Roll Measurements and Tolerances by Application
Papex'93 International Conference
Maastricht, Holland – 2/5 November 1993
Speakers : Juhani Jaske, FMT Equipment Corporation & Wolfgang Schönthaler, Wolfgang Schönthaler Ingenieurbüro
Accurate measurements of the roll profile, roundness and concentricity are more important than ever before. Demand for high quality paper and higher paper machine speeds have been tightening the roll tolerances in all areas of a paper machine, particularly in machine calenders and press sections. A roll grinding operation has a direct effect on the quality of paper. Modern PC recording and display systems plot measurement results into graphs, representing continuous measurements over the length or circumference of a roll. The graphs also display the nominal or base measurement parameter [zero-line, cosine crown, or compound crown target] and tolerances.
This paper discusses necessary roll measurements, tolerances by roll types and applications, and available equipment for accurate measurement and displaying the results.
The results can be used as diagnostic tools for trouble shooting roll wear, roll grinder, and paper machine problems. For instance, the measurement results of a worn roll may easily be compared on the display, or using print-outs, to the results before the roll was put in the paper machine, or to the in-line roll rotation graphs of condition monitoring systems.