Mechanics of Thin-Walled Tube Cropping

Abstract

This paper examines the mechanisms of thin-walled tube cropping and the necessary equipment and tooling to minimize the cross-sectional distortion of billets. Tube cropping experiments identify the main process parameters that influence the quality of billets; the material of the tube and its size, as the application of a compressive preload before and during the process in the direction perpendicular to cropping also reduces the distortion of the billets. The large plastic deformation suffered by the billet up to the point of peak load is verified by a theoretical model based on plastic work calculations. Peak cropping loads are correlated with the standard tensile tests using von Mises criterion of yielding. Finally, some bar feed mechanisms and billet weight/volume control techniques are discussed for the purpose of developing a computer-controlled on-line system. The practical application of this research would be in nuclear reprocessing where there is a need to extract irradiated fuel from thin-walled steel tubes.