This research is based on observations on paper quality problems. These observed quality problems were found out to be synchronous to the half of the perimeter of the backing roll of the blade coating station, and to be a function of the running speed. The backing roll has a large diameter compared with its shell thickness. Run-out measurement of the roll showed a running speed dependent run-out behaviour. Ultrasonic shell thickness measurement showed a relatively large systematic variation. The thickness measurement data was used as geometry information in two different FE models. The results from the analyses of these two FE models showed rotational speed dependent geometry changes, showing that the shell thickness variation is a possible cause of the observed paper quality problems.

Abstract. This work presents a method for in situ runout measurement of large cylindrical rotors, such as paper machine rolls. The method is based on an acceleration sensor attached to a sliding probe which is held against the rotating surface. Measured acceleration signal is averaged and double-integrated using a computer to get radial surface displacement, i.e., runout. Laboratory tests showed that, with this method, it is possible to measure runout with accuracy in the scale of a few micrometers. Measurements showed that, by using this method, it is possible to detect and measure phenomena like thermal bending or so-called polygon effect in running thermo rolls. These phenomena have not been reported to have been measured in situ before.

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This paper discusses the creation of a model which can be used to analyse the behaviour of a chilled cast iron thermo roll at different operating conditions. In order to acquire additional information about the internal structure of the roll shell ultrasonic measurements of a full size roll were carried out. The created roll model's shapes and dimension correspond well to general knowledge about the chilled cast iron thermo rolls