Numerical Study of a Four-Roll Coating System

Abstract

The characteristics of a four-roll coating system were numerically investigated and compared with experimental data to validate the theoretical models used in this study. In the theoretical models, a film splitting model using a power-law-type equation, a roll-gap model based on elastohydrodynamics, and a flow model from a rotating-cylinder system were applied. The parametric computations for each operational condition revealed the steady and dynamic behaviors of a coating film and liquid films on the coating rolls. The results of the frequency response to the speed disturbances of the coating rolls indicated that the sensitivity of the lowest coating roll to the disturbance was half that of the others; this implies that the requirement for the accuracy of a driving system of the coating roll is not as severe as compared with others. The experimental data and the numerical results at steady state agreed well. Therefore, the theoretical models used in this research were found to be appropriate.

Keywords

• numerical analysis
• experiments
• film flow
• roll coating
• dynamic response