LAST DEVELOPMENTS OF AUTOMATICALLY HYBRID
WELDING IN SHIPBUILDING USING HIGH POWER FIBRE
LASER WITH INTELLIGENT CLAMPING SYSTEM
Peter Seyffarth
IMG Rostock
Laser welding is coming up more and more in the last decade also in shipbuilding.
The reasons are the high productivity and the lower heat input in comparison with
other arc welding methods. This gives lower distortions and less reworking and
straightening. Laser welding is in use at German shipyards for instance for about 10
years in Papenburg (Meyer Werft) or about 5 years in Hamburg (Blohm & Voss). In
both cases the laser type is a CO2-laser and they use laser-hybrid-welding, too.
Last developments in high power laser technology in multi-kilowatt range are fibre
lasers using Ytterbium as active element for laser generation. Fibre lasers with a
maximum power of 10 kW are on the market since 2004 and nowadays the power is
scaled up to 20 kW and more. There is no upper limit for the power.
All worldwide in shipbuilding installed panellines with high power fibre lasers are
designed, constructed and delivered by IMG Ingenieurtechnik und Maschinenbau
GmbH Rostock.
Fibre lasers of this type give a lot of advantages:
 Very high power (up to 20 kW and more)
 Very high efficiency (about 30 %)
 Very high flexibility (working fibre up to 200 m)
 Very high beam quality (about 10 mm*mrad or better)
 Very low maintenance costs (no moving parts inside, no wear)
 Very high life cycle (500 000 working hours)
 Very low foot print. (0,8 x 1,4 m)
 Very low weight and therefore movable. (less 1 ton)
In a very short time the enterprise IPG developed this new system and the enterprise
IMG, which is a worldwide working outfitter for yards, delivering all welding
equipments for shipbuilding and steel constructions, using all the advantages and built
the first 16 m one-side-welding-gantry with fibre-laser-hybrid technique in 2005 for a
German shipyard, picture 1.
For 10 mm thickness of shipbuilding steel grade A the welding rate is 1,5 m/min for
laser-hybrid welding with 10 kW laser power, but for 6 mm thickness the result was 3
m/min with 7,8 kW laser power. The design of this gantry allowed weld with 4
various technologies depending of the material thickness:
 Laser welding alone for thin plates,
 laser hybrid welding for plates with higher gap tolerances,
 gas metal arc welding and
 submerged arc welding, too.
2-100
Fig. 1. One-side-welding gantry for 16
m length, equipped with a 10 kW fibre
laser (in foreground).
The gantry works with an intelligent hydraulic clamping system and the clamping
stamps can be controlled by the moving weld temperature field, picture 2. This gives
lower distortion on the clamping system and is a way to increase the weld path
accuracy.
Fig. 2. Intelligent clamping system fixed
on an experimental one-side-welding
gantry in the IMG-workshop.
The installed system allows to clamp the plates only on this range, where the
temperature field acts on the dilatation of the material, picture 3.
Fig. 3. Transversal forces at various clamps in 3 mm thick plates by moving
temperature field versus weld time.
2-101
Next installation of a fibre laser in shipbuilding made by IMG was the refitting of an
existing weld gantry at a Finnish yard, picture 4. In this case the installed laser power
was 6 kW. The panelline got the certification of the ships classification organization
DNV and on the base of more as a half year experience the yard is planning now the
next bigger panelline for 22 m weld length with a 10 kW fibre laser.
Fig. 4.
Refitting of an existing 12 m weld
gantry with a 6 kW fibre laser at a huge
Finnish yard in 2006.
In 2008 the enterprise IMG Rostock delivered a large panelline for another big
European shipyard. This panelline has some special features, giving further
advantages for welding. IMG Rostock uses a milling machine for the edge preparation
of the 16 m plate length. Both plates are clamped in the milling machine which gives
the guarantee to get exactly parallel edges. One side of the milling device is movable
and without opening of the clamps this side with one prepared plate moves after
milling towards to the other plate. Movement in the same equipment without opening
delivers a high geometrical accuracy of the edges and is the base for high weld
quality. Picture 5 shows the very straight panel after welding and the high accuracy.
Fig. 5. The flat panel after fiber laser hybrid welding.
2-102
The weld gantry is in position over the milling gantry, but detached from the milling
station to avoid some inaccuracy by vibrations or other disturbing factors, picture 6.
This last equipment is able to weld up to 20mm plate thickness in one run with very
high weld rate, using after laser hybrid welding head a second welding torch for GMA
tandem welding. The technology guarantees a high productivity as a very important
factor for the competitiveness of the shipyard.
Fig. 6. View at the one site welding station with the detached milling and welding
gantry.
Next installation is to realize in 2008 at a large German shipyard, using one fiber laser
for butt and fillet welding as well. With this installations IMG is the only deliverer of
fiber laser equipment in shipbuilding all over the world and at the same time fiber
laser equipment of IMG fulfils the longest seams with fiber laser technique up to 20 m
in the length.
2-103