Preventing Core and Interlayer Buckling Defects in Wound Rolls During Manufacturing

Carnegie Mellon University, Pittsburgh PA

Investigators

Abstract

Flat continuous strips of sheet metal, paper, polymers and other thin materials (referred to as "webs") are generally transported under tension and at high speed during production. Stages of web processing include thickness reduction in rolling mills, slitting, coating, printing, and laminating. These materials are wound onto, transported, and stored in the form of large multi-ton rolls. Improvements in their production are restricted to a large degree by mechanics problems associated with precisely moving and winding webs without introducing significant defects. This research project focuses on reducing the stress-induced damage associated with wound roll production. In the presence of unfavorable stresses, rolls of material and the cores onto which they are wound can buckle locally or entirely. At best, such defects are viewed by customers as a sign of poor quality, and at worst, they require the entire roll to be scrapped. Failure modes describe complete mechanical instability and are often termed V-buckling, sag collapse, starring, and spoking. A predictive model is being developed for the stress field within wound rolls which accounts for realistic complicating effects that have not previously been studied. The research identifies the roles played by such manufacturing process parameters as tension, speed, roll width, web and core material properties, surface roughness of the web material, core stiffness, and mandrel or core chuck design. The results are being used to guide the development of engineering solutions for controlling and improving the stability and quality of wound rolls during their production.