The Experts below are selected from a list of 4935 Experts worldwide ranked by ideXlab platform
A K Tieu - One of the best experts on this subject based on the ideXlab platform.
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measurement of the Forward Slip in cold strip rolling using a high speed digital camera
Journal of Mechanical Science and Technology, 2007Co-Authors: A K TieuAbstract:The Forward Slip in strip rolling was defined as the relative difference between the roll surface speed and strip exit speed. It was always an important parameter because of its significant influence on friction and tension control. In this study a Phantom V3.0 digital high speed image acquisition and motion analysis system was used to record the movement of the roll and the workpiece during rolling. The pictures captured were analyzed to obtain the speeds of the roll and the workpiece along the roll bite, which then yielded the Forward Slip. The measurement accuracy has been validated by the mass conservation. The maximum relative error of the Forward Slip was only 1.6 %. The results have shown that the Forward Slip increased as the reduction increased for both dry and lubricated rolling. The roll speed did not change the Forward Slip in the case of dry rolling, but the Forward Slip was significantly reduced with roll speed when lubricated.
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a 3 d finite element method analysis of cold rolling of thin strip with friction variation
Tribology International, 2004Co-Authors: Zhengyi Jiang, A K TieuAbstract:In this paper, a three-dimensional rigid-plastic finite element method (FEM) model to simulate the cold rolling of thin strip with different friction models is described. The effects of rolling parameters, such as work roll diameters and reductions, are analysed in this study. The simulation and experimental values of rolling pressure and spread (the difference of strip width before and after rolling) show a good agreement when friction variation in the roll bite is considered. The roll separating force, spread and Forward Slip for constant friction and friction variation models are also compared. The friction variation in the roll bite has a significant effect on the simulation results.
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Forward Slip measurements in cold rolling by laser doppler velocimetry uncertainty analysis and accuracy improvement
Journal of Materials Processing Technology, 2003Co-Authors: A K Tieu, W Y D YuenAbstract:Abstract Accurate determination of the relative motion between the work rolls and the strip, known as Forward Slip, is required in the metal rolling process. Laser Doppler velocimetry (LDV) is one of the promising methods to measure this small relative speed in cold rolling. In this paper, the accuracy of Forward Slip measurements in cold rolling is addressed. The uncertainty of the LDV system designed for Forward Slip measurement is analysed. It is demonstrated that with small Slips, a high accuracy is difficult to achieve, although both the roll and the strip speeds are measured with a reasonably high accuracy. A method for further improving the accuracy of the LDV system is proposed and tests made on an experimental rolling mill are described.
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a simulation of three dimensional metal rolling processes by rigid plastic finite element method
Journal of Materials Processing Technology, 2001Co-Authors: Zhengyi Jiang, A K TieuAbstract:Abstract Using different frictional shear stress models, mesh division and number of elements in the deformation zone, this paper focuses on analysing the influence of friction variation on the convergence and results of simulation such as rolling pressure, Forward Slip and spread by 3D rigid–plastic FEM. The effects of mesh division and the number of elements on the precision, stability and convergence of the simulation are also discussed. This investigation shows that the frictional shear stress model with a variation in the deformation zone can provide satisfactory results that are in good agreement with experimental values, and are also more accurate than results from other methods. Suitable mesh division can improve the precision and effectiveness of the simulation. The results of the simulation are discussed for front and back tensions.
John G. Lenard - One of the best experts on this subject based on the ideXlab platform.
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an advanced finite element model of the flat cold rolling process
Primer on Flat Rolling (Second Edition), 2014Co-Authors: John G. LenardAbstract:A finite element model is presented which takes careful account of the three components of the cold, flat rolling process: the work roll, the rolled strip and their interface. The work roll is treated as an elastic cylinder. The elastic and plastic regions of the rolled strip are considered. The events at their interface are modelled by a coefficient of friction which depends on the relative velocity between the contacting bodies. The model calculates the roll separating force, the roll torque and the Forward Slip. These calculations compare well to experimental data. Following the comparisons, the model is used to examine the distributions of the stresses, strains and rates of strain in the work roll and in the rolled strip.
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Estimating the resistance to deformation of the layer of scale during hot rolling of carbon steel strips
Journal of Materials Processing Technology, 2002Co-Authors: Yangchun Yu, John G. LenardAbstract:Abstract Low carbon steel strips were hot rolled at various temperatures, speeds and reductions. The thickness of the layer of scale before and after the rolling pass was carefully controlled. Pre-heated oxygen-free nitrogen was used to purge the heating furnace while the strips to be rolled were brought to the test temperature. As well, after the rolling pass the strips were cooled in a closed box, which was also purged using oxygen-free nitrogen. The roll forces, roll torques, the Forward Slip and the scale thickness, before and after rolling, were measured. The coefficient of friction, calculated using Geleji’s formula, was found to decrease as the scale thickness increased. The thickness of the oxide layer before and after rolling and the duration of the pass were used to calculate the strains and strain rates it experienced. These, along with the surface temperature, were related to the interfacial pressure and hence, to the resistance of the scale layer to deformation. The strength of the scale increased with increasing contact times and with decreasing temperatures.
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the effect of scaling on interfacial friction in hot rolling of steels
Journal of Materials Processing Technology, 1999Co-Authors: P. A. Munther, John G. LenardAbstract:Abstract Hot oxidation and hot rolling experiments were undertaken in order to investigate scale formation and its effect on the frictional conditions in the hot flat-rolling of steels. The effect of scale thickness on the coefficient of friction in the hot rolling of a low carbon and a microalloyed steels is examined. A model of scale growth is presented, predicting the magnitude of the scale index as well as the thickness of the scale as a function of the temperature and time. The coefficient of friction is inferred from a finite-element code as a match between the measured and calculated roll force, torque, and Forward Slip. It is shown that the coefficient of friction increases with decreasing scale thickness. The break-up of the scale and surface defects are discussed.
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chapter 4 one dimensional modeling of the flat rolling process
Mathematical and Physical Simulation of the Properties of Hot Rolled Products, 1999Co-Authors: Maciej Pietrzyk, John G. Lenard, L CserAbstract:This chapter reviews boundary conditions, connected with tribology, and the initial conditions connected with a material's flow strength. In each, the success or failure of the ability of the model to predict the rolling variables is dependent on the mathematical rigor of the development, as well as on the knowledge and representation of the boundary and initial conditions: the coefficient of friction and the metal's resistance to deformation. An empirical model and several one-dimensional models are presented, all of which are designed to calculate one or more of the rolling parameters: the roll separating force, the roll torque, the roll pressure, the power, the temperature rise, and the Forward Slip. The sensitivity of the predictions of the models to various parameters is also looked into. Finally, the chapter examines the predictive capabilities of the models, in both cold and hot rolling processes, by comparing them to experimental results.
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Friction and Forward Slip in Cold Strip Rolling
Tribology Transactions, 1992Co-Authors: John G. LenardAbstract:Forward Slip, interfacial normal and shear stresses, roll separating forces, and roll torques are measured during cold rolling of commercially pure aluminum strips. The validity of the measured contact stresses in the deformation zone is substantiated by comparing roll forces and torques obtained through mathematical modeling, via the force and torque transducers and by integration of the normal pressure and shear force distributions over the contact surface. The usefulness of previously published Forward-Slip coefficient of friction formulae is examined. After comparing the predictions of five of these relationships, their unreliability is pointed out.
Yonggang Dong - One of the best experts on this subject based on the ideXlab platform.
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research on the characteristics of Forward Slip and backward Slip in alloyed bar rolling by the round oval round pass sequence
The International Journal of Advanced Manufacturing Technology, 2016Co-Authors: Yonggang Dong, Jianfeng SongAbstract:For determining the neutral line on the contact zone to distinguish the Forward Slip zone and backward Slip zone on the contact surface between the deformed pieces and the roll, the contact surface was discretized as finite flow line elements to build a novel analytic model to reconstruct the geometry of contact surface. Moreover, the velocity of flow lines on the contact surface along the direction of x-axis was derived by the condition of steady-state incompressible flow, and the function of neutral line was obtained by determining the neutral radius and the neutral angle of the points on the neutral line. In addition, the Forward Slip coefficient and backward Slip coefficient was derived and the relative Slip condition of contact surface between the roll and the rolled pieces was determined. Based on these mathematical models the geometry of contact surface and neutral line were drawn up by mathematical software. The validity of the theoretical model was verified by rolling experiments of alloyed bar and the numerical simulation by rigid-plastic FEM software. Compared with the experimental data and simulation results, the prediction error of the mathematical model is acceptable and results from the mathematical model are satisfying.
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a research on the Forward Slip coefficient in alloyed bar rolling by the round oval round pass sequence
Advanced Materials Research, 2011Co-Authors: Jianfeng Song, Yonggang DongAbstract:For predicting the Forward Slip coefficient and veocity of outgoing workpiece exactly during alloyed bar rolling by Round-Oval-Round pass sequence, the influence of the spred of the outgoing workpiece and its contact boundary condition was considered and the calculating formula for the effective height of outgoing workpiece and the mean roll radius was proposed individually. Moreover, the new parameters were substituted into the Shinokura and Takai Formula to modify it. Then a modified Forward Slip coefficient firmula was proposed. The validity of the theoretical model has been examined by the bar rolling experiment and the numerical simulation using three-dimensional rigid-plastic FEM. Compared with the Shinokura and Takai dormula, the predict accuracy of the modified formula was improved apparently. So, it can be applied in alloyed bar rolling to predict the the Forward Slip coefficient and veocity of outgoing workpiece exactly.
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the theoretical and experimental research on the Forward Slip coefficient in rail universal rolling
Isij International, 2009Co-Authors: Yonggang Dong, Wenzhi Zhang, Jianfeng SongAbstract:In rail universal rolling, the Forward Slip coefficient is one of the most important parameters. For simplifying the analytic model, the vertical roll with box pass has been simplified as an equivalent flat roll firstly. Then the equation of neutral line and the area of Forward Slip zone on the flank of horizontal roll have been derived. Furthermore, the horizontal resultant force acting on the rolled workpiece has been obtained and the Forward Slip coefficient of rail universal rolling has been proposed. For verifying the theoretical model, the universal rolling process of 60 kg/m heavy rail and 18 kg/m light rail have been simulated by the Rigid-Plastic FEM software DEFORM-3D V5.0, and the universal rolling experiments of 18 kg/m light rail has been accomplished in the Yanshan University Rolling Laboratory. Moreover, the theoretical results and numerical simulation results of Forward Slip coefficient are in agreement with the experimental data basically. So, this theoretical model can be applied in rail universal rolling.
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determination of Forward Slip coefficient during heavy rail rolling using universal mill
Journal of Iron and Steel Research International, 2008Co-Authors: Yonggang Dong, Wenzhi Zhang, Hui CaoAbstract:The Forward Slip coefficient is one of the most important parameters for heavy rail rolling using universal mill. For simplifying the theoretical model, the vertical roll with box pass was simplified as an equivalent flat roll first, Second, the neutral angle of horizontal roll and vertical roll was represented. Then, the equation of neutral line on the flank of horizontal roll was determined and the Forward Slip coefficient of the web was derived according to different positions of neutral line. Finally, the Forward Slip coefficient of the top and base of heavy rail was obtained. The theoretical results were basically in agreement with the experimental data.
Jianfeng Song - One of the best experts on this subject based on the ideXlab platform.
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research on the characteristics of Forward Slip and backward Slip in alloyed bar rolling by the round oval round pass sequence
The International Journal of Advanced Manufacturing Technology, 2016Co-Authors: Yonggang Dong, Jianfeng SongAbstract:For determining the neutral line on the contact zone to distinguish the Forward Slip zone and backward Slip zone on the contact surface between the deformed pieces and the roll, the contact surface was discretized as finite flow line elements to build a novel analytic model to reconstruct the geometry of contact surface. Moreover, the velocity of flow lines on the contact surface along the direction of x-axis was derived by the condition of steady-state incompressible flow, and the function of neutral line was obtained by determining the neutral radius and the neutral angle of the points on the neutral line. In addition, the Forward Slip coefficient and backward Slip coefficient was derived and the relative Slip condition of contact surface between the roll and the rolled pieces was determined. Based on these mathematical models the geometry of contact surface and neutral line were drawn up by mathematical software. The validity of the theoretical model was verified by rolling experiments of alloyed bar and the numerical simulation by rigid-plastic FEM software. Compared with the experimental data and simulation results, the prediction error of the mathematical model is acceptable and results from the mathematical model are satisfying.
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a research on the Forward Slip coefficient in alloyed bar rolling by the round oval round pass sequence
Advanced Materials Research, 2011Co-Authors: Jianfeng Song, Yonggang DongAbstract:For predicting the Forward Slip coefficient and veocity of outgoing workpiece exactly during alloyed bar rolling by Round-Oval-Round pass sequence, the influence of the spred of the outgoing workpiece and its contact boundary condition was considered and the calculating formula for the effective height of outgoing workpiece and the mean roll radius was proposed individually. Moreover, the new parameters were substituted into the Shinokura and Takai Formula to modify it. Then a modified Forward Slip coefficient firmula was proposed. The validity of the theoretical model has been examined by the bar rolling experiment and the numerical simulation using three-dimensional rigid-plastic FEM. Compared with the Shinokura and Takai dormula, the predict accuracy of the modified formula was improved apparently. So, it can be applied in alloyed bar rolling to predict the the Forward Slip coefficient and veocity of outgoing workpiece exactly.
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the theoretical and experimental research on the Forward Slip coefficient in rail universal rolling
Isij International, 2009Co-Authors: Yonggang Dong, Wenzhi Zhang, Jianfeng SongAbstract:In rail universal rolling, the Forward Slip coefficient is one of the most important parameters. For simplifying the analytic model, the vertical roll with box pass has been simplified as an equivalent flat roll firstly. Then the equation of neutral line and the area of Forward Slip zone on the flank of horizontal roll have been derived. Furthermore, the horizontal resultant force acting on the rolled workpiece has been obtained and the Forward Slip coefficient of rail universal rolling has been proposed. For verifying the theoretical model, the universal rolling process of 60 kg/m heavy rail and 18 kg/m light rail have been simulated by the Rigid-Plastic FEM software DEFORM-3D V5.0, and the universal rolling experiments of 18 kg/m light rail has been accomplished in the Yanshan University Rolling Laboratory. Moreover, the theoretical results and numerical simulation results of Forward Slip coefficient are in agreement with the experimental data basically. So, this theoretical model can be applied in rail universal rolling.
Zhengyi Jiang - One of the best experts on this subject based on the ideXlab platform.
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a 3 d finite element method analysis of cold rolling of thin strip with friction variation
Tribology International, 2004Co-Authors: Zhengyi Jiang, A K TieuAbstract:In this paper, a three-dimensional rigid-plastic finite element method (FEM) model to simulate the cold rolling of thin strip with different friction models is described. The effects of rolling parameters, such as work roll diameters and reductions, are analysed in this study. The simulation and experimental values of rolling pressure and spread (the difference of strip width before and after rolling) show a good agreement when friction variation in the roll bite is considered. The roll separating force, spread and Forward Slip for constant friction and friction variation models are also compared. The friction variation in the roll bite has a significant effect on the simulation results.
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a simulation of three dimensional metal rolling processes by rigid plastic finite element method
Journal of Materials Processing Technology, 2001Co-Authors: Zhengyi Jiang, A K TieuAbstract:Abstract Using different frictional shear stress models, mesh division and number of elements in the deformation zone, this paper focuses on analysing the influence of friction variation on the convergence and results of simulation such as rolling pressure, Forward Slip and spread by 3D rigid–plastic FEM. The effects of mesh division and the number of elements on the precision, stability and convergence of the simulation are also discussed. This investigation shows that the frictional shear stress model with a variation in the deformation zone can provide satisfactory results that are in good agreement with experimental values, and are also more accurate than results from other methods. Suitable mesh division can improve the precision and effectiveness of the simulation. The results of the simulation are discussed for front and back tensions.
