After the nut spot welder completes the welding, the torque value is usually used as a measurement standard for the strength test of the nut projection weld. However, in actual operation, even if the torque after the nut spot welder meets the established standard, the nut will occasionally fall off...

In view of this, some automotive nut welding manufacturers have proposed that when welding nuts, the nut spot welder must not only meet the torque requirements, but also pass the destructive test verification. This means that the products welded by the nut spot welder must ensure that the nuts are stable and do not fall off, and maintain the stability of the spot welder.

The weld fracture after the nut spot welder is welded mainly presents two forms:

Fracture in the fusion zone, this fracture mode is brittle;

Fracture in the heat affected zone of the plate, this fracture mode shows toughness.

In terms of the welding quality of the nut spot welder, the welded joint should avoid brittle fracture. Therefore, even if the welded nut meets the torque standard, it is expected to have a certain toughness when it breaks, so that the fracture occurs in the heat affected zone of the plate, and such a fracture mode is safer and more reliable.

In summary, the variable frequency nut spot welder It is more in line with the needs of nut welding. It has low requirements for the power grid, helps energy conservation and environmental protection, and the welding effect can meet the expected structural requirements.

Selection strategy of nut spot welding machine

According to different requirements of welding effect (such as welding strength, torque, appearance and efficiency, etc.), AC spot welding machine, medium frequency spot welding machine, energy storage spot welding machine and variable frequency spot welding machine can all be used for nut welding.

If only the torque requirement is considered, the pneumatic AC spot welding machine can usually meet it;

If it is necessary to meet higher requirements such as strength penetration, torque and penetration depth, it is necessary to use medium frequency spot welding. Machine;

If you need to have both deep penetration and avoid back-threading, the energy storage spot welder is a better choice;

If you pursue higher welding quality, including torque, appearance, strength, thread protection, welding appearance, efficiency and low requirements for the power grid, you should choose a variable frequency spot welder and use it with a nut automatic conveyor.

When choosing a nut spot welder, you also need to pay attention to its power margin. Some equipment may only meet current welding needs, but may not be able to meet higher requirements for weldments. Therefore, this also needs special attention when choosing.