The doctoral dissertations of the former Helsinki University of Technology (TKK) and Aalto University Schools of Technology (CHEM, ELEC, ENG, SCI) published in electronic format are available in the electronic publications archive of Aalto University - Aaltodoc.
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Method and Device for In Situ Runout Measurement of Calender Thermo Rolls
Panu Kiviluoma
Dissertation for the degree of Doctor of Science in Technology to be presented with due permission of the Faculty of Engineering and Architecture for public examination and debate in Auditorium K216 at Helsinki University of Technology (Espoo, Finland) on the 18th of December, 2009, at 12 noon.
Dissertation in PDF format (ISBN 978-952-248-260-0) [6265 KB]
Dissertation is also available in print (ISBN 978-952-248-259-4)
Abstract
Geometric and rotational errors of the paper machine rolls have a direct influence on the quality of the finished paper and may also weaken the runnability of the machine. In the calender section where the paper gets the final structure and finish, the surface temperature of a thermo roll may be 250 °C or even more. High temperature causes roll deformations such as bending and so-called polygon effect.
The measurements of the roll geometry are usually carried out in the workshop conditions. However, to find out the true dynamic behavior of the rolls requires that the measurements should be done in the real operating conditions during the process. This is difficult and often impossible to do because of the harsh environment and issues with the sensor mounting. Many conventional displacement measuring methods are sensitive to either the target material properties or to the environment.
In this study, a device and a method for the in situ measurement of a roll shell runout based on the measurement of radial acceleration of the surface was described. In this method, an acceleration sensor attached to a sliding probe is held against the rotating roll surface. Acquired acceleration signal is averaged and double integrated using a computer to get the surface displacement, i.e., runout. A number of measurements were done to demonstrate the applicability of the method. The laboratory measurements showed that it was possible to measure runout with an adequate accuracy. The case measurements showed that by using the method it was possible to detect and measure phenomena in the rotating rolls that were difficult or impossible to measure earlier. The method can be used, for example, for applications related to problem solving in the paper quality and runnability issues, online geometry measurement and balancing.
Keywords: paper machine, roll geometry, roundness, dynamic error, thermal deformation, measuring
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© 2009 Helsinki University of Technology
Last update 2011-05-26