1 2 Modelling the Doctor Blade - Roller Tribosystem for Improving 3 the Cleaning Performance During Paper Production 4

8 Abstract Doctor blades are commonly used in paper 9 machines to keep the surface of rollers clean. Due to higher 10 demanding conditions, the requirements for doctor blades 11 have steadily increased. The wear rates must remain low, 12 while simultaneously their cleaning function has to be 13 ensured. For this reason, the paper industry has developed 14 a high degree of empirical knowledge concerning the 15 cleaning of roller surfaces. However, up to now, no sys16 tematic approach has been successfully applied to optimize 17 the cleaning performance of the doctor blade-roller tribo18 system. This study presents an attempt to model the system 19 based on the force equilibrium conditions at the blade tip 20 between hydrodynamic and contact forces. The change of 21 the blade geometry due to wear is also taken into account. 22 By these means, a non-dimensional group involving the 23 key parameters is obtained. This allows for a systematic 24 improvement of the cleaning efficiency, by targeted chan25 ges of the process parameters. 26 27