Tandem Hot Rolling Research Articles

Dynamic modeling and rolling data analysis of the tandem hot rolling process

Hot rolling is an essential industrial process in the production of sheet steel, a widely used product in manufacturing and construction. The hot strip mill is a complex unit including many processes and control loops and its modeling is a challenging task owing to the variety of phenomena that occur within the mill. Model validation is also challenging owing to a scarcity of measurements. In this study, a computer simulative emulation that can analyze the dynamic behaviors of the tandem hot rolling process with original non-linear rolling models has been developed and validated against a linear model and measured data. Moreover, the influence coefficients of rolling process parameters were calculated by analyzing the rolling data.

Adaptive Strategy of Short Stroke Control in Tandem Hot Rolling

Adaptive Strategy of Short Stroke Control in Tandem Hot Rolling

Multi-objective optimization of rolling schedules on aluminum hot tandem rolling

In hot strip rolling process, rolling schedule is a key technology which directly influences strip product qual- ity. Rolling schedule optimization is actually a problem of load distribution. To make a better rule of the load dis- tribution of aluminum hot tandem rolling, multi-objective optimization algorithm is used to optimize rolling schedule. Preventing slipping, power margin and minimum energy consumption are selected as the optimization objectives. To make a precision calculation of rolling schedule, an adap- tive neural network which is based on classification system is applied to improve the prediction ability for the rolling force, and its on-line training system reduces the prediction errors caused by different rolling conditions. The improved differential evolution algorithm is used to search the Pareto front, and it obtains a good approximation of the Pareto- front and decreases computation time. Load distribution strategies focused on different objectives are generated from the Pareto front to meet the requirements of industrial spots. The experiment result shows the algorithm covers the front quickly and distributes well. Comparing with the original schedule, the proposed method reduces the probability of slippage and energy consumption.

Control of the Tandem Hot Strip Mill Under Expanded Uncertainties and Disturbances

Previously, it has been shown that a controller based on the use of the state-dependent-Riccati-equation technique has resulted in significant improvements in performance. In our previous work, controller performance under certain disturbances and uncertainties that are considered typical for tandem hot rolling was addressed. While the performance under these conditions was quite successful, performance under an expanded set of conditions remained to be evaluated. In this paper, we examine performance under such a set of disturbances and uncertainties and show that the improvement in controller performance is retained under these expanded operational aspects. This improves the confidence in the performance of the previously developed controller.

Multisample Processing Strategy of Data Acquisition in Tandem Hot Rolling

Multisample Processing Strategy of Data Acquisition in Tandem Hot Rolling

Microstructure and Tensile Deformation Features of Tandem Hot Rolling GH4169 Superalloy

AbstractBy means of solution treatment, microstructure observation and mechanical property measurement, the microstructure and tensile deformation features of tandem hot rolling GH4169 alloy have been investigated. Results shown that, after solution treatment and aging, large numbers of the spherical γ′ phase and the flat-ellipsoidal γ″ phase dispersedly precipitate in the matrix, and acicular or short rod-like δ-phase discontinuously distribute along grain boundaries. As the tensile temperatures increases, the tensile strength and yield strength of the alloy gradually decrease. The tensile deformation features of the alloy are that the twinning and slipping dislocations with double orientations are activated in the matrix. In the later tension, the deformed dislocations pile up near the grain boundary to induce initiation and propagation of cracks due to stress concentration.

Analysis of Hot Tandem Rolling Force with Logarithmic Velocity Field and EA Yield Criterion

In order to analyze the hot tandem rolling force, a new logarithmic velocity field is proposed. Using the field and linear EA (equal area) yield criterion, the plastic deformation power for plate rolling is analyzed, and the friction power is obtained based on the co-line vector inner product method. Then analytical solution of plate rolling power functional is obtained. Finally, by minimizing the power functional, the rolling force and torque are received. Compared with those measured ones in hot tandem rolling on-line, the calculated rolling forces are in good agreement with the actual measured ones since the maximum error is less than 12%. Moreover, the effects of various rolling conditions such as thickness reduction, friction factor and shape factor, upon separating force, location of neutral angle, and stress state coefficient are discussed systematically.

Effects of Strip Thickness Difference on Deviation in Aluminum Hot Rolling

In aluminum hot rolling process, strip thickness difference plays a more important role in deviation. An FE model was presented to simulate the rolling process in which strip thickness difference was taken as a horizontal asymmetry factor of disturbance. Parameters information of nodes is processed, with the characteristic quantity of deviation and the asymmetrical thickness difference rate calculated. The result of simulation illustrates the deviation result under the disturbance of thickness difference, and the relationship among deviation function, characteristic quantity of deviation and the asymmetrical thickness difference rate. Deviation tracks under these circumstances are figured out. The effect of thickness difference on deviation in aluminum tandem hot rolling is revealed.

Tail Deviation Mechanism and Neural Network Control of the Tandem Rolling Strap

In the rolling process, deviation is the phenomenon that the strap width direction's centerline deviates from rolling system setting centerline,serious deviation will cause product quality drop and rolling equipment fault. This paper has established the finite element model to the hot tandem rolling aluminum strap, analyzed the strap’s deviation rule under four kinds of incentives,obtained the neural network predictive model and the control policy of the tail deviation.The result to analyze a set of fact deviation data shows this method may control tail deviation in preconcerted permission range.

A Useful Control Model for Tandem Hot Metal Strip Rolling

The tandem hot metal strip rolling process is a highly complex nonlinear system that presents a difficult control challenge. This challenge is exacerbated by the hostile hot metal rolling environment, which precludes the location of sensors to measure variables that are important for control. In addition, the controller must have a structure that offers simplicity of tuning during commissioning by personnel who usually are unfamiliar with advanced process control techniques. Based on our previous work using a state-dependent Riccati equation technique for control of the tandem cold metal rolling process, it is considered that a similar method might also be useful for control of tandem hot strip rolling. For the hot rolling process, the development of a process model in a form that is suitable for control development is a significant and challenging task. This paper describes our work to expand on an initial portion of this model to develop a comprehensive nonlinear model of this process. Based on simulation results, it is determined that the complete model has the potential to be useful in the development of a viable nonlinear control method for significant improvement in the control of the tandem hot rolling process.

On the Plastic Flow Behavior of Ti-6Al-4V Alloy during Multi-Stand Tandem Hot Rolling

Titanium alloys are usually used as structural parts in forged and subsequent heat treated state. Up to now, there have been rare researches appeared on their shaping or forming by multi-stand tandem hot rolling. In this article, we choose Ti-6Al-4V as experimental material and a simulated research has been carried out in a thermo-mechanical simulator MMS-300 to model its hot-rolling process. The plastic flow behavior for Ti-6Al-4V alloy during hot-working has been determined at various deformation temperatures and deformation rates by considering its hot-rolling in single or two phase region. The deformation mechanisms at elevated temperatures are also analyzed in correlation with its deformation activation energy. This research can provide guidance in designing processing parameters for hot-rolling of Ti-6Al-4V alloy.

Integrated Production Technologies for Ultra-fine Grained Steel Sheets

A national project was conducted by NEDO and executed by a consortium organized by JRCM with aims to develop integrated production technologies necessary for manufacturing ultra-fine grained steel (UFGS) sheets. In the project, the diverse technologies were concurrently developed relating with (1) high-speed large-reduction semi-continuous hot forging, (2) high-speed short-interval hot tandem rolling, (3) multi-cycle hot bending for strain accumulation, (4) high-strength anti-wear rolls, (5) multi-functional lubricants, (6) mathematical modeling and simulation of ultra-fine grain generation and (7) joining of UFGS sheets. The project succeeded in building up the integration of advanced technologies available for overall steel sheets manufacturing as well as production of UFGS sheets. Utilizing the developed technologies, UFGS sheets of plain low carbon steel having 1.0-2.0 mm thickness, 300 mm width, 1.0 μm grain diameter and 600-700 MPa tensile strength were successfully manufactured and found assuredly formable to practical products.

Through-process simulation of texture and properties during the thermomechanical processing of aluminium sheets

Computer-based alloy and process development requires the integration of models for simulating the evolution of microstructure, microchemistry and crystallographic texture into process models of the thermomechanical production of Al sheet. In this paper, a softening model simulating the progress of recovery and recrystallization and the following texture changes is linked to deformation and microchemistry models. The possibility of such coupled simulations is illustrated by way of the thermomechanical processing of Al–Mn–Mg AA 3104 can stock. In particular, the impact of inter-stand recrystallization between the tandem hot rolling passes as well as recrystallization during coil cooling (“self-annealing”) on the resulting hot strip and final gauge textures are explored. Finally, the predicted textures are input into a polycrystal–plasticity model to simulate anisotropic properties (earing behaviour) of the sheets. Thus, it is possible to link the materials properties at final gauge to the decisive steps of deformation and recrystallization along the thermomechanical process chain.

Applications of Through Process Modelling Developed in VIRSTAR

In February 2004, the outcome of a four-year European collaboration on Through Process Modelling (TPM) of aluminium alloys was presented in Brussels. This was a 17 M euro project in which key research institutes and universities, together with major aluminium companies, developed a series of linked and physically based microstructure models to predict the behaviour of aluminium alloys during fabrication and subsequent processing. Since then, Corus RD&T has implemented the modelling tools developed in the project and integrated them into a comprehensive in house TPM framework called Roll-it. The model framework of Roll-it is constructed by combining a series of sub-models that predict precipitation, work-hardening, recovery and recrystallization. It has been coupled with a finite difference based process model which provides the necessary input variables like strain, strain rate and temperature and applied to predict the evolution of microstructure during thermo-mechanical processing of aluminium alloys. With Roll-it, it is now possible to predict microchemistry, grain structure, and degree of recrystallization at any given point during the fabrication process. In this paper, three TPM applications are presented to illustrate the efficacy of Roll-it. In the first example the aim was to improve reproducibility of properties of hot rolled AA5083. The model showed that the control of dispersoid size during the homogenisation phase and the finish temperature of hot rolling were the critical parameters. In the second example customer's required a sheet product with improved forming characteristics, in particular reduced roping. TPM was used to simulate recrystallization behaviour during two breakdown hot rolling schemes that produce sheets with different roping behaviour. Finally, Roll-it was coupled with the advanced texture models developed by IMM Aachen to predict the texture evolution during tandem hot rolling and subsequent annealing of a 6xxx-alloy.

Simulation of Rolling and Recrystallization Textures in Aluminium Alloy Sheets

Computer-based alloy and process development requires integration of models for simulating the evolution of microstructure, microchemistry and crystallographic texture into process models of the thermo-mechanical production of Al sheet. The present paper focuses on recent developments in linking softening modules that simulate the progress of recovery and recrystallization with the following texture changes to deformation and microchemistry models. The potential of such coupled simulations is illustrated by way of the thermo-mechanical processing of Al-Mn-Mg AA 3104 can stock. In particular, the impact of inter-stand recrystallization between the tandem hot rolling passes as well as recrystallization during coil cooling (“self-annealing”) on the resulting hot strip and final gauge textures are explored. Finally, the predicted textures are input into a polycrystal-plasticity approach to simulate anisotropic properties (earing behaviour) of the sheets. Thus, it is possible to link the materials properties at final gauge to the decisive steps of deformation and recrystallization along the thermo-mechanical process chain.

Co-ordinated control of profile and shape in hot strip finishing mills with nonlinear dynamics

A method of modelling and controlling profile and flatness in hot strip tandem rolling mills is described. The method for controlling the profile is based on explicit manipulation of the strip thickness across its width. The flatness is controlled by appropriately distributing and constraining the profile actuators, so that defects do not occur. Model-based predictive control is employed to generate the control signal for each stand and to co-ordinate the stands for optimal profile and shape control. Simulation results are presented to demonstrate the performance of the proposed co-ordinated control scheme.

Mathematical modelling for rolling force and microstructure evolution and microstructure controlling with heavy reduction in tandem hot strip rolling

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熱間強圧下連続圧延による細粒鋼薄板・厚板の製造を目的とした圧延負荷・内部組織の理論解析

熱間強圧下連続圧延による細粒鋼薄板・厚板の製造を目的とした圧延負荷・内部組織の理論解析

熱間タンデム圧延における鋼板張力の動特性方程式解析

熱間タンデム圧延における鋼板張力の動特性方程式解析

塑性加工 熱間タンデム圧延における難加工性材料の線材製造技術

塑性加工 熱間タンデム圧延における難加工性材料の線材製造技術