„An important pilot project“

Siemens: Reliable manufacture of protective contact pieces

With a new Bihler welding and soldering line, Siemens AG in Amberg is boosting its production efficiency in the manufacture of protective contact pieces. At the heart of the servo-controlled system lies the B 20K welding controller with its new linear actuator.

Siemens Gerätewerk Amberg (GWA) was founded in 1949 and its portfolio includes, for example, circuit breakers and protective connectors for switching electrical current. The fixed and moving contact pieces with their silver contacts are important components of these products. The size S2 is designed for power ratings of up to 37 kW and 80 A. The dimensions of the contact pieces are therefore correspondingly large, with an edge length of 6.8 cm and a thickness of 1.85 mm. In the past, the S2 contact pieces were produced on a Bihler welding machine equipped with conventional electrode holders. “However, in terms of manufacturing technology, we are now at the limit of what we can achieve with this system, in particular with regard to the movement of the electrode and the current intensities of up to 30 kilo amperes,” explains Heinz Speil, who is responsible for connection technology at Siemens. “At up to 300 kilograms, the forces at work in the system due to the magnetic field are enormous. They affect the entire system and can, for example, shift the positions of the axes.”

Equipped with the new linear actuator

To get to grips with this issue and, more generally, to extend the existing capacity, Siemens will in future use a new Bihler welding and soldering line to manufacture its contact pieces. At the heart of this solution lies the B 20K welding controller with its new linear actuator. This ensures that the force generated by the welding current and the magnetic field does not have any impact on the welding process. Another advantage of the linear actuator lies in the fact that the linear movement of the welding head permits particularly fast repositioning, which also reduces the formation of spatter. However, the solution also includes other Siemens-specific features. These include a servo-controlled 50-tonne screw press and a new module for the optical positioning of the welding and wobbling stations at a strip that is now free from stresses. The solution also includes a thermal station developed by Bihler for the production of the surfaces of the silver contacts.

Twice as fast

Overall, the new system provides any number of advantages: “The new linear welding module brings our manufacturing process the stability we need, in particular when running at full capacity,” stresses design engineer and project manager Alfred Schnellinger. “At the same time, we can manufacture the fixed contact pieces for the connectors twice as fast as before.” Thanks to the active power supply module, the system is secured against mains power supply fluctuations caused by other large consumers. Another important advantage lies in the fact that the previous, time-consuming setup operations have been eliminated and the setup time has been reduced to just a quarter of the time required in the past. “The increase in productivity is of decisive importance for us and was one reason for the investment in the new welding line,” explains Erwin Kohl, Group Head for Manufacturing and Engineering at Siemens. However, just as important are the possibilities for intelligent, digitalized process control that the new system offers. “The analysis of the NC data permits better process monitoring, including a more precise definition of the threshold separating conforming and nonconforming parts. In the future, the acquisition will pay for itself many times over and will also justify the investment costs for the system,” continues Kohl.

Best in class

“We are delighted with the development work that Bihler has put into the new system,” says Kohl. “For us, the use of this system is an important pilot project and we also have confidence in the strength and expertise of Otto Bihler Maschinenfabrik.” And Siemens is well aware of Bihler’s skills because the two companies have been working together successfully since the early 1970s. “We are convinced that with this new system, we will be able to manufacture our contact pieces at best-in-class costs,” says Kohl. At the same time, the welding line is a forward-looking solution that is fully networkable and Cloud-capable in line with Industry 4.0 principles. As a result, its performance capabilities can be harmonized with those of other systems. This, in turn, guarantees optimum machine utilization. “At the same time, this allow us to be optimally prepared for the throughput rates demanded by our customers. In the future, this aspect, in combination with production efficiency, will play an ever more important role,” concludes Kohl.