Located in Erfurt (Germany), the Siemens generator plant is acknowledged as one of the world‘s leading facilities for the design and manufacture of turbogenerators with a power output of up to 300 MW. Against the backdrop of ever-increasing competition, the production plant was eager to introduce new technological solutions aimed at further optimising its manufac- turing processes. Within this context, the main focus was on the production of conductors, a particularly labour-intensive part of the overall process.
In cooperation with the Steinbeis Transfer Center Drive and Hand- ling Technology in Mechanical Engineering, the company came up with an innovative manufacturing method and a new opera- ting system that revolutionize the complex production process for conductors, consisting of axial and tangential conductors. The individual tangential conductors – 15 to 24 in total – are made of electrolytic copper and are up to 64 mm in width, 8.0 mm in thickness and 1.7 m in length. The conductors are soldered on to the axial conductors (up to 7 m in length) on both sides. The radius of the tangential conductor package corresponds to the rotor radius of the generator, i. e. up to 0.5 m. The maximum pa- ckage thickness is 160 mm.
Using the conventional technique, the conductors are bent by hand with the help of circular tools, both individually and sta- cked on top of each other, to form a conductor package that makes up a complete half-coil. Applying this manual method, the overall processing time required to make a conductor pa- ckage for a half-coil is 145 minutes. Based on many years of experience, the manual production technique involved aligning and inspecting the items several times during the overall proce- dure. This approach was in stark contrast to the state-of-the-art technology applied by the company in other areas of generator production. The aim: to streamline this section of manufacturing by introducing entirely new bending / forming technology. One of the key challenges was to eliminate the springback associated with the material itself while also ensuring that the surface was in no way damaged by the process and the conductors retained their prescribed length rather than expanding as a result of the rolling procedure.
Owing to the innovative, patented bending process and the newly installed bending machine, the complete conductor package for a half-coil can be produced in a single step. The overall processing time was scaled down from 145 to 27.5 minutes.
Prof. Dr.-Ing. habil. Eberhard Köhler
Steinbeis Transfer Center Drive and Handling Technology in Mechanical Engineering (Chemnitz)