Page 61 - Welding Robots Technology, System Issues, and Applications
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Welding Robots
46
Power
supply Partially
mirror
Turning
mirror Laser light source mirror
Laser beam
Beam focus
system
Workpiece
Figure 2.13. Schematic representation of a laser welding system
1
4
3 6
5
a
1
4
2
3
6
5
b
Figure 2.14. Laser welding modes: Heat conduction-mode – a; deep-penetration mode – b.
Laser beam – 1; vapor channel – 2; weld pool – 3; welding direction – 4; work-piece – 5;
solid melt – 6.
10
-2
For power densities above a critical threshold of about 10 Wm the laser beam
causes melting and vaporization of metal, creating a keyhole in the work-piece, as
shown in Figure 2.14 b). The keyhole and plasma generated aid the adsorption of
energy by the work-piece and the distribution of heat deep in the material. Metal
vapor continuously generated tends to maintain the keyhole while metal flow and
