Spectroscopic closed loop control of penetration depth in laser beam welding process

Teresa Sibillano; Antonio Ancona; Domenico Rizzi; Francesco Mezzapesa; Ali Riza Konuk; Ronald Aarts; Bert Huis in 't Veld; Pietro Mario Lugarà

doi:10.1117/12.906778

6 February 2012 Spectroscopic closed loop control of penetration depth in laser beam welding process

Teresa Sibillano, Antonio Ancona, Domenico Rizzi, Francesco Mezzapesa, Ali Riza Konuk, Ronald Aarts, Bert Huis in 't Veld, Pietro Mario Lugarà

Author Affiliations +

Proceedings Volume 8239, High Power Laser Materials Processing: Lasers, Beam Delivery, Diagnostics, and Applications; 82390S (2012) https://doi.org/10.1117/12.906778
Event: SPIE LASE, 2012, San Francisco, California, United States

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.

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Teresa Sibillano, Antonio Ancona, Domenico Rizzi, Francesco Mezzapesa, Ali Riza Konuk, Ronald Aarts, Bert Huis in 't Veld, and Pietro Mario Lugarà "Spectroscopic closed loop control of penetration depth in laser beam welding process", Proc. SPIE 8239, High Power Laser Materials Processing: Lasers, Beam Delivery, Diagnostics, and Applications, 82390S (6 February 2012); https://doi.org/10.1117/12.906778

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