Page 173 - Welding Robots Technology, System Issues, and Applications

Robotic Welding: Application Examples 161

The second example approaches the difficulties associated with the welding of
fillet welds in complex paths such as those found in the manufacture of metallic
beams or trusses.

5.3.1 Test Case 1 – Multi-layer Welding
In this example it is shown how to perform a simple multi-layer weld using the
definitions presented in Figure 5.11, and Table 5.1 and Table 5.2. The number of
layers and the placement of each one of them are obtained empirically using charts
from The Welding Institute [3] and our own experience. The process is performed
step-by-step, and any adjustment is introduced in the welding sequence being
programmed. Those adjustments can be position adjustments, welding parameter
adjustments and introduction or removal of layers. Since the program is stored in a
file, it can be used later to weld other similar pieces. The obtained procedure is
easy to use and very useful for industrial exploitation because the programmer can
easily setup a multi-layer welding procedure controlling and observing the effect of
each layer, and acting when necessary. Figure 5.11 shows the working piece,
composed by two 20mm thick plates, separated by 2mm, constituting a 60º V-
groove joint preparation, and the welding sequence (layers necessary to finish the
weld). The position of the torch in each layer is indicated in Table 5.1. The origin
of the reference axis system is centered in the bottom of the V-groove. This
information is generally not available in the welding databases. The welding data
used in this case is indicated in Table 5.2.

5.3.2 Test Case 2 – Multiple Welding Paths

In this example it’s shown how to perform a multipoint weld, very common in
companies that manufacture metal structures for the construction industry. The
idea is to extract points from the CAD model of the piece to be welded. It is
usually very simple to build a routine within the CAD software, enabling the user
to extract points from the working piece and defining the type of trajectories
between those points. This may be the initial procedure, very handy for companies
having CAD models of their products. After having the sketch of the definition
file, the user must work with it using the WeldPanel and WeldAdjust tools. The
working cycle should result in a properly tuned file for the purpose. An example of
the definition file has already been presented in Figure 5.6. The welding
parameters may again be obtained from a database. The process can then be
simulated for trajectory and welding parameters adjustment, and tested until
desirable performance is achieved, including acceptable welding quality.