Effect of rolling conditions on cross-sectional shape of rolled tube and forward slip ratio for single stand rolling of the mandrel mill

摘要

In the Mandrel rolling process, the set-up model of roll peripheral speed, essentially determined by two factors i.e., cross-sectional shape of the tube at the exit of the roll-bite and the forward slip ratio, is very important for the accuracy of tube dimensions and the surface quality of the tube. The above two factors depend on various rolling conditions. Here, the relationships between the five rolling conditions (thickness reduction at groove center, ratio of thickness to diameter (t/D) ofinlet tube, mandrel bar speed, friction coefficient with the mandrel bar and flange diameter of rolls) and each of the two factors have been investigated by the rigid-plastic finite element method and by rolling experiments with a single stand model mill. As a result, the mathematical models for the cross-sectional shape of the tube at the exit of the roll-bite and the forward slip ratio for single stand rolling are derived. The validity of the model for the forward slip ratio is verified in the commercial mill.