title: Closed loop control of penetration depth during CO₂ laser lap welding processes.
abstract: In this paper we describe a novel spectroscopic closed loop control system capable of stabilizing the penetration depth during laser welding processes by controlling the laser power. Our novel approach is to analyze the optical emission from the laser generated plasma plume above the keyhole, to calculate its electron temperature as a process-monitoring signal. Laser power has been controlled by using a quantitative relationship between the penetration depth and the plasma electron temperature. The sensor is able to correlate in real time the difference between the measured electron temperature and its reference value for the requested penetration depth. Accordingly the closed loop system adjusts the power, thus maintaining the penetration depth.
authors.affiliation: CNR-IFN Institute for Photonics and Nanotechnologies, UOS Bari, 70126 Bari, Italy. teresa.sibillano@fisica.uniba.it
authors.forename: Teresa
authors.initials: T
authors.lastname: Sibillano
authors.forename: Domenico
authors.initials: D
authors.lastname: Rizzi
authors.forename: Francesco P
authors.initials: FP
authors.lastname: Mezzapesa
authors.forename: Pietro Mario
authors.initials: PM
authors.lastname: Lugarà
authors.forename: Ali Riza
authors.initials: AR
authors.lastname: Konuk
authors.forename: Ronald
authors.initials: R
authors.lastname: Aarts
authors.forename: Bert Huis In 't
authors.initials: BH
authors.lastname: Veld
authors.forename: Antonio
authors.initials: A
authors.lastname: Ancona
keywords: closed loop control; laser welding; plasma spectroscopy