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Proceedings Paper

Spectroscopic closed loop control of penetration depth in laser beam welding process
Author(s): Teresa Sibillano; Antonio Ancona; Domenico Rizzi; Francesco Mezzapesa; Ali Riza Konuk; Ronald Aarts; Bert Huis in 't Veld; Pietro Mario Lugarà
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Paper Abstract

In-process monitoring and feedback control are fundamental actions for stable and good quality laser welding process. In particular, penetration depth is one of the most critical features to be monitored. In this research, overlap welding of stainless steel is investigated to stably reproduce a fixed penetration depth using both CO2 and Nd:YAG lasers. Plasma electron temperatures of Fe(I) and Cr(I) are evaluated as in process monitoring using the measurement of intensities of emission lines with fast spectrometers. The sensor system is calibrated using a quantitative relationship between electron temperature and penetration depth in different welding conditions. Finally closed loop control of the weld penetration depth is implemented by acquiring the electron temperature value and by adjusting the laser power to maintain a pre-set penetration depth. A PI controller is successfully used to stabilize the electron temperature around the set point corresponding to the right penetration depth starting from a wrong value of any initial laser power different than the set point. Optical inspection of the weld surface and macroscopic analyses of cross sections verify the results obtained with the proposed closed-loop system based on a spectroscopic controller and confirms the reliability of our system.

Paper Details

Date Published: 6 February 2012
PDF: 8 pages
Proc. SPIE 8239, High Power Laser Materials Processing: Lasers, Beam Delivery, Diagnostics, and Applications, 82390S (6 February 2012); doi: 10.1117/12.906778
Show Author Affiliations
Teresa Sibillano, CNR-IFN UOS Bari (Italy)
Antonio Ancona, CNR-IFN UOS Bari (Italy)
Domenico Rizzi, Univ. degli Studi e Politecnico di Bari (Italy)
Francesco Mezzapesa, Univ. degli Studi e Politecnico di Bari (Italy)
Ali Riza Konuk, Univ. Twente (Netherlands)
Ronald Aarts, Univ. Twente (Netherlands)
Bert Huis in 't Veld, Univ. Twente (Netherlands)
Pietro Mario Lugarà, CNR-IFN UOS Bari (Italy)
Univ. degli Studi e Politecnico di Bari (Italy)

Published in SPIE Proceedings Vol. 8239:
High Power Laser Materials Processing: Lasers, Beam Delivery, Diagnostics, and Applications
Eckhard Beyer; Timothy Morris, Editor(s)

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