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John G. Lenard - One of the best experts on this subject based on the ideXlab platform.
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8 – Material Attributes
Primer on Flat Rolling, 2020Co-Authors: John G. LenardAbstract:The need for understanding the behaviour of metals when subjected to plastic deformation under various Process conditions is emphasized. Newly developed steels are mentioned. The mechanical and metallurgical attributes are reviewed. Attention is paid to the available, traditional testing Processes that may be used to establish the metal’s resistance to deformation. Their advantages and disadvantages are listed. Corrections for frictional effects and for isothermal conditions are given. The mathematical models that describe the resistance to deformation are listed and compared. Their suitability for the analysis of the Flat Rolling Process, is presented, compared and discussed.
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16 – Problems and Solutions
Primer on Flat Rolling, 2020Co-Authors: John G. LenardAbstract:In the first part of this chapter assignments are presented, listed according to the chapters in the book. The problems in the first section, General Background, are designed to recall the basic information needed in the understanding of the ideas to be presented in the discussion of the Flat Rolling Process, concerning mechanics, strains, incompressibility, theory of plasticity, plastic deformation and flow, heat transfer and boundary conditions. This is followed by a set of problems for most of the remaining chapters. Some of these problems require extensive calculations, using the derivations and the expressions given in the text. While some of them are designed to illustrate the material by simply applying the formulae as presented, some will require in-depth thinking as well. Several of them request that the equations stated in the text be derived from first principles. Many problems will be tractable only after a visit to a library and/or the Internet. In the second section, the solutions to most, but not all, of the problems are presented. These are given in various ways. For some, detailed step-by-step solutions are shown. For some others, hints and advice that indicate a possible, but not necessarily unique, approach towards the solutions are offered. Numerical answers to some of the questions are also provided. It is possible that in some instances the answers the readers will obtain may differ from those given here as the set of assumptions may well be different from those made by the author.
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Chapter 3 – Mathematical and Physical Modelling of the Flat Rolling Process
Primer on Flat Rolling, 2020Co-Authors: John G. LenardAbstract:Publisher Summary This chapter elucidates mathematical and physical modeling of the Flat-Rolling Process. It presents the modeling of the mechanical events that occur during the Flat-Rolling Process, including the ideas of static and dynamic equilibrium of the rolled strips and plates, the elastic and plastic response of the materials to loading, interfacial friction, and temperature effects. It describes the modeling of the metallurgical phenomena as a result of the treatment the strip receives during its passage through the Rolling mill, including the hardening, and the restoration mechanisms. It presents mathematical models of the Processes with the observations and ideas described in terms of the laws of nature, empirical relations, and physical simulation and assumptions. The chapter also describes empirical and one-dimensional (1D) models applicable for strip Rolling. It also discusses the use of artificial intelligence (AI) in predicting the Rolling variables. It examines a model, employing the friction factor instead of the coefficient of friction. It also presents the development of microstructure, as a result of the restoration and hardening phenomena, during hot Rolling. It also suggests an approach to modeling that considers the difficulties associated with determining the relevant values of the coefficient of friction and the metal's resistance to deformation.
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Chapter 2 – Flat Rolling — A General Discussion
Primer on Flat Rolling, 2020Co-Authors: John G. LenardAbstract:Publisher Summary This chapter presents a general discussion on the Flat-Rolling Process. It defines the various components of a metal Rolling system. The chapter discusses the Rolling mill designed by Leonardo da Vinci and the scale model built following his drawings. It describes the physical and metallurgical phenomena during the Rolling Process, including the events as the strip to be rolled is ready to enter the roll gap, as it is partially reduced and as the Process becomes one of steady state. This chapter enlists the independent variables of the system—connected to the mill, the rolled metal, and their interfaces. It describes the minimum value of the coefficient of friction necessary to commence the Rolling Process. It discusses some of the simplifying assumptions that are usually made in mathematical models of the Process of Flat Rolling. These assumptions include the ideas of “plane-strain plastic flow” and “homogeneous compression of the strip.”
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Flat Rolling — A General Discussion
Primer on Flat Rolling, 2020Co-Authors: John G. LenardAbstract:This chapter presents a general discussion on the Flat-Rolling Process. It defines the various components of a metal Rolling system. The chapter discusses the Rolling mill designed by Leonardo da Vinci and the scale model built following his drawings. It describes the physical and metallurgical phenomena during the Rolling Process, including the events as the strip to be rolled is ready to enter the roll gap, as it is partially reduced and as the Process becomes one of steady state. This chapter enlists the independent variables of the system—connected to the mill, the rolled metal, and their interfaces. It describes the minimum value of the coefficient of friction necessary to commence the Rolling Process. It discusses some of the simplifying assumptions that are usually made in mathematical models of the Process of Flat Rolling. These assumptions include the ideas of “plane-strain plastic flow” and “homogeneous compression of the strip.”
Maciej Pietrzyk - One of the best experts on this subject based on the ideXlab platform.
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Mathematical and Physical Simulation of the Properties of Hot Rolled Products
1999Co-Authors: John G. Lenard, Maciej Pietrzyk, L CserAbstract:PART I Introduction: steel production future changes of personnel competition from other materials current concerns the Rolling Process improvements of the Rolling Process the contents of the book. PART II Tribology of Flat Rolling and the boundary conditions: the tribological system interactions at the surface of contact the dependence of interfacial phenomena on Process and material parameters roll wear case studies boundary conditions. PART III The resistance of the material to deformation: tension, torsion and compression testing potential problems encountered during mechanical testing representation of true stress-true strain curves case studies. PART IV One-dimensional modelling of the Flat Rolling Process: free-body diagram of the roll-strip system an empirical model the traditional models - Orowan, Sims, Bland and Ford refinements of Orowan model a model with no friction hill sensitivity of the roll force and the torque to some of the parameters the predictive ability of the one-dimensional models. PART V The finite-element method in metal forming: rigid-plastic finite-element method elasto-plastic finite-element model heat transfer case studies. PART VI Microstructure evolution and mechanical properties of the final product: conventional microstructure evolution models properties at room temperature substantiation of thermal-mechanical-microstructural models the internal variable method case studies - industrial applications. PART VII Shape Rolling: generalized plane strain approach case studies. PART VIII Parameter evaluation in metal forming: parameter evaluation - the inverse analysis optimization techniques case studies. PART IX Knowledge based modelling: knowledge in hot Rolling knowledge in acquisition numerical data for decision-making data and data mining in hot Rolling numerical data covering the gaps in knowledge case studies.
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Mathematical and Physical Simulation of the Properties of Hot Rolled Products - Chapter 5 – The Finite-Element Method in Metal Forming
Mathematical and Physical Simulation of the Properties of Hot Rolled Products, 1999Co-Authors: J. G. Lenard, Maciej Pietrzyk, L CserAbstract:This chapter analyzes the finite-element model, as applied to the Flat Rolling Process. The basic ideas of the finite-element approach are described and illustrated with several examples. Rigid-plastic and elastic–plastic formulations are described and symmetric and non-symmetric Rolling are examined. Several examples of experimental validation of the model's predictions are also presented, including the calculation of the distributions of stresses, strains, strain rates, and temperatures. The chapter then discusses elastic deformations in the flow formulation approach. There are two major and distinct approaches to the simulation of metal forming Processes. The first is the solid state incremental approach, which usually employs elastic–plastic or elastic–viscoplastic material models. The second approach, the flow formulation, uses the rigid-plastic or rigid-viscoplastic material models. Since in metal forming operations, the non-linear plastic strains are much larger than the elastic ones, the latter are usually neglected, allowing the use of a simpler rigid-plastic model in the analysis. The resulting constitutive equations in this approach are identical to those of non-Newtonian fluid.
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Mathematical and Physical Simulation of the Properties of Hot Rolled Products - Chapter 4 – One-dimensional Modeling of the Flat Rolling Process
Mathematical and Physical Simulation of the Properties of Hot Rolled Products, 1999Co-Authors: J. G. Lenard, Maciej Pietrzyk, 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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chapter 4 one dimensional modeling of the Flat Rolling Process
Mathematical and Physical Simulation of the Properties of Hot Rolled Products, 1999Co-Authors: John G. Lenard, Maciej Pietrzyk, 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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Analysis of the Flat-Rolling Process: one-dimensional and finite-element models
Journal of Materials Processing Technology, 1993Co-Authors: Z Malinowski, Maciej Pietrzyk, John G. LenardAbstract:Abstract The predictive capabilities of a one-dimensional model, a rigid-plastic finite-element and an elastoplastic finite-element solution of the Flat Rolling Process are compared. It is found that the rigid-plastic solution gives almost identical rates of deformation and strain- and temperature-fields as the elastoplastic solution. The roll-separating forces and roll torques are also close and compare well to the measured data. Stress fields predicted by the rigid-plastic model are less accurate than those generated by the elastoplastic method. The one-dimensional model cannot predict the stress and the velocity fields with confidence. However, it is capable of calculating the roll-separating forces and the roll torques with good accuracy, provided that strip Rolling is considered. The information provided may be helpful to engineers in the steel industry in deciding which model should be used under which set of circumstances.
Karimi A Taheri - One of the best experts on this subject based on the ideXlab platform.
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applicability of the fsem for analyzing wire Flat Rolling Process
Engineering Computations, 2006Co-Authors: M Kazeminezhad, Karimi A TaheriAbstract:Purpose – The purpose of this paper is to present an assessment of the ability of combined finite and slab element method (FSEM) for analyzing the wire Flat Rolling Process.Design/methodology/approach – Using the FSEM, the effective strain field of Flat rolled wire is predicted for different reductions in height and frictional conditions. The validity of the method is assessed by performing the Vickers microhardness measurements on the Flattened wire cross section. Also, the creation of macroscopic shear bands in cross section of the Flat rolled wire is investigated and confirmed by microhardness and metallographic examinations. Moreover, the lateral spread and width of contact area are predicted by the FSEM for different reductions in height and frictional conditions.Findings – The FSEM and microhardness results show the minimum and the maximum effective strains at the round edge and center of the Flattened wire, respectively. Also, the results show the bands of maximum effective strain at cross section ...
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calculation of the Rolling pressure distribution and force in wire Flat Rolling Process
Journal of Materials Processing Technology, 2006Co-Authors: M Kazeminezhad, Karimi A TaheriAbstract:Abstract In this study a slab analysis is developed to predict the Rolling pressure distribution and Rolling force in the wire Flat Rolling Process. In the slab analysis the variations of width of contact area between the rolls and wire during Rolling is considered. Two differential equations are derived and solved using a modified Eulerian numerical method. The effects of friction coefficient, reduction in height and yield stress of wire on the Rolling pressure distribution and Rolling force are assessed. It is found that in the Flat Rolling of wire, there exists a maximum in the pressure distribution similar to that of the strip Rolling Process. Also, the effects of friction coefficient, reduction in height and yield stress on the neutral angle are investigated. It is observed that by increasing the reduction in height and friction coefficient, the neutral angle is increased and the yield stress has no effect on the neutral angle. A good agreement is found between the calculated and measured Rolling force.
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a theoretical and experimental investigation on wire Flat Rolling Process using deformation pattern
Materials & Design, 2005Co-Authors: M Kazeminezhad, Karimi A TaheriAbstract:In this research the deformation of wire in Flat Rolling Process has been investigated. A theoretical relationship has been developed to relate the reduction in height of wire to the width of contact area between the rolls and wire. This relationship depicts that the width of contact area is proportional to square root of reduction in height of wire. Using that relationship the width of contact area for wires of different diameter have been calculated and compared with the appropriate experimental data after Flat Rolling. Also, a relationship is developed to assess the effect of reduction in height of wire on the lateral spread in wire Flat Rolling Process. Moreover, the effect of material properties and roll speed on the width of contact area and lateral spread of wire are investigated. It is found that the material properties and roll speed have a negligible effect on the width of contact area and lateral spread of wire.
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an experimental investigation on the deformation behavior during wire Flat Rolling Process
Journal of Materials Processing Technology, 2005Co-Authors: M Kazeminezhad, Karimi A TaheriAbstract:Abstract In the present study a laboratory Flat Rolling machine is utilized to assess the deformation behavior of low and high carbon steel wires in wire Flat Rolling Process. The effects of friction coefficient, Rolling reduction and roll speed on Rolling force and deformation behavior of the wires are experimentally investigated. It is found that the roll speed affects considerably the Rolling force but a negligible effect on deformation behavior. It is noted that by increasing the roll speed, the Rolling force may decrease or increase depending on the magnitude of the roll speed. Also, the deformation behavior of the wires in Flat Rolling is formulated. A relationship is developed for calculating the width of contact area between the wire and rolls as a function of Rolling reduction. This relationship depicts that the width of contact area is proportional to square root of Rolling reduction. Furthermore, two relationships are derived to predict the spreading of the wires after Flat Rolling. It is found that the relationships are applicable for both the low and high carbon steel wires.
M Kazeminezhad - One of the best experts on this subject based on the ideXlab platform.
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Flow Stress Evolution in Further Straining of Severely Deformed Al
Metallurgical and Materials Transactions A, 2019Co-Authors: V. Charkhesht, M KazeminezhadAbstract:To investigate the flow stress evolution in further straining of severely deformed Al sheets, a comprehensive model which considers both mechanical and metallurgical alterations is needed. In this study, constrained groove pressing (CGP) as a severe plastic deformation method, and a Flat Rolling Process for further straining are utilized. Using basic mechanical models, strain and strain rate were calculated for this Process. Dislocation density and flow stress evolutions were predicted by utilizing initial mechanical data, considering the ETMB (Y. Estrin, L. S. Toth, A. Molinari, and Y. Brechet) dislocation density model. Based on these model predictions, the combination of the CGP Process with a further Rolling Process results in higher flow stresses than repeating the specific Process discretely. This phenomenon can be attributed to the ability of the Rolling Process to produce a greater strain rate, which, in turn, leads to the higher flow stresses. Thorough data from the mechanical tests as well as X-ray diffraction profiles strongly support the validity of the model in the prediction of flow stress and dislocation density, respectively.
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applicability of the fsem for analyzing wire Flat Rolling Process
Engineering Computations, 2006Co-Authors: M Kazeminezhad, Karimi A TaheriAbstract:Purpose – The purpose of this paper is to present an assessment of the ability of combined finite and slab element method (FSEM) for analyzing the wire Flat Rolling Process.Design/methodology/approach – Using the FSEM, the effective strain field of Flat rolled wire is predicted for different reductions in height and frictional conditions. The validity of the method is assessed by performing the Vickers microhardness measurements on the Flattened wire cross section. Also, the creation of macroscopic shear bands in cross section of the Flat rolled wire is investigated and confirmed by microhardness and metallographic examinations. Moreover, the lateral spread and width of contact area are predicted by the FSEM for different reductions in height and frictional conditions.Findings – The FSEM and microhardness results show the minimum and the maximum effective strains at the round edge and center of the Flattened wire, respectively. Also, the results show the bands of maximum effective strain at cross section ...
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calculation of the Rolling pressure distribution and force in wire Flat Rolling Process
Journal of Materials Processing Technology, 2006Co-Authors: M Kazeminezhad, Karimi A TaheriAbstract:Abstract In this study a slab analysis is developed to predict the Rolling pressure distribution and Rolling force in the wire Flat Rolling Process. In the slab analysis the variations of width of contact area between the rolls and wire during Rolling is considered. Two differential equations are derived and solved using a modified Eulerian numerical method. The effects of friction coefficient, reduction in height and yield stress of wire on the Rolling pressure distribution and Rolling force are assessed. It is found that in the Flat Rolling of wire, there exists a maximum in the pressure distribution similar to that of the strip Rolling Process. Also, the effects of friction coefficient, reduction in height and yield stress on the neutral angle are investigated. It is observed that by increasing the reduction in height and friction coefficient, the neutral angle is increased and the yield stress has no effect on the neutral angle. A good agreement is found between the calculated and measured Rolling force.
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a theoretical and experimental investigation on wire Flat Rolling Process using deformation pattern
Materials & Design, 2005Co-Authors: M Kazeminezhad, Karimi A TaheriAbstract:In this research the deformation of wire in Flat Rolling Process has been investigated. A theoretical relationship has been developed to relate the reduction in height of wire to the width of contact area between the rolls and wire. This relationship depicts that the width of contact area is proportional to square root of reduction in height of wire. Using that relationship the width of contact area for wires of different diameter have been calculated and compared with the appropriate experimental data after Flat Rolling. Also, a relationship is developed to assess the effect of reduction in height of wire on the lateral spread in wire Flat Rolling Process. Moreover, the effect of material properties and roll speed on the width of contact area and lateral spread of wire are investigated. It is found that the material properties and roll speed have a negligible effect on the width of contact area and lateral spread of wire.
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an experimental investigation on the deformation behavior during wire Flat Rolling Process
Journal of Materials Processing Technology, 2005Co-Authors: M Kazeminezhad, Karimi A TaheriAbstract:Abstract In the present study a laboratory Flat Rolling machine is utilized to assess the deformation behavior of low and high carbon steel wires in wire Flat Rolling Process. The effects of friction coefficient, Rolling reduction and roll speed on Rolling force and deformation behavior of the wires are experimentally investigated. It is found that the roll speed affects considerably the Rolling force but a negligible effect on deformation behavior. It is noted that by increasing the roll speed, the Rolling force may decrease or increase depending on the magnitude of the roll speed. Also, the deformation behavior of the wires in Flat Rolling is formulated. A relationship is developed for calculating the width of contact area between the wire and rolls as a function of Rolling reduction. This relationship depicts that the width of contact area is proportional to square root of Rolling reduction. Furthermore, two relationships are derived to predict the spreading of the wires after Flat Rolling. It is found that the relationships are applicable for both the low and high carbon steel wires.
U. S. Dixit - One of the best experts on this subject based on the ideXlab platform.
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inverse estimation of thermal parameters and friction coefficient during warm Flat Rolling Process
International Journal of Mechanical Sciences, 2015Co-Authors: V Yadav, Arbind K Singh, U. S. DixitAbstract:Abstract In this work, an inverse method for estimating the average thermal parameters and friction coefficient is proposed based on exit strip temperature and slip measurement. The inverse model makes use of a direct model for temperature determination, which uses the finite element method for the deformation analysis and an analytical method for the estimation of the temperature distribution. The direct model uses the temperature dependent thermal properties of roll and strip to estimate the temperature of exit strip. For minimizing the mean squared fractional error (MSFE) between the measured and computed temperatures of exit strip, a heuristic algorithm is used. The inverse method is tested by carrying out a number of numerical experiments on the warm strip Rolling. Less than ±7% error is observed between the actual and estimated thermal parameters and friction coefficient.
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An application of fuzzy inference for studying the dependency of roll force and roll torque on Process variables in cold Flat Rolling
The International Journal of Advanced Manufacturing Technology, 2009Co-Authors: P. P. Gudur, U. S. DixitAbstract:In this work, the roll force and roll torque in a cold Flat Rolling Process are modelled using first order Takagi–Sugeno fuzzy models. The fuzzy models predict the most likely lower and upper estimates of the roll force and roll torque. Although the fuzzy models can be based on the experimental data, in the present work, the required data is generated by radial basis function neural networks. The neural networks, in turn, are trained by a finite element method-based code. It is demonstrated that the coefficients of the linear crisp function used to represent the output variables in the fuzzy inference system can be used for assessing the sensitivity of these variables with respect to the Process variables. An algorithm to detect and suppress the outliers in the data is proposed. The effectiveness of the proposed algorithm is demonstrated through an example.
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A neural network-assisted finite element analysis of cold Flat Rolling
Engineering Applications of Artificial Intelligence, 2008Co-Authors: P. P. Gudur, U. S. DixitAbstract:The finite element analysis of the cold Flat Rolling Process is well established. However, the requirement of large computational time makes it unsuitable for online applications. Recently, there have been some applications of modeling the Rolling Process by means of neural networks. In most of the previous works, trained networks predict only roll force and roll torque. The input data for training the neural network have been obtained either through experiments or from finite element method (FEM) code. In this work, the neural networks have been used for predicting the velocity field and location of neutral point. The training data are obtained from a rigid-plastic finite element code. The trained network provides a suitable guess for the velocity field and location of the neutral point, that is further refined by the finite element code. The post-Processor of the FEM code computes roll force, roll torque, strain distribution, etc. This procedure provides highly accurate solution with reduced computational time and is suitable for on line control or optimization.
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A neural network based methodology for the prediction of roll force and roll torque in fuzzy form for cold Flat Rolling Process
The International Journal of Advanced Manufacturing Technology, 2003Co-Authors: U. S. Dixit, S. ChandraAbstract:Neural network models can be effectively used to predict any type of functional relationship. In this paper, a neural network model is used to predict roll force and roll torque in a cold Flat Rolling Process, as a function of various Process parameters. A strategy is developed to obtain a prescribed accuracy of prediction with a minimum number of data for training and testing. The effect of increasing the size of training and testing data set is also examined. After the prediction of most likely value, upper and lower bound estimates are also found with the help of the neural network. With these estimates, the predicted value can be represented as a fuzzy number for use in fuzzy-logic based systems.