What is the reason for the misalignment of the nugget of the mobile spot welder?
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Update time : 2022-05-16 08:52:07
When resistance welding is used to weld materials with different thicknesses or different materials, the nugget will be asymmetrical to its interface, but will be offset to the thick plate or the side with poor electrical conductivity and heat transfer. , The penetration rate of workpieces with good heat transfer is reduced, and the strength of solder joints is reduced. The nugget offset is caused by different thicknesses of the two workpieces due to different heat generation and heat dissipation conditions, and the resistance of one side of the thick workpiece is large.
In this way, the interface will be far away from the electrode, so the heat generation is more and the heat dissipation is less, which leads to the tendency of the nugget to be thick. The condition of adjusting the nugget offset is to increase the heat generation of the thin plate or the workpiece with good electrical conductivity and heat transfer and reduce its heat dissipation.
Common ways are:
The strong case is selected to enlarge the influence of heat generation by contact resistance between workpieces and reduce the influence of heat dissipation of electrodes. The capacitor energy storage welding machine can weld workpieces with relatively large thickness by using high current and short power-on time. Select electrodes with different contact surface diameters and select smaller diameters on one side of thin parts or workpieces with good electrical conductivity and heat transfer to increase the current density on this side and reduce the influence of electrode heat dissipation.
Choose different electrode materials. Use copper alloys with poor heat transfer on the side of thin plates or workpieces with good electrical conductivity and heat transfer to reduce the heat loss on this side. Use process gaskets A gasket made of metal with poor heat transfer (thickness 0.2-0.3mm) is placed on one side of thin parts or workpieces with good electrical conductivity and heat transfer to reduce heat dissipation on this side.