Unscheduled decreases in gauge during the coiling of cold-rolled strip

Abstract

A theory is developed to predict the degree of thinning that elastic/perfectly plastic strip metal experiences as it passes over a billy-roll while being subjected to a longitudinal tensile force. The percentage thinning is a function of initial strip thickness, roller radius, material yield strength, and applied tensile force per unit width of strip. The particular case of the coiling of cold-reduced strip as it leaves the last reduction stand is considered; representative data is applied to the theory, the results being depicted in graphical form. Based on this particular practical application, a simple empirical linear equation is proposed whichfacilitates the rapid calculation of thinning strain. It is shown that these unscheduled decreases in gauge can amount to about 20% of the negative tolerance afforded to strip metal producers and as such are significant.