LIBRARY ı6ıul 0) - Cranfield University

profile to a more uniform profile. Also, a greater depth of penetration! in the
workpiece was observed in all the stand-off and voltage controlled spray transfer
trials, despite lower welding voltages and currents being applied. The change in the
bead profile and the increase in fusion depth were possibly caused by a change in the
fluid flow and heat transfer mechanisms inside the weld pool. Such a change was
probably due to a more efficient transfer of power from the arc and the molten
droplets which resulted from the reduced arc length and the more constricted arc
[refs. 6,32,202]. It should be noted, however, that a detailed study of penetration
mechanism was beyond the scope of this work.
8.5 The significance of this work
The proposed strategy of moving the workpiece in order to adapt to
positioning errors between the weld joint and the programmed robot welding path
provides a flexible way of compensating for positioning errors independently of the
type of robot being used. This gives rise to the possibility of development of adaptive
jigging systems.
The main benefit of the automatic voltage tuning method developed in this
work is that it could reduce for the power source manufacturers the time and effort
used in developing synergic welding curves for different gases and wires, by
automatically setting up the welding voltage. It is noted that most power sources
already have voltage trim facility, the effective use of which requires (and depends on)
skilled welder(s). The results of this research work show that the voltage control
method developed could be used to replace the trim facility, thus ensuring that an
unskilled welder could still produce good quality welds.
The integration of welding procedure generation into a CAD software makes
it possible to use the component geometrical data and the welding information for
optimising component design and productivity. For example, by using simulation it
would be possible to determine the welding procedures and the sequence of welds in a
component that would result in the highest production rate.
9 Measured axially to the arc from the joint line (intersection between joint adjacent surfaces)
towards the base plate.
197