The selection of spot welding process parameters: the process parameters that affect spot welding include the structural diameter of the welding electrode, welding energy, welding time and welding pressure. According to the welding speed and welding effect can be divided into fast welding, medium speed welding, ordinary welding three conditions, for the workpiece requirements of high welding strength, welding deformation of small occasions, the use of high-power, short time strong specification fast welding. For the workpiece with less stringent requirements, the ordinary welding method of low power and long time can be used, so that a relatively small welding equipment can be selected, and the impact on the power grid is also relatively small. It is usually selected according to the material and thickness of the workpiece, referring to the welding condition table of the material, first determine the end face shape and size of the electrode, then preliminarily select the electrode pressure and welding time, and then adjust the welding current, weld the sample with different currents, and then adjust the electrode pressure, welding time and current within the appropriate range after checking that the diameter of the molten core meets the requirements. The sample is welded and inspected until the quality of the solder joint fully meets the requirements specified in the technical conditions. The most commonly used method for testing samples is the tear method, and the mark of a good quality solder joint is that there is a round hole in one piece of the tear sample and a round boss in the other piece. Thick plates or quenched materials sometimes cannot tear out round holes and convex tables, but the diameter of the molten core can be judged by the shear fracture. If necessary, it is also necessary to carry out low-power measurement, tensile test and X-ray inspection to determine the penetration rate, shear strength and whether there are shrinkage holes and cracks. When selecting the process parameters with the sample, the differences between the sample and the workpiece in the shunt, the influence of ferromagnetic substances, and the assembly gap should be fully considered, and the appropriate adjustment should be made.

 

The main factors affecting the welding quality of spot welding joints are welding current, electrode pressure, welding time, prepressure and rest time, welding electrode diameter and so on.