Traction Between a Web and a Smooth Roller

Abstract

Web traction over rollers is known to deteriorate due to air entrainment at high web speeds. In this paper, a general model is presented to predict the traction capability of an impermeable web over a smooth roller. The model considers the effects of the web and roller speeds, roller radius, combined roughness of the two surfaces, web tension and thickness, friction coefficient, and compressible air bearing. The change of tension ΔN due to mechanical slip between the roller and the web is calculated by a simultaneous solution of the in-plane and out-of-plane equilibrium of the web and the compressible Reynolds lubrication equation. The problem is nondimensionalized and the effects of nine of the eleven nondimensional parameters on traction are investigated for a range of values. Formulas involving the nondimensional parameters for the traction capability are presented in two-variable polynomial forms.