There are many interrelated variables, associated with the spot welding process, which cause weld quality variation. Because the small change of the variables affects the weld quality, the process is operation-dependent. Therefore, the need of an on-line weld quality control is evident.
One of the process variables which reflect the nugget formation is the dynamic resistance. The dynamic resistance was used as a controlled variable (output) for an on-line weld quality control previously. But, the work has some point to be complemented.
In this thesis, the relation between the dynamic resistance and the weld quality is studied. Also, improvement of the signal processing circuits and the control algorithm in the previous work is performed. The results of this work is shown by comparing the conventional (uncontrolled) spot welding through the figure of the dynamic resistance and the tensile-shear strength test.