Process direction dynamic model for high precision web/belt transport systems

Abstract

This article proposes a process direction dynamic model for closed loop belts and open loop webs used in high precision transport systems such as those found in printers where micron level registration is required. It gives the detailed derivation of the lumped parameter-based, elastically-stretchable dynamic model and shows that the angular velocities of the rolls, instead of the surface velocities of the belts/webs, should be the variables directly used in the governing equations. It discusses the effects of traction as well as disturbance sources such as roll eccentricities and the drag from stationary rolls (backer-bars). The focus of this article is on the enhanced inertia compensated tension rolls (dancers) which may be used in either open loop webs or closed loop belts (US patents pending). The design formula of the enhanced inertia compensated tension rolls takes into consideration the belt/web elasticity, belt/web tension and wrap angle. Validation of the model by other numerical methods and experiments is also discussed at the end of this article.