Measurement of Dynamic Characteristics of Arc Sensor in GMA Welding in Dip Transfer Modet

摘要

The experimentally measured results of the dynamic characteristic of the arc sensor in GMA welding in dip transfer mode are introduced in this paper, where the dynamic characteristic of the sensor is expressed by a set of a sensitivity-frequency characteristic and a phase-frequency characteristic. In order to effectively remove the noise imposed on the detected welding electric signals, authors used the data-processing techniques of FIR digital low-pass filtering and DFT method. The obtained results show that the arc sensors sensitivities are quite higher than that in an open arc welding. It is made clear that this is due to the short-circuiting happened in the welding process, the higher is the short-circuiting frequency, the lower the sensitivities of the arc sensor become. Moreover, the arc sensor's current sensitivity reaches the highest level at around 3 Hz and the SN ratio in current seems to be also the best at 3 Hz. However, the arc sensor's voltage sensitivity increase with frequency increasing in principle, but it's SN ratio is quite poorer than that of current. It has been also clarified that the arc sensors current phase delays but the voltage phase advances relative to the variation of the torch height but the phase delay of current and the phase advance of voltage all do not exceed 180 degree according to experiments.