To increase the stiffness of aircraft fuselages aluminium profiles are used. In order to reduce weight and fuel consumption, these stringer profiles have variable material thicknesses in longitudinal direction, which is currently realized by chemical milling. A subsequent treatment by mechanical milling is required. Due to the high expenditure and use of chemicals, this process is classified as economically and ecologically critical. Therefore it should be replaced by an alternative, purely mechanical process.
For this purely mechanical process, flexible rolling is chosen because of the good material utilization. With flexible rolling it is possible to produce tailored blanks. However, the production of branched profiles with variable thickness, e.g. the T-profile, cannot be realized with conventional roll forming stands. This requires the development of a new flexible rolling process.
A variable wall thickness is to be formed subsequently into extruded aluminium stringers. Therefore the development of a new flexible roll stand is necessary to enable uniform rolling of branched profiles without deformations.
The functionality of the technological concept is to be verified and the feasibility must be demonstrated numerically. The next step is the development of the flexible rolling process in real operation. The goal of the project is the experimental validation of the technology at a prototype plant in a research environment. Thus the research project consists of three work packages:
1. Numerical analysis of flexible rolling of profiles with variable thickness
The feasibility of the concept and the manufacturing boundary conditions of the profiles are to be determined numerically by FEA. Thereby different realizable profile forms of the stringers as well as further alternative profile forms are to be considered and included in the design of the new flexible roll stand. Furthermore, the suitability of the profiles for FSW welding should be analysed.
2. Concept, design and manufacture of a flexible roll forming stand
3. Commissioning of the plant and performance of experimental investigations
The project MeGro ist part of the Lower Saxony aviation research program and is funded by the Investitions- und Förderbank Niedersachsen (NBank). Furthermore the Institute of Production Engineering and Forming Machines would like to thank the industrial partners Premium AEROTEC GmbH and Fooke GmbH.