Research on the Control Method of Multi-parameter Comprehensive Decision Making for Spot Welding

Abstract

Resistance spot welding quality is always one of key subject matters for study to which many welding scholars at home and abroad in the world devote themselves.It has not been solved satisfactorily at present. The complexity of spot welding process, invisibleness of nugget formation and singleness of control method decide that stabilizing quality is a rather difficult task. The limitations of describing how the nugget grows up based on single-sensor information source is analyzed. A control method of multi-parameter comprehensive decision making for spot welding is put forward. The multi-sensor information fusion is adopted for real time monitoring four parameters which are closely concerned with the weld nugget size(welding current, electrode displacement, dynamic resistance, welding time). Information fusion algorithm includes sensor-based weighted average fusion algorithm and knowledge-based production rule fusion algorithm. The spot welding experiments indicate that nugget size fluctuations are within 8%∼22% under constant current control, and are within 6%∼12 under information fusion control. It conforms that the new quality control method can compensate for various factors of influence in the welding process such as shunt, loop inductive reactance variation and electrode wear, etc, and assure the spot welding quality to be stable