Rolling System Research Articles

07.32: The flexural strength behavior of profiled steel sheet – with hot rolled plate panel system with bolted connection

ABSTRACTAn investigation on a new lightweight floor system using cold‐formed steel (CFS) sheet connected to the hot rolled steel (HRS) plate by bolts were carried out in the present study. A total of 18 numbers of specimens with varying lengths (short, moderate and long), bolt spacing (L/4, L/6 and L/8) and thickness (0.45mm; 0.45mm + 0.45mm) of CFS trapezoidal sheet were studied in three‐point bending to understand the moment carrying capacity and flexural behavior (deflection, stiffness and rotation) for composite panels in two phases. Phase I was based on single trapezoidal CFS sheet whereas the phase II was based on doubling the thickness by nesting (placing one sheet on top of another) two sheets together. The test results indicate that entire phase II specimens attained 50% to 80% higher ultimate load compared to phase I specimens. Moreover, significant increase in stiffness observed in all the phase I and phase II specimens with a decrease in spacing between the bolts. In general, it can observed that moderate length (1200 mm, l/d = 29.4) specimens was attained maximum moment carrying capacity compared to shorter (700 mm, l/d =14.7) and longer (1700 mm, l/d = 44.1) specimens. In addition, the mode of failure changed from local bending to tearing of CFS sheet under the maximum moment region with increase in span length.

Non-axisymmetric structure of the boundary layer of intensive cyclonic vortex

The secondary flows of different types were studied in a boundary layer of cyclonic vortex over localized heater. Near the periphery of the heating area system of horizontal rolls oriented along the basic flow is formed. Thermal plumes which are originated between counter-rotating horizontal rolls are pushed to the centre by basic flow and create spiral bands. Both types of observed secondary flows (rolls and spiral bands) are of convective nature. Cyclonic vortex becomes unstable at low values of viscosity and fast rotation of the experimental model. The instability of the vortex is tightly connected with a structure of the radial inflow. For moderate values of rotational Reynolds number Re the radial flows consist of several branches which transport angular momentum to the centre of the model. When Re exceeds critical value (about 23) radial inflow changes its structure and appears as one wide branch which does not reach the centre. As a result the vortex that slowly moves around the centre is formed instead of the vortex localized in the centre. Further increase of Re leads to chaotic state with several vortices which appears at different locations near the periphery of the heating area. The map of regimes with stable and unstable vortices is presented. The applicability of experimental results to the formation of large-scale atmospheric vortices is discussed.

A New Model-Based Control Structure for Position Tracking in an Electro-Hydraulic Servo System With Acceleration Constraint

A new variable structure control strategy consists of two separate sliding mode controllers (SMCs) with a switching mechanism designed to address position tracking problem of electro-hydraulic servo systems (EHS) with acceleration constraint, which can be found in numerous mechatronics and industrial control system applications. Examples include fatigue testing systems, plate hot rolling systems, injection molding machines, hydraulic elevators, and robotic arms. In this paper, first, a complete model of an electro-hydraulic system is proposed in which detailed mathematical descriptions for all elements are included. Not only is a more accurate model capable of providing a fertile ground for simulation studies but also it could contribute toward better results in the control approach. Furthermore, based on the variable dynamic behavior of EHS in forward and return motions, two separate SMCs synchronizing with a switching mechanism are applied. This novel approach calculates two separate control input in each instance for each dynamic behavior of the system and the switching mechanism decides which one should utilize. It is shown that the proposed control method, despite model uncertainties and external disturbances, tracks the reference position with error in scale of 10−3, and its remarkable accuracy in tracking trajectories with acceleration constraint, which has a great deal of importance in the sense of many industrial applications, is proved.

Analysis of Mechanical Parameters of 20-High Sendzimir Mill During Rolling Process

Taking the 20-high Sendzimir mill as research object, the contact force and contact stress of the roll system were calculated and analyzed, and the distribution of them has been gained. What is more, the drive torque, including the rolling torque and rolling frictional torque was also analyzed, and the composing condition of the driving torque and rolling frictional torque has been obtained. The research results are significant for the design of the 20-high Sendzimir mill.

Simulation and analysis of Magnus rotating roll stabilizer at low speed

Magnus rotating roll stabilizer generates lift to stabilize ship roll motion through the rotating rotor wing at the bilge of ship hull based on Magnus effect. The present work aims to investigate its hydrodynamic characteristics and anti-rolling effect at low ship speed. The roll damping mechanism of Magnus rotating roll stabilizer is analyzed and its lift/drag characteristics are achieved using Fluent. For practical purposes, the numerical simulation results of lift/drag force to the rotation speed at certain ship speeds are analyzed. The calculation model of the anti-rolling force is established with the vertical velocity components caused by ship roll motion into consideration. The LSR-based third order polynomial fitting is adopted to fit the lift and drag data from numerical simulations. The comparison of Magnus rotating roll stabilizer with the equivalent fin stabilizer for a given ship is accomplished. Finally, the roll reduction system of Magnus rotating roll stabilizer with an improved PID controller is developed to demonstrate its effectiveness. The simulation results show that Magnus rotating roll stabilizer is suitable and effective for roll reduction at low speed.

An approximate model to predict the surface profile of material sections in a 3-roll rolling process

This paper proposes an approximate model to predict the spread and surface profile of cross sections of material in a Kocks mill that a string of mills driven by three-roll is lined-up in tandem. The spread at the exit of roll gap is expressed as a function of the effective roll diameter, area fraction of the cross section of incoming material intersecting the roll groove shape, and contact length at the interface of the roll and material. The surface profile of a material is assumed to be a second-order polynomial function; additionally, the shape of the function was determined by the shape of the cross section of the incoming material, roll gap geometry, maximum width, and the reduction ratio. We then evaluated the possibility of 3D FE analysis, which is generally used for predicting the surface profile of materials in a three-roll rolling system, being superseded by the model proposed in this study. The generality and robustness of the model proposed in this study was verified by comparing the approximate model-predictions with FE analysis. Difference in terms of the maximum width, B1, was in the range of 0.05~0.76 % and those in terms of the surface profile radius, Rs, ranged from 0.54 to 1.23 %.

Antibacterial and Structural Properties and Printability of Starch/Clay/Polyethylene Composite Films

A composite of thermoplastic starch (TPS), low-density polyethylene (LDPE) and citric acid-modified montmorillonite (CMMT) was prepared in a twin screw extruder for packaging film application. Starch was first converted to the thermoplastic state by using sorbitol and water. Composite films were produced on a chill roll system and then were modified for printability by grafting of acrylonitrile onto the starch backbone. Antimicrobial property and printability of the films were studied from which the sample with the highest antimicrobial property and the best printability was selected. This optimal sample was then characterized by Fourier transform infrared, thermal gravimetric analysis, differential scanning calorimetry, X-ray diffraction, and scanning electron microscopy. The composite film showed a matrix/dispersed morphology in which LDPE formed a continuous phase and TPS/CMMT nanocomposite particles appeared as dispersed phase. Biodegradability, water absorption, oxygen permeability, tensile strength and transparency of optimal film were also studied. The results indicated very good properties of the produced composite film for packaging application.

Effect of rolling methods and storage on volatile constituents of Turkish black tea

AbstractThe leaves of harvested tea [Camellia sinensis (L.) O. Kuntze] can be processed into different products such as black tea, green tea and oolong tea. Black tea is the mostly consumed worldwide among these products. Black tea production is achieved by a series of processing steps namely withering, rolling, fermentation, drying, sieving and packaging. Rolling is one of the most important steps in the production as it ensures uniform maceration of tea leaves and promotes oxidation reactions catalysed by phenol oxidase enzymes during the fermentation process. The rolling of tea leaves is generally performed by either Crushing‐Tearing‐Curling (CTC), rotorvane or Orthodox methods. However, in Turkey, rolling is also performed using a combination of rotorvane and orthodox which is called the “ÇAYKUR” method. The rolling method provides a unique taste and flavours. Thus, this study was conducted to compare volatile constituents of the black teas produced by the above rolling methods and to determine the volatiles during the 6‐month storage period. Some specific compounds such as 2,6‐nonadienal, 3‐hexen‐2‐one and dodecanal for ÇAYKUR, 2,5‐octanedione for Orthodox and methylpyrazine for CTC were identified to differentiate the rolling system. This study also showed that a few compounds can be used as markers of storage. The number and amounts of volatiles, especially compounds with a high molecular weight, increased by storage. In addition, the flavour quality of the teas was evaluated by the Wickremasinghe–Yamanishi ratio (WYR), Mahanta ratio (MR) and Owuor Flavour Index.

Impact of main drive system of 5 m wide and heavy plate mill on screw-down load deviation

Abstract Universal couplings cause additional moments on the sleeve shaft of work roll. The problem becomes more obvious in the wide and heavy plate mill due to the large tilt angle and the great rolling torque, which may affect the deflection of roll system and the screw-down load deviation. Aiming at the structural characteristics of the drive system of a 5000 mm wide and heavy plate mill, additional moment models acting on the work roll are established, and the influence coefficients of the additional moment of the main drive system are obtained according to Mohr integral method. The screw-down load deviation affected by the additional moment is calculated based on the influence function method. Results show that the additional moment of the work roll drive end has little effect on the screw-down load deviation. And the fluctuation period of the additional moment is 180° with the input shaft rotating. The additional moment enlarges with the tilting angle increasing. If the tilt angle is equal to 4.82°, the vertical additional moment is about 8.5% of the output torque of motor shaft, while the horizontal additional moment is about 4.2% of that.

Influence of vanadium and nitrogen on the structure formation and properties of K60 (X70) rolled steel coils

The production of microalloyed steel coils (thickness 8 mm) of strength category K60 (X70) with requirements on the low-temperature strength is studied in industrial trials. Microalloying of the steel with 0.10% V and 0.020% N and controlled rolling in the casting and rolling system, with a final deformation temperature of 800°C, results in the production of metal with high strength (σB ≥ 600 N/mm2, σy ≥ 520 N/mm2) and plasticity (δ5 = 28%) with satisfactory strength at –40°C according to impact-flexure and drop tests.

Comparative Analysis of Root Traits and the Associated QTLs for Maize Seedlings Grown in Paper Roll, Hydroponics and Vermiculite Culture System.

Root system architecture (RSA) plays an important role in the acquisition of both nitrogen (N) and phosphorus (P) from the environment. Currently RSA is rarely considered as criteria for selection to improve nutrient uptake efficiency in crop breeding. Under field conditions roots can be greatly influenced by uncontrolled environment factors. Therefore, it is necessary to develop fast selection methods for evaluating root traits of young seedlings in the lab which can then be related to high nutrient efficiency of adult plants in the field. Here, a maize recombination inbred line (RILs) population was used to compare the genetic relationship between RSA and nitrogen and phosphorous efficiency traits. The phenotypes of eight RSA-related traits were evaluated in young seedlings using three different growth systems (i.e., paper roll, hydroponics and vermiculite), and then subjected to correlation analysis with N efficiency and P efficiency related traits measured under field conditions. Quantitative trait loci (QTL) of RSA were determined and QTL co-localizations across different growth systems were further analyzed. Phenotypic associations were observed for most of RSA traits among all three culture systems. RSA-related traits in hydroponics and vermiculite weakly correlated with Nitrogen (NupE) uptake efficiency (r = 0.17–0.31) and Phosphorus (PupE) uptake efficiency (r = 0.22–0.34). This correlation was not found in the paper roll growth system. A total of 14 QTLs for RSA were identified in paper rolls, 18 in hydroponics, and 14 in vermiculite. Co-localization of QTLs for RSA traits were identified in six chromosome regions of bin 1.04/1.05, 1.06, 2.04/2.05, 3.04, 4.05, and 5.04/5.05. The results suggest the problem of using the phenotype from one growth system to predict those in another growth system. Assessing RSA traits at the seedling stage using either hydroponics or a vermiculite system appears better suited than the paper roll system as an important index to accelerate the selection of high N and P efficient genotypes for maize breeding programs.

Roll System and Stock’s Multi-parameter Coupling Dynamic Modeling Based on the Shape Control of Steel Strip

The existence of rolling deformation area in the rolling mill system is the main characteristic which distinguishes the other machinery. In order to analyze the dynamic property of roll system’s flexural deformation, it is necessary to consider the transverse periodic movement of stock in the rolling deformation area which is caused by the flexural deformation movement of roll system simultaneously. Therefore, the displacement field of roll system and flow of metal in the deformation area is described by kinematic analysis in the dynamic system. Through introducing the lateral displacement function of metal in the deformation area, the dynamic variation of per unit width rolling force can be determined at the same time. Then the coupling law caused by the co-effect of rigid movement and flexural deformation of the system structural elements is determined. Furthermore, a multi-parameter coupling dynamic model of the roll system and stock is established by the principle of virtual work. More explicitly, the coupled motion modal analysis was made for the roll system. Meanwhile, the analytical solutions for the flexural deformation movement’s mode shape functions of rolls are discussed. In addition, the dynamic characteristic of the lateral flow of metal in the rolling deformation area has been analyzed at the same time. The establishment of dynamic lateral displacement function of metal in the deformation area makes the foundation for analyzing the coupling law between roll system and rolling deformation area, and provides a theoretical basis for the realization of the dynamic shape control of steel strip.

Improving the quality of steel grinding balls

The development of steel-ball production within the Commonwealth of Independent States over the last 50 years is analyzed. Three periods are identified and characterized. The factors responsible for poor ball quality are discussed. The requirements for the production of high-quality balls with hardness up to HRC 65 are outlined, in terms of the chemical composition of the steel, the equipment required, and the production technology. Significant increase in ball quality requires the creation of specialized rolling systems. The fundamental principles to be adopted in creating such systems are reviewed.

A Goal-Oriented, Sequential, Inverse Design Method for the Horizontal Integration of a Multistage Hot Rod Rolling System

The steel manufacturing process is characterized by the requirement of expeditious development of high quality products at low cost through the effective use of available resources. Identifying solutions that meet the conflicting commercially imperative goals of such process chains is hard using traditional search techniques. The complexity in such a problem increases due to the presence of a large number of design variables, constraints and bounds, conflicting goals and the complex sequential relationships of the different stages of manufacturing. A classic example of such a manufacturing problem is the design of a rolling system for manufacturing a steel rod. This is a sequential process in which information flows from first rolling stage/pass to the last rolling pass and the decisions made at first pass influence the decisions that are made at the later passes. In this context, we define horizontal integration as the facilitation of information flow from one stage to another thereby establishing the integration of manufacturing stages to realize the end product. In this paper, we present an inverse design method based on well-established empirical models and response surface models developed through simulation experiments (finite-element based) along with the compromise decision support problem (cDSP) construct to support integrated information flow across different stages of a multistage hot rod rolling system. The method is goal-oriented because the design decisions are first made based on the end requirements identified for the process at the last rolling pass and these decisions are then passed to the preceding rolling passes following the sequential order in an inverse manner to design the entire rolling process chain to achieve the horizontal integration of stages. We illustrate the efficacy of the method by carrying out the design of a multistage rolling system. We formulate the cDSP for the second and fourth pass of a four pass rolling chain. The stages are designed by sequentially passing the design information obtained after exercising the cDSP for the last pass for different scenarios and identifying the best combination of design variables that satisfies the conflicting goals. The cDSP for the second pass helps in integrated information flow from fourth to first pass and in meeting specified goals imposed by the fourth and third passes. The end goals identified for this problem for the fourth pass are minimization of ovality (quality) of rod, maximization of throughput (productivity), and minimization of rolling load (performance and cost). The method can be instantiated for other multistage manufacturing processes such as the steel making process chain having several unit operations.

Instabilities and pattern formation in rotating spherical cavity with oscillating inner core

The flows in a rotating spherical cavity with liquid and a free solid core in the center are experimentally investigated. The core performs small amplitude circular oscillations in the cavity frame due to a static external field. It results in the excitation of a lagging differential rotation of the core and a two-dimensional axisymmetric azimuthal motion of the fluid with several points of inflection in the velocity profile. The flow has the form of nested columns, one of which is formed on the geometrical continuation of the inner core (Taylor column). With an increase in the differential rotation rate of the core the axisymmetric fluid flow becomes unstable and several modes of instability manifest themselves. First, two-dimensional vortices appear inside the Taylor column. After it, an azimuthal wave appears, which manifests itself in the deformation of the tangent cylinder and has a retrograde phase velocity. A new mode of instability manifests itself outside the Taylor column with an increase in steady flow intensity: a regular system of 2D rolls, parallel to the cavity axis, which propagate in the prograde direction. The discovered modes are characterized by different phase velocities, the dispersion relations are determined experimentally. It is shown that for small Ekman numbers the thresholds of instabilities are determined by the critical values of Reynolds number calculated on the differential rotation rate of the core.

Force Model and Elastic Deformation Analysis of 20-High Sendzimir Mill Rolls

A 20-high Sendzimir mill is widely used in cold rolling. The deformation of rolls within the roll system as a whole is analyzed without pin-pointing upon each roll and impact on the rolling process. The mechanical model of the work roll, first intermediate roll, second intermediate driven roll, and second intermediate idler roll was proposed and the contact force of each roll was calculated in the rolling process. The finite element model was constructed on the basis of calculation results, the elastic deformation of each roll was analyzed in three rolling passes. It was found that the resultant force of the work roll was the maximum of all rolls, and the maximum elastic deformation of each roll was observed in the second rolling pass; the radial elastic deformation of each roll would influence the plate, its quality, viz. an uneven strip thickness. Each roll is subjected to cyclic stress, so the bending deformation of roll can reduce its service life, producing the fatigue crack.

Method of Reduction of an Edging and Horizontal Rolls Electromechanical Systems Interrelation in Universal Stand of a Rolling Mill

The issue of limiting power correlation of electromechanical systems of edging and horizontal rolls of universal mill stand is relevant and understudied. The paper determines causes of looping or tension in the strip in the steady-state rolling mode. Main causes are incoordination of linear speeds of edging and horizontal rolls and steady-state error of speed control of DC electric drive at on-load operation. The method of coordination of horizontal components of linear roll speeds at universal stand has been developed. It is based on condition of equality of metal second volumes at outputs of edging and horizontal rolls. The paper considers the method of control of electric drives at the universal stand that provides compensation of static speed deviation of horizontal rolls due to control of edging roll speeds during simultaneous rolling. It proposes the structural diagram and analyses the functional concept of the device implementing this method. There are oscyllographs of coordinates of electric drives of edging and horizontal rolls obtained during experimental investigations of this method. It is shown that speeds of edging rolls may be corrected practically without error. The authors substantiate that speed control of the edging roll electric drive according to the difference of horizontal roll speeds before and after strip gripping eliminates inter-stand forces. They give recommendations for commercialization of the algorithm realizing the developed methods of speed coordination of electric drives at the universal stand.

Shape-control characteristics of six-high mill with roll offset

To improve the stability of the six-high cold rolling mill, the roll offset method is often used. This paper uses ABAQUS finite element software to establish the rolls-strip coupling model. The study analyzes typical roll systems with different roll offsets to determine the effect of different roll offsets on the shape-control characteristics of the six-high cold rolling mill. Specifically, the results show that when the intermediate roll offset is positive, the bending force of the work rolls has the best control effect on the quadratic crown, as well as great influence on the quartic crown. For the four roll offsets used, the efficiency of the bending force of the intermediate rolls on the quadratic and quartic crowns of the strip is almost the same, ranging from 0-300 kN. When the intermediate roll offset is positive, the bending force of the intermediate rolls has the best control effect on the quadratic crown, ranging from 300-500 kN. When the work roll offset is positive, the bending force of the intermediate rolls also has a great influence on the quartic crown. The controlling tendencies of the shift of the intermediate roll on the quadratic crown are almost the same for different roll offsets, and the efficiency of negative roll shifting on the quadratic crown is better than that of positive roll shifting. Intermediate roll shifting also has a great influence on the quartic crown when the work rolls are offset.

Analytical solution for nonlinear vertical vibration model of mill roll system based on improved complexification averaging method

Rolling mill is the core equipment in modern iron and steel industry, and the reliability of its mill roll system (MRS) is the key to ensure the rolling process with high precision, high speed, continuity and stability. However, the MRS possesses some features such as high nonlinearity, time variability and strong coupling. The vertical vibration easily happens in its working process. Nevertheless, the mathematical model of MRS is difficult to be established and hard to be solved. In this paper, the nonlinear dynamics theory and modern signal processing method were introduced to solve this difficult problem. A two degree of freedom (DOF) nonlinear vertical vibration model of MRS was established. And the model was analytically solved by using complexification averaging (CA) method. The solution error of CA method was thoroughly analyzed. Moreover, the CA method was improved by combining the fast empirical mode decomposition (FEMD) method. Research results indicate that the improved CA method presents a significant advantage in improving the solution precision, and can be used to solve strong nonlinear vibration system (NVS) with two DOF.

Stress and Springback Analyses of API X70 Pipeline Steel Under 3-Roller Bending via Finite Element Method

3-Roller bending is a widely applied manufacturing process, particularly in structural steel pipe industry. However, due to the difficulty and high cost of measuring stress distribution inside sheet material via traditional method, internal stress/strain response during forming is largely unexplored. The focuses of this study are two: (1) to map the radii of curvature as well as the stress inside the work piece during forming by utilizing the meshing mechanism of finite element method, and (2) to further provide some numeric guidelines for the configuration of the rolling system in order to improve production efficiency and product quality. The results of this study indicate that: (1) it is crucial to properly choose forming parameter in order to produce product with desired radii; (2) much like a gradual springback process, the radii of curvature gradually increase from the top roller to the exit-side bottom roller; (3) under the assumptions made in this study, to produce pipes with a specified diameter with varying configurations of the 3-roller system will not significantly change the final residual stress; and (4) finally, shifting of the neutral axis up to 2.0% of the thickness toward the compressing side during the forming process is observed.