In fact, the process parameters of the stainless steel spot welder are not isolated in the process of welding, and often changing one of the parameters will cause another parameter to change and restrict each other. Changing the welding current IW, welding time TW, electrode force FW, electrode working surface diameter de will affect heat dissipation, and tW and FW are closely related to the plastic zone size of the solder joint. Increasing IW, and TW, reducing FW, increasing the heat of precipitation, can increase the size of the nugget. At this time, if the heat dissipation is poor (de small), splashing, overheating, etc. may occur; otherwise, the size of the nugget is small, or even Solder through.
Increasing IW and TW increases the nugget size and penetration rate and improves the shear strength of the solder joint. If the two process parameters are adjusted differently, two kinds of welding conditions with different heating speeds, namely strong conditions (standard), will be obtained. The strong condition is that the welding current is large and the welding time is short. The effect is fast heating speed, the steep temperature distribution in the welding zone, narrow heating zone, good joint surface quality, less superheated structure, good joint performance, and high productivity. Therefore, as long as the power of the welder is allowed, the control of each process parameter is accurate and should be used. However, due to the high heating speed, it is required to increase the electrode force and the heat dissipation condition to cooperate with it, otherwise, it is prone to splash and other defects.
The weak condition is that the welding current is small and the welding time is long. The effect is that the heating rate is slow, the temperature distribution in the weld zone is gentle, the plastic zone is wide, and the deformation is easy under pressure. Therefore, for materials with insufficient welder power, large workpiece thickness, difficult deformation or easy quenching, it is advantageous to use weak condition welding.
According to the requirements of different metal materials or structures for welding quality, the adjustment of process parameters is various. In all the process parameters of spot welding, the welding current and the energization time are the main parameters affecting the temperature of the welding zone. By changing the number of pulses of the welding current, the magnitude of the amplitude and the length of the on-off time, different temperature changes can be obtained in the weld zone. In order to achieve the purpose of smoothly welding weldments of different materials and thicknesses.
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