Chatter in Rolling

Northwestern University, Evanston IL

Investigators

Abstract

This project is to conduct a theoretical and experimental research program on chatter in the rolling of flat products. The theoretical research will include the development of dynamic models of mill structures and of the rolling process, coupling these models to create a comprehensive model for chatter in tandem rolling mills. The research places particular emphasis on the phenomena that are known to have a profound influence on tandem mill stability where only a few theoretical results are available. These process dependent phenomena include the effect of multi-modal three dimensional mill vibrations introducing variations in roll-bite geometry; fifth-octave-mode chatter leading to roll grinding chatter marks and banding due to debris pickup that can cause variations in roll geometry and friction; and the consequences of strip transverse vibrations and dynamic friction effects upon the entry angle of the strip. The developed structural and rolling process dynamics models will be combined into an all-encompassing chatter model to ascertain mill stability with respect to negative process damping, strip and roll regeneration, torsional oscillations, and other composite mechanisms in single and multi-stand mills. Experiments will be conducted on unique, full instrument, laboratory-scale mill in combination with data measured on actual production-scale mills in industry. This will assist the development and validation of the theoretical models. Validation on steel and aluminum industry mill stands will be performed. The research is expected to result in better methods for mill and process design and to lay the groundwork for more intelligent mill control systems for the processing of sheet metal.