Roll Profile Research Articles

Justifying and Implementing Concept of Object-Oriented Observers of Thermal State of Rolling Mill Motors

Implementing the IIoT concept in industry involves the development and implementation of online systems monitoring the technical state of electromechanical equipment. This is achieved through the use of digital twins and digital shadows (object state observers). The tasks of mastering new rolling profiles and optimizing plate mill rolling programs require improved methods for calculating equivalent motor currents and torques. Known methods are generally based on calculations using smoothed load diagrams, which are assumed to be identical for the upper and lower main drive (UMD and LMD) rolls. These methods do not consider the differences in actual loads (currents or torques) in steady rolling states. Experiments performed on the 5000 plate mill have shown that due to speed mismatches, the UMD and LMD torques differ three times or more. This causes overheating of the more heavily loaded motor, insulation life reduction, and premature failure. Therefore, the problem of developing and implementing techniques for monitoring the load and thermal regimes of motors using digital observers is relevant. The paper’s contribution is the first justification of the concept of object-oriented digital shadows. They are developed for specific classes of industrial units using open-source software. This research justifies a methodology for assessing motor load and temperature by processing arrays of motor currents or torques generated during rolling. An equivalent load observer and a temperature observer were proposed and implemented using Matlab-Simulink resources. The algorithm was implemented on the mill 5000 and tuned using an earlier-developed virtual commissioning methodology with digital twins. Thermal regimes were studied, proving that torque alignment ensures equal motor temperatures. The proposed considerations contribute to the development of the theory and practice for creating digital systems to monitor the technical condition of electromechanical and mechatronic systems and implementing the Industry 4.0 concept at industrial enterprises.

Influence of corrugated/flat rolling on microstructure and tensile property of coarse-grained AZ31–0.25Ca cast alloy

Novel corrugated rolling technology (CR) and conventional flat rolling (FR) were employed for rolling the AZ31–0.25Ca cast alloy without prior predeformation. The impact of corrugated rolling and/or flat rolling on texture modification, microstructure evolution, and mechanical properties of the magnesium alloy during two-pass rolling was examined using optical microscopy (OM), X-ray diffraction (XRD), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), transmission electron microscopy (TEM), tensile tests at ambient temperature, and ABAQUS finite element simulation analysis. The results indicate that the AZ31–0.25Ca cast alloy, after homogenization with a coarse grain structure of ∼200 μm, can endure significant plastic deformation with a 60 % total rolling reduction in both corrugated-flat rolling (CFR) and flat-flat rolling (FFR) without experiencing edge cracking. Twinning is activated dramatically except for dislocation slip during CFR, which induced high-density dislocations piling up at the twin boundaries and grain boundaries of α-Mg grains. The CFR sheet exhibited a macroheterogeneous structure attributed to the distinctive corrugated roll profile. Elevated shear strain and intensified frictional shear stress were observed at the trough, resulting in the formation of an asymmetric cross shear band in the CFR sheet. Denser deformation twins and finer recrystallized grains are present at the trough, whereas fewer and coarser ones are observed at the peak, while there is a significant texture weakening effect for corrugated rolling in contrast to the conventional flat rolling. but the stress and strain heterogeneity and asymmetric cross shear band also induce strong stress concentration and result in a premature cleavage fracture and a lower tensile property in CFR sheet compared to that of the FFR sheet.

Energy and Power Parameters of Rolling Profiles for Wheel Rims of Reduced Metal Intensity with Toroidal Flanges

Energy and Power Parameters of Rolling Profiles for Wheel Rims of Reduced Metal Intensity with Toroidal Flanges

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.

A universal simulation model of the continuous pipe rolling process on a controllably movable mandrel.

To study the technological process of rolling solid and hollow round profiles, it is important to have a correct mathematical description of the patterns that determine the boundaries of the deformation zone. The article analyzed scientific works that examine the calculation of geometric parameters of the deformation zone during the rolling of solid and hollow round profiles in two-roll and multi-roll calibers. As a result of the analysis, a conclusion was drawn regarding the necessity of a more detailed description of the determination patterns for the geometric boundary conditions of the deformation zone. This led to the proposal of a universal method for determining the shape of the billet and the shape of the caliber groove, as well as the derivation of the equations for the roll surface and the boundary of the contact surface of the deformation zone for various rolling schemes. The developed method allows for an increase in the accuracy of calculating the energy-force parameters of the rolling processes, including continuous rolling, in the production of solid and hollow round profiles according to the circular–oval scheme in calibers formed by any number of rolls, thanks to the consideration of a sufficiently wide range of geometric features

THREE-DIMENSIONAL MODEL OF EQUIVALENT ROLL GAP OF CVC MILL UNDER CONDITIONS OF ROLL CROSSING AND NO LOAD

Traditional roll technologies focus solely on the contour of the roll gap at the outlet under ideal conditions. However, upon roll crossing, the three-dimensional distribution of the deformation zone becomes asymmetrical, leading to an adverse impact on the rolling pressure in the deformation zone. To study the screw-down load deviation of plate mills, it is necessary to accurately calculate the equivalent three-dimensional roll gap in the deformation zone under roll-crossing conditions. In this paper a model for calculating the equivalent three-dimensional roll gap under the conditions of roll crossing and no load was established based on the method of the coordinate nonlinear transformation of the spatial rectangular coordinate system. Based on this model, the influences of roll-crossing angles and translation parameters on the symmetry of the equivalent three-dimensional roll gap were analyzed. The distribution of the three-dimensional equivalent roll gap was calculated with different roll lengths, roll radii, and the roll gap’s nominal thickness. The intuitive contour map reveals that under the same condition of crossing angle and translation parameters, the larger the roll length and roll radii and the smaller the roll gap’s nominal thickness are, the greater the influence of the roll crossing on the asymmetrical distribution of roll gap is. It put forward a quantitative calculation method for evaluating the symmetrical distribution of the roll gap, and the calculation results can provide the equivalent roll profile for the roll-deformation model.

Investigation of the Efficiency of Roll Profiles and Technological Schemes of Deformation of Asymmetric Rolling in Relief Rolls of C11000 Copper Alloy by FEM Simulation

In this paper, finite element simulation of asymmetric rolling in relief rolls of C11000 copper alloy in order to analyze the effectiveness of possible roll profiles and technological schemes of deformation was performed. The scientific innovation of this work lies in determining the patterns of development of stress-strain state parameters for various configurations of rolls, as well as determining the effectiveness of metal processing using various technological schemes. It was found that the use of trapezoidal relief makes it possible to increase the level of metal processing by almost 5 times compared with the use of radial relief. Comparison of technological schemes of deformation showed that deformation with 180° workpiece turning between passes significantly reduces the influence of the asymmetry factor. Deformation without changing the workpiece position between the passes has the opposite effect, and such a scheme significantly increases the influence of the asymmetry factor. Deformation with a transverse workpiece shift for the relief period between passes has the effect of a “golden mean.” The conducted laboratory experiment for lead billet showed that the shape change of lead billet during computer simulation has a high level of convergence with real conditions. At each stage of deformation, the difference in the geometric parameters of the workpiece between the model and the experiment did not exceed 3-5%. When deforming a copper billet, the maximum difference level was 8%, which is the result of the low rigidity of the rolling cage with smooth rolls.

Epigenetic MLH1 silencing concurs with mismatch repair deficiency in sporadic, naturally occurring colorectal cancer in rhesus macaques

BackgroundNaturally occurring colorectal cancers (CRC) in rhesus macaques share many features with their human counterparts and are useful models for cancer immunotherapy; but mechanistic data are lacking regarding the comparative molecular pathogenesis of these cancers.MethodsWe conducted state-of-the-art imaging including CT and PET, clinical assessments, and pathological review of 24 rhesus macaques with naturally occurring CRC. Additionally, we molecularly characterized these tumors utilizing immunohistochemistry (IHC), microsatellite instability assays, DNAseq, transcriptomics, and developed a DNA methylation-specific qPCR assay for MLH1, CACNA1G, CDKN2A, CRABP1, and NEUROG1, human markers for CpG island methylator phenotype (CIMP). We furthermore employed Monte-Carlo simulations to in-silico model alterations in DNA topology in transcription-factor binding site-rich promoter regions upon experimentally demonstrated DNA methylation.ResultsSimilar cancer histology, progression patterns, and co-morbidities could be observed in rhesus as reported for human CRC patients. IHC identified loss of MLH1 and PMS2 in all cases, with functional microsatellite instability. DNA sequencing revealed the close genetic relatedness to human CRCs, including a similar mutational signature, chromosomal instability, and functionally-relevant mutations affecting KRAS (G12D), TP53 (R175H, R273*), APC, AMER1, ALK, and ARID1A. Interestingly, MLH1 mutations were rarely identified on a somatic or germline level. Transcriptomics not only corroborated the similarities of rhesus and human CRCs, but also demonstrated the significant downregulation of MLH1 but not MSH2, MSH6, or PMS2 in rhesus CRCs. Methylation-specific qPCR suggested CIMP-positivity in 9/16 rhesus CRCs, but all 16/16 exhibited significant MLH1 promoter hypermethylation. DNA hypermethylation was modelled to affect DNA topology, particularly propeller twist and roll profiles. Modelling the DNA topology of a transcription factor binding motif (TFAP2A) in the MLH1 promoter that overlapped with a methylation-specific probe, we observed significant differences in DNA topology upon experimentally shown DNA methylation. This suggests a role of transcription factor binding interference in epigenetic silencing of MLH1 in rhesus CRCs.ConclusionsThese data indicate that epigenetic silencing suppresses MLH1 transcription, induces the loss of MLH1 protein, abrogates mismatch repair, and drives genomic instability in naturally occurring CRC in rhesus macaques. We consider this spontaneous, uninduced CRC in immunocompetent, treatment-naïve rhesus macaques to be a uniquely informative model for human CRC.Graphical abstract

ТЕХНОЛОГИЧЕСКИЕ МЕТОДЫ УВЕЛИЧЕНИЯ ДОЛГОВЕЧНОСТИ КОЛЕС ПАССАЖИРСКОГО ЖЕЛЕЗНОДОРОЖНОГО ВАГОНА

The cut of passenger cars due to wear damage to the rolling surface of the wheelset in 2022 is considered. It is found out that the most typical damage is a shelled tread. An analysis of the methods for restoring the rolling profile of wheels showed that the wheel milling with an end mill can be used as a promising one. To assess the effectiveness of the method, metallographic and tribological studies of wheel samples subjected to turning and milling are compared. According to the study results, it is found that when machining samples of wheel steel by end milling, their wear resistance is 22% higher, compared with samples machined by turning, the wear rate of samples of rail steel is lower in a friction pair with milled samples than with turned samples due to a decrease in the friction factor of milling samples.

Online Partition-Cooling System of Hot-Rolled Electrical Steel for Thermal Roll Profile and Its Industrial Application

The shape and convexity are crucial quality assessment indicators for hot-rolled electrical steel strips. Besides bending rolls, shifting rolls, and the original roll profile, the thermal roll profile also plays a significant role in controlling the shape and convexity during the hot-rolling process. However, it is always overlooked due to its dynamic uncertainty. To solve this problem, it is necessary to achieve online cooling-status control for the local thermal expansion of rolls. Based on the existing structure of a mill, a pair of special partition-cooling beams with an intelligent cooling system was designed. For high efficiency and practicality, a new online predictive model was established for the dynamic temperature field of the hot-rolling process. An equivalent treatment was applied to the boundary condition corresponding to the practical cooling water flow. In addition, by establishing the corresponding target distribution curve for the partitioned water flow cooling, online water-flow-partitioning control of the thermal roll profile was achieved. In the practical application process, a large number of onsite results exhibited that the predicted error was within 5% compared to the experimental results. The temperature difference between the upper and lower rolls was within 5 °C, and the temperature difference on both sides of the rolls was controlled within 0.7 °C. The hit rate of convexity (C40) increased by 33%. It was demonstrated that the partition-cooling processes of hot rolling are effective for the local shape and special convexity. They are able to serve as a better control method in the hot-rolling process.

TO THE DEVELOPMENT OF STATISTICAL MODELS OF WEAR ROLLS OF LONG PRODACTS MILLS

For long products rolling mills, a change in the indicators of wear and costs in a relatively wide range is characteristic, depending on the type of rolled product, the features of the technology, the materials used in the rolls, and other factors. This largely determines the level of operating costs when rolling profiles. Therefore, increasing the wear resistance of long product mill rolls was and remains an urgent task in metallurgy.
 The purpose of the work is to analyze the structure of known mathematical models of wear of rolls of rolling mills, features of wear of rolls of individual long-products rolling mills, and to determine a general approach to the construction of statistical models for predicting the wear of such rolls.
 From the review of the literature, it was established that the structure of most wear models includes technological parameters, that are most significant for a certain state, and an empirical coefficient. For the conditions of long products mill, in each of the stands, most of the parameters change within rather narrow limits due to technological deviations. Therefore, for stands mills in such conditions, it is advisable to use "local" statistical models obtained from the results of wear measurements. The structure of such models can be represented as the product of the empirical coefficient, which indirectly reflects the influence of the main technological parameters, and the friction way, as the main factor of the Archard model.
 As an empirical coefficient, it is recommended to use the indicative wear intensity of the rolls, defined as the ratio of the amount of wear of the groove roll to the mass of rolled products obtained from this pass. The revealed features of the change in the wear intensity indicator are due to the processes of processing the initial surface and the formation of a certain microstructure. After the rolling of the threshold mass of rolled products, these processes are completed and the indicator of wear intensity reaches a stable value. The initial and permanent value of the wear intensity indicator, as well as the threshold value of the mass of rolled steel, are determined based on empirical data on wear and mass of rolled steel for each of the stands mill.
 The proposed method of determining wear using the wear intensity indicator as an empirical coefficient that indirectly reflects the influence of all significant factors of the process provides sufficient accuracy of wear prediction and can be used to determine the costs of rolls.

Root cause analysis of indentation mark defect on Zn coated steel sheet in continuous galvanizing line

The coated steel industry is growing as demand of corrosion resistant steels are ever increasing in automotive, construction, appliances, and general engineering segments. The surface requirement of the coated steel is becoming more stringent that demands coated surfaces within specified roughness, waviness, reflectance and free from surface defects. The continuous galvanising line number 2 of Tata Steel Limited, Jamshedpur suffers from a chronic surface defect that appears like a scratch mark in the coated steel. The present study deals with the root cause analysis of the defect focussing on the rolls within annealing furnace in CGL#2, Jamshedpur. The roll profile, roll and strip slippage, roll surface compositions (using profilometer, XRF) are studied in detail. Similarly, the steel strip collected from inside the furnace was also studied for the defect orientation, surface composition (using SEM & EDS), trapped particles etc. The mathematical calculation of slippage along with the characterization evidence confirm the formation of defect through a complex mechanism of particle formation due to non-uniform roll profile, followed by particle coagulation and finally formation of the defect on the strip under tension by those particles. Possible operational strategies to eliminate the defect is also outlined.

Analysis of the energy efficiency and control ability under different magnetic flux forms in RPECT

Roll profile electromagnetic control technology (RPECT), which has the flexible control ability of the roll profile, is a new roll gap control technology that can be applied in the cold rolling process. The electromagnetic stick (ES) is generally used as the main bulging driving to adjust the roll profile. However, the ES structure can be changed with the variation of the electromagnetic flux forms, which further results in the difference of the energy efficiency and control ability. In this paper, the transverse magnetic flux form (TMF) and longitudinal magnetic flux form (LMF) of RPECT are proposed, and the principles of TMF and LMF are analyzed, and their advantages in the heat transfer paths are discussed. To conduct the parameterized impact analysis, the electromagnetic-thermal-structural coupled model matching the two electromagnetic flux forms are established and verified. Through the analysis of the current density, the current frequency, the external cooling and the initial roll temperature, the results show that the variation of the current densities, the current frequencies or the initial roll temperatures can change the control ability of RPECT, while changing the external cooling can not affect that of RPECT. The energy efficiency intersection of TMF and LMF can be achieved by changing the current density or current frequency separately. However, compared with changing the current frequency, increasing the current density of TMF to two times of LMF at different initial roll temperatures can realize the energy efficiency intersection of TMF and LMF, which is the best way to achieve this goal.

Online dynamic self-compensation of roll wear based on electronic temperature control technology

Shape control is the core link in the production of sheet steel products, and the shape mainly depends on the control of the original roll profile of the rolling rolls. The wear of the roll is inevitable in the process of strip rolling. The electronic temperature control technology of the roll profile utilizes a heat source to drive flexible adjustment of the roll profile and directionally achieves the preset, adjustment, compensation, and other roll shape control requirements of local rolls. This article establishes an electronic temperature controlled roll model and uses numerical simulation methods to research the wear compensation of electronic temperature controlled rolls. The reliability of the model is verified using an electronic temperature controlled roll experimental platform, providing an online dynamic self-compensation method for roll wear.

Optimization of Multi‐Segment Work Roll Profile for 1340 mm HC Tandem Cold‐Rolling Mills Based on DBSCAN and NSGA‐II Algorithms

To address issues with saturated work roll bending force (WRB), maximum contact pressure between the work roll and intermediate roll (QWI), and challenging flatness lifting in a four‐stand, six‐high tandem cold mill with a 1340 mm width, the density‐based spatial clustering of applications with noise algorithm and the non‐dominated sorting genetic algorithm II are used for optimal design and online application research of a five‐segment work roll profile. When compared to a flat roll and a parabolic roll profile with a maximum crown of 15 μm, the optimized roll profile decreases the secondary crown of the roll gap (CW2) by 5.99 and 1.055 μm, respectively, and the fourth crown of the roll gap (CW4) by 0.21 and 0.39 μm, respectively. Additionally, QWI in the field of roll gap crown adjustment decreases by 1.04 and 0.445 kN mm−1. Industrial testing shows that the average integrated value of flatness in rolling the four extreme specifications of 1340 mm tandem cold‐rolling mills lowers by 2.65 IU following the application of the new roll profile, and the average reduction of WRB in the last stand is 2.215 MPa.

Elastic-plastic torsion of a two-layer rod

We study the elastic-plastic torsion of a two-layer rod under the action of torque in this article. It is assumed that the rod consists of two layers. Each layer has its own elastic properties, but the plastic properties of both layers are the same. The contact boundary of the layers is located along the oh axis. The lateral boundary of the rod is stress-free, displacements and stresses are continuous at the interface. The components of the stress tensor at a point are calculated using contour integrals derived from conservation laws calculated along the lateral boundary. Next, the second invariant of the stress tensor is compared with the yield strength. At those points where the yield point is reached, the plastic state is realized, in the rest -elastic. This allows you to build a boundary between the plastic and elastic regions. This technique provides a way to calculate elastic-plastic boundaries for the main rolling profiles of rods. This is supposed to be done in subsequent works. We remind you that earlier, with the help of conservation laws, the main boundary value problems for a plastic two-dimensional medium, elastic-plastic torsion of isotropic rods and elastic media for bodies of finite dimensions were solved.solutions.

Study on Error Compensation Method of Online Roll Profile Measurement

Flatness and surface quality are important quality indexes of strip steel, and roll wear will directly affect the product's flatness and surface quality. Online roll profile measurement technology can obtain the information of roll profile in real time, guide the optimization of roll change rhythm, and improve the flatness control ability of rolling mill and surface quality of strip product. However, the error caused by roll displacement, clearance, roll thermal crown, and other factors is usually the same order of magnitude as the roll shape or roll wear, or even one order of magnitude higher. So error compensation is the key to ensuring the accuracy of online roll profile measurement. Herein, the position measurement technology of the roll bearing block is considered in the online roll profile measurement, and the measurement error caused by the deviation of the roll axis is separated. The thermal crown model is established to separate the measurement errors caused by the thermal crown. The error compensation model of online roll profile measurement is established, and the simulation calculation is carried out. This error compensation method is of great significance to improve the accuracy of online roll profile measurement and realize the fine management of mill roll in service.

General phase-difference model of round dies for inner and external helical profile rolling processes with radial-feed and through-feed

General phase-difference model of round dies for inner and external helical profile rolling processes with radial-feed and through-feed

Theoretical and experimental research on the joint control mechanism of the roll gap in large diameter ratio rolling mill

To adjust the roll gap shape in the large diameter ratio rolling mill, this paper proposes a new mechanism for controlling the roll gap of the large diameter ratio rolling mill, based on the principle of working roll bending technology (WRB) and roll profile electromagnetic control technology (RPECT). According to the principle of the mechanism, it can be called WRB-RPECT joint control mechanism. To analyze the roll gap shape control ability of this mechanism, a joint finite element model of the large diameter ratio roll system with the electromagnetic control roll (ECR) is established, and verified by the rolling experiment in the Y-type electromagnetic control rolling mill. Based on the finite element model, the loaded characteristic of the working rolls, the contact stress between rolls, the transverse thickness distribution of strip and the adjustment range of roll gap crown are analyzed for different rolling forces and different WRB-RPECT joint control mechanisms. The results show that the WRB-RPECT joint control mechanism has certain roll gap shape control ability of the large diameter ratio rolling, and can achieve the roll gap control goal of uniform transverse size distribution.

ИССЛЕДОВАНИЕ ИЗНОШЕННОГО ПРОФИЛЯ ПОВЕРХНОСТИ КАТАНИЯ ЖЕЛЕЗНОДОРОЖНОГО КОЛЕСА С ПОМОЩЬЮ КРИВЫХ ИЗНОСА

Based on the data obtained by calculating the curvature and radius of the worn profile, as well as the angles of inclination of the tangent to it at different rolling, a refined wear model is considered. For this purpose, additional wear graphs are constructed according to the rolling profile, taking into account the very complex nature of the wheel and rail contacting surface wear at different locations of the reference points. Calculation errors are estimated, calculated parameters such as wear at various points are corrected. For further research of the theoretical nature, analytical expressions are used, on the basis of which graphical dependencies are constructed. The calculations are performed using the finite difference method, and the calculation error is estimated. Along with this, a tabular method of presenting a significant amount of data was used. The published article will be useful for understanding the complexity of the processes and quantifying the interaction between the wheel and rail in contact.