Modeling of nip pressures and web feed rates in rubber covered nip rollers

Abstract

Nip rollers are used extensively in converting processes; however, correct design and usage of these types of rollers requires a sound understanding of the mechanics of the nip in both the machine and cross-width directions. This behavior is difficult to predict owing to the nonlinear nature of the contact region and the near incompressible material characteristics of typical nip roller coverings. This paper is a companion to a paper presented at IWEB11 where experimental data characterizing web feed rates, nip pressures and wrinkling in nip rollers comprised of single and dual durometer cover systems was presented. In this paper, modeling techniques are developed for predicting nip pressures and nip roller feed rates in both the machine and cross-width directions. The models presented include the ability to analyze roller coverings engineered with the ability to control nip roller feed rate while retaining desirable nip pressure characteristics. Parametric studies demonstrating the influence of many of the material and design parameters of nip rollers on nip roller feed rate and nip pressure are presented. Nondimensionalized parameters are also developed to assist engineers in the design of nip rollers to insure suitable performance.