Roll Structure Calculations at Constant Wound-In Tension, 1990 Finishing and Converting Conference Proceedings

The theory of roll structure is used to calculate internal pressures and tensions in a roll or reel wound at constant tension. The calculation is able to theoretically predict the interlayer pressure at the core which is of interest in the case of gearing effects, and it predicts the relationship between the roll density monitor and wound-in tension. The equations used are consistent with those of Altmann and Hakiel, and they incorporate Pfeiffer’s non-linear stress-strain relationship for compression perpendicular to the sheet. However, the computational problem has been simplified by assuming constant wound-in tension and by ignoring localized core effects. The resulting equations are very easy to solve on a personal computer and are intended as a compromise solution, to give acme qualitative understanding of the problem with a minimum of computational effort. Comparisons are made with the results obtained by Pfeiffer and Hakiel, for both paper and plastic film, and theoretical predictions of the corresponding roll density are presented.