Continuous Rolling Mill Research Articles

Selection of parameters of high-speed thermodeformation of Cr–Ni–Mo steel processing on the basis of imitation modeling

The temperature of the end of finishing stage, cooling rate and coil winding temperature are structure-sensitive parameters for bainite-grade steels in the production of plate less than 10 mm thick. Simulation modeling of high-speed thermo-deformation processing of Cr–Ni–Mo bainitic steel samples has been carried out in order to select the most rational technological modes in continuous hot rolling mills. The influence of strain rate and temperature as well as niobium and vanadium microalloying additives on phase transformations has been investigated.

An integrated approach to analysis and assessment of condition parameters of the surface layer of backup roll bodies of a continuous broad-strip hot rolling mill

An integrated approach to analysis and assessment of condition parameters of the surface layer of backup roll bodies of a continuous broad-strip hot rolling mill

Roll profile and roll shifting strategy for silicon steel edge drop control in cold rolling CVC mill

The cold rolling CVC rolling mill, which is a primary piece of equipment for producing thin-gauge nonoriented silicon steel, lacks suitable edge drop control methods. To construct a theoretical system for high-quality edge drop control of CVC rolling mills, this study focused on a 1780 mm CVC cold continuous rolling mill at a specific factory. Using ABAQUS software, a finite element model was constructed to simulate and validate the production process. Work roll profiles were developed to enhance the mill's edge drop control capability for silicon steel, effectively preventing issues related to excessive edge tensile stress caused by strip misalignment. Additionally, a multistand simulation model was developed to analyse the edge drop and curvature control capabilities of different mill stands. Based on the buckling theory under high tension conditions, an intermediate roll shifting strategy was developed for edge drop control in a cold continuous rolling CVC rolling mill. Field applications have shown that this research effectively reduces edge drop issues, improving the pass rate by 25.1 %, thus confirming the effectiveness of this study.

ВИЗНАЧЕННЯ АДЕКВАТНОСТІ КОМП’ЮТЕРНИХ МОДЕЛЕЙ СКЛАДНИХ БАГАТОЗВ’ЯЗНИХ ОБ’ЄКТІВ

Proving the adequacy of models of complex, multi-connected objects such as continuous rolling mills poses a problem due to the impossibility of accurately reproducing the conditions of an industrial experiment during modeling. Most of the input and output variables in the given continius bar rolling mill computer model are not experimentally measurable and therefore cannot be compared with simulation results. It is proposed to determine the adequacy of such models by comparing the qualitative and quantitative effects of the mutual influence of various modeled parameters with similar effects, the presence of which has been clearly established in practice. The application of the specified method made it possible to test a new method of interstand tention regulation based on the data on armature currents of rolling mill motors.

Improving the Methodology for Calculating the Finishing Group Power of a Continuous Wide-Strip Hot Rolling Mill

Improving the Methodology for Calculating the Finishing Group Power of a Continuous Wide-Strip Hot Rolling Mill

Numerical Simulation Research on the Temperature Field and Hot Roll Crown Model of Hot Continuous Rolling Mills

Addressing the challenge of roll loss and strip deformation arising from the lack of precise prediction of the roll temperature field in hot tandem rolling mills, this study employs numerical analysis via the finite difference method. Based on the roll temperature field and hot roll crown model, an intelligent support cooling control system for the roll cooling water of hot rolls is established. This system comprehensively considers the direct impact of specific parameters on the roll temperature field in the intricate context of cooling water dynamics. The study focuses on the cyclic superposition effect of rolling coil quantities on the roll temperature field and the resulting hot roll shape, and theoretical calculations along with simulation analyses were conducted using finite element software. Through the integration of field-measured values, the study achieves accurate predictions of the temperature field and hot roll profile for both work rolls and backup rolls.

MODELING THE STRUCTURE EVOLUTION DURING HOT ROLLING OF ALUMINUM ALLOYS USING THE DEFORM SOFTWARE

The investigation of the structural evolution of aluminum alloys during hot rolling is a pertinent challenge in modern metallurgy. This study involves the modeling of the process of aluminum alloy structure formation during hot rolling using the DEFORM-3D software suite. The software allows for the replication of real rolling conditions and the prediction of changes in alloy structures. The article presents modeling of evolutionary structures during the hot rolling of aluminum alloy 5182 BT (Al-Mg 4.5%) in a five-stand continuous hot rolling mill. The DEFORM-3D software product was used for mathematical modeling, and the Johnson-Mehl-Avrami-Kolmogorov equation was employed to account for recrystallization kinetics. The results of calculations yielded the volume of recrystallized grains and their sizes throughout the entire rolling process. However, it is crucial to note that changes in grain sizes during the rolling of aluminum alloys are a complex process and do not follow a constant pattern. This is due to the influence of numerous factors related to both the metal's internal structure and the specific technological processes. Therefore, the modeling results require further verification through industrial experiments. In this context, data regarding the evolution of texture and structure obtained during forced hot rolling "2800" with subsequent thread cooling of the metal were used for comparison. In conclusion, this article contributes to a deeper understanding of processes occurring during the hot rolling of aluminum alloys and provides valuable insights into the impact of recrystallization on the final structure and material properties.

Development of Cold‐Rolling Edge‐Drop Control Technology for Electrical Steel: A Review

As an emerging technology in the production of electrical steel, edge‐drop control (EDC) caters to the increasing requirements for the overall shape quality of strips. Herein this review, the development of EDC theory, method, and control system used in the cold‐rolling process is summarized. Also, in this review, research on EDC theory is found to be based on the 3D plastic deformation model of the strip, considering the lateral metal flow. Further, an analytical model and a numerical calculation method are employed to establish an edge‐drop calculation model with high accuracy and speed. Next, taper‐work‐roll shifting (T‐WRS), a conventional EDC technology, is found to have been greatly improved in actual production. However, T‐WRS technology involves coupling problems in terms of edge drop and crown and flatness control. Finally, the closed‐loop EDC is found to depend on the online WRS of multiple stands. Particularly, the genetic law of strip thickness in the continuous rolling process and the edge‐drop regulation characteristics of each stand in the continuous rolling mill are significant aspects; thus, a reasonable roll‐shifting control strategy must be formulated. Based on the reviewed research, the development prospect of EDC is characterized.

Adjustment of the Hot Rolling Technology of Micro-Alloyed Pipe Steel Using a Digital Twin to Provide the Targeted Structure and Properties of the Metal

The results of computer and physical modeling of pipe steel hot rolling on a continuous rolling mill 2000 are presented. The moment of growth of austenite grains and the reasons for their growth are determined. The possibility of grinding the microstructure of the metal before controlled cooling, and the thermal deformation conditions conducive to grinding are investigated. It is shown that Nb (C,N) are not a factor in stopping the growth of austenite grains, but only inhibit the growth processes.

Research on Strip Profile Control Characteristics of 1500 mm Quintic CVC Mill

Compared with cubic Continuously Variable Crown (CVC), quintic CVC presents integrated control capability of quadratic and quartic crown. In order to take full advantage of quintic CVC and have better comprehensive control of the edge wave, center wave, high order wave and complex wave in practical application, it is necessary to further clarify the complicated profile control characteristics of quintic CVC. In this paper, quintic CVC technology in a 1500 mm continuous hot rolling mill production line has been taken as the research object and use finite element method to study its profile control characteristics. Through finite element simulation, an integrated model of rolls and strip was established to analyze the influence of the shifting, bending force and rolling force on strip profile with different strip widths. Both crown adjustment area and transverse stiffness are gained to study the control capability of quintic CVC. The simulation results show that the positive shifting and positive bending of CVC work roll reduce the quadratic crown and increase the quartic crown, and the controlling effect of shifting on both quadratic and quartic crown is more remarkable than that of bending. The control capability of the crown increases with the increase of strip width. That is, wider strip has a larger crown adjustment area. Meanwhile, there is a strong coupling relationship that the increase of quadratic crown can lead to the decrease of the quartic crown, which is not good for the flexible control of strip profile. With the increase of rolling force, the quadratic crown of strip increases significantly, while the quartic crown does not change obviously. Additionally, the increase of strip width significantly increases the transverse stiffness of mill.

Experimental testing of the technology of asymmetric cold rolling of a strip of high-carbon steel grades to exclude intermediate annealing operations

In the production of cold-rolled strip from high-carbon steel grades with a thickness of 0.5–1.5 mm on continuous cold rolling mills, the technological process consists of 2–3 operating cycles "cold rolling – intermediate annealing", either of which significantly increases production costs and reduces productivity of technological process. One of the promising non-traditional ways to solve this problem is the technology of asymmetric rolling. Rolling with different circumferential speeds of work rolls, when both rolls are driven by two independent motors, is the most suitable way to implement the asymmetric rolling technology in industry. The mismatch of speeds of the work rolls will make it possible to reduce the rolling forces, increase the reduction ability of stands and, as a result, obtain a thinner strip without the use of intermediate annealing. This paper presents an experimental testing and a comparative analysis of the energy-power parameters of processes of symmetrical and asymmetric rolling, as well as an assessment of the possibility of reducing the number of operating cycles "cold rolling – intermediate annealing" in the production of strip from high-carbon steel grades in the PJSC MMK`s continuous five-stand mill 630. Data on the mode of operation of main electric drives of this mill during symmetric and asymmetric rolling are presented, some electrical and power parameters are calculated. A comparison of obtained results was carried out, which showed a significant reduction in rolling forces, total moments and powers, as well as the consumption of electrical energy during asymmetric rolling. Conclusions are drawn and directions for further research in this area are proposed.The research was supported by a grant from the Russian Science Foundation (agreement no. 22-49-02041 dated 09.03.2022) in terms of the development of asymmetric rolling modes and industrial experiments, as well as a mega-grant from the Ministry of Education and Science (agreement no. 075-15-2021-627 dated 08.06.2021 ) in terms of processing the results of industrial experiments.

Local Chromium Plating as a Promising Method for Refurbishing Long Retained Mandrels in Continuous Rolling Mills

Local Chromium Plating as a Promising Method for Refurbishing Long Retained Mandrels in Continuous Rolling Mills

Modernization of Cooling System for Mandrel of PQF Continuous Rolling Mill at JSC Tagmet

Modernization of Cooling System for Mandrel of PQF Continuous Rolling Mill at JSC Tagmet

Rolling of long-length rails with acceleration

The article explains a new temperature-speed mode of rolling long-length rails. Rails up to 50 m long were rolled on linear mills. The production of rails of longer length required the use of larger mass billets and equipment of a new design. At the modern rail-beam rolling mill, the number of stands has increased and some of the stands are combined into a continuous group. Universal rolling stands began to be used not only as calibration stands. Rails with a length of 100 m are rolled from large-mass billets on mills with a continuous reversible group of universal stands. A significant length of the billet leads to the formation of a «temperature wedge» – a decrease in temperature along the length of the rail during rolling in the last stand of the mill. The calculation showed that a decrease in temperature along the rail length can lead to an increase in its height. A similar problem existed in the production of thin sheet metal at continuous broadband hot rolling mill. Rolling the rolled metal in the finishing group of stands with acceleration made it possible to reduce the cooling time of rear section of the rolled metal and warm up the metal due to more intense deformation. The acceleration value is chosen such that at the exit from the finishing group of stands, temperature of the strip is the same along the length of the strip. In this paper, rolling rails with acceleration is proposed. The acceleration value should ensure the same neck temperature along the length of the rail in the mill last stand, which will reduce the height difference along the length of the rolled product. The same rails height along the length will reduce the cost of grinding and accelerate the rail laying, thereby increasing consumer demand and competitiveness of the product.

Study of causes of vibrations in a continuous cold rolling mill

A retrospective review of studies of the problem of vibrations (chatter) during highspeed cold rolling at the five-stand mill 2030 of the Novolipetsk Iron and Steel Works, as well as the results of operation of vibration diagnostics and speed control systems at the mill, is presented. As part of the continuation of research on the 2030 mill, a series of experimental rolling of thin strips with chatter provocation was carried out, a statistical analysis of the dynamics of technological parameters and vibration accelerations of the roll chocks in time and frequency (spectral) representations was performed. It is shown that the reason for the development of the chatter is the mutual synchronization of vibrations of stands at the frequency corresponding to the natural frequency of the vertical vibrations of the housing posts stretching. The dynamics of the oscillations phases ratio of the stands has been studied and it has been established that when the frequencies are synchronized and the phases of neighboring stands coincide, the amplitudes of their oscillations increase sharply, indicating the beginning of the chatter. A criterion for violation of the stability of the rolling process is proposed, which makes it possible to diagnose the critical level of vibrations and the moment of occurrence of the chatter. A mathematical model of vibrations of the stand during rolling is presented, taking into account the nonlinear damping of the dynamic deformation zone, on the basis of which the dependence of the amplitude of synchronized vibrations of the stand on the magnitude of disturbances and technological parameters is obtained using the Van der Pol method. The adequacy of the relation obtained was confirmed during a series of experimental rolling with varying technological parameters, which made it possible to increase the maximum rolling speed without the chatter to 25%. The results obtained can be used to stabilize the technological process and increase the productivity of cold rolling, when creating systems for diagnosing vibrations and controlling continuous mills. NLMK workers A. V. Morozov, N. A. Dikarev, Yu. K. Slaby, A. V. Litvinov, Yu. A. Tsukanov, M. E. Orekhov, et al took part in carrying out the experimental rolling.

Requirements for graphite-containing lubricants and equipment for applying to a controlled-moving mandrel in the manufacture of pipes from stainless steel grades in a continuous mill line

In order to reduce the negative impact of temperature-deformation conditions on a working surface of a controlled-movable mandrel and improve the quality of resulting pipes, graphite-containing lubricants are used in modern pipe rolling mills in the line of a continuous rolling mill in the production of pipes, which is applied in the form of an aqueous suspension. Thus, the resulting continuous separating graphite coating makes it possible to reduce the coefficient of friction when the mandrel contacts the deformable metal. This, in turn, ensures the stable operation of the rolling equipment, increasing the durability of the mandrels and the quality of finished pipes. A lubricant is made up of several components, the most important of which is graphite. It is its properties that largely determine the quality and effectiveness of the resulting lubricating coating. The paper presents the results of studies of various properties of graphite, on the basis of which the requirements for its use as a lubricant were developed. The requirements for a suspension of graphite-containing lubricant and equipment for its application to the surface of a controlled-movable mandrel are also indicated, which together make it possible to obtain a high-quality graphite coating. The non-compliance of the properties of the graphite-containing lubricant with the requirements, as well as its poor application to the working surface of the mandrel, leads to incomplete separation of contact surfaces during the hot deformation of the metal. This can cause mandrels to rolling lap, reduce the quality of the inner surface of finished pipes, primarily from stainless steel grades, due to the formation of various defects in the form of deep scratches, cavities, and flaw, as well as a source of reducing the durability of continuous mill mandrels.

Аналіз ефективності способів розкрою заготовок при виробництві дрібносортного прокату в стрижнях

The purpose of the work is to analyze the effectiveness of methods of cutting blanks on continuous blanking machines (CBMs) in the production of graded rolled metal in rods. Practically 100% of the orders for small-grade rolled products in rods are measured products, while the actual output of measured products from the rolling mill is 95-98%, and the rest is non-measured products. At the final stage of rolled production, metal losses also occur due to excessive technological cutting during the cutting of rolled products. There are economic losses associated with the sale of bundles of irregular rods at a lower cost. The analysis of numerous studies and scientific publications made it possible to formulate the task of inventing such cutting strategies and algorithms that ensure the minimization of finished rolled products due to the coordinated management of continuous blanking mills (BZS) and continuous small grade mills (BDS). It is shown that at the final stage of the production of commercial products on continuous rolling mills, metal losses occur due to non-dimensional residues and excessive trimming, which arises, on the one hand, as a result of the fact that the length of the workpiece, which is fed to the entrance of the rolling mill, is not a multiple of the finished dimensional profile , and on the other - due to the peculiarities of the equipment of the rolling mills that implement cutting operations. The paper shows that the choice of methods for cutting rolled metal is a multi-criteria task. The analysis of the marginal deviations of the geometric dimensions of the blanks and small rolled products was carried out. On the basis of the calculations, it is shown that the simultaneous provision of the economic criterion and the criterion of the maximum yield of dimensional rolled bars is possible only in the production of reinforcing profiles larger than No. 14, and in the production of smaller profiles, the criterion of the maximum filling of the refrigerator should be used. It is shown that in the production of fine-grade profiles, the most effective method is the method of cutting rolled steel with cutting off the non-dimensional part. The obtained data can be used to build cutting plans in the production of commodity rolled metal.

PSYCOLOGICAL PROVISION OF PROCESSES MODERNIZATION OF METALLURGICAL PRODUCTION MANAGEMENT

The creation of an ergonomic methodical approach to the processes modernization of metallurgical production management, which involves a human factor at the difficult man-machine system development and exploitation and the realization degree estimation of ergonomic requirements on the different stages of operator`s activity planning. The purpose of the research is to define the influence features of ergonomic and psychological factors on the activity efficiency of continuous broadband rolling mill operators in the conditions of metallurgical enterprises modernization of the two countries. An analytical model of the organization of the research works devoted to the ergonomic modernization of man-machine systems was developed. Searching and purpose-oriented investigations on the different stages of man-machine system development and exploitation were modelled from the sketchy projection till the exploitation of the system. Theoretical, system analytical and experimental methods were used. The results of processes ergonomic modernization of metallurgical production management were discussed in two countries under new economic (market) conditions. The factors, which define the tension in rolling-mill operator`s activity, were exposed. Some recommendations on modernization of the existing technology and labor organization were formulated. The scientific novelty consists in the development and adaptation of the methodical approach that describes adequately the cognitive complexity and psychophysiological tension in operator`s activity as the modernization factors of modern metallurgical production in two countries. The practical value is the creation of an ergonomic ensuring system of development, exploitation and modernization of difficult men-machine systems and metallurgical production management processes.

Life enhancement of bent pipe by heat treatment

Wire rod mill is continuous high speed rolling mill to produced wire rods of varying diameters from billets. Bent pipe is a thick-walled hollow pipe located in between the pinch roll and laying head of the wire rod mill, which feeds wire rod from mill to the laying head. The pipe is not straight and the bending of the pipe is designed in such a manner so that it can accommodate the height difference between the pinch roll and the laying head in the WRM.Bent pipe absorbs lot of mechanical shock due to its shape and it absorbs thermal shock as finish rolling temperature is around 1000 °C. Thus, significant abrasive wear of bent pipe takes place during operation as a result it punctures almost regularly after around 1200 T of rolling. This kind of failure of bent pipe is predominant in lower section plain wire rods which are rolled at relatively higher speed. The puncture of bent pipe during rolling leads to cobble and production losses.The failed bent pipe was investigated by metallurgical investigations. JMat pro software was used to determine the CCT diagram from where the maximum hardness of material was determined. Heat treatment experiments were performed in laboratory to optimize the heat treatment parameters. After proper heat treatment, life of bent pipe was improved by using the existing material by 150%. This was validated by plant trials.

Elaboration of forecasting methods of analysis of metallurgical facilities electric drives technical state

To prevent losses of equipment downtime, analytical algorithms and data of automated control systems sensors are used to estimate time to the equipment failure approach. It was shown that modern technical systems, such as automated electric drives are equipped by measuring devices which allow to accomplish self-diagnostic of the system in real time mode at existing methods of data processing and analysis. This approach is more effective than traditional methods of diagnostic and does not include additional capital expenses for specialized diagnostic equipment and personal qualification. Hypothesis of forecasting of electromechanical driving system state was elaborated and checked for continuous rolling mill runaway roller, based on character of loading modes by using only one parameter – the electric motor current. Based on the data analysis of wide strip rolling mill 2000 runaway rollers operation, normalized curves of distribution of average values of the runaway roller drive current at its normal operation and origination of a malfunction were built. It was shown that a technical system state change is fixed at appearance of a deviation of load current distribution comparing with a standard deviation. Analysis of dynamics of a statistical parameter, the standard error (the difference between actual and standard distribution) at a transition process allowed to make a forecast of roller jamming several days before the malfunction took place. The proposed approach of equipment state estimation can become a base for elaboration of a principally new methods of diagnostic of metallurgical rotor equipment.