Vertical Rolling Process Research Articles

Numerical Analysis of Edge Deformation and Force via Continuous Function Curves in Vertical Rolling Process

Numerical Analysis of Edge Deformation and Force via Continuous Function Curves in Vertical Rolling Process

A coupling model of vertical rolling process based on upper bound method and elastic theory

A coupling model of vertical rolling process based on upper bound method and elastic theory

Analysis of 3D plastic deformation in vertical rolling based on global weighted velocity field

Energy method is an essential theoretical approach to analyze plastic forming, which is widely used in rolling process. An analysis model for vertical rolling process is established according to energy theory. By using global weighted method firstly, the 3D continuous velocity field, strain rate field and the corresponding power functional are proposed. The unknown variables are calculated numerically based on the principle of minimum energy. Then, deformation parameters and rolling force are determined. The analysis on specific examples shows that the theoretical prediction value of weighted model is in good agreement with experimental results. Moreover, the effects of several shape and rolling parameters on rolling force, rolling power and edge deformation are studied. Both the width reduction rate and initial slab thickness have significant influences on dog-bone size and rolling force. A wider slab slightly increases the nonuniformity of dog-bone deformation. And the increase of vertical roller radius can weaken the edge deformation.

Optimization solution of vertical rolling force using unified yield criterion

Vertical rolling is an important technique used to control the width of continuous casting slabs in the hot-rolling field. Accurate prediction of vertical rolling force is a core point maintaining rolling-mill equipment. Owing to the limitation of the algorithm in use, the prediction accuracy of most vertical rolling force models based on the energy method can only reach more than 10%. Therefore, it is challenging to optimize the rolling-force model to improve prediction accuracy. An innovative approach for optimizing the calculation of vertical rolling force with a unified yield criterion is presented in this paper. First, the maximal width of a dog-bone region is determined by the slip-line method, and the dog-bone shape is described using a sine-function model. Second, the velocity and corresponding strain-rate fields satisfying kinematically admissible conditions are proposed to calculate the total power of the vertical rolling process. Finally, the analytical solution of the rolling force and the dog-bone-shape model is obtained by repeatedly optimizing the weighted coefficient b of intermediate principal shear stress on the yield criterion. Moreover, the effectiveness of the proposed mechanical model is verified by measured data in the strip hot-rolling field and other models’ results. Results show that the prediction accuracy of the vertical rolling force model can be improved by optimizing the value of b. Then, the impacts of reduction rate, initial thickness, and friction factor on dog-bone shape size and vertical rolling force are discussed.

Effects of Vertical and Pinch Rolling on Residual Stress Distributions in Wire and Arc Additively Manufactured Components

Residual stresses are inherent in parts manufactured using the wire + arc additive manufacturing (WAAM) technique, resulting in unpredictable mechanical response and structural integrity (Colegrove et al.: J Mater Process Technol 213:1782-1791, 2013). An effective post-processing technique, which enhances the mechanical properties of WAAM parts, is rolling. This study investigates the vertical and pinch rolling effects on residual stress distribution in WAAM components. Initially, a WAAM model was created using a thermo-mechanical finite element modelling approach and validated against the experimental results. Subsequent to the validation of the model, the effect of the main parameters involved in vertical and pinch rolling processes, namely the rolling depth, the curvature depth of the roller, the roller shape, transversal displacement, rolling direction and roller thickness, was investigated. The results from this study show that the residual stress profile in the vertical rolling process applied on a WAAM wall can be enhanced by increasing the rolling depth and curvature depth of the roller. Moreover, it is shown that in the pinch rolling process, the residual stress profile is sensitive to the rolling direction and more compressive residual stresses can be induced into the wall by applying fewer passes of rolling using thicker rollers.

Analysis of railway wheel rolling process based on three-dimensional simulation

Rolling is one of the key stages of railway wheel hot forming process. In this work, a three-dimensional finite element analysis on wheel vertical rolling process based on some strategies proposed has been carried out by using FE code SuperForm. In modeling, a virtual mandrel is exploited in the hub hole to keep the wheel central instead of the guide rolls and centering rolls. Some features of the wheel forming are deeply investigated such as the rim diameter expanding, the rim lateral spreading, the metal flow in the circumferential direction, and the stresses distribution. The results show that (1) the rim radius expanding mainly occurs in the two affected zones before and after the back roll deformation zone; (2) the rim metal has flow trend in the circumferential direction during rolling, the metal of the intersection area, between the tread and the rim external side surface has the largest relative angular displacement; and (3) the tensile stresses of the web both in radial and circumferential directions during rolling result in the web thickness decreasing by about 3 mm for the investigated wheel. The simulations results reveal the forming mechanisms of wheel rolling, laying the basis for designing and optimizing railway wheel forming process.

사이징 프레스에서 폭 압하 공정중 결함 저감을 위한 엔빌의 형상설계

Generally, a vertical rolling process is used to achieve extensive width reduction in hot strip mill. However, it is impossible to avoid the defects such as dog-bone and edge-seam defect. The sizing press process has been developed in response to the defects mentioned above. Especially, this study is carried out to investigate the deformation of slab by two-step sizing press. The deformation behavior of slab in the sizing press process is more favorable than that in conventional vertical rolling edger. The FE-simulation is applied to predict the deformation behavior of the slab. In this paper, the several causes of the asymmetrical deformation are mentioned for the purpose of understanding of the anvil shape. Load, dog-bone and edge-seam defect are discussed in width sizing process considering the anvil shape. And to reduce the problems generated at rougher mill just after sizing press, these are studied in this paper. The deformation behavior of slabs and optimum anvil shape are obtained by rigid-plastic finite element analyses and neural network.

Behavior of Transversal Crack on Slab Corner During V-H Rolling Process

The behavior of transversal cracks on the surface of the slab corner during vertical and horizontal (V-H) rolling process with flat vertical roll and groove vertical roll was simulated by explicit dynamic finite element method. The closure and growth of crack and the contact pressure on surfaces of the crack in contacting zone between slab and roll during rolling process were analyzed. The results showed that during vertical rolling process, when the groove vertical roll is used, the maximum contact pressure on surfaces of the crack is 115 MPa, and the closure of crack is stable; when the flat vertical roll is used, the maximum contact pressure on surfaces of the crack is 70 MPa, and it fluctuates greatly. During horizontal rolling process, when groove vertical roll is used, the contact pressure becomes zero which may accelerate the growth of crack; when flat vertical roll is used, there is still contact pressure. The calculated results are in good agreement with the results of test.