A hot research topic

Photos: © TU Graz / Lunghammer

We have high expectations of B-pillars, side impact protection beams and bumpers. The safety of passengers depends on their properties in the case of a road traffic accident. At the FSI we are working on being able to manufacture these complex parts faster. The B-pillar of a car is paramount when it’s a question of transferring forces during an impact. Supporting vehicle pillars connect the roof area with the bottom section of the body. The B-pillar is the connection between the bottom section and roof in the middle of the passenger cell. If the car rolls over during an accident, the pillars stabilize the passenger cell against vertical deformation. For this reason, this part – like several other parts – must exhibit very special ultra-high strength properties –  and this means that very special processes are necessary in their manufacture. “Such highly complex structures with high-strength qualities can be produced using press hardening,” explains Ralf Kolleck, professor and spokesperson for the FSI, a co-operation between Graz University of Technology and Magna. The thermorforming of sheet metal is one of the most important topics in the automobile industry and it combines automotive engineering with vehicle safety.

Prototype at the FSI

Press hardening is principally a matter of heating up a steel sheet to a very high temperature –  namely 950° Celsius – and then reshaping  it using a cooled tool and quenching it. At the FSI in Graz, we’ve been striking out on innovative paths for some time with regard to how  to heat up the material, and we already have a prototype of an induction furnace for the automobile industry in our laboratory. This means that the same principle is applied as with a commercial induction cooker in the kitchen. To heat up the sheet, energy is transmitted in the form of an electromagnetic alternating field and converted to heat. “The heating technology was developed by us. Eleven years ago everyone said that it would be impossible and today this heating plant prototype is in the hall at the FSI,” emphasised Professor Kolleck, who has been occupied with this kind of heating right from the beginning.

Numerous Advantages

A major advantage of this technology is that the plant is much more efficient in terms of energy. For making bodies in the automobile industry, the use of such an induction furnace for press hardening would mean drastic energy savings. “Furthermore, work could be done faster and in a more target-directed way,” explains expert Ralf Kolleck from the Institute of Tools & Forming at Graz University of Technology. On top of this, these furnaces could be much smaller than those currently used in the automobile industry. The next point in the success story of this hot topic is the plant’s implementation which, unlike the prototype at the FSI, has to be big enough for the automobile industry. For this reason, contact has already been made with a plant and equipment maker. Another research topic at the FSI, by the way, concerns cooling the tool during press hardening. In the production process in the car industry, a new sheet is inserted and processed every 15 seconds – and so the tool has to be “refreshed” by means of cooling channels which are drilled into it. How these channels can be optimally adapted to the surface, how they can be drilled, screwed and bonded to yield the best results is being investigated by the tool engineers at Graz University of Technology.

Worldwide Teaching from Graz

“The biggest difference to other tools and forming institutes is that we work in a very application-oriented way,” stresses Professor Kolleck. For instance, work is carried out together with industry in the early stage of the development of a new material in order to evaluate the importance of this new material and to find out how it could be integrated into production. An approach which is very well received internationally, as shown by an increasing number of co-operation projects. “Co-operation with German companies has been going well for a long time. Currently, we’re becoming more international and are strengthening contacts with France and North America, among other places.” In so doing, the projects and ideas of the engineers go beyond the confines of the automobile industry. In stainless steel processing, material properties should be exploited better – and this also applies to the production of “white goods” – i.e. products such as kitchen sinks. Parallel to this, worldwide connections in the world of further education – seminars of researchers from the FSI, Graz, in co-operation with companies from industry, for instance, are running in North America, Mexico, Brazil, Beijing and Shanghai.

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