Time： 2023-04-14 09:01:32
Author： Guangdong Hwashi Technology Inc.
Projection welding is a deformation of spot welding, usually by punching a protrusion on one of the two panels and then welding. Due to the concentration of current, the disadvantage of melt drift during spot welding is overcome, so the thickness ratio of the workpiece during projection welding can exceed 6:1. When using multi-point projection welding, if the welding conditions are not appropriate, it can cause displacement of the projection points and lead to a decrease in joint strength. Experiments have shown that displacement is caused by the electromagnetic force when current passes through.
1. The function of convex points is to limit the current and pressure to specific positions on the workpiece, and their shape and size depend on the application situation and the strength of the solder joint required. The recommended solder joint sizes from different sources often vary greatly. In general, it is recommended to use the protrusion size specified in the table below. Compared to the thickness of the plate with protrusions, small protrusions are used when the plate is thinner, and large protrusions are used when it is thicker.
2. The Thermal equilibrium between the two plates to be welded shall also be achieved during projection welding, otherwise, the plate will be melted before reaching the welding temperature. Therefore, when welding the same metal, the bump shall be punched on the thicker workpiece, and when welding dissimilar metal, the bump shall be punched on the workpiece with higher conductivity. But when it is difficult to punch protrusions on thick plates, it is also possible to punch protrusions on thin plates.
Electrode materials also affect the Thermal equilibrium of the two workpieces. When welding thin plates with thickness less than 0.5mm, tungsten copper sintered materials or tungsten are commonly used as inserts of electrodes to reduce heat dissipation on one side of the plate.