CONTROL OF WELDING CONDITION IN AUTOMATIC WELDING

PURPOSE:To perform welding always at optimum condition in FCB one side welding, by paying attention only to the amount of gap of the groove and controlling automatically welding condition for each plate thickness predetermined according to the amount of gap. CONSTITUTION:The first, second and third electrodes 1, 2, 3 are positioned successively behind the direction of advance off from a gap sensor 4 attached to a welding truck. The distance between the first and second electrodes 1, 2 and the distance between the second and third electrodes 2, 3 are kept at specified values. A penetration bead is formed by the first and second electrodes 1, 2 and groove sectional area is filled by the third electrode 3. The amount of gap of the groove is detected, and conditions that give good results of welding are plotted according to the amount of gap. This is performed at every changing of plate thickness, and change of current and velocity is expressed in primary function from conditions obtained according to the amount of gap for each plate thickness and put in a computer. Detected amount of gap is inputted as data, and appropriate welding condition for each plate thickness is maintained.