Effect of Web Non Homogeneity and Core Effects on Wound Roll Stress

Abstract

Winding models developed so far have been used to compute wound roll stresses only in homogeneous webs and have not been utilized to compute roll stresses in non-homogeneous webs like laminates and non-woven webs. It is difficult to assess the thickness of non woven webs since there are many internal voids and the web is very compressible. The effect of uncertainty in web thickness will be explored in winding models. The pressure in the vicinity of the core is impacted by the core stiffness. During winding the core stiffness is often augmented by a core shaft or an expanding mandrel. The impact of core shaft deflation/extraction on wound roll stresses will be studied. It was found that if web thickness was kept totally separate as an input parameter in a winding model that the wound roll stresses are very sensitive to thickness. It was found that the axisymmetric definition of core stiffness yields stiffnesses that are unrealistic when fiber cores are supported on expanding mandrels and then later extracted.