Rolling System Research Articles

Numerical Investigation of Sectional Buckling Behaviors of Cold-Rolled Aluminium Alloy Channel Columns

Cold-rolled aluminium sections can be seen as the new products and are manufactured by using the existing rolling system for cold-formed steel sections. These new sections have illustrated their advantages in comparison with the extruded aluminium sections. The buckling behaviors of cold-rolled aluminium sections are different from those of the extruded ones; and their behaviors have been illustrated to be significant impacts by geometric imperfections due to unavoidable reasons in manufacturing, transportation and assembly. The paper, therefore, investigates the sectional buckling behaviors of cold-rolled aluminium alloy channel columns with the consideration of the geometric imperfections in the analysis. The imperfection amplitudes used for the investigation are randomly selected based on the collected data from previous research studies. The investigated results are the base for the analysis of sectional buckling behaviors of cold-rolled aluminium alloy channel columns, and for the determination of detrimental strengths that can be used for further studies.

Evaluating the Lifetime of Quarto Stand Rolls on the Basis of the Contact Fatigue Criterion

One of the principal failures of the supporting and working rolls on the Quarto rolling system is the spalling of their surfaces due to the gradual accumulation of defects in contact volumes of a material. Nowadays to prevent such kind of degradation failures it is necessary to check out the stationary condition of the contact strength, which doesn’t answer to the question of the duration of the roll staying in the working state, i.e., its resource (lifetime). In the article a new physical-analytical model of the roll’s failure is suggested by the criterion of the surface layer fracture and the corresponding methodology of the expected resource calculation. The approach is based on the kinetic concept of damage of solid bodies, the energy (thermodynamic) condition of fracture of solid bodies and the fundamentals of reliability forecasting for technical objects. The feature of the suggested methodology is that the definition of the failure moment for the supporting or working rolls of the Quarto system derived from the condition of the current density of defects in surface layer of a material reaching the critical value, which is the function of the enthalpy of a material melting..

Stability of nonlinear vibrations induced by rolling force in a precise cold mill system

This paper investigates the stability of horizontal nonlinear vibration of four-high cold mill under the effects of gyro-precession and eccentricity between rolls. The threshold value of chaos about Smale horseshoe commutation is given from Melnikov method, and the correctness of the result is verified by the fractal process of the attraction basin. Through the analyzes of bifurcation, maximum Lyapunov exponents and bi-parameter bifurcation, it is revealed for the effect of different parameters variation on the nonlinear dynamic behavior of horizontal vibration in rolling system. The results show, the fluctuation amplitude of horizontal force increases, the stable domain decreases, and once its value ≥3.5, it is necessary to prefer to the adjustment of parameter-exciting stiffness; meanwhile, it is noticeable that the critical points of damping and average force of the system with bifurcation or chaos appear hysteresis. The evolutions of system dynamics with four pairs of parameter changes confirm the quantitative optimal couple of one structural plus one process parameter in the system. Based on this, we can also find a balance between the average horizontal force and eccentricity, so as to optimize the structural design so that there is a proper and reliable eccentricity between the rolls. The results provide a theoretical reference for service stability and dynamic reliability of the rolling mill system.

Multi-objective optimal scheduling of laminar cooling water supply system for hot rolling mills driven by digital twin for energy-saving

As a result of the complex structure of laminar cooling water supply systems, both facets of strict process requirements and various intermittent running conditions could cause challenges of energy-saving and equipment upkeep. Given the energy wastage issue of the laminar cooling system of hot rolling, this paper develops an optimal scheduling system according to digital twin using Online Sequential Extreme Learning Machine (OS-ELM) and multi-objective evolutionary optimization using Improved Sparrow Search Algorithm (ISSA). The optimal scheduling system according to digital twins can accurately predict the water consumption trend of the water supply system and optimize the scheduling instructions and operation scheme through dynamic information interaction and mapping of process constraints, intermittent operating conditions, rolling rhythm, measured data, etc. between physical space and virtual space. Experimental results reveal that the proposed method can lessen power usage by 13.60% and water consumption by 10.54% regarding the premise of ensuring what is needed of cooling procedures. In addition, the water pump can maintain high effectiveness during operation to guarantee the security and stability of laminar cooling water supply systems.

Time series modelling of a radial-axial ring rolling system

Time series modelling of a radial-axial ring rolling system

Time series modelling of a radial-axial ring rolling system

Time series modelling of a radial-axial ring rolling system

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.

DEVELOPMENT OF A MODEL FOR STIMULATING THE MANAGED SUBSYSTEM OF A CHARITABLE FOUNDATION

Currently the perception of charity and charitable foundations is through the prism of donations in the form of alms. It is believed that the resource potential of a charitable foundation can be formed only if there are donations made by many people. In fact, the financial stability of a charitable foundation cannot be ensured only by one-time donations from compassionate citizens. Therefore, the development of a model for stimulating the managed subsystem of the BF, the application of which will ensure an increase in the resource potential of the fund, is an urgent area of research. The article defines the concept of "resource potential of a charitable foundation", presents its structure. The main conditions for the accumulation of financial resources of a charitable foundation are identified from the standpoint of market relations with donors. A mathematical model has been developed for the formation of the resource potential of a charitable foundation, based on the choice of a rolling system for accumulating financial flows.

Numerical analysis of contact pressure between rolls of Sendzimir mill based on double influence function method and conjugate gradient techniques

This paper established a model for calculating the contact pressure between the rolls of the Sendzimir 20-high mill based on the influence function method with considering the dispersion distribution characteristics of backup rolls. Stone's and Hirschcock's formula are used to calculate the rolling force between the work rolls and the rolling stock. The force balance equations and the moment balance equations of the roll system are established to determine the relationship between the contact pressure of rolls and the rolling force. The deformation-compatibility equation is established by combining the flattening deformation, deflection deformation, and rigid displacement of the rolls and roll crown. The influence function method is used to solve the flattening deformation and deflection deformation between the rolls. The conjugate gradient method is used to solve the contact pressure between the rolls by combining the force balance equation group, the moment balance equation group, and the deformation compatibility equation group of the roll system. The contact pressure between rolls obtained by the model established is compared to that by the finite element method. The results show that the calculation accuracy of the model established in this paper is consistent with that of the finite element method. Significantly, the contact pressure between the backup roll and the second intermediate roll can be accurately calculated by considering the dispersion distribution characteristics of the backup roll, and the computation time can be greatly reduced.

A Novel Heat-Assisted Three-Roll Incremental Rolling System for Flexible Rolling

Abstract The increasing demand for customized products and rapid prototyping triggers the development of dieless forming process where the need of part-specific dies is eliminated compared to conventional forming processes. This paper presents a heat-assisted three-roll incremental rolling system capable of producing rods and tubes of various diameters without the need for die/tool replacement. The system incorporates two possible heating mechanisms, namely, an induction heater and a high-current power supply for electrically assisted forming. Due to its high flexibility and hot forming ability, this rolling system is ideal for low volume production or scientific research. The newly fabricated rolling machine was initially evaluated using low carbon steel rods. The experiments have shown that the machine can produce metallic rods down to 6 mm in diameter without apparent spiral marks on the outer surface of the rolled product using multiple passes. The finite element method (FEM) was used to analyze the reaction moment, depth of the spiral marks, and the effect of axial feeding speed on the spiral marks. The simulation model predicted the results of the experiments with less than a 10% error. The work established a flexible rolling platform for possible future research, which can include the study of interface behavior in the thermo-mechanical rolling processes, and the study of material behavior in this multi-axial multi-physics environment.

Influence of roll diameter configuration of 20 high mill on roll shifting control characteristics of wide titanium strip cold rolling

In the production of wide titanium strips cold rolled by 20 high mill, when the diameter of the 1st intermediate roll is reduced, the work roll with a large roll diameter will be used to match it, which is called non-standard roll diameter configuration in this study. In order to master the control characteristics of the 1st intermediate roll shifting under non-standard roll diameter configuration, the coupled static model of roll system and strip is established by FEM, and the model is verified by using the corresponding relationship between the change of load roll gap and the change of titanium strip residual stress after cold rolling. The simulation results show that under the same rolling force, the contact stress peaks of non-standard roll diameter configuration in flat area and cone area of the 1st intermediate roll are about 1.44 times and 1.51 times of standard roll diameter configuration respectively. Compared with the standard roll diameter configuration, when the roll shifting amount increases, the longitudinal plastic strain of non-standard roll diameter increases most significantly in the range of 0-300mm from the titanium strip edge. Under the non-standard roll diameter configuration, increasing the roll shifting amount is more prone to occur the high-order buckle problem.

Classroom Management In EFL For Young Learners at SDIT Syahiral 'Ilmi : The Strategies And Challenges

This study aims to examine classroom management in EFL for young students, especially about strategies and challenges. This research uses qualitative methods with case study design and data collection techniques using semi-structured interviews and observation. The participants of this study were 2 English teachers who teach at SDIT Syahiral Ilmi and were selected using a purposive sampling technique where the participants involved were English teachers who taught as homeroom teachers. The findings of this study are that the teacher uses seating arrangements based on student qualifications and uses a rolling system, the teacher tries to maximize the lesson plan, the teacher corrects the students depending on the student's condition and based on the student's pronouncement, the teacher also uses storytelling strategies and by provoking students' curiosity, class rules read and agreed at the beginning of the semester. This study also found several challenges for teachers in classroom management including; there are some children who are hyper active in class, parents are dishonest to the teacher, discipline the class, make students focus, then there are some children who are inclusive.

Auto-Tuning PI Controller Design Using Fuzzy Logic Controller for Web Tension Control in Roll Rewinder System

Paper has a very important role, because it increases the productivity of pulp and paper companies in Indonesia. The company's development in 2018 increased by 2.1%, this was indicated by increasing consumer demand. Therefore, paper becomes a necessity in everyday life. The criteria for the paper to be produced are paper with a flat surface and cannot be wrinkled. However, errors in paper production that often occur are a lot of wrinkles and uneven paper surfaces. This happens because of a discrepancy in the dynamics of paper tension with the standards that have been set. The paper record is caused by the dynamics of the web tension in the Rewinder Roll system. In order for the web tension to remain stable, a controller is needed. The controller used is Auto-Tuning PI controller using Fuzzy Logic Controller (FLC). The controller can be said to be successful when it is able to perform automatic tuning of setpoint changes. The results showed that the system was able to achieve setpoint values, overcome overshoot and steady-state error (Ess) with response time values, namely Tr=0.3151 seconds, Ts=0.3750, Td=0.0721, overshoot=0.0044%, and Ess=0 N.

Vibration monitoring and analysis of strip rolling mill based on the digital twin model

A vibration monitoring method of strip rolling mill based on the digital twin model was proposed which could effectively reduce the structure complexity and test cost of the traditional monitoring system. Firstly, the coupling vibration mechanism model of the dynamic characteristics of roll system and bearings of four-high mill was established. Secondly, the digital twin model of strip rolling mill vibration was built based on the mechanism model. At the same time, the traditional monitoring test of the rolling mill was carried out to verify the accuracy of the digital twin model. Through analyzing the experimental results, it could be found that the roll system is vibrating intensely with the increase of rolling force obvious fluctuation. Finally, based on the above research results, the corresponding measures were put forward to suppress the rolling mill vibration. In conclusion, the rolling mill vibration monitoring theory based on the digital twin model provided the technical support and theoretical basis for improving equipment operation stability and reducing testing costs.

Fluidic rolling robot using voltage-driven oscillating liquid

Rolling motions have been observed in many animals and insects. In the previous fluidic rolling system, a deformed chamber and long cables were imperative to drive the soft rolling actuators, which required high pressure and a sophisticated controlling strategy. In this study, we propose a soft fluidic roller using a simple structure composed of a bendable and twistable electrohydrodynamic (EHD) pump and a layer of natural latex. To realize the rolling motion, we first optimized the electrode and channel height of the EHD pumps using different patterns and designs. We also examined the output power, efficiency, pressure loss, bending, and twisting performance. Subsequently, the optimized electrodes and channel height were selected to design the power source of the EHD roller. This roller was lightweight (0.7 g) with an amount of liquid (0.6 g). This EHD robot can roll as the EHD liquid oscillates under a duty-controlled voltage realized using a high-voltage circuit. Next,we investigated the influence of frictional forces on rolling performance. Finally, the rolling motion in the liquid was demonstrated. This study extends the EHD pumps to independent soft actuators integrated with a soft power source.

Optimization of a Proposed Cooling Bed with Nanoparticles for Superheated Sheet-Metal Rolling

A novel configuration for cooling system of a superheated sheet metal rolling is proposed. The system consists of a water pool containing nanoparticles lies under a variable velocity stretching sheet. The main goal of present work is to model the problem as a boundary layer nanofluid flow and present an analytical solution for it, based on appropriate selection of similarity variables. Different effective parameters including the magnetic field, solid volume fraction, heat radiation, as well as viscous dissipation are considered. In addition to simplification of a complicated problem with a simple model base on a similarity solution, the novelty of this work is to utilize non-dominated sorting genetic algorithm with five decision variables for its optimization. The results reveal that by enhancing the volume fraction of nanotube particles, the velocity slightly rises, while change in the temperature is more considerable. At higher magnetic field parameters, the velocity profile descends and temperature ascends. Higher Eckert number, as well as bigger irradiation parameter, causes more heat generation in nanofluid and enhances the temperature. We made a comparison between three criteria decisionmaking methods and found that lower skin friction coefficient and higher Nusselt number are achieved by TOPSIS and LINMAP methods, where the optimum values for friction factor and Nusselt number are 0.54 and 1.86, respectively.

Downstream Processing of Itraconazole:HPMCAS Amorphous Solid Dispersion: From Hot-Melt Extrudate to Tablet Using a Quality by Design Approach.

The downstream processing of hot-melt extruded amorphous solid dispersions (ASDs) into tablets is challenging due to the low tabletability of milled ASDs. Typically, the extrudate strand is sized before milling, as the strand cannot be fed directly into the milling system. At the lab scale, the strand can be sized by hand-cutting before milling. For scaling up, pelletizers or chill roll and flaker systems can be used to break strands. Due to the different techniques used, differences in milling and tablet compaction are to be expected. We present a systematic study of the milling and tableting of an extruded ASD of itraconazole with hypromellose acetate succinate (HPMCAS) as a carrier polymer. The strand was sized using different techniques at the end of the extruder barrel (hand-cutting, pelletizer, or chill roll and flaker) before being milled at varying milling speeds with varying screen sizes. The effects of these variables (sizing technology, milling speed, and screen size) on the critical quality attributes (CQAs) of the milled ASD, such as yield, mean particle size (D50), tablet compaction characteristics, and tablet dissolution, were established using response surface methodology. It was found that the CQAs varied according to sizing technology, with chill roll flakes showing the highest percentage yield, the lowest D50, and the highest tabletability and dissolution rate for itraconazole. Pearson correlation coefficient tests indicated D50 as the most important CQA related to tabletability and dissolution. For certain milling conditions, the milling of hand-cut filaments results in similar particle size distributions (PSDs) to the milling of pellets or chill roll flakes.

Evaluation of roll dry granulation process on the high‐viscosity melt solidification and heat recovery

AbstractHigh‐viscosity melt with temperature above 1600 K has great potential for energy saving. A mathematical model was proposed on the heat transfer between the rotating roll and melt in a roll dry granulation system, aiming at the efficient granulation and heat recovery of high‐viscosity melt. In the model, the relationship between the rotation angle and time was utilized to simplify the three‐dimensional dynamic process to a one‐dimensional static problem. Then, the influences of the roll material, dimension, rotational speed, and the melt shedding angle on the system performance were investigated. Simulation results indicated that increasing the thermal conductivity or decreasing the wall thickness will result in a higher cooling rate but a more nonuniform heat flux distribution. The possible vibration and thermal fatigue due to the nonuniform heat flux distribution will cause a poor working stability. Heat‐resistant steel is a better choice than copper alloy. The optimum wall thickness is about 19 mm, and the rotational speed should be kept below 17 rpm. The overall exergy efficiency increased from 37% to 59%, when the melt shedding angle changed from 120° to 28.8°. This study provides a further feasible method for the efficient granulation and heat recovery of high‐viscosity melt.

Design of a damped vibration absorber to control the resonant vibration of roll

Strip rolling is currently the main steel production process. The vertical vibration of the rolling mill caused by the large reduction ratio and high rolling speed reduces the qualification rate of strip products, and even damages the rolling equipment. In this paper, a new particle damping absorber (PDA) is designed to suppress the vertical vibration of the mill. The adaptive genetic algorithm (AGA) is used to optimize the basic parameters of PDA. Considering the nonlinear stiffness between the roll and the rolling stock, a four-degree-of-freedom vertical vibration model of the roll system with the PDA is established. The amplitude-frequency characteristic equations of the primary resonance and the internal resonance are solved by using the multi-scale method. The static bifurcation of the primary resonance of the system is investigated based on the singularity theory. The effects of parameters on vibration are analyzed. The control effect of the vibration absorber is investigated experimentally, and it is found that the experimental results are basically consistent with the theoretical analysis, which verifies the reliability of the established vibration model. The results show that the PDA can effectively suppress the vertical vibration of the roll. It provides some theoretical guidance for the research on vibration suppression of rolling mills.

An Original Vibrodiagnostic Device to Control Linear Rolling Conveyor Reliability

On the basis of an analysis of the number of goods that are transported and handled in maritime transport, the ports for cargo ships may be considered as places with concentrated emissions. Reducing the emissions in ports can be achieved by shortening the stay times of cargo ships. The time that ships spend in ports may be reduced to the time that is required for the effective handling of the goods. One of the solutions for effective handling is using equipment with linear rolling systems. To prevent the idle time of cargo ships and the unnecessary increment of emissions in ports because of the possible failure of the linear rolling systems, their reliability and failure prediction are greatly required. Unfortunately, the common diagnostic systems of linear rolling systems in transportation practice still fail in particular cases of great external loads. Therefore, an original solution of the diagnostic system was designed on the basis of a load-free diagnostic part with a vibration sensor that is integrated into a carriage of the linear rolling system. A functional sample of the diagnostics was produced, and the vibrations that were measured on a loaded carriage and on the diagnostic part were compared in laboratory conditions under significant external loads. Encouraging results were reached by a time-domain analysis of the measured data. On the diagnostic part, the damage appeared clearly, while, on the loaded carriage, there were no observable signs of damage.