Measures to overcome nugget offset of intermediate frequency spot welding machine

Under normal conditions, when the intermediate frequency spot welding machine spot welds with different thicknesses and materials, the nugget will not deviate from the thick plate or the weldment with poor conductivity and thermal conductivity due to the symmetrical bonding surface. As a result, the size on the bonding surface will be lower than the nugget diameter. At the same time, the penetration rate on the thin part or the weldment with good conductivity and thermal conductivity will be lower than the specified value, this makes the solder joint bearing capacity is reduced. Measures for

Intermediate Frequency Spot Welding Machine to Overcome Nugget Deviation

1. Deviation: The main reason for the deviation of

nugget is that the heat evolution and heat dissipation of the two weldments in the welding area are different during the heating process, and the deviation direction naturally moves towards the side with more heat evolution and slow heat dissipation. During spot welding of

with different thicknesses, the thick part has large resistance and much heat analysis, while the heat analysis center is away from the electrode and the heat dissipation is slow, and the thin part is in the opposite condition, which causes the welding temperature field and nugget to deviate from the thick plate. During spot welding of

different materials, the workpiece with poor conductivity has a large resistance and a lot of heat analysis, but the heat dissipation is slow, and the material with good conductivity is in the opposite condition. This also causes the welding temperature field to deviate from the workpiece with poor conductivity, and the deviation of the temperature field produces the corresponding deviation of the nugget.

2. measures to overcome the deviation of nugget:

, adopting hard specification:

hard specification, the spread of current field during spot welding can better reflect the effect of concentrated heating of the edge facing the bonding surface, and because the short welding time reduces the heat loss and the influence of heat dissipation is relatively reduced, which can be corrected. The deviation of nugget is beneficial, for example, capacitive energy storage welding machine can be used to spot weld precision parts with a large thickness ratio.

2. Different electrodes are adopted:

adopts electrodes with different diameters. The thin part (or weldment with good electrical and thermal conductivity) adopts small diameter electrodes to expand current density and reduce heat loss, while the thick part (or weldment with poor electrical and thermal conductivity) adopts large diameter electrodes. The different diameters of the upper and lower electrodes make the temperature field tend to be reasonable, the deviation of the nugget is reduced. However, in the spot welding of stainless steel or heat-resistant alloy parts with relatively large thickness, contrary to the above principles, only small-diameter electrodes are effectively placed on thick parts. It is also called reverse welding in factories. Reverse welding has been applied in practice for many years, but its principle and reasonable application range are still controversial. Using electrodes of different materials, because the upper and lower electrode materials are different, the degree of heat dissipation is different, the material with good thermal conductivity is placed on the side of the weldment (or the weldment with poor electrical conductivity and thermal conductivity) to make the loss large, and the temperature field can also be adjusted to spread all over to reduce the deviation of the nugget.