Resistance Spot Welding – Real Science Fiction
Lightweight construction in the automotive industry is booming. In the course of this, manufacturers are increasingly turning to aluminium, which poses a challenge for resistance spot welding.
Station 1
DeltaCon
... is the Fronius answer. The futuristic DeltaCon welding guns (conventional spot welding) ensure the massive traction required, for example, in aluminium spot welding. The DeltaCon can expend thereby up to 8 KN of pressure, about the weight of a small car. Also with the Product News the heavy cannon is driven up: The RSW department shows the robot-controlled DeltaCon welding gun right away, in two combined live applications:
- First, an EMC cage is dotted (housing, which ensures the electromagnetic compatibility)
- At the same time, the process is being utilized on typical aluminium segments from the automotive sector
The speed with which the guns are moved by the robot, as well as the precision of the spot welding, are overwhelming! All in all, the RSW entrance show is reminiscent of real science fiction.
In another experiment, two metal sheets are welded. The point does not last, the amount of welding stream was too low. The system detects the error immediately. The following shows how the parameters can be easily adjusted due to the absolutely intuitive user interface. There's no question about it: The repetition of the experiment is successful!
To demonstrate the resulting, now enormously durable addition, subsequently, one proceeds according to the descriptive guiding principle: 'The strength of resistance spot welding can only be tested through destruction.' Only with use of massive force it is possible to destruct the weld spots!
Custom Electrodes
In the next area, RSW exhibited customized applications for various areas of application. Fronius develops special electrodes for both special and complex application solutions. The concept of solution provider feels very present here.
Station 2
Deltaspot
However, one is particularly proud of the DeltaSpot. Worldwide, these special guns constitute the only resistance spot welding system with intermediate belt electrode ('dynode', or process belt)!
Originally, the DeltaSpot was designed for aluminium applications because the ultra-light material has little electrical resistance (about 1/3 compared to steel). In the course of this, aluminium would require much higher welding currents than steel. With the help of the process belts, it is now possible to inject the same amount of heat with lower current as with conventional RSW welding.
However, the benefits of the process tape are much more complex:
- The welding spots always remain of the same quality.
- It eliminates the need for electrode cleaning (milling)
- Alloy residue (electrode contamination) is excluded - the tape protects against it
- The heat management at the welding point can be influenced by the band selection
Wherever conventional RSW welding has problems, Delta-Spot can also be a solution - for example for complex three-sheet connections. In the impressive in vivo live trial this challenge should be presented:
A typical three-plate connection will get spots in the area of the B-pillar (chassis / vehicle construction).
(Steel grades of three-sheet connection)
- DP600 + Z100
- Usibor (with AlSi coating)
- DX56 + Z100 (thin sheet metal of the outer skin - very flexible, easy to shape)
The two thick sheets (DP600 and Usibor) can generate heat fast - the thin sheet (DX56), however, only with significant delay and generally, less heat. The two thicker steel sheets are already liquefied in the core, while the thin outer sheet metal (DX56) would require even more energy. Heat can now be applied with the process belt - the resulting connection will be perfect!
Conclusion: Tying the DX56 to the two high-tensile strength steels is an absolute challenge. Deltaspot can master this because of its unique technology!
Prospects: To date, Fronius has been represented predominantly in the automotive industry with the RSW systems. In the future, however, significantly more areas would be conceivable in which these technologies could be used profitably - for example in ship-building, railway construction and many more.
