T-Profile-Rolling of Stringers with Tailored Thicknesses – Challenges and Approaches

Stringers in aircrafts have a longitudinally variable, load-adapted material thickness, which has been realized to date by chemical milling. A new flexible rolling process for T-profiles is being developed to enable more environmentally friendly and resource-efficient production of stringers in the future. The tailored distribution of wall thicknesses in the T-profiles in the longitudinal direction requires geometries of rolls that enable uniform rolling of the web and flange. This can be achieved by rolls with varying radii. However, due to the varying roll radii, varying longitudinal strains are introduced across the profile cross-section, which in turn lead to unwanted profile bowing. This paper presents the basic idea of a new flexible rolling process for T-profiles - Flexible T-Profile-Rolling. Numerical investigations with different parameters of the roll circumferential speed and the roll gap are performed. The results show that accurate and straight T-profiles with longitudinally variable thicknesses can be produced by the proposed process.