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gussetplatesat thecornersof the frames issuggested.Gusset
plates connected to the short frame profiles serve as contact
faces for the positioning of the long frame profiles, which
reduces positioning complexity by one level.
Thecompletemanufacturingscenario for fixture-freeweld-
ing using a cooperating robot system is depicted in
Figure4
.
The manufacturing scenario comprises all handling tasks,
tacking andwelding processes.
In the first step, short frame profiles are positioned into
the stopsof the set-upplatformandclampedwithpneumatic
toggle clamps. Then, the gusset plates are successively po-
sitioned into the recessesof theprofiles, tackedandwelded.
The rotating unit is then turned through 180° and the two
long frame profiles are, one after the other, positioned on
the gusset plates and tacked. According to the welding
sequence, the corners are welded using different types of
joints. As a last step, the grid is positioned, tacked and
connected to the framewith short welded seams along the
corresponding webs. Finally, the finished fence element is
taken off the platform and the systemmade ready for the
next component.
To ensure the effectiveness of theproduction sequences
being designed, the application of virtual planning is a
promising tool.Here, simulationallows one to carry out the
evaluation of the technical and economical requirements
and the cycle times for preparedmanufacturing scenarios
before the processes start [7].
Figure 5
depicts the visu-
alisation level for the graphical simulation, the motion
sequence plan of the individual robots and the required
processing time.
System-usablewelding expert knowledge
Another important point to increase flexibility in welding
production is the provision of system-usable welding expert
Fixture-free robot welding
Figure 5: Offline programming and graphical simulation of the
welding sequence.
Figure 6: Procedure for the generation of surrogatemodels inwelding.
