1997 年 15 巻 2 号 p. 272-280
This paper gives a method to experimentally determine the dynamic characteristics of arc sensor in GMA welding in dip transfer mode. The method mainly involves a vibration device to excite sinusoidal wave forms of torch height and data processing by means of FIR digital low-pass filter as well as digital fourier transformation (DFT). Experimental results show that the sensitivities of arc sensor are quite greater than that in DC open arc welding. The response of welding current to the variation in torch height gets to reach the highest level at around 3 Hz in our experiments. Although the response continues to hold higher level when the frequency exceeds about 5-6 Hz, the SN ratio becomes poorer than that at 3 Hz. The response of welding current shows a delayed phase relative to the variation in torch height. Contrary to this, the response of welding voltage has an advanced phase relative to the variation in torch height, and the response becomes higher and higher with the increase of the variation frequency of torch height, but it's SN ratio is quite poorer than that of the response of welding current.
To clarify the effects of shielding gases on the arc sensor, experiments were made by using different mixed gases of Ar and CO2. It is found that contrary to these in open arc welding, the responses in short-circuit arc welding using pure Ar are higher than that using mixed gases of Ar and CO2.
Simulation analysis was also made based on an arc sensor's model proposed by authors for the short-circuit arc welding. The results displayed that the theoretical and experimental results are quite similar in qualitatively but did not yet achieve agreement quantitatively. The theorectical results also show that not only the average short-circuit frequency, but also the change rate of the short-circuit frequency induced by the variation in arc length have great effect on the sensitivities of the arc sensor.