LAUSR

Projection welding is the variations of the spot welding, which is a kind of resistance welding. The projection points are arranged on the workpiece and the nuggets are formed at the projection points. The projection welding technology of nut to steel is a key process in auto manufactories. The welding position of the nut can be accurately positioned and the welding quality can be improved by the projection welding process in the manufacturing process of the white body. In the spot welding, the current flow is determined by the size of the electrode tip, whereas in projection welding the current flow is constricted to the contact surfaces by an embossed or machined projection. Metal sheets, wires and fasteners such as nuts, bolts, screws and pins can be joined with projection welding.1) In the study of Tolf and Hedegard,1) different resistance welding equipments were compared and both alternating current and direct current were evaluated in resistance projection welding of weld nut to thin sheet steels. They found that alternating current (AC) power sources, which outputted sinusoidal current, increased the current range and the tensile strength of weld nut joints compared to medium frequency direct current (MFDC) machines. However, significant differences in pull-out strength were recorded in joints welded with different AC power sources due to the different initial heating capacity. Wang2) investigated the effects of surface Effects of Welding Procedures on Resistance Projection Welding of Nuts to Sheets