Technology series part IV – Roller seam welding
KUKA Systems is ideally set up to provide welding solutions since the company offers a wide variety of technologies: from laser hybrid welding to friction welding and magnetarc welding to gas metal-arc and submerged-arc welding. Spot welding is probably one of the best-known joining processes, a discipline that KUKA has thoroughly mastered. But roller seam welding is hardly ever mentioned, even though it is another important joining technology that has been practiced on a daily basis for decades.
Roller seam welding is a type of resistance welding and is mainly used to join steel panels in automotive manufacturing and sheet-metal processing. The advantage of resistance welding is that a great deal of energy in the form of electricity, which can reach up to 40,000 amperes, can be concentrated on a small area within an extremely short time. When pressure is added, using a welding gun or roller, for example, the result is a stable and permanent joint.
“Roller seam welding is a special type of resistance welding. In this process, instead of two electrodes at the end of the welding gun forming the spot welds, there are two copper rolls arranged one above the other (called electrode wheels) which weld a series of overlapping spots,” explains Miroslav Sauer, who works in sales and project planning in the Technology Solutions division at KUKA Systems GmbH. “After the component has been processed, these many spots result in a continuous seal weld seam,” Sauer continues. Robots, to which the wheels are attached as tools, guide the electrodes along the component. In this joining process, the weld current flows without interruption, as it were – this makes it closely related to continuous current welding. This welding process is absolutely necessary to form seal welds. KUKA has been using this procedure since the early 1980s. And today it is still used to weld tanks and heating radiators. Recently a complete welding line for the rear panel of dishwashers was installed as part of the existing production system of a renowned household appliance manufacturer.