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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.


(a) Electron temperature signal behavior. Controller parameters: Te,ref = 5,460 K corresponding to a penetration depth of 2 mm; Kp = −2 W/K; Ti = 150 ms. Initial laser power = 1,440 W. (b) Laser power measured by fast power sensor. (c) Penetration depth measurements.
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f6-sensors-12-11077: (a) Electron temperature signal behavior. Controller parameters: Te,ref = 5,460 K corresponding to a penetration depth of 2 mm; Kp = −2 W/K; Ti = 150 ms. Initial laser power = 1,440 W. (b) Laser power measured by fast power sensor. (c) Penetration depth measurements.

Mentions: Finally, the starting laser power was set at 1,440 W, 20% higher than the optimal value, thus producing a higher penetration depth as shown in Figure 6(a,b). As soon as the controller was activated, the laser power started to decrease and, consequently, the measured electron temperature signal began to rise until its set point was achieved, corresponding to the optimized laser power value. Also in this case, the results of macrographs, plotted in Figure 6(c), showed that the penetration gradually approached and stabilized to its target value of 2 mm.


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)

(a) Electron temperature signal behavior. Controller parameters: Te,ref = 5,460 K corresponding to a penetration depth of 2 mm; Kp = −2 W/K; Ti = 150 ms. Initial laser power = 1,440 W. (b) Laser power measured by fast power sensor. (c) Penetration depth measurements.
© Copyright Policy
Related In: Results  -  Collection

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

f6-sensors-12-11077: (a) Electron temperature signal behavior. Controller parameters: Te,ref = 5,460 K corresponding to a penetration depth of 2 mm; Kp = −2 W/K; Ti = 150 ms. Initial laser power = 1,440 W. (b) Laser power measured by fast power sensor. (c) Penetration depth measurements.
Mentions: Finally, the starting laser power was set at 1,440 W, 20% higher than the optimal value, thus producing a higher penetration depth as shown in Figure 6(a,b). As soon as the controller was activated, the laser power started to decrease and, consequently, the measured electron temperature signal began to rise until its set point was achieved, corresponding to the optimized laser power value. Also in this case, the results of macrographs, plotted in Figure 6(c), showed that the penetration gradually approached and stabilized to its target value of 2 mm.

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.