Paper bending stiffness and web tension measurement from a running web using a vacuum and computer imaging

A novel method for measuring the bending stiffness of paper online during manufacturing is intro-duced. The uses photometric stereo imaging to detect shape deflection surface caused by a controllable pressure difference over paper’s surfaces. hardware measurement based on combination two existing sensors, which has accelerated and facilitated development implementation. loads are tied together governing differential equation an orthotropic elastic plate with selected simplifications. An approach resolve material parameters in-plane without knowledge traditional boundary conditions suggested. presented was tested in mill manufacturing. For stiffnesses measured online, correlation coefficients 0.88 0.92 were obtained compared state-of-the-art laboratory measurements. However, results gained from moving web noisy data requires correction slope offset. Although several issues remain be resolved before can considered as accurate industrial use, theoretical background, performance implementation, promising. Possible causes observed discrepancies future discussed.