Abstract: An electrode displacement monitoring and control system for predicting and adaptively controlling resistance weld quality. The relative displacement (34) between a movable electrode (16) and a fixed electrode (20) is monitored during a resistance weld cycle. The displacement information is processed and applied as a control signal for dynamically and adaptively varying various weld parameters including current application in order to control weld quality. A reversal in the direction of electrode displacement is identified and used in the adaptive control strategy to determine the amount of dynamic indentation achieved in a weld cycle.

Abstract: A system (10) and method for predicting weld quality in a stud welding system by measuring the displacement of a movable shaft (20) with respect to the gun body (12) during the weld process. A sensor (34) is positioned with respect to the welding system in order to produce a series of discrete signal values each indicative of this displacement. These values are plotted graphically and used to produce a weld "signature" which can be compared with signatures of welds of known quality to more accurately predict the quality of the current weld. Based on these weld signatures, various weld parameters including current, time and lift can then be adjusted until a consistent signature indicative of good weld quality is produced.