A Stand Power Predictive Model for Tube Stretch Reducing Mills

The stretch reducing hot rolling of tubes is a process so complex that a complete simulation by using finite elements method, even at steady-state conditions, cannot be yet carried out within a reasonable time. However this process is being increasingly used in seamless tube manufacture and, to this aim, a simple analytical approach for the determination of stand power has been formulated and presented in this paper. Based upon the splitting of tube shaping taking place in the pass and in the inter stand space, the model assumes the friction between the rolls and the tube to satisfy the Coulomb law; furthermore, the rolling pressure distribution, the shear stress along the contact interface and the neutral point can be rapidly calculated. The comparison between simulated results and available experimental data confirms the validity of the model.