The resistance welder is a method of heating the resistance thermal effect to a molten or plastic state and forming a metal combination by passing an electric current through the contact surface of the workpiece and adjacent areas. There are four main welding methods of resistance welder, namely spot welding, seam welding, projection welding and butt welding.
Characteristics of resistance welder:
1、The resistance welder uses the resistance heat generated inside the welded parts, which is conducted through the high temperature area to the low temperature area, to heat and melt the metal to achieve welding. It is an internally distributed energy source.
2、Resistance welder's seam welding is solidified or set crystal under pressure and has the characteristics of forging, which belongs to the category of pressure welding.
3、As the welding heat is concentrated, the heating time is short, the heat-affected zone is small, and the welding deformation and stress are small. Therefore, post-welding calibration and heat treatment are usually not required.
4、Low welding cost, generally do not need welding wire, flux, shielding gas and other welding materials.
5、The molten metal is isolated from the air, the welding cure process is relatively simple, and the molten nucleus of resistance welding is always surrounded by solid metal.
6、Simple operation, easy mechanization and automation, good labor conditions.
7、High productivity, can be arranged with other processes on assembly welding lines. However, as flash welding has spark spatter, it still needs to be isolated.
8、Due to the high power, mechanization and automation of resistance welding equipment, large investment in equipment, maintenance difficulties, commonly used high-power single AC welding machine is not conducive to the normal operation of the power grid.
9、The lap joint of spot welding not only improves the quality of the component, but also reduces the tensile strength and fatigue strength of the joint.
10、The quality of resistance welding, there is a lack of reliable nondestructive testing methods, can only rely on process samples, destructive testing and various monitoring techniques to ensure.
