Make Flat Sheet Using Contrabend Rolls

Abstract

Most plastic sheet produced today is made using a typical three-roll sheet stack. Material is passed through a preset gap between the rolls to form the final thickness of the sheet. The variation in this gap is related to the bending of the chill roll, which is a major factor in the gage variation of the sheet. Producing “flat sheet” has always been the goal of the sheet producer. Until recently there has been little advancement in cooling roll construction as it relates to bending in the cross line direction. The Contrabend^TM Reverse Bending Roll has been developed to greatly reduce the effect of roll deflection on sheet thickness variation. This work will explore the Contrabend concept and compare the bending to standard chill rolls.