Influence of power supply control mode on micro-resistance spot welding process of nickel chip

Constant current control mode is the most important control mode of resistance welding power supply.However, this mode has a larger energy input in the initial stage of welding, which easily leads to the occurrence of bad welding phenomenon and energy waste.In order to solve this problem, the influence of different power control modes on formation process and performance of the joint, and process energy consumption was studied by taking thin nickel sheet as welding object in the paper.Taking shear strength as evaluation index of the joints’ quality, the influence of welding parameters on tensile strength of joints was studied by orthogonal test, and the optimal welding parameters were obtained under constant pressure mode, constant current mode and constant power control mode.The tensile strength, fusion core size, morphology of joints, dynamic resistance and energy consumption of the samples under conditions of optimal welding parameters with different modes were compared and studied.The results showed that the welded joints with similar tensile strength, surface morphology and core size could be obtained under constant current mode, constant pressure mode and constant power mode, and the physical characteristics of formation process of joins were similar.However, the energy consumption of welding process under constant pressure control mode was only 23.73 J, which was far less than that under constant current mode and constant power mode, and it had obvious advantages in practical production.Highlights: Orthogonal test method was used to study the influence of welding parameters on the performance of micro-resistance spot welded joints of thin nickel sheet under different power supply control modes.Based on the electrical characteristic curve of welding process, the formation process of fusion core under different power supply control modes was analyzed.It was found on the premise of obtaining similar joint performance that the welding duration was shorter and energy consumption was lower under constant voltage control mode.