Automotive Engineering - March 2023 - BET9

can provide variable beam-shaping options
that increase laser flexibility. This
option requires a single-axis shift or rotation
to change the ratio intensity between
the core and ring beams. Another approach
uses variable superimposed intensity
distribution with a two-in-one (dual-core)
fiber.
While such beam-shaping solutions
can improve the flexibility of a given proShape
Sequence Focal length Parameters
Resize matrix to 32
Shape generation
[um] Max normalization
1.434
1.075.5
717
358.5
[x,y]:(219.01,-62.57) [µm]
ρ:2.11 [w/cm^2]
-358.5
-717
-1.075.5
-1.434
1.434
Selected Points:(50)
R
P
-6,3
-8,-3
-6,-8
-2,-12
4,-12
-8.-11
12.-8
15.-4
16,1
16.5
ExportShape
Cursor
manually
max
Dz :
Reset
Load
Reorder
DelateShape
Figure 5: OPA technology, a type of coherent beam combining (CBC), merges many singlemode
laser beams into one larger beam to manipulate the beam shape in real time, without
any moving parts, creating a dynamic beam laser. (Image: Civan Lasers)
Aluminum dimple weldingSolidification process of melted material
Laser Welding of Battery
Cooling Plates
To overcome cooling-plate welding
challenges, tailored beam shaped were
needed and designed (Figure 6). These
beam shapes use high shape frequency
together with a sequence of beam shapes,
this enables fast switching between
beam shapes, adding more flexibility. For
example, if one shape stabilizes the keyhole
and prevents spatter while a different
shape prevents
cracking,
then a
Temperature (K)
298.0 1000
T_melting
1500 2000 2500 3000 3500
T_evaporation
0.0025
0.0025
Figure 6: DBL software makes it easy to design the relevant beam shape, frequency, sequence,
and focus; upload it to the laser; and see the effect on the weld using cross-section analysis.
(Image: Civan Lasers)
Battery & Electrification Technology, March 2023
well-designed sequence of these two
shapes can achieve all three goals.
Processes for welding cooling plate configurations
have recently been developed,
including designs with channel and dimple
geometries made in Al 3003 and Al 5754
alloys. Simulations created by Professor
Andreas Otto at the Institute for Production
Engineering and Photonic Technologies at
the Vienna University of Technology (TU
Wien), Wein helped optimize the many process
parameters (Figure 7).
Simulations reveal that humping is a
periodic phenomenon. When the melt
pool is long and the speed is fast, cooling
starts from the sides, narrowing the molten
channel. As the molten channel narrows,
molten material flows up and creates
the hump.5
9
-1.075.5
-717
-358.5
358.5
717
1.075.5
1.434
Automatic shapes
cess - enabling a single machine to carry
out specialized tasks in serial production,
for instance - a static beam cannot adequately
stir the melt pool to accomplish
the frequently changing operations that
constitute the daily business of industry.4
Dynamic Beam Shaping
Known for overcoming welding defects,
dynamic beam shaping methods
currently include four options: galvanometer
scanners, piezo-driven actuators, micro-electrical-mechanical
(MEM) scanners,
and optical phased arrays (OPAs).
Galvanometric scanners can be used to
oscillate single-mode fiber lasers during
the welding process in the pattern of, for
example, a circle or a figure eight.
However, such solutions have power and
frequency limitations. Inherent mechanical
and kinetic trade-offs related to moving
parts limit the maximum achievable
frequency due to the mass of the scanner's
oscillating mirrors. Smaller, lightweight
mirrors limit laser power.
In contrast, OPA technology, a type of
coherent beam combining (CBC), merges
many single-mode laser beams into one
larger beam (Figure 5). Each laser emits
its own light, which overlaps with other
beams in the far field to create a diffraction
pattern, providing the flexibility to
easily manipulate the beam shape in real
time, without any moving parts, creating
a dynamic beam laser (DBL).
Automotive Engineering - March 2023

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