Friction characterisation in levelling processes

Abstract Current numerical optimisation of levelling processes is focused in the calculation of the correct facility setting and the levelling force. The calculation of this last variable is important, even more important for such materials showing high yield strength where facilities could be close to their working limits, for the mechanical construction of the facilities. However, another important process variable which is not estimated yet by numerical simulation is the torque necessary to flatten the material. This value is needed to define the power train of the levelling facilities. The present paper characterises the friction behaviour in roll levelling processes by means of a special tooling constructed at Mondragon Unibertsitatea. The tooling is able to calculate both the static and the dynamic coefficient of friction (COF) between a circular surface, which reproduces the leveller rolls, and a semiflat surface, which reproduces the sheet. In order to reproduce the contact conditions at roll levelling, the special tooling replicates the geometry of roll levelling facilities. The COF is calculated introducing the obtained data from the experimental test in 2D and 3D numerical models. Considering that levelling processes are being optimised with 2D models, the 2D friction model is more adequate for estimating the COF in levelling processes.