Work Roll Research Articles

Study of the drive mechanism of the working bodies of a roller machine

A design of a roller machine with an improved drive mechanism of working bodies is developed in the article. The roller machine has expanded functionality when performing technological operations of dehydrating moisture-saturated fiber materials. The developed mechanism ensures stable and reliable operation of the drive of working bodies, regardless of the unevenness and variations in the parameters of the processed moisture-saturated fibrous materials, achieving synchronicity of the working body operation. The study aims to expand the functionality of the roller machine, ensure stable and reliable operation of working roller drives regardless of the unevenness and changes in the parameters of the processed moisture-saturated fibrous materials, and ensure synchronicity of the working rollers.

Degradation Modeling and RUL Prediction of Hot Rolling Work Rolls Based on Improved Wiener Process.

Hot rolling work rolls are essential components in the hot rolling process. However, they are subjected to high temperatures, alternating stress, and wear under prolonged and complex working conditions. Due to these factors, the surface of the work rolls gradually degrades, which significantly impacts the quality of the final product. This paper presents an improved degradation model based on the Wiener process for predicting the remaining useful life (RUL) of hot rolling work rolls, addressing the critical need for accurate and reliable RUL estimation to optimize maintenance strategies and ensure operational efficiency in industrial settings. The proposed model integrates pulsed eddy current testing with VMD-Hilbert feature extraction and incorporates a Gaussian kernel into the standard Wiener process to effectively capture complex degradation paths. A Bayesian framework is employed for parameter estimation, enhancing the model's adaptability in real-time prediction scenarios. The experimental results validate the superiority of the proposed method, demonstrating reductions in RMSE by approximately 85.47% and 41.20% compared to the exponential Wiener process and the RVM model based on a Gaussian kernel, respectively, along with improvements in the coefficient of determination (CD) by 121% and 19.76%. Additionally, the model achieves reductions in MAE by 85.66% and 42.61%, confirming its enhanced predictive accuracy and robustness. Compared to other algorithms from the related literature, the proposed model consistently delivers higher prediction accuracy, with most RUL predictions falling within the 20% confidence interval. These findings highlight the model's potential as a reliable tool for real-time RUL prediction in industrial applications.

Symmetrical Variable Taper Plus: a novel variable crown work roll technology for enhancing edge drop control of hot-rolled strips

Symmetrical Variable Taper Plus: a novel variable crown work roll technology for enhancing edge drop control of hot-rolled strips

Analysis of fatigue damage of hot rolling work rolls coupled with wear effect

During the hot rolling process, the work roll experiences cyclic contact stress due to the deformation of the strip steel, as well as thermal stress from periodic heating and cooling. The surface failure of the work roll results from the combined effects of wear and fatigue damage. This study proposes a comprehensive approach to analyzing coupled wear and fatigue damage using a method based on the Manson-Coffin equation, modified slope formula, and the Miner criterion. Finite element models were developed to simulate simplified heat transfer and thermal coupling, taking into account the actual rolling parameters and high-temperature material properties of the work roll. The evolution of the physical field of the work roll during the rolling process was analyzed. The analysis of these models revealed that the maximum strain on the work roll occurred at the rolling exit and was predominantly influenced by temperature. The effects of rolling speed and temperature on work roll strain varied, with fatigue damage being significantly reduced when wear was considered compared to scenarios where wear was not accounted for, under the same number of cycles.

Premature Failure Analysis of the High-Speed Steel Work Roll of Hot Strip Mill

Premature Failure Analysis of the High-Speed Steel Work Roll of Hot Strip Mill

Deformation behavior and microstructure evolution of graphene/copper laminated composites

The strength and electrical conductivity of copper-based conductors are always contradictory, while graphene/copper (Gr-Cu) composites are expected to meet the strict requirements of high strength, high conductivity, and even high thermal stability conductors’ materials. In this work, hot compression and cold rolling behaviors of Gr-Cu composites were investigated. The results indicate that graphene at the Gr-Cu interface in the composites can inhibit dislocations movement and grain boundary migration thus affecting dynamic recovery and recrystallization during hot compression. The pinning effects of dispersed graphene on grain boundaries were gradually weakened, leading to the coarsening of grains at 850 °C. Moreover, the thermal processing maps were plotted and the optional thermal processing parameters of 650–850 °C and 0.03–0.35 s−1 were determined. In addition, laminated Cu grains were refined to nanoscale after 98 % rolling reduction owing to inhibiting restoration by the dispersed graphene. The Gr-Cu interface in the composites assisted deformation and induced nanotwins resulting in pronounced Brass type texture after 50 % rolling reduction. Furthermore, the dispersed graphene enhanced the thermal stability and nanotwins were remained stable at 1073 K for 1h.

Prediction Model of Wear Amount of Work Roll and Replacement Moment in Finishing Rolling Based on Lévy's Improved Arithmetic Optimization Algorithm Twin Support Vector Regression

Prediction Model of Wear Amount of Work Roll and Replacement Moment in Finishing Rolling Based on Lévy's Improved Arithmetic Optimization Algorithm Twin Support Vector Regression

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.

Failure Investigation and Crack Characterization of Spalled Work Roll in Hot Strip Mill

Failure Investigation and Crack Characterization of Spalled Work Roll in Hot Strip Mill

Vertical vibration model for the roll system of a six-high rolling mill based on the Timoshenko beam theory

During the production of cold-rolled strips, the high-speed operation of rolling mills generates vibrations that significantly impact the production efficiency, the strip quality, and the rolling mill service life. Therefore, investigating the vibration characteristics of rolling mills is of paramount importance. Previous studies predominantly treated the rolls as point masses, overlooking variations in the vibrations along the lengths of the rolls. In this study, the working, intermediate, and backup rolls were regarded as continuous elastic bodies, and they were simplified as Timoshenko beams. The modal superposition method was used to solve the vertical vibration equations for the rolls of a six-high rolling mill; thus, the natural frequencies and modal shapes for the rolls were obtained for both free and forced vibrations. A finite-element model validation confirmed that the accuracy of the novel Timoshenko beam six-high rolling mill vibration model introduced in this paper is significantly higher than that of the traditional Euler beam model when the roller length-to-diameter ratio is relatively small. Further analysis based on this model indicates that the forced vibration of the rolls is primarily influenced by fluctuations in rolling force. The amplitude of forced vibration is affected by factors such as the friction coefficient in the deformation zone, rolling speed, and cumulative rolling distance of the work rolls. These findings provide a precise representation of the characteristics of forced vibrations in rolling mills and offer valuable theoretical insight to ensure stable rolling mill operation.

A multi-stand work roll bending and shifting approach for profile contour and flatness control of electrical steel in multi-width schedule-free rolling using NSGA-II algorithm

To overcome the severe uneven work roll wear and uneven deformation of the wide-width electrical steel in the SFR (Schedule-Free Rolling) is an effective way to organize production flexibly and maximize production efficiency in hot rolling. In order to meet the increasingly stringent requirements of PCFC (Profile Contour and Flatness Control) of multi-width electrical steel in hot rolling, the collaborative control strategy of multi-stand work roll bending and shifting for profile and flatness of electrical steel in multi-width SFR was developed using NSGA-II approach. The work roll wear prediction model, thermal crown model, and strip crown model were established based on on-site measured data. Combining the work roll wear characteristics with principle, the mathematical model for work roll shifting considering multi-width was established. The main parameters of the multi-width work roll shifting strategy are obtained using the multi-objective NSGA-II algorithm. On this basis, a multi-stand collaborative control strategy, including rolling contour, short stroke roll shifting, and work roll bending, in the downstream stands during multi-width SFR was proposed. The industrial application of the developed control strategy shows that can prominently enhance the PCFC capability of electrical steel, which the uneven wear contour can be reduced.

The effect of highly elongated micro-contacts on rolling contact stress field

This study presents a boundary element model to analyze contact pressure distribution and the subsurface stress field in rough rolling elements. The methodology is demonstrated by the stress field of the backup roll and work roll in the cold/temper rolling process and characterized by a parallel orientation of roughness lay with rolling direction, resulting in a cluster of highly elongated elliptical micro-contacts. The numerical outcomes revealed that the amplitude of in-plane and out-of-plane shear stress components are strongly dependent on the ellipticity of the micro-contacts. Comparison with experimental results shows that the crack plane is oriented transversal to the rolling direction and the crack initiation location corresponds to the location where the shear stress components are maximum.

Flatness defect control during cold rolling of SUS430 stainless steel

Abstract A statics finite element (FE) model as well as a dynamics FE model for Sendzimir mill have been established. It is in order to solve the bilateral wave defect caused by loose edge rolling during the cold rolling process with SUS430 stainless steel strip. The profile and flatness control effects are quantitatively analyzed by adjusting various roll contour configurations such as work roll crown, the second intermediate idler roll crown, the first intermediate roll taper depth and taper length. The coupling relationship between strip edge-drop and flatness under different roll contour configurations has been studied to analyze their effects on flatness defect control. The first intermediate roll taper depth is the most effective way to control edge wave. The first intermediate roll taper depth has been adjusted from 0.4 mm to 0.6 mm in the industrial production line. The overall profile has been improved by 21.5 %. The deviation of residual stress at strip edges has been reduced by 32.9 %. An excellent flatness defect control result has been achieved for the industrial production of SUS430 stainless steel. The present work is responsible for providing a theoretical basis and practical experience for the flatness defect control technology of a Sendzimir mill.

Enhanced predictive modeling of hot rolling work roll wear using TCN-LSTM-Attention

Enhanced predictive modeling of hot rolling work roll wear using TCN-LSTM-Attention

Analysis of Edge Drop on Strip Due to Bending and Elastic Deformation of Back up Rolls in a Four-High Cold Mill

The superficial quality of the strip is a very important issue in steel production. Considering the dimensions, the thickness is one of the most important variables in the production of a strip. In the present study, the elastic curve of Back Up Rolls (BURs) is analyzed, considering them as simply supported beams as well as the effect of rolls on the profile of the strip, specifically in the strip edge producing edge drop. The analysis included theoretical and numerical measurements in the mill. The results showed that there is an instability zone of 76 mm in the strip edge, and this geometry is symmetrical in both ends of the strip. This study not only provides a theoretical basis for the edge drop, but also provides a basis for the understanding of deformation on rolls used in rolling mill processes and their effect on the thickness, profile, shape, and dimensional quality of strips. To reduce the edge drop and significantly improve the surface quality of the strip, it is suggested to complement the simulation by compensating for the elastic curve of BUR, in the process applying bending on Work Roll (WR) combined with the use of positive crowns on it.

Numerical simulation of void elimination in the billet during hot shape rolling processes based on the Gurson–Tvergaard–Needleman model

The presence of voids can compromise the strength and continuity of downstream products. The Gurson–Tvergaard–Needleman model was utilized to obtain the relevant parameters. A 3D finite element model was then employed to investigate the elimination of voids in a porous free-cutting steel 1215MS during the hot shape rolling process. The center distribution of voids in the billet was considered in the finite element model, and the relationships between the void elimination and the pressure stress in the billet were analyzed. The influences of rolling reduction, rotation speed, and friction between the work roller and billet on the void elimination were also discussed. The results revealed that the pass reduction has a significant influence on the ultimate value of void volume fraction, which is beneficial for better material self-healing during the shape-rolling process. These findings suggest that accurate predictions of void elimination in the workpiece can be achieved using the finite element method for successful simulation of the hot shape rolling process.

Effect of laser shock peening on the retention ability of surface roughness in forged Cr5 steel

The roughness retention ability of the work roll surface during the cold rolling process is of great significance, especially in the production of the high-quality rolling section. Laser shock peening (LSP) is an advanced and effective surface treatment technique to improve the fatigue life, wear resistance, and other mechanical characteristics of metal components. Current studies commonly examined the reinforcement effect of single and multiple LSP treatments on Cr5 steel samples through XRD analysis, hardness testing, and residual stress measurements of different parameters. In addition, the abrasion test is widely conducted to determine the wear resistance. Compared to unprocessed samples, LSP could promote grain refinement and thus significantly increase the hardness and residual stress. Furthermore, the slight decrease in surface roughness shows that LSP treatment is an effective approach to slowing down the roughness decline rate and prolonging the roller service life. It is also found that multiple LSP impacts could remarkably improve the surface roughness retention of Cr5 steel, in which the optimal laser power density was around 23 GW/cm2.

Research on the control strategy of coning amount and ASU adjustment considering profile and high-order flatness cooperative control

ABSTRACT In the production of a 20-high mill, high-order flatness defects occur frequently. To achieve collaborative control of the profile and high-order flatness of a 20-high mill, an integrated coupling model of the roll system and strip has been established based on ABAQUS software. It has been found that as the coning amount of the intermediate taper roll increased, the profile evaluation index C25 decreased, while the work roll axis exhibited high-order deflection deformation, which could lead to the generation of high-order flatness defects. Subsequently, a novel control strategy of the coning amount and backup roll segmented reduction (ASU) control adjustment has been proposed to ensure that the profile evaluation index C25 meets the requirements while eliminating the risk of high-order flatness defects caused by roll shifting (coning amount) control. The specific combination form of the control strategy has been determined by using the particle swarm optimisation (PSO) algorithm. The Industrial application results show that the maximum compressive stress in the area 75 mm-300 mm away from the edge can be reduced by more than 40% after using the novel control strategy.

A high-precision crown control strategy for hot-rolled electric steel using theoretical model-guided BO-CNN-BiLSTM framework

The prediction accuracy of strip crown is low under complex industrial data environments to general machine learning models, i.e., lack of reasonable mechanism explanation and spatial dimension dependence, which will directly affect the product quality of hot-rolled electrical steel. Therefore, a high-precision crown prediction model is proposed for electrical steel in hot rolling based on a theoretical model-guided BO-CNN-BiLSTM (Bayesian optimization, Convolution Neural Network, and Bidirectional Long Short-term Memory) framework. The work roll wear model, thermal crown model, and the secondary deformation model of the strip between stands, based on the primary deformation by the loaded gap profile, were constructed. The mechanism parameters and measured parameters are integrated into a dataset as input feature variables. In the TG-BO-CNN-BiLSTM framework, the CNN-BiLSTM model, which can achieve spatial dimension dependence, was used to extract its feature component and sequentially predict the crown using the dataset, simultaneously, the BO module optimizes the hyperparameter of the CNN-BiLSTM model. The advantages of the proposed model are verified by adopting multiple evaluation indicators, which improves running speed and prediction accuracy. The effects of process parameters on the crown with typical upstream and downstream stands were comprehensively analyzed with the proposed model. A high-precision crown control strategy, combining the framework and influence law, for multi-stand and multi-method was proposed to obtain the high-precision crown. The control strategy applied in 1450 mm 4-high hot strip mills shows that the production performance of electrical steel is significantly improved.

Study on roll shape control characteristics of electromagnetic control sleeve support roll

The paper proposed a new type of electromagnetic control support roll to obtain a better ability of controlling the plate shape. According to the principle of induction heating, the bulge shape of the support roll and the contact pressure between the rolls are changed to control the crown of the work roll. To analyze the shape control characteristics of the electromagnetic control sleeve support roll, the roll system model of the four-high mill was established and the no-load bulging experiment was carried out. The simulation results show that under different roll sleeve thickness, current frequency and current intensity, the bulge amount of support roll, contact pressure between rolls and work roll crown increase with heating time, but the growth rate gradually decreases to zero. The bulge of the support roll, the contact pressure between the rolls, the crown of the work roll change quasi-linearly with the current frequency and parabolically with the current intensity. The bulging amount of the support roll and contact pressure decrease with the increase of the thickness of the roll sleeve, and the crown of the work roll increases first and then decreases. This paper verifies the feasibility of adjusting the shape of roll gap by electromagnetic control sleeve support roll, which provides a basis for multi-zone joint control.