EFFECT OF DEFORMABLE ROLL COVER ON ROLL COATING

Of the two rolls that make a forward or reverse roll coating gap or ni p (negative gap), one is often covered by a layer of more-or-less defo rmable elastomer Liquid carried into the converging side of the nip ca n develop high enough pressure to deform the elastomer cover, which ch anges the nip profile and alters the velocity and pressure fields in t he nip. This elastohydrodynamic coupled action is not yet well underst ood Theoretical modeling has to take into account both the viscous flo w and the elastic deformation in order to predict the relation of coat weight to roll loading and the rheological properties of the coating liquid and of the roll cover Theoretical modeling in the same way shou ld predict ribbing behavior In this work, the flow is described by the lubrication approximation, and the elastic deformation by three diffe rent models: Hookean and neo-Hookean (ideal elastomer elasticity) spri ngs oriented radially, which constitute one-dimensional models, and a layer in Hookean plane strain, which is a more realistic volume-conser ving, two-dimensional model. The predictions of the models are compare d, and their relative merits are analyzed in the light of available ex perimental data.