Laser head Controller
a) b) c)
TECHNOLOGY HAS USES IN WELDING THIN
SHEETS AND DISSIMILAR MATERIALS
High-power and high-beam-qual- ity solid-state lasers, such as the thin-disk laser and fiber laser, have made laser welding popu- lar in manufacturing industries. More recently, kilowatt direct-di- ode lasers have become commercially available with beam quality competitive to thin-disk or fiber
lasers [ 1–2] because of a laser beam combining method called
wavelength beam combining, by which beam quality can be
maintained without deterioration when power scaling. Replacing
CO2 lasers, these solid-state lasers are becoming the main players in the field of remote laser welding.
Remote laser welding (RLW) is characterized by a long focal
length and a fast-moving laser spot on a workpiece, generally by
a pair of mirrors called a scanner [ 3]. The weight of the scanner is
said to be over 30kg [ 4], making it necessary to use a heavy load
robot. This article reports a newly developed Laser Processing
Robot Integrated System Solution (LAPRISS) with a compact
laser welding head for RLW, and shows several applications.
FIGURE 1 shows the main components and connection of this
system, including a 4k W direct-diode laser scaled by wavelength beam-combining technology [ 1] and a newly designed
trepanning type of laser welding head mounted directly on a
robot manipulator. Robot motion and laser oscillation, including its power and irradiated laser pattern on the workpiece, are
controlled by a robot controller.
In the laser welding head, two parallel optical plates are
driven independently by two servo motors to change the optical paths and form different types of irradiated laser patterns
on a workpiece (FIGURE 2). The laser welding head is designed
to weigh less than 5kg, making it possible to be carried with a
light load robot.
From the typical irradiated laser patterns shown in FIGURE 2d, it
is easy to consider that LAPRISS could replace resistance spot
welding (RSW) or arc welding by using a circle- or line-shaped
welding bead. Among the many merits of remote laser welding,
LAPRISS can decrease cycle time when replacing RSW, and
increase gap tolerance in thin metal sheet welding.
Decreasing cycle time
Cycle times by RSW and LAPRISS were evaluated on
0.8mm-thick mild steel, with the nugget diameters of RSW and
the circle diameter in LAPRISS both set to 4mm. FIGURE 3 shows
welding times of each action and tensile shearing test results,
where the average times for welding are 2.85 and 0.675 sec in
RSW and LAPRISS, respectively, and the cycle time of LAPRISS
is one-quarter that of RSW.
FIGURE 2. The laser welding head (a), its optics (b), beam
paths (c) and typical irradiated patterns formed on a
workpiece (d) are shown.
FIGURE 1. The main components and connection of the
LAPRISS system are shown.