"Most of what you can see of a Volvo comes from Olofström," explains Leif Winberg, the plant engineer in charge of resistance welding in the Volvo Olofström factory. This includes load-bearing components like the A, B and C columns, the bumper reinforcement, the front side members, the side impact beams, the cross beams and the roof arch and roof rail, together with doors and frames. All these components are produced in different versions for the various Volvo models, ranging from the compact V40 through to the S60 saloons and the large SUV, the XC90.
A key element in bodywork production is resistance welding, since correctly welded sheet metal components play a crucial role in the passive safety of a vehicle. Within the welding process, there is great potential for increased productivity in the milling of electrodes. Welding gun electrodes become blunter as they are being used and have to be milled after approximately 150 spot welds to ensure the spot welding is perfectly accurate. "Electrode milling operates on the same principle as the sharpening of a blunt pencil," explains welding expert Winberg.
Mobile tip dressers are not necessary for the welding guns on the ABB articulated-arm robots. These robots can feed their electrodes to the electrode milling device themselves after 150 spot welds. This freedom of movement of the welding guns opens completely new horizons. In a first step, the articulated-arm robot brings the welding gun to the tip dresser. This then mills the electrodes. In the next step, the robot swings its electrodes in front of the lens of the Festo SBO… - Q vision system. "The system produces an image which supplies the robot system with all the data necessary in order to position the electrodes correctly to weld the next sheet metal components," says Winberg. "The vision system is also easy to integrate and simple to commission via parameterization." The system includes not only the sensor system for the acquisition of image data but also a complete electronic evaluation unit and the interfaces (Ethernet/CAN) required for communication with primary PLC controllers. The vision system itself is accommodated in a housing which is no bigger than a one-liter carton of milk.
Olofström, Sweden
Key activity: Vehicle manufacturing
Västerås, Sweden
Key activities: Energy technology, factory and process automation