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Closed loop control of penetration depth during CO₂ laser lap welding processes.

Sibillano T, Rizzi D, Mezzapesa FP, Lugarà PM, Konuk AR, Aarts R, Veld BH, Ancona A - Sensors (Basel) (2012)

Bottom Line: 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.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.

View Article: PubMed Central - PubMed

Affiliation: CNR-IFN Institute for Photonics and Nanotechnologies, UOS Bari, 70126 Bari, Italy. teresa.sibillano@fisica.uniba.it

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.

No MeSH data available.


Experimental set-up.
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f1-sensors-12-11077: Experimental set-up.

Mentions: Lap weldings were carried out with a CO2 laser source delivering a maximum output power of 2,500 W in cw regime, focused onto the workpiece surface through a parabolic focusing mirror of 200 mm focal length. For the welding trials, overlap welds have been realized with 1 mm-thick on top of 2 mm-thick AISI304 stainless steel plates. The welding speed has been kept constant at 50 mm/s for all the experiments, as well as the beam focus position on the top surface of the sample. The argon gas has been provided from the top side of the weld at a flow rate of 60 L/min and a nozzle stand-off distance of 6 mm, as depicted in Figure 1. Only the laser power has been changed during the experiments, from 800 W to 1,700 W, corresponding to a heat input ranging from 16 J/mm to 36 J/mm [26], to obtain different penetration depth values.


Closed loop control of penetration depth during CO₂ laser lap welding processes.

Sibillano T, Rizzi D, Mezzapesa FP, Lugarà PM, Konuk AR, Aarts R, Veld BH, Ancona A - Sensors (Basel) (2012)

Experimental set-up.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3472874&req=5

f1-sensors-12-11077: Experimental set-up.
Mentions: Lap weldings were carried out with a CO2 laser source delivering a maximum output power of 2,500 W in cw regime, focused onto the workpiece surface through a parabolic focusing mirror of 200 mm focal length. For the welding trials, overlap welds have been realized with 1 mm-thick on top of 2 mm-thick AISI304 stainless steel plates. The welding speed has been kept constant at 50 mm/s for all the experiments, as well as the beam focus position on the top surface of the sample. The argon gas has been provided from the top side of the weld at a flow rate of 60 L/min and a nozzle stand-off distance of 6 mm, as depicted in Figure 1. Only the laser power has been changed during the experiments, from 800 W to 1,700 W, corresponding to a heat input ranging from 16 J/mm to 36 J/mm [26], to obtain different penetration depth values.

Bottom Line: 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.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.

View Article: PubMed Central - PubMed

Affiliation: CNR-IFN Institute for Photonics and Nanotechnologies, UOS Bari, 70126 Bari, Italy. teresa.sibillano@fisica.uniba.it

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.

No MeSH data available.