Numerical modelling of the multi-stage production process of large-size rings rolling for the shipbuilding industry including analysis of internal discontinuities

Abstract

This article presents the problems related to production of large-size rings for the shipbuilding and offshore industries. The technology of shaping this type of products includes initial preparing of ingots, making a central hole and rolling on a multi-tool ring rolling mill. The main goal of the plastic deformation, in addition to obtaining the required geometric shape of the products, is to ensure an appropriate internal structure and thus the desired operational properties. A significant problem in the processes of shaping products from forging ingots is a proper characteristic of the internal defects of the cast structure. The purpose of plastic deformation applied at high temperature is to minimize these defects. This study examines the changes in the relative density of the material depending on the degree of structure modification (deformation degree). The results as well as boundary conditions reflected from the industrial processes were used as a data for the computer simulations of the large rings production processes. All of the technological operations are included in these simulations, from heating of the forging ingot to final rolling of the finished product. Numerical simulation was performed using QForm – commercial software based on finite element method (FEM).