Forging force in resistance spot welding: analyzing the electrically generated forging force for two different electrode actuations

Abstract

The forging force effect on resistance spot welding field is an ambiguity because it is believed to be just a mechanical force escalation in the classical theory. So far, the mechanically generated forging forces have been observed by many researchers and only the mechanical features have been considered for the investigation. Unfortunately, the journey of this exploration has not been continued after several superficial results were found for the past few decades. In real, there are still some cohesive existences of forces that have not been properly expounded yet, although it has frequently been noticed by other researchers. In this paper, the electrically generated forging force is introduced and also discussed for better realization. Several case studies for the fluctuation of electrode forces in terms of forces, vibrations, and acoustic emissions are primarily referred to support the classical concerns. With the inconstant and inaccurate force exertion, a computational analysis is derived as to distinguish the electrically generated forging forces with respect to the variation of process variables. Four types of metals are welded with two different electrode actuations and the corresponding force profiles are carefully measured. Only the stainless steel weld-based signals are presented in this paper to simplify the analysis because other materials too have similar phenomena. Experimental results show that the electrically generated forging forces are directly proportional to welding current, welding time, and compressing force but inversely proportional to electrode tips, provided the computation lies within welding lobe limits.