Penetration control by monitoring molten pool oscillation in TIG arc welding

In automatic bun welding of relatively thin plates, it is important to control welding conditions in order to obtain a sound fun penetration weld. Recently, it was reported flat there is an intimate relationship between the oscillation of the molten pool and penetration. The frequency of a molten pool decreases drastically with transformation from partial penetration to full penetration and with an increasing molten pool size. Therefore, the oscillation phenomena of the weld molten pool we analyzed and the estimation of penetration by detecting frequency of the molten pool is attempted, In this study, a new oscillating method, Pulse Shielding Gas oscillating (PSG) method is proposed. The natural frequency of molten pool is measured from the molten pool oscillation detected by arc sensor. A control system, which controls welding current on the basis of oscillation frequency measured, is constructed.