Xiong Shangwu

A three-dimensional finite element simulation of the vertical–horizontal rolling process in the width reduction of slab

Abstract A thermal coupling analysis is carried out by the full three-dimensional rigid–plastic finite element method to simulate vertical–horizontal rolling process during width reduction in the roughing stands of a hot strip mill. The slab shape, the spread and temperature as calculated are in good agreement with the experimental results in production mills, and the sectional distribution of temperature is given.

3-D rigid–plastic FEM analysis of the rolling of a strip with local residual deformation

Abstract A strip with longitudinal ribs is one type of new-shaped strip that has been developed in recent years. The main characteristic of the rolling of a strip with ribs is that there is local residual deformation on a normal flat, and it is a new forming process that has the deformation characteristics of both strip- and shaped-steel. Using the rigid–plastic FEM, the forming process is analyzed in this paper and the numerical results of the change of the rib height in the deformation zone and of quantities such as rib height, the separating rolling load and the spread ratio have been obtained, the result of calculation being in accordance with those of the experiment.

On the utilization of the reproducing kernel particle method for the numerical simulation of plane strain rolling

This paper draws from fundamental research on the reproducing kernel particle method (RKPM) to the development of an innovative numerical approach for analyzing rolling under plane strain conditions. The approach is based on the flow formulation for slightly compressible rigid-plastic materials and a detailed description of the method and its numerical implementation is presented with the objective of making clear the fundamental differences to the well-established finite element method for slightly compressible rigid-plastic materials. Special emphasis is placed on the construction of shape functions and their derivatives, enforcement of the essential boundary conditions and treatment of frictional effects, along the contact interface between the workpiece and the roll. The effectiveness of the proposed approach is discussed by comparing theoretical predictions with experimental data found in the literature.

Three-dimensional thermo-mechanical finite element simulation of the vertical–horizontal rolling process

Abstract This paper presents a three-dimensional thermo-mechanical analysis of the vertical–horizontal rolling process utilised in the large width reductions of slabs in hot strip mills. The theoretical analysis is based on the utilisation of the finite element flow formulation to characterise the material flow, to predict the distribution of temperature and to estimate the roll separating force. The numerical predictions were verified by metal experiments performed at the hot strip mill unit of Bao Steels (China). The experimental work consisted of the monitorisation of the surface temperature and of the roll separating force for several rolled slabs. The theoretical distribution of stress obtained from the numerical simulation of the process is also analysed.

Three-dimensional modelling of the vertical-horizontal rolling process

This paper discusses the utilisation of the slightly compressible finite element formulation to the numerical analysis of the vertical-horizontal rolling process. The first part of the paper details the basis of the plasticity theory for slightly compressible materials and presents an overview of its numerical implementation. Of particular interest in vertical-horizontal rolling are topics related to the prediction of the dog-bone shape when using a Eulerian formulation, the treatment of the frictional boundary conditions along the three-dimensional roll-workpiece contact interfaces and the modelling of the material streamlines within the plastically deforming region.The second part of the paper presents a comparison between theoretical predictions obtained by means of a special purpose computer program developed under the proposed approach and experimental results taken from the literature. Assessment is made in terms of the cross-sectional shapes, roll separating force and torque.

Analysis of the non-steady state vertical–horizontal rolling process in roughing trains by the three-dimensional finite element method

Abstract The vertical–horizontal rolling process is often used to accomplish width reduction so as to provide a synchronising operation between the continuous slab casting and hot rolling processes. Numerical simulation of the non-steady state deformation behaviour around the head and tail ends during this process is made by the full three-dimensional rigid–plastic finite element method. An explanation is provided in the theory for the ‘thin element technique’ at the inlet surface of velocity discontinuity. To deal with the interpolation of friction within a surface of an element contacting partly with the roll, a new term, so-called ‘pseudo shape function’, is presented and a related new equation formula is deduced. The calculated shape of the slab edge, the separating force and the rolling torque are consistent with those measured experimental ones for the model material lead.

Three-dimensional simulation of flat rolling through a combined finite element-boundary element approach

Abstract This paper presents an innovative approach for analysing three-dimensional flat rolling. The proposed approach is based on a solution resulting from the combination of the finite element method with the boundary element method. The finite element method is used to perform the rigid–plastic numerical modelling of the workpiece allowing the estimation of the roll separating force, rolling torque and contact pressure along the surface of the rolls. The boundary element method is applied for computing the elastic deformation of the rolls. The combination of the two numerical methods is made using the finite element solution of the contact pressure along the surface of the rolls to define the boundary conditions to be applied on the elastic analysis of the rolls. The validity of the proposed approach is discussed by comparing the theoretical predictions with experimental data found in the literature.

Simulation of plane strain rolling through a combined finite element–boundary element approach

Abstract This paper presents an innovative approach for analysing plane strain rolling. The proposed approach is based on a solution resulting from the combination of the finite element method with the boundary element method. The finite element method is used to perform the rigid–plastic numerical modelling of the workpiece allowing the estimation of the roll separating force, the rolling torque and the contact pressure along the surface of the rolls, whilst the boundary element method is applied for computing the elastic deformation of the rolls and for obtaining the resulting distribution of stress. The combination of the two numerical methods is made using the finite element solution of the contact pressure along the surface of the rolls to define the boundary conditions to be applied on the elastic analysis of the rolls. The validity of the proposed approach is discussed by comparing the theoretical predictions with experimental data found in the literature.

Rigid-plastic boundary element analysis of the upsetting of slabs

Abstract This paper presents an innovative approach for analysing plane strain metal forming processes. The proposed approach is based on the rigid-plastic boundary element method for slightly compressible material models. The main advantage of the rigid-plastic boundary element method over existing numerical simulation methods is the necessity of requiring the unknowns to be mainly set at the contour of the workpiece, simplifying the analysis and offering additional computational advantages. A numerical example consisting of the frictionless upsetting of rectangular slabs between flat anvils under plane strain conditions is included to show the applicability of the proposed approach. Assessment with the analytically exact solution is made in terms of geometry, pressure and distribution of strain and stress inside the workpiece.