Analysis of profile ring rolling by the upper-bound elemental technique

Abstract

Since the material flow involved in profile ring rolling shows non-steady and three-dimensional characteristics, it has been very difficult to describe accurately the flow or the deformation pattern during rolling. In this study an analytical method using the upper-bound elemental technique has been proposed for the simulation of closed-pass profile ring rolling. In order to describe the plastic flow of material, the whole deforming zone is divided into elements of simple configuration. Three types of elements are introduced for the modular approach of the UBET to the profile ring rolling process. Almost every shape of profiled ring can be assembled by the simple combination of elements of rectangular cross-section with elements of triangular cross-section and/or elements with an arbitrarily curved oblique side. The corresponding kinematically admissible velocity field which includes the expression for the material flow between neighboring elements as well as the closing speed of the pressure roll is derived for each type of element. Comparing with the experimental results, the calculated results of the present analysis shows good agreement in the estimations of roll torque and profile formation. For a comprehensive simulation of profile ring rolling, the effects of several process parameters have also been predicted and compared with the experimental work on open-pass rolling of rings. The computed results showing such effects are found to be in reasonable agreement with experimental results. As a simple but versatile engineering tool, the upper-bound elemental technique has been applied successfully to the theoretical analysis of the profile ring rolling process.