Pulsed operation of a DC welding power source in resistance projection welding

Abstract The effect of pulse welding current (DC, 1 kHz) on the progression of projection welding process of nuts was analysed. The study involved a comparative analysis using identical average value for pulsed DC current with continuous direct current (DCc), which is commonly used in conventional mode. The analysis was conducted for nuts featuring four trapezoidal projections, made of grade 10B21 steel (AISI1017-SORPAS library), with a projection height of 1.2 mm and an initial contact area between the projection and the sheet metal of 7.8 mm 2 . The second welded component was a 3.0 mm thick DC04 sheet metal. Numerical analyses in both cases were conducted using the SORPAS ™ software. The characteristic parameters evaluated were weld strength, volume of melted material (in both the sheet and the projection), area of molten material in the contact region, welding energy, and average welding current. The results of the numerical calculations were verified experimentally. The study demonstrated the beneficial effect of pulsed welding current (DC, 1 kHz) on weld quality, particularly in terms of improved strength. It is possible to both reduce welding time and increase weld strength for pulsed DC welding. With comparable weld strength, welding time can be reduced by over 30%. In turn, for the same welding time (and thus the same energy), the weld strength can be increased by 35%.