Reversible Rolling Mill Research Articles

Fractional-order backstepping sliding mode control for the speed tension and screw down system of the reversible cold strip rolling mill

This paper investigates the robust control problem of the speed tension and screw down system of Reversible Cold Strip Rolling Mill (RCSRM). A finite-time observer is proposed to observe the uncertainties of the system. Based on the finite time observer, a fractional-order backstepping sliding mode controller is designed for each sub-system of the speed tension and screw down system of RCSRM. The Particle Swarm Optimization (PSO) algorithm is used to optimize the main parameters of the designed controller. By Lyapunov stability, the tracking error of the system can converge to the neighbourhood of the equilibrium point in a finite time. Finally, simulation research is carried out on the actual data of a 1422 mm RCSRM, and the effectiveness of the designed controller is verified.

Adaptive sliding mode observers‐based dissipative Hamilton finite time optimization control for the speed and tension system of reversible cold strip rolling mill

SummaryFor the complex time‐varying uncertain nonlinear speed and tension system of reversible cold strip rolling mill, an adaptive sliding mode observers (ASMOs)‐based dissipative Hamilton finite time optimization control method is given in this article. First, the ASMOs are developed to observe rolling mill system's unmatched uncertainties, and their observation errors can converge to the origin in finite time. Second, combined with rolling mill system's physical structure characteristics, its dissipative Hamilton model is established by pre‐feedback processing, and then the dissipative Hamilton finite time controllers are designed based on interconnection and damping configuration and energy shaping method, and the system states can converge in finite time. Third, the adaptive mutation particle swarm optimization algorithm is adopted to optimize the controller parameters, which can further improve rolling mill system's control performance. Finally, the simulation results verify the validity of the given method based on actual field data.

Fixed‐time prescribed performance optimization control for the speed and tension system of the cold strip rolling mill with output constraints

SummaryFor the speed and tension system of the reversible cold strip rolling mill with output constraints, parameter perturbations and load disturbance, a fixed‐time prescribed performance optimization control method is proposed based on disturbance observers in this article. First, the disturbance observers are constructed to estimate the system's unmatched uncertainties, and the observer errors can converge in fixed time. Second, a time‐varying logarithmic barrier Lyapunov function (TLBLF) is given and combined with the command filtered backstepping approach, the fixed‐time control and the prescribed performance control to complete the controller designs for the speed and tension system of the cold strip rolling mill, which make the system states converge in fixed time and are always constrained within predefined ranges. Third, particle swarm optimization‐gray wolf optimization (PSO_GWO) hybrid intelligent algorithm is used to optimize the main control parameters of the designed controllers, which further improves the convergence speed and steady‐state accuracy of the rolling mill system. Theoretical analysis proves that the proposed control method can ensure the closed‐loop system is stable in fixed time. Finally, the simulation comparison study is carried out by using the field actual data of a reversible cold strip mill system, and the simulation results verify the effectiveness of the proposed control method.

A New Electrohydraulic Hybrid Energy-Saving System Used on the Reversible Rolling Mills

In the face of the global energy crisis, the use of hybrid technology is an important way to achieve efficient energy storage and utilization. Hybrid systems have been successfully applied to automobiles and construction machinery, but no research study has been conducted on the design and application of energy recovery systems for reversible rolling mills. This article proposes a new type of noncoaxial parallel electrohydraulic hybrid drive system configuration for reversible rolling mills to save energy. It is proposed to collect the braking energy of the previous pass of the reversible rolling mill roll and the surplus power of the original primary drive motor and then start or accelerate the process for the next roll pass. A test experiment was established and the energy-saving efficiency of the proposed system was verified. By rolling 14 passes, 255.892 kJ of energy can be recovered. The overall energy efficiency rate is around 71.547%. The system will significantly promote energy saving, low carbon, green, and other aspects of the reversible rolling mills.

Дослідження ефективності схеми керування напругою конденсатора уніфікованого регулятора якості електроенергії для зменшення коливань напруги

This article investigated the effectiveness of using a unified power quality regulator (UPQR) to reduce voltage fluctuations in electrical networks with a rapidly changing nonlinear load. It is proposed to use a voltage control scheme on the URYAE storage capacitor based on an FIR filter in order to minimize rapid voltage changes and the flicker indicator, as well as the total coefficient of harmonic distortions in the distribution system. The final simulation of the study is carried out using MATLAB/Simulink. To demonstrate the effectiveness of the proposed control scheme, a comparison of simulation results with a PI controller is made from the point of view of improving the specified power quality indicators. The initial data for performing calculations of voltage fluctuations are information on the parameters of the electrical network and the graph of a random, rapidly changing electrical load. Rapidly changing loads cause rapid changes in the network voltage, the amplitudes of which can reach unacceptable values, for example, in the case of frequent start-ups of an asynchronous motor with a large starting current. Voltage fluctuations can also be caused by technological installations, the operation of which is accompanied by active and reactive power surges , such as the drive of reversible rolling mills, arc steel melting furnaces, contact electric welding installations, etc. The main task of the research is to improve the quality of electricity, and, as a result, to increase the service life of electrical equipment and to ensure the conditions for the normal technological process of electricity consumers. Indicators characterizing voltage fluctuations were quantified: voltage change range (δUt) and flicker indicator (Pt). The effectiveness of the new capacitor voltage control scheme for reducing higher current harmonics compared to the classical one based on the PI-regulator is verified.

Thermomechanical rolling of heavy plates with 100 mm thickness, from highstrength bridge steels S460K2W and S460J5W with improved atmospheric corrosion resistance

The article describes the results of industrial production on NLMK DanSteel reversing rolling mill 4200 of heavy plates with thickness of up to 100 mm made of low-carbon micro-alloyed high-strength steels of categories S460K2W and S460J5W. This are copper-alloyed and chromealloyed steel grades, which provides increased atmospheric corrosion resistance. Steels of categories S460K2W and S460J5W are manufactured in accordance with new edition of standard EN 10025-5:2019 and are used primarily in the construction sector for bridge and overpass constructions. The required level of mechanical and operational properties is ensured by optimal combination of the designed chemical composition and technological modes of thermomechanical processing with final accelerated cooling. According to the findings presented in the article, NLMK DanSteel has received TUV NORD approval for the manufacturing of these steels in the thickness range up to 100 mm as per supplement dated 18.05.2021 to certificate 0045-CPR-0554 dated 12.06.2020 in accordance with regulations 305/2011/EU: System 2+.

Are edger rolls useful to control the plate motion and camber in a reversing rolling mill?

In heavy-plate hot rolling, reversing rolling mills are typically used to reduce the thickness of steel slabs. Some reversing rolling mills are equipped with edger rolls to control the width of the rolled plate. At best, the straight plate centerline coincides with the lateral centerline of the rolling mill and the desired rectangular shape is exactly realized. In reality, lateral asymmetries like temperature gradients and thickness inhomogeneities cause a lateral movement, a camber, and a wedge-shaped cross section of the plate. These effects can reduce the product quality and entail collisions with the mill stand or other equipment along the roller table. To prevent this, active control of the lateral position and contour shape is desirable. In this work, a roughing mill where the roll gap adjustment is self-retaining, meaning that it can only be adjusted between rolling passes, is considered. As a control input during the rolling passes, the lateral position of the edger rolls is exploited. A mathematical model for both the lateral motion and the resulting shape of the plate is derived. The model is validated by measurement data recorded in an industrial plant. Based on the validated model, the question if edger rolls are useful to control the plate motion and shape is discussed. A two-degrees-of-freedom control concept composed of an optimization-based feedforward controller and a proportional feedback controller with Smith predictor is derived for the lateral motion and shape. The performance of the proposed control concept is demonstrated in simulation studies based on the validated model.

Immersion and invariance adaptive decentralized control for the speed and tension system of the reversible cold strip rolling mill

AbstractAn immersion and invariance (I&I) adaptive decentralized control strategy is proposed for the speed and tension system of the reversible cold strip rolling mill, which is characterized by multiple variable, nonlinearity, strong coupling effect, and uncertainty. First, a sliding mode observer (SMO) is constructed to estimate the unmatched uncertainty of the system to improve the tracking control precision. Second, the I&I theory‐based estimators are designed to estimate the perturbation parameters of the system, and the parameter estimation errors converge monotonically following an exponential law. Third, the I&I theory‐based decentralized controllers are designed for the speed and tension system of the reversible cold strip rolling mill, which achieve precise tracking controls for the given values of the system. Theoretical analysis shows that the resulting closed‐loop system is globally stable. Finally, the simulation research is carried out on the speed and tension system of a 1422 mm reversible cold strip rolling mill using actual data, and the simulation results verify the superiority of the proposed control strategy in comparison with the I&I control strategy and the backstepping dynamic surface control strategy.

Investigation the structure in cast and deformed states of aluminum alloy, economically alloyed with scandium and zirconium

The structure and mechanical properties of an alloy of the aluminum-magnesium system with a scandium content of no more than 0.1% (wt.) (experimental alloy) at the stages of obtaining sheet semi-finished products have been investigated. The macro and micro structure of cast, hot, and cold rolled sheet semi-finished products has been studied by the methods of light and diffraction transmission electron microscopy, and their mechanical properties have been tested. Casting of ingots, hot, and cold rolling of the alloy was carried out in the conditions of a metallurgical enterprise. The section of the ingots was a rectangle 300 × 1460 mm in size. Preparation of ingots for rolling included milling of all surfaces and two-stage annealing at temperatures of 350 °C (first stage) and 425 °C (second stage). Rolling was carried out across the casting direction. For hot rolling, the billets were heated to 400–410 °C and carried out on a reversible hot rolling mill of grade quart with a roll barrel length of 2800 mm to a thickness of 8.2–9.2 mm. Then, the strips were rolled into rolls and annealed according to the following regime: temperature 390–400 °С, holding for 1 h, cooling with a furnace to 250–270 °С, and unloading into air. Cold rolling was carried out on a QUARTO mill of the CRM grade with a roll barrel length of 2800 mm to a thickness of 5.9–6.3 mm. Microstructural analysis was performed on a Carl Zeiss Axio Observer A1m light microscope using the AxioVision software package. The fine structure of semi-finished products was studied using Tecnai 30 G2 and JEM-2100 EX transmission electron microscopes. The chemical composition of dispersed particles of the secondary phases was determined using energy dispersive X-ray microanalysis (EDX) of thin foils in transmission using an INCA x-sight attachment. It is shown that alloying the experimental alloy with small additions of scandium, zirconium, and manganese leads to the formation of a supersaturated solid solution in the ingot. And upon annealing of the ingot and subsequent hot and cold rolling, a subgrain structure with inclusions of Al6Mn and Al3(Sc, Zr) phases of distribution density is formed in the alloy structure, explaining dispersion and structural hardening of sheet semi-finished products. It was found that the mechanical properties of cold-rolled sheets from the experimental alloy significantly exceed the properties of alloy 5083 with the same magnesium content. But without scandium and are approximately on the same level with alloy 1570 in which the scandium content in comparison with the experimental alloy is three times higher.

Effect of Trace Mg on Impact Toughness of 2.25Cr1Mo Steel Doped with 0.056% P at Medium Temperature Aging Process

In order to investigate the effect of Mg addition on the embrittlement of Cr-Mo steels, the 2.25Cr1Mo steel plates containing Mg, P contents were refined with vacuum induction furnace and rolled with double-stick reversible rolling mill. The impact toughness evolution and microstructural characteristics of these steels after aging at 580 °C for up to 5000 h were systematically investigated. The grain boundary segregation behaviors of P, S, and Mg before and after aging were analyzed with auger electron spectroscopy (AES), and the microstructure characteristics of the steels were detected with optical electron microscope (OM) and transmission electron microscope (TEM). The research results show Mg addition can improve the impact toughness of the 2.25Cr1Mo steel to a certain extent even with 0.056 wt.% P doping. It was clarified that Mg can segregate to grain boundary during the aging process, and its strong segregation tendency can reduce the grain boundary segregation of P to some degree. The effects of Mg on the impact toughness after subjecting to 580 °C ageing, including element segregation behaviors at grain boundary, ferrite formation, prior austenite grain characteristics, and carbides at grain boundary were also identified and discussed.

Nonlinear control of the HAGC by backstepping with integral action based on a circle-criterion observer

Controlling the hydraulic automatic gauge control (HAGC) of cold reversible rolling mill is a significant engineering challenge mostly because of the complexity of the interactions between the process variables, the nonlinearities which change with the operating conditions, the time delay generated by the thickness measurement, and the long-time delays which change significantly with the mill speed. This paper describes a new control strategy by nonlinear control of the HAGC by backstepping with integral action based on a circle-criterion observer. We propose this new circle-criterion observer to estimate the unmeasured state for the nonlinear system. The main contributions of the proposed method are overcoming the interaction between tension stabilization and thickness control, considering time delay caused by measurements, and guaranteeing robustness against model uncertainties and external disturbances. The performance of the controller is also demonstrated and discussed by various simulations using MATLAB/SIMULINK software. The simulation results show clearly the effectiveness of the proposed control for improving the quality of the output web.

The effect of M (M = Ce, Zr, Ce–Zr) on rolling microstructure and mechanical properties of FH40

AbstractCe, Zr and Ce–Zr composite experimentl steel were prepared by vacuum induction furnace and 550 twin-roll reversible rolling mill. Optical microscope (OM), scanning electronic microscopy (SEM) and energy dispersive spectrometer (EDS) were used to observe the rolling microstructure of the experimental steel. The mechanical properties of the experimental steel were tested and analyzed. The effect of cerium zirconium oxide inclusions on nucleation, tensile and impact fracture mechanism of intragranular acicular ferrite (IAF) was investigated. The results show that the rolling microstructure of steel containing 0.0052% Ce and the steel under composite treatment containing 0.0053% Ce and 0.0055% Zr is refined. IAF generation can be induced by Al–Ce–O inclusion of the size of 4 µm or induced by Al–Ce–Zr–O + MnS inclusion of the size of 3 µm. The yield strength and tensile strength of the steel treated by Ce–Zr are 428 and 590 MPa, respectively, the elongation is 23.55%, the longitudinal impact energy at −60°C is 189 J, which are 31, 45, 46 J and 6.25%, respectively, higher than those of the matrix steel. The dimple of the experimental steel at the fracture surface is larger and deeper than that of the matrix steel. The small inclusions in uniform distribution contribute to the high tensile strength of the experimental steel.

Effect of vacuum smelting method on the quality of pipe steel of northern application

Pipe metal of Northern application must meet increased requirements of strength properties, low-temperature ductility, cold resistance and weldability. Cracks, skins, flaws, roll-ins and other defect are not allowed on the surface of pipes. The fulfillment of the requirements substantially can be provided by the process of steel smelting by a vacuum remelting method. Study of the effect of 03ХГ grade pipe steel smelting in vacuum and without vacuum on its contamination by nonmetallic inclusions and resistance against hydrogen cracking was accomplished. The smelting of ingots of adjusted chemical composition was carried out in a vacuum induction furnace ZG-0.06L. To imitate the process of hot roughing rolling, hydraulic press П6334 of 250 t force was used. Finishing rolling was carried out at reversible hot rolling mill 500 duo, combined with a controlled cooling facility. It was determined, that the samples, smelted in vacuum, had insignificant number of nonmetallic inclusions and withstand the test of resistance against hydrogen cracking; cracks were not detected on them. After testing on resistance against hydrogen cracking of the samples smelted without vacuum, cracks were discovered, located on both the surface and central layers amounting to 600 mm and 1700 mm length correspondently. It was shown, that steel smelting in vacuum allows to reach a high degree of the steel purity, results in increased crack growth resistance and in decreased number of nonmetallic inclusions in the pipe steel of Northern application.

Research on Tribological Properties of Environment-Friendly Nano-MoS<sub>2 </sub>Water-Based Rolling Liquid

In this research, the four-ball tribometer was examined to evaluate the tribological behavior of environment-friendly nano-MoS2 water-based rolling liquid. This experimental method is used to measure the maximum non-seizure load (PB) and the coefficient of friction (μ). The newly introduced parameter ω can be combined with PB and μ to evaluate the tribological performances of the rolling liquid comprehensively. The rolling lubrication performance of nano-MoS2 water-base lubricant was investigated using a single stand 4-high reversing rolling mill. The surface morphologies and rolling textures of the samples were measured by laser scanning confocal microscope after cold rolling. The results show that when the concentration of nano-MoS2 is 0.4wt.%, the water-based rolling liquid has excellent tribological and lubricating properties. Meanwhile, compared with the surface quality of the rolled strip under other lubrication conditions, the surface quality of the cold-rolled strip using 0.4wt% nano-MoS2 rolling liquid as the lubrication condition is smooth without visible surface defects.

Modelling and dynamic surface backstepping recursive sliding mode control for the speed and tension system of the reversible cold strip rolling mill

For the speed and tension system of the reversible cold strip rolling mill, a dynamic surface backstepping recursive sliding mode control (DSBRSMC) strategy is proposed based on the immersion and invariance (I&I) adaptive method and the nonlinear disturbance observer (NDO). First, a relatively complete mathematical model for the speed and tension system of the reversible cold strip rolling mill driven by alternating current (AC) asynchronous motors is established. Next, the I&I adaptive method is adopted to estimate the system perturbation parameters, and the NDO is developed to observe the system uncertainty. Again, controllers for the speed and tension system are presented by combining the backstepping control, the dynamic surface control, and the recursive sliding mode control together. Theoretical analysis shows that the closed-loop system is stable in the Lyapunov sense. Finally, simulation research is conducted by using the actual data, and results show the validity of the proposed control strategy.

Optimal control of plate motion and camber in a reversing rolling mill

In plate rolling, reversing roughing mills are commonly used as a first processing step after casting. They are typically equipped with edger rolls for width reduction. During a rolling pass, lateral asymmetries like temperature gradients or thickness inhomogeneities can cause two major problems. The plate may rotate in the rolling gap and thus move in lateral direction. Another problem is that the plate may leave the mill stand with a cambered shape. In the worst case, these problems entail collisions with the mill stand or other equipment along the roller table. It is an essential control task to avoid such problems. In general, the exit thickness profile and the motion of the plate are controlled by adjusting the roll gap height. The latter has also an influence on the contour shape but, for active control of the plate width and contour shape, the use of edger rolls is more common. This is especially true if the roll gap adjustment is self-retaining, meaning that it cannot be adjusted during a rolling pass. In this work, such a roughing mill and its edger rolls are considered. A mathematical model for the motion and the camber of the plate is derived. Based on this model, a linear quadratic regulator (LQR) for both the plate motion and the resulting camber is developed. It uses the lateral forces of the edgers as control inputs. In a cascaded control structure, these forces are regulated by a subordinate admittance controller. The developed control system is validated in simulation studies.

Influence of rolling on wear and friction behaviour of spray formed Al alloy composites

In the present investigation, Influence of rolling on wear and friction behavior of Al alloy composite has been studied. The composite, namely Al-Si alloy reinforced with graphite was developed through the unique spray forming route in the spray forming chamber by using N2 as an atomization gas. Developed spray formed Al alloy composite was gone through to the warm rolling with different thickness reduction ranges on non reversing rolling mill at constant temperature 250 °C. The microstructural and mechanical testing results indicate that the warm rolling of the composite increases the distribution of the graphite and silicon particles, minimizing the porosity with the refinement of α-aluminium grains of the matrix and improves the mechanical properties. The wear and friction testing results indicate that with an increase in sliding distance, volume loss of the composite with all rolling reduction increases. Similar kind of behaviour is also observed between the wear rate and applied load. However, with the rolling reduction, the wear rate of the composite decreases. In spite of that, the average coefficient of friction decreases with an increasing the applied load and the rolling reduction of the composite while it shows a fluctuation tendency with the sliding distance. The surfaces after the wear tests are also studied under the different surface characterization techniques to quantify the surface parameter and the operative wear mechanisms. The tribological properties are also correlated with the microstructural properties of the composite with different rolling reduction.

Modelling and dynamic surface backstepping recursive sliding mode control for the speed and tension system of the reversible cold strip rolling mill

Modelling and dynamic surface backstepping recursive sliding mode control for the speed and tension system of the reversible cold strip rolling mill

Command Filter-based Backstepping Control for the Speed and Tension System of the Reversible Cold Strip Rolling Mill Using Disturbance Observers

This paper investigates the decoupling and coordinated tracking control problem for the speed and tension system of the reversible cold strip rolling mill. Using a diagonal matrix decoupling network and neural network disturbance observers, we propose a command filter-based backstepping control strategy. First, the diagonal matrix decoupling network is constructed to weaken the coupling between the speed and tension of the rolling mill system, which reduces the complexity of the system model effectively. Second, controllers are designed by combining the backstepping with the command filter, which solves the “explosion of complexity” problem in backstepping procedure, and optimizes the system’s control structure. Next, neural network disturbance observers are developed to observe the uncertain items of the system, which improve the tracking control precision of the system effectively. Theoretical analysis shows that all signals in the closed-loop system are uniformly ultimately bounded. Finally, simulation research is carried out on the speed and tension system of a 1422 mm reversible cold strip rolling mill; results show that using the proposed control strategy increased the dynamic response speed of the system by approximately 1s, and the stability precision improved by approximately 2000 N.

Corrosion behaviour of cold‐rolled aluminium AA8015‐alloy in natural seawater at 0.18 μm surface roughness

AbstractAluminium is one of the most produced and used metals globally, second to ferrous metals. Its good corrosion resistance is one of the reasons for its heavy usage in typical applications, such as in marine applications. Electrochemical corrosion study of cold‐rolled aluminium AA8015‐alloy at 0.18 μm surface roughness in natural seawater was explored. The aluminium AA8015‐alloy utilized in this study was cold rolled in a reversible Achenbach cold rolling mill in four pass schedules to a thickness gauge of 1.2 mm. A surface roughness of 0.18 μm with three cold mounted samples was achieved on an automated grinding/polishing machine using 320 grit, 800 grit, and 1200 grit SiC paper. Electrochemical corrosion experiments were conducted on the samples in natural seawater using a computer‐controlled potentiostat in an open polarization cell set‐up at room temperature. The corrosion behaviour on surface morphologies of the samples was observed by high mega pixel camera and scanning electron microscope. Findings reveal asymmetric polarization curves for all the samples and energy dispersive X‐ray spectrometry elemental analysis shows the existence of insoluble substrate complexes formed on the surfaces. Consequently, the scanning electron microscope analysis confirms localised corrosion in the mode of pitting.