Page 18 - Welding Robots Technology, System Issues, and Applications

Welding Robots
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Industrial Robotic Welding is by far the most popular application of robotics
worldwide [6]. In fact, there is a huge number of products that require welding
operations in their assembly processes. The car industry is probably the most
important example, with the spot and MIG/MAG welding operations in the car
body workshops of the assembly lines. Nevertheless, there are an increasing
number of smaller businesses, client oriented, manufacturing small series or unique
products designed for each client. These users require a good and highly automated
welding process in a way to respond to client needs in time and with high quality.
It is for these companies that the concepts of Agile Production [7],[8] apply the
most, obviously supported by flexible manufacturing setups. Despite all this
interest, industrial robotic welding evolved slightly and is far from being a solved
technological process, at least in a general way. The welding process is complex,
difficult to parameterize and to effectively monitor and control [1]-[7]. In fact,
most of the welding techniques are not fully understood, namely the effects on the
welding joints, and are used based on empirical models obtained by experience
under specific conditions. The effects of the welding process on the welded
surfaces are currently not fully known. Welding can in most cases (i.e. MIG/MAG
welding) impose extremely high temperatures concentrated in small zones.
Physically, that makes the material experience extremely high and localized
thermal expansion and contraction cycles, which introduce changes in the materials
that may affect its mechanical behavior along with plastic deformation [9]-[11].
Those changes must be well known in order to minimize the effects.

Figure 1.1. Industrial robot zone

Using robots with welding tasks is not straightforward and has been a subject of
various R&D efforts [12]-[16]. And that is so because the modern world produces
a huge variety of products that use welding to assemble some of their parts. If the
percentage of welding connections incorporated in the product is big enough, then