MEASUREMENT AND THEORETICAL INVESTIGATION OF ARC SENSOR SENSITIVITY IN DYNAMIC STATE DURING GAS METAL ARC-WELDING

This paper shows the experimental and the theoretically predicted resu lts of the sensitivity characteristics of the arc sensor in a dynamic state during gas metal arc welding. First, a mathematical model of the sensor for theoretical prediction was introduced, and then the ration ality of the model was confirmed by a series of corresponding experime nts. Finally, simulation analyses were made in order to clarify how th e welding system and welding conditions affect the sensitivity charact eristics of the arc sensor. It is shown that the frequency of torch he ight variation (the sensor's input) significantly affects the sensitiv ities of the welding current and the welding voltage (the sensor's out puts). The current sensitivity is highest when the frequency of torch height variation is similar to 5 Hz, but the voltage sensitivity simpl y increases with the increase of torch height variation frequency. It is also clarified that a decrease in the welding loop's inductance and /or the equivalent output resistance of the welding power source impro ves the sensor's current sensitivity but decreases voltage sensitivity . Decreasing the electrical resistance, but with an increase in electr ic field intensity of the arc column, or using a shorter setting elect rode extension are useful ways of increasing the current and voltage s ensitivities of the sensor. (C) 1997 The Institute of Materials.