抄録
In automatic butt welding of relatively thin plates, it is important to control welding conditions in order to obtain a sound full penetration weld. Recently, it was reported that there was an intimate relationship between the oscillation of the molten pool and penetration. Therefore, the oscillation phenomena of the weld molten pool were analyzed and the estimation of penetration by detecting frequency of the molten pool was attempted.
In this study, a new oscillating method, Pulsed Assist Gas (PAG) oscillating method is proposed. The natural frequency of molten pool was measured from the molten pool oscillation detected by arc sensor. A control system, which controled welding current on the basis of oscillation frequency measured, was constructed. Main results obtained are summarized as follows:
1) In order to oscillate molten pool during TIG arc welding of thin steel plate, Pulsed Assist Gas (PAG) oscillating method was proposed and effectiveness of this method was confirmed.
2) The PAG oscillating method was superior to conventional pulsed current oscillating (PC) method in amplitude of oscillation and robustness of frequency measurement.
3) Applying PAG oscillating method and detecting oscillation of arc voltage, the peculiar frequency of the oscillation of molten pool could be detected.
4) A system to control weld penetration using the principle of detecting the peculiar frequency of the molten pool was constructed and the effectiveness of the system was demonstrated.
