Modelling of an arc sensor for DC MIG/MAG welding in open arc mode: Study of improvement of sensitivity and reliability of arc sensors in GMA welding (1st Report)

Summary

A non‐linear model is developed to describe the relationship between the output (welding current and voltage) and input (torch height) of a through‐the‐arc sensor (arc sensor) for DC MIG/MAG welding in open arc mode. This model is expressed by the following five equations:

All model parameter values are determined for welding with both 1.2 mm dia. mild steel and stainless steel wires in a 100%Ar shielding gas. The simulated results based on the model show good agreement with the experimental ones.

A linearised arc sensor model is also derived from the non‐linear model on the assumption of any variable showing only a smaller variation around a given operating point. This model has the following form:

Some other features, such as the dynamic characteristics of electrode wire melting in GMA welding, are also clarified.