NEW METHOD FOR PROACTIVE MAINTENANCE OF PAPER MACHINE ROLLS

摘要

Paper machine processes are improved continuously for higher production and cost efficiency. Typically, this is pursued by increasing the running speed of a paper machine. In many cases the dynamic behaviour of paper machine rolls restricts the speed-up and therefore, investment on new components is recommended. A new method for enabling machine speed-up without excessive investments is presented. The goal is to improve the performance of a paper machine roll at normal operating conditions by measuring the on-line dynamic behaviour and using that information in maintenance procedure. Erroneous behaviour of the rolls derives from typically limited dimensional accuracy, inhomogeneous material and structural discontinuities. Most of these errors are systematic and deformation i.e. geometry distortion and dynamic deflection caused by operating conditions can be taken into account in roll shop by utilizing a predictive 3D grinding technology. The geometry or run out of the roll is measured and this data is used as a control curve in non-circular grinding of the roll; therefore, the geometry or run out reaches its optimum at the operating speed or temperature. Experimental results from a study of backing rolls of a blade coating station are presented. The running behaviour is obtained at roll shop where a special measurement device is used to measure the dynamic geometry at operating speed. This proactive maintenance method enables continuous improvement of machine performance by getting feedback from the process measurements such as roll run-out or paper quality measurements to further optimise the roll behaviour during its life cycle.