Under normal conditions, when the intermediate frequency spot welding machine is spot welding of different thicknesses and different materials, the nugget will not be offset to the thick plate or the weldment with poor electrical conductivity and thermal conductivity due to the symmetrical bonding surface. As a result, it will be attached The size of the joint surface is lower than the diameter of the nugget, and at the same time, it also makes the penetration rate of thin parts or weldments with good electrical and thermal conductivity lower than the specified value, which reduces the load-bearing capacity of the solder joint.

　　Measures to overcome the shift of nugget for intermediate frequency spot welding machine

　　1. The reason for the deviation:

　　The main reason for the deflection of the nugget is that the heat dissipation and heat dissipation of the two weldments in the welding zone are different during the heating process. The deflection direction naturally moves toward the side with more heat dissipation and slow heat dissipation.

　　In spot welding of different thicknesses, the resistance of thick parts is large and the heat dissipation is large, and the heat dissipation center is far away from the electrode and the heat dissipation is slow. The condition of thin parts is the opposite, which causes the welding temperature field and the nugget to deviate to the thick plate.

　　During spot welding of different materials, workpieces with poor conductivity have high resistance and heat dissipation, but heat dissipation is slow, and the conditions of materials with good conductivity are the opposite. This also causes the welding temperature field to deviate to the workpiece with poor conductivity and the deviation of the temperature field. Then a corresponding shift of the nugget is produced.

　　2. Measures to overcome the deviation of the nugget:

　　1. Adopt hard specifications:

　　The spreading of the current field during hard standard spot welding can better reflect the effect of concentrated heating of the edge facing the bonding surface, and because the welding time is short, the heat loss is reduced, and the effect of heat dissipation is relatively reduced, which can be corrected, and the nugget is offset. The phenomenon is beneficial. For example, a capacitor energy storage welding machine can be used to spot weld precision parts with a large thickness ratio.

　　2. Use different electrodes:

　　Use electrodes of different diameters, and use small-diameter electrodes on the side of thin parts (or weldments with good electrical and thermal conductivity) to expand current density and reduce heat loss, while those on thick parts (or weldments with poor electrical conductivity and thermal conductivity) Large-diameter electrodes are used. The difference in the diameter of the upper and lower electrodes makes the temperature field more reasonable and reduces the deviation of the nugget. However, in the spot welding of stainless steel or heat-resistant alloy parts with a relatively large thickness, it is contrary to the above principles. It is effective to place small-diameter electrodes on thick parts. It is also called anti-welding in the factory. Anti-welding has been practically used for many years, but its principle and reasonable application range are still controversial. Electrodes of different materials are used because the upper and lower electrode materials are different, and the heat dissipation degree is different. The material with good thermal conductivity is placed on the side of the weldment (or the weldment with poor thermal conductivity), so that the loss is also large, and the temperature field can also be adjusted. All over, reduce the deflection of the nugget.