Continuous Casting Machine Research Articles

Methodology and model for predicting energy consumption in manufacturing at multiple scales

Certain fields of manufacturing, like casting, forming or cutting, may cause high energy load. Especially under the consideration of renewable energy sources it is beneficial to negotiate production schedules and consumption forecasts with the energy supplier. This would enable an optimized management of energy sources and infrastructure components on the supplier side, helping to reduce costs. Optimal and balanced expenses for production would be the consequence.The problem of power consumption prediction in manufacturing was subject of many studies in the past. Most of them either consider the physical modeling of processes at a very detailed level, or they introduce tailored prediction models for specific production processes. Thus, it is hard to apply their results to other uses cases in different scenarios.As a consequence, a generic methodology and model regarding power consumption prediction in manufacturing is required in order to cover the variety of processes, machines and materials. Furthermore, an approach must support flexible levels of granularity for predicting the energy consumption of manufacturing processes. On the one hand, a whole factory may be the object of investigation while, on the other hand, predictions for finer-grained levels, such as certain parts of a machine, are required to allow for specific optimizations.Our contribution is twofold. First, we propose a generic model for the specification of the power-consuming machine. A tree-based compositional approach supports arbitrary levels, depending on the structure of the machine, or external factors, such as company policies. This approach is highly extensible since the models are stored in ontologies. Second, we propose a methodology for static and dynamic modeling of power consumption for every structural level. Based on that model the prediction can be realized. In addition, we provide an example implementation and prediction for a continuous casting machine process.

Incremento de la productividad en proceso de extrusión de perfiles de aluminio con billets de aleación experimental 6063

The chemical composition of the raw material has a direct effect on the extrusion process and it is reflected in the key performance indicators. By varying main alloying elements levels to produce AA 6063 cast billets made in horizontal continuous casting machine, it was possible to increase productivity levels during extrusion process. During nine consecutive work shifts using homogenized billets of aluminum alloy 6063, a 7.37 mm/s average extrusion speed was registered; it means there was a significant increase in productivity of 13.54 % with an average recovery of 82.42 %.

A vertical continuous casting machine for large blooms

ABSTRACTThe Zhong Yuan Special Steel Company installed a vertical continuous casting machine to achieve higher productivity and product yield while retaining world-leading product quality. The vertical continuous casting machine was commissioned by Voestalpine Stahl in 2015. Zhong Yuan Special Steel required a special design for quality and size, comprising a special tundish, mould, secondary cooling system, and vertical roll layout. Other advanced technology packages included stopper rod controls, hydraulic oscillator, online solidification model, and online breakout prevention system. The new machine not only improved casting billet quality, but also improved production efficiency and reduced costs compared with tradition ingot casting. The tundish and electromagnetic mixing were optimised by extensive computational fluid dynamics simulations. The tundish design was optimised by physical water model experiments.

INFLUENCE OF ROTARY CCM CASTING WHEEL WORKING SURFACE CONDITION ON STEEL PRODUCT QUALITY

The paper presents the results obtained when studying how the condition of the casting wheel working surface in the rotary continuous casting machine (CCM) influences the quality of copper metal products on the Southwire modern high-tech continuous casting and rolling line at PJSC «Artemovsk Non-Ferrous Metals Processing Works». Industrial research identified the main defects occurred on the casting wheel working surface during its operation: transverse cracks located on the working surface in planes perpendicular to the casting direction – both at the trapezoid base and on its side faces (10–45 mm long cracks located 7–40 mm apart); dents, longitudinal dimples and scratches along the direction of billet movement mainly in the obtuse angles of the trapezoid and in areas adjacent thereto; deformed wheel profile in the corners of the working channel, primarily due to friction wear. It was found that the main causes of surface and internal cracks in the wheel are challenging temperature modes of operation associated with the technology of copper casting on the rotary CCM. Alternating cycles of heating and cooling of individual sections of the casting wheel cause two-dimensional tensile stresses in its internal layers resulting in cracks. An equally important factor in crack formation is further excessive secondary cooling of the wheel with water as it is followed by reheating of the billet surface. However, a lowered temperature gradient of the wheel surface between the cooling areas will reduce the degree of surface deformation, increase the service life and improve the quality of continuously cast billets and finished steel.

Modernization of Baku Steel Company Metallurgical Plant Section CBCM for Producing Round Pipe Billets

VNIIMETMASh completes modernization of an existing section continuous steel casting machine for the metallurgical plant of Baku Steel Company (Azerbaijan). The work makes it possible in CBCM-2 with base radius R = 6 m to produce round pipe billets 130, 170, 190, and 220 mm in diameter, and also square billets 130 ×130 mm in cross section.

Distribution of electric drives of pulling rollers on the continuous casting machine: simulation and experiment

The paper presents the results of the study aimed at solving the problem of rational distribution of electric drives of pulling rollers along the technological line of a continuous casting machine and selecting a minimum number of pulling rollers in different areas of the secondary cooling zone. The research includes construction and ranking the criteria for distribution of drive rollers along the production line of the continuous casting machine; development of methods and algorithms for calculating the required distribution of load moments on pulling rollers and distribution of electric drives of pulling rollers along the secondary cooling zone in three modes of the electric drive operation of the pulling-straightening device: containment of the dummy bar in the preparatory casting mode of the continuous casting machine; pulling the dummy bar with the head of the ingot at the initial stage of pouring the metal; withdrawal of the ingot in the working mode of casting. Theoretical studies were carried out with the use of analytical and numerical methods for solving algebraic equations, methods of structural modeling. Experimental studies were carried out in the conditions of a large metallurgical enterprize with subsequent processing of the obtained data by statistical methods. The technical and economic analysis of the options of the electric drive execution of the pulling-straightening device showed that due to a significant reduction in the number of electric drives of pulling rollers, the payback period of replacement of a group scheme of power supply of electric motors to an individual one in new continuous casting machines decreases from 5.8 to 7.8 years with the traditional distribution of pulling rollers along the secondary cooling zone to 2.8–3 years with their rational distribution, calculated by the developed methods. The results of the work were used in the design of a slab machine for continuous casting of curvilinear strands intended for casting wide slabs up to 2.5 m. According to the proposed method, the number of electric drives pulling the rollers was reduced to 56.

Robust backstepping control of double-rod cylinder for motion synchronization of mold oscillator

High-performance synchronization control of two double-rod cylinders used to oscillate the mold of a continuous casting machine is considered in this article. Friction between strand shell and mold plays an important role to achieve high-precision control of mold oscillator. A new friction model is proposed for exact system modeling and is proved useful. Using a force-distribution method to consider the coupling effect between two cylinders, mathematical models of each cylinder are presented and a simple robust backstepping control strategy is proposed, which can reduce the influences of time-varying system parameters and unmodeled uncertainties. The transient performance and stability of the proposed controller are rigorously proved. Simulation and experimental results show that proposed synchronization control method can achieve good performance for given tracking task.

In-situ monitoring and characterization of airborne solid particles in the hostile environment of a steel industry using stand-off LIBS

The analytical possibilities of laser induced breakdown spectroscopy (LIBS) to carry out in-situ and real-time detection and compositional characterization of aerosols in the atmosphere of a steelmaking factory, have been evaluated. To this aim, a compact and versatile dual-pulse LIBS analyzer, able to sample at distances up to eight meters, has been designed to work in these hostile industrial environments. Due to the discrete nature of the particulate matter, the particle sampling rate was less than 2.5% and 6% for single- and double-pulse regimes, respectively. An efficient statistical procedure, based on the calculation of standard deviations, is used to qualitatively characterize the elemental composition of the aerosol. Then, a conditional analysis based on the limit of detection, is employed to assess the elemental sampling rate. This experimental methodology has been used to evaluate the influence on the aerosol formed of the oxycutting process in a continuous casting machine producing steel slabs, revealing a strong presence of elements derived from the casting powder used in the production. Moreover, chromium, present in the steel cast, is detected in aerosol suspension in the steel shop. An increase in the concentration of particulate matter was expected when oxycutting was on. Single-pulse and dual-pulse excitation modes are also evaluated.

Azimuthal MHD stirring of metal in vessels with cross-sections of different configuration

Continuous casting of cylindrical ingots from aluminum and preparation of aluminum-based alloys and composites require intensive mixing of liquid metal phase in the crystallization area of the melt. It is evident that the topology of the flow in the liquid phase of an ingot should influence the processes occurring during crystallization. Contemporary continuous casting machines use MHD-stirrers that generate an azimuthal motion in a crystallizer with a warm top of circular cross-section in the presence of rotating magnetic field. The flow of metal in the liquid phase of an ingot is similar to its rotation in a solid state, and transport processes are most intensively carried out in the near near-wall region and near the ingot solidification front, where shear flows are essential. In this work, we consider the possibility of amplifying transport processes in the entire volume of a stirred metal by making the cross-section shape of the warm top of the crystallizer different from a circle. It has been found numerically that the total energy of the flow in a crucible of square cross-section is twice as lower as that in a crucible with circular cross-section at the same inductor current. Turbulent pulsations in the square crucible, as well as in the circular one, are concentrated mainly in the near-wall region. The energy of pulsations in the square crucible also reduces, but the time of stirring of the passive impurity introduced into the volume of the metal is less than in the circular crucible. The effect of MHD stirring on the vertical temperature distribution on the square crucible is higher than in the “round crucible”.

Physical Modelling of Tundish Slag Entrainment under Various Technological Conditions

AbstractThis paper deals with the issue of physical modelling of vortexes creation and tundish slag entrainment over the mouth of the nozzle into the individual casting strands. Proper physical model is equivalent to the operational continuous casting machine No. 2 in TŘINECKÉ ŽELEZÁRNY, a.s. Physical modelling methodology and simulated operational conditions are shortly described. Physical modelling was used for the evaluation of current conditions of steel casting at the application of different impact pads in the tundish. Further, laboratory measurement on the physical model aiming the determination of exact critical periods of vortexes creation and study of the slag entrainment as a consequence of changes in surface level during the tundish refilling to standard level were realised. The obtained results were analysed and discussed.

Simulation of Power Efficient Cooling Technology for Continuously Cast Bars

The article describes a power efficient technology, allowing to preserve and maintain the heat content in a continuously cast bar at the production line “Continuous Casting Machine – Rolling Mill”. It considers a possibility of obtaining the maximum heat content in the continuously cast bar by means of rational cooling schedules in the secondary cooling zone. In order to maintain the achieved heat content in the bar, it is proposed to utilize heat insulation of the bar in the air cooling zone prior to its cutting-to-length. The article describes the design of the heat insulating shell in the CCM process scheme and the materials to be used for it. To analyze the interaction of heat flows between the bar and the shell in the heat insulation zone, the author has made a thermal balance of this zone. A mathematical model of the concast bar cooling with due consideration of the heat insulation zone and its implementation by means of numerical methods is described here. The application of numerical simulation has allowed to predict rational cooling schedules for the continuously cast bar and to determine the heat content of the bar at the exit from the continuous casting machine with respect to the heat insulation. According to the results of the simulation, there have been plotted the charts of temperature distribution along the CCM length, comparing the air cooling of the bar and its thermal conditioning in the heat insulation zone. These results confirm the effectiveness of utilizing heat insulation for maintaining the maximum heat content of the bar, which makes it possible to reduce the power costs for its heating prior to the rolling.

Improving Refractory Constructions in the System “Steel-Pouring Ladle – Pouring Basket” of CBCM

The refractory equipment of the system “steel-pouring ladle – pouring basket” of continuous billet casting machines (CBCM) is considered. Designs of elements of the unit intended for protecting streams of metal in the course of pouring steel are developed. Designs of the unit with the use of inserts made of plastic refractories to prevent passage of air into the metal stream as it is being poured and assure rational parameters of the delivery of argon into the annular groove of the refractory tube are considered. Stability of the pouring process and an increase in the quality of the poured metal are achieved as a result.

Internal (Convection) Cooling of CCM Rolls Under Scale Formation Conditions

A procedure for the evaluation of the thermal conditions for the rolls of continuous casting machines operating in the conditions of scale formation in the cooling channel is proposed. The procedure allows a differentiated approach to the determination of the axisymmetric and maximum surface temperature of the rolls with allowance for the magnitude and behavior of the thermal load and the cooling and scale formation conditions on the heat-exchange surfaces. It can be used to predict the roll service life and to rate the quality of cooling water.

Heat removal analysis on steel billets and slabs produced by continuous casting using numerical simulation

Simulation of a continuous casting process (CCP) is very important for improving industrial practices, reducing working times, and assuring safety operating conditions. The present work is focused on the development of a computational simulator to calculate and analyze heat removal during continuous casting of steel; routines for reading the geometrical configuration and operating conditions were developed for an easy management. Here, a finite difference method is used to solve the steel thermal behavior using a 2D computational array. Conduction, radiation, and forced convection equations are solved to simulate heat removal according to a steel position along the continuous casting machine. A graphical user interface (GUI) was also developed to display virtual sketches of the casting machines; moreover, computational facilities were programmed to show results such as temperature and solidification profiles. The results are analyzed and validated by comparison with industrial trials; finally, the influence of some industrial parameters such as casting speed and quenching conditions is analyzed to provide some recommendations in order to warrant safety operating conditions.

Metal flow in the mold of a continuous-casting machine

Analysis of the flow of liquid metal in the mold during continuous casting is a challenging mathematical problem. Nevertheless, precise solutions have bene found for some cases. Such analytical solutions may be used to verify numerical solutions. In the present work, the melt flow in the mold is studied numerically on the basis of the finite-difference approximation of the initial system of equations. This method is relatively universal: it has been successfully used in continuum mechanics, in mathematical modeling of the stress–strain state of shells in casting, and in other industrial contexts. In the present work, it is applied to the hydrodynamic and thermal fluxes of liquid metal in steel casting in a rectangular mold in a continuous-casting machine. The three-dimensional mathematical model that is obtained describes the liquid-metal fluxes in the mold. The processes that accompany the filling of the mold with melt are simulated by means of Odissei software. The calculations are based on the fundamental hydrodynamic equations, a formula from mathematical physics (the heat-conduction equation with allowance for mass transfer), and a familiar numerical method. The resulting system of differential equations is solved numerically. The region investigated is divided into finite elements. For each element, the system of equations is written in finite-difference form. Solution yields the field of flow velocities of the metal and the temperature field within the mold. The algebraic equations obtained by this means are solved by means of numerical algorithms. On that basis, a program is written in Fortran-4. The mathematical model permits variation of the mold dimensions and the cross section of the metal outlet from the submersible nozzle. It may also assist in understanding the motion of the cast metal, which affects the heat transfer by the mold walls, and in finding the optimal parameters of the liquid metal as it leaves the submersible nozzle. As an example, steel casting in a rectangular mold (height 100 cm) is considered. In casting, the metal leaves the submersible nozzle symmetrically on both sides, in the horizontal plane. The results are graphically displayed. The motion of the metal flux is shown in different cross sections of the mold. Regions of circular flow are identified, as well as regions of vertical motion in the mold. The magnitude and intensity of these regions are determined. The temperature field indicates a local hot zone at the mold wall. That may be attributed to the direct flux of hot metal from the aperture in the submersible nozzle.

Influence of Cooling Conditions on a Slab’s Chill Zone Formation During Continuous Casting of Steel

AbstractThe cooling conditions of a slab during continuous casting of steel have an impact on the crystalline structure formation. Numerical methods allow real processes to be modelled. Professional computer programs are available on the market, so the results of their simulations allow us to understand the processes that occur during the casting and solidification of the slab. The study attempts to evaluate the impact of the intensity of the secondary cooling on the chilled zone size. The calculations show the differences in the structure of a slab cast with various speeds while maintaining industrial cooling parameters during operation of a continuous casting machine.

Improved tundish refining of steel in continuous-casting machines

The influence of the structure of the tundish on the hydrodynamics of the melt flux is investigated on physical models and in industrial conditions. The influence of design modifications in the tundish on the refining of the steel is analyzed. Factors that affect tundish operation include the injection conditions, the tundish capacity, and the melt level.

Research on Soft Reduction Amount Distribution to Eliminate Typical Inter-dendritic Crack in Continuous Casting Slab of X70 Pipeline Steel by Numerical Model

AbstractTo investigate the formation of one kind of typical inter-dendritic crack around triple point region in continuous casting(CC) slab during the operation of soft reduction, fully coupled 3D thermo-mechanical finite element models was developed, also plant trials were carried out in a domestic continuous casting machine. Three possible types of soft reduction amount distribution (SRAD) in the soft reduction region were analyzed. The relationship between the typical inter-dendritic cracks and soft reduction conditions is presented and demonstrated in production practice. Considering the critical strain of internal crack formation, a critical tolerance for the soft reduction amount distribution and related casing parameters have been proposed for better contribution of soft reduction to the internal quality of slabs. The typical inter-dendritic crack around the triple point region had been eliminated effectively through the application of proposed suggestions for continuous casting of X70 pipeline steel in industrial practice.

Distributed predictive process control in metallurgy

The advantages and basic concepts of model-based predictive control (MPC) are discussed. Possible MPC application in metallurgy is outlined. An example of an MPC system for billet cooling developed for a continuous casting machine is adduced.

Development of Criteria Specifying the Conditions of Interaction between the Scale with the Rolls of Continuous Cast Machine and Continuous Cast Billets

The study of surface condition of the rolls of continuous casting machine (CC-machine) of the secondary cooling zone is undertaken. It was stated that their working surfaces include the segments with stuck and peeled-off scale. The surface profilograms of the rolls with pickup scale are obtained. The domelike, tapered and trapezoidal form of fragments of the scale with a height 3-4 mm and tilt angles between the side faces of 43-88 are the most typical forms.Based on the elements of the plasticity theory, the problem of determination of stress-strain behavior of continuous casting steel billets is solved in the process of indentation of the scale fragments into it. The mathematical relation between geometrical parameters of scale fragments and the thickness of crystallized jacket is found that allows determining a stress strain state criteria in accordance with that the scale pickup on the roll surface is carried out or its indentation into internal layers of CC steel billets with its following holding. It was stated that the indentation of good-size scale fragments in relatively thin crystallized skin creates comfortable facilities for pick-up of scale on the rolls, and the indentation of small-sized scale fragments in the thick crystallized jacket especially with large tilt angles between the side surfaces of fragments makes possible for their hold-up at the surface of concast steel billets in the imbedded condition. It was determined the criteria which contains two necessary conditions whereby the scale sticking on the rolls of CC machine is carried out or the indentation in continuous-casting machine followed by holding in it.