3D FEM analysis of strip shape during multi-pass rolling in a 6-high CVC cold rolling mill

Abstract

A 3D elastic-plastic finite element method (FEM) model of cold strip rolling for 6-high continuous variable crown (CVC) control rolling mill was developed. This model considers the boundary conditions such as accurate CVC curves, total rolling forces, total bending forces and roll shifting values. The rolling force distributions were obtained by the internal iteration processes instead of being treated as model boundary conditions. The calculated error has been significantly reduced by the developed model. Based on the rolling schedule data from a 1,850-mm CVC cold rolling mill, the absolute error between the simulated results and the actual values is obtained to be less than 10 μm and relative error is less than 1 percent. The simulated results are in good agreement with the measured data. The developed model is significant in investigating the flatness control capability of the 6-high CVC cold rolling mill in terms of work roll bending forces, intermediate roll bending forces and intermediate roll shifting values.

Prediction of Plate Crown during Aluminum Hot Flat Rolling by Finite Element Modeling

“…The other established modeling method is also based on FEM and has been widely employed by many researchers for rolling simulations, due to the increased quality of the results and the possibility to apply realistic boundary conditions and constraints in complicated models [12][13][14][15][16][17][18]. The method has been effectively applied for the prediction of strip crown in both cold and hot rolling operation.…”

“…Shigaki et al [20] coupled a commercial FEM model with a Multi-Slab model for strip deformation in order to predict the roll stack deflection. Sun et al and Linghu et al [3,14] employed an elastic-plastic FEM model to determine the work roll bending forces, intermediate roll bending forces and intermediate roll shifting on a CVC 6-High mill under certain rolling conditions for pass schedule strategy allocation. Chao et al [4] used finite elements coupled with infinite elements to analyze the crown after introducing residual stresses into the strip.…”

A New Mill Design for the Production of a Strip with Zero Strip Crown

“…To control the strip profile and flatness, various technologies have been developed in recent decades. As shown in Figure , they may be categorized as follows: 1) Multi‐high mill such as a six‐high mill, cluster mill, or Z‐mill; 2) roll crown control such as pair cross mill (PCM); 3) roll bending control such as a work roll bender and backup roll bender; 4) roll shifting control such as continuously variable crown (CVC) or work roll shifting; and 5) multiple control methods such as a six‐high CVC mill and other combinations of the above methods …”

“…As shown in Figure 1, they may be categorized as follows: [1,2] 1) Multi-high mill such as a six-high mill, cluster mill, or Z-mill [3][4][5][6] ; 2) roll crown control such as pair cross mill (PCM) [7][8][9] ; 3) roll bending control such as a work roll bender and backup roll bender [10] ; 4) roll shifting control such as continuously variable crown (CVC) or work roll shifting [11][12][13] ; and 5) multiple control methods such as a six-high CVC mill and other combinations of the above methods. [14][15][16][17][18][19] A question that may be raised is, "Is it possible to produce a strip with flat strip profile, which means a perfectly rectangular cross section, so as to achieve zero strip crown or zero edge drop, and at the same time, to eliminate the flatness problem once and for all?" Unfortunately, this is very difficult to achieve with conventional mills, even with a sound strategy for mill setup and control.…”

Modification of Roll Flattening Analytical Model Based on the Plane Assumption

“…In the model, a novel calculation approach is proposed to obtain the actuator efficiency factors of the flatness actuators in terms of intermediate roll bending, work roll bending and intermediate roll shifting. Du and Linghu et al [29][30][31] developed a 3-D FEM simulation model of six-high CVC rolling process by using nonlinear elasticplastic finite element method and the elastic flattening of rolls and the elastic workpiece are coupled as a whole in the model. From the existing research results, it's seen that the analytical method based on semi-infinite body model lack of theoretical support and the FEM cost considerable time [32].…”