Due to the large number of interrelated variables associated with the process, weld quality of the resistance spot welding is extremely operation-dependent and thus requires an on-line weld quality control. In this thesis such on-line control is attempted to assure the satisfactory quality of the weld joints.
The process variable used herein for the control is the dynamic resistance, which varies significantly during the process. Since the weld quality depends largely upon the dynamic resistance response curve, an appropriate control of this variable becomes critical. The proportional control algorithm is implemented through a microcomputer to generate the welding control current, which is proportional to the error between a reference dynamic resistance and an instantaneously monitored dynamic resistance during the welding.
The effectiveness of this control is evaluated in comparison to the conventional spot welding by conducting a tension-shear test.
