ,Gas-shielding ,Electromagnetic shielding ,YAG laser ,Optical inspection ,Materials science ,Quality parameters ,Welds ,Plasma spectroscopy ,Optics ,AISI-304 stainless steel ,PI controller ,Constant penetration ,Optical emissions ,Electron temperature ,Monitor and control ,YAG laser [Nd] ,Spectrometer ,Laser power ,Sensors ,business.industry ,Quality control ,Melt pool control ,Mechatronics, Mechanics & Materials ,Real time control ,Laser ,Spectrum analysis ,Carbon dioxide ,TFT - Thin Film Technology ,Sensor data ,Optical testing ,Nd:YAG laser ,Laser welding ,Microscopic analysis ,business ,Weld surfaces ,Neodymium lasers - Abstract
Recent developments in laser joining show the applicability of spectral analysis of the plasma plume emission to monitor and control the quality of weld. The analysis of the complete spectra makes it possible to measure specific emission lines which reveal information about the welding process. The subsequent estimation of the electron temperature can be correlated with the quality of the corresponding weld seam. A typical quality parameter, for laser welds of stainless steel, is the achieved penetration depth of the weld. Furthermore adequate gas shielding of the welds has to be provided to avoid seam oxidation . In this paper monitoring and real-time control of the penetration depth during laser welding is demonstrated. Optical emissions in the range of 400nm and 560nm are collected by a fast spectrometer. The sensor data are used to determine the weld quality of overlap welds in AISI 304 stainless steel sheets performed both with CW Nd:YAG and CO2 lasers. A PI-controller adjusts the laser power aiming at a constant penetration. Optical inspection of the weld surface and microscopic analysis of weld cross sections were used to verify the results obtained with the proposed closed-loop system of spectroscopic sensor and controller.
- Published
- 2011