Challenges in Online Paper Surface Topography Computing while Changing the Surface Velocities

摘要

Online surface quality inspection in Pulp and paper industries is important to anticipate and determine the final quality and printability of the paper and paper board using hi speed computers. Switching the dependencies from laboratory measurements to computer based online measurements needs prior authentication of online surface instrument and its limitation to the speed of the paper roll. The online measurements can be up to the speed of 2000 m/min in paper mills. The surface measurements can be influenced by processing velocities of the web mainly due to smearing effects. To know the measurement accuracy at different processing speed is important for any online topographical device. The degree of measurement correlation among different speeds determines the accuracy of the devices. In this study online measurements were performed at various speeds starting from 0 to 600 m/min and the correlation of measurements at different speeds was examined. Measurements were obtained from OnTop, a recently developed online profilometer. Overall measurements are presenting encouraging results and closely matching and correlating at different speeds up to 600 m/min. Some longer wavelength components are slightly deviating among various speeds depending on the type of paper and the dynamic behavior of the paper web. The measurement methods, challenges and the influence of velocities on surface topographical measurements are discussed and results are presented from standstill to 600 m/min velocity of the paper web.