Bead formation and Characteristics of Heat Transfer and Damped Oscillation. Monitoring Bead Formation by Detection of Molten Metal Characteristics during Pulsed GTA Welding.

This report deals with a detection and estimation of change in the characteristics of molten metal such as heat transfer and damped oscillation during an arc welding with a pulsed current for monitoring the bead formation of the back side of a thin plate.An idea of the detecting method had been proposed in 1974 (Japanese Patent No.876269, U.S. Patent No.3988567, British Patent No.1493524) and to apply the idea to a new welding system to be developing, reasonableness and effectiveness of the method are reconsidered and made clear.It is possible that the depth in a partially penetrating weld is roughly estimated from detecting the waveform and the phase difference of change in the heat rediation on the back side due to the difference of heat transfer in welding a plate.In addition, it is possible that the stability in the back side bead formation as well as the back bead size in fully penetrating weld are estimated from detecting the waveform of change in the heat radiation due to the damped oscillation of the molten metal in the back side.