Closed-loop power and focus control of laser welding for full-penetration monitoring.
We describe a closed-loop control system ensuring full penetration in welding by controlling the focus position and power of a 4-kW Nd:YAG laser. A focus position monitoring system was developed based on the chromatic aberration of the focusing optics. With the laser power control system we can determine the degree of penetration by analyzing the keyhole image intensity profile. We demonstrate performance in bead-on-plate welding of Inconel 718 and titanium. The focus control system maintained a focal position on tilted and nonflat workpieces, and the penetration monitoring technique successfully controlled the laser power to maintain the full-penetration regime in the presence of linear and step changes of thickness. Finally we discuss the performances and the limits of the systems when applied to a realistic complex aerospace component.
Bardin
Fabrice
F
School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom. f.bardin@hw.ac.uk
Cobo
Adolfo
A
Lopez-Higuera
Jose M
JM
Collin
Olivier
O
Aubry
Pascal
P
Dubois
Thierry
T
Högström
Mats
M
Nylen
Per
P
Jonsson
Peter
P
Jones
Julian D C
JD
Hand
Duncan P
DP