10.05.2006 - Research for wing production
Now measuring over 180 metres, wind turbines have long outgrown the Bremen drop tower and Cologne cathedral. But it is not just their size that inspires associations with the aviation industry; the new research project of the Bremen Institute for Engineering Design (BIK) at the Bremen University faculty of production engineering and Abeking & Rasmussen Rotec GmbH, the rotor blade manufacturer based in Lemwerder, uses the knowledge that the university scientists acquired through their cooperation with the aviation industry on the production of extremely resilient lightweight components. PREBLADE, the two-year project, focuses on the manufacture of rotor blades, comprises an investment of roughly one million euros and is funded by 900,000 euros from the Federal Ministry for the Environment.
Rotor blades for wind turbines are today up to 62 metres long and weigh up to 20 tonnes. They are made of glass or carbon fibre fabrics and synthetic resins, the so-called matrix material. This creates a fibre composite material. The fibre fabric is cut and placed in a mould and then the resin is added. Once the shells have cured in tempered moulds during heating, the rotor blade halves are glued together and, after additional tempering, taken out of the moulds. All that is left to do is some post-processing, like adding the coat. This is mostly done manually. However, from now on some of the steps will be automated.
"Cutting and positioning the fabric is very difficult and time-consuming", PREBLADE’s project manager Dipl.-Ing. Ingo Gebauer explains at BIK. "The fabric must be draped carefully over the mould, and the fibre direction maintained." In other words: the fibres have to be perfectly aligned. Nothing can be allowed to lie sideways or in folds. This is where our project enters. Gone are the cutting, carrying, tearing and pulling –
soon a robot will assume these tasks, ensuring quick and precise cutting and positioning of the glass fibre fabric.
Rotor blade production is very people-intensive. The wings are mostly hand-made. "The share of staff costs amounts to 50-60%", Dipl.-Ing. Lars Weigel, technical director at ROTEC, says. "Our competition is located in Poland, Brazil and Mexico, where wage costs are significantly lower." Yet the ROTEC management has made a clear commitment to their Lemwerder plant: quality, for one, will give the company an edge on the market. "In the future we will speed up production and enhance quality, which is why we want to automate certain areas of the production process", Weigel says. "By doing so, we will secure the jobs of our employees locally."
Wind turbines are becoming more and more efficient, but as a consequence, larger and heavier. Particularly offshore installations are subject to tremendous loads. This places new requirements on the materials used, and on production methods: "Today’s methods are reaching their limits", BIK director Prof. Dr.-Ing. Dieter H. Müller says. "This is where we come in, with our knowledge. Hands-on experience from industry – for example, Abeking & Rasmussen have been active in this field since 1926 – and scientific know-how, which is pooled here in Northern Germany, offer a solid basis for economic success." Weigel adds that the physical proximity facilitates effective cooperation. Collaboration between industry and research, such as with the PREBLADE project, demonstrates the great dynamism in Northern Germany and justifies establishing a centre of excellence for wind energy right here.
For more information, please contact:
Universität Bremen
Fachbereich Produktionstechnik
Bremer Institut für Konstruktionstechnik
Prof. Dr.-Ing. Dieter H. Müller, Tel.: +49 (0)421 218-55 31,
E-mail: ml@biba.uni-bremen.de
Dipl.-Ing. Ingo Gebauer, Tel.: +49 (0)421 218-49 91,
E-mail: igebauer@uni-bremen.de
Dipl.-Ing. Lars Weigel, Tel.: +49 (0)421 67 33-717,
E-mail: lweigel@abeking.com
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