METHOD FOR CONTROLLING WELDING QUALITY OF SPOT WELDER

摘要

PURPOSE: A method for controlling the welding quality of a resistance spot welder is provided to decrease the generation of expulsion and to a welding condition close to an expulsion limit. CONSTITUTION: Conduction is performed by a firing angle based on a previously set up welding current value, and resistance is measured every conduction cycle. It is judged whether the present number of a conduction cycle reaches the previously set up basic number of a conduction cycle. As a result, when the present conduction cycle number does not reach the basic conduction cycle number, it is returned to a first step. When it reaches, a resistance decrease rate is calculated from a measured resistance value, and the resistance decrease rate is compared with a reference value. When the resistance decrease rate is less than the reference value, additional conduction is performed as much as the previously set up cycle number. The resistance is measured again and the decrease rate is calculated.