Oxides, dirt, oil and other impurities on the surface of the automatic soldering machine will add touch resistance. Too thick an oxide layer can even prevent current from passing through. Partial conduction causes splashing and exterior burning. Because the touch area of the electrode determines the current density, the resistivity and thermal conductivity of the electrode data are related to the generation and loss of heat. Therefore, the shape and data of high-temperature fan electrode have obvious influence on the formation of molten core. With the deformation and wear of the electrode head and the increase of the touch area, the strength of the solder joint will decrease. The reference process data of the automatic soldering machine and the existence of the oxide layer in the welding time setting of the automatic soldering machine will also affect the uneven heating of each solder joint, resulting in wavering welding quality. The impedance of the automatic soldering machine changes because of several changes in the circuit or the introduction of different amounts of magnetic metals in the secondary circuit. For DC welders, the impedance change of the secondary circuit has no obvious effect on the current. The role of the welding time is to ensure the size of the molten core and the strength of the solder joint. The strength of solder joints can compensate for each other within a certain range.

 

1. The selection of hard or soft standards depends on the performance, thickness and power of the welder used. The current and time required for different properties and thicknesses of metals have upper and lower limits, subject to practice. Effect of electrode pressure Electrode pressure has a significant effect on the total resistance R between the two electrodes. With the increase of electrode pressure, R decreased significantly, but the increase of welding current was not large, which could not affect the reduction of heat caused by the decrease of R. Solder joint strength always decreases with the addition of welding pressure.

 

2. The solution is to add welding current while adding welding pressure. Because of the influence of electrode shape and data characteristics, the electrode touch area determines the current density, and the resistivity and thermal conductivity of the electrode data are related to the heat generation and loss. Therefore, the shape and data of electrode have obvious influence on the formation of molten core. With the deformation and wear of the electrode head, the touch area increases, and the strength of the solder joint decreases. The electrode pressure of the automatic soldering machine has a significant effect on the total resistance R between the two electrodes. With the addition of electrode pressure, R decreased significantly, but the addition of welding current was not large, and would not affect R to reduce heat. Therefore, the strength of the solder joint always decreases with the addition of welding pressure.

 

3. On the DC welding machine, when the secondary circuit impedance change has no obvious effect on the workpiece and the electrode, the resistance of the workpiece depends on its resistivity. Therefore, resistivity is an important characteristic of welding data. Metals with high resistivity have poor electrical conductivity (such as stainless steel) and metals with good electrical conductivity (such as aluminum alloy). Therefore, stainless steel spot welding is easy to heat and difficult to heat, and aluminum alloy spot welding is easy to heat and difficult to heat. When spot welding, the former can use a small current (several thousand amps), and the latter must use a larger current (tens of thousands of amps). The resistivity depends not only on the variety of the metal, but also on the heat treatment state, processing method and temperature of the metal