The control of the asymmetric shape of strips has always been an important and difficult part of the production of cold rolling strips. In this paper, the S6-High cold rolling mill is taken as the research object. A finite element model of this mill is constructed using ABAQUS 2022 software, and a multistage working condition simulation analysis is carried out. The independent effects of asymmetric Intermediate Roll Bending (IRB) and asymmetric Intermediate Roll Shifting (IRS) on the strip shape are investigated by constructing an asymmetric convexity evaluation index. The equivalent relationship between the asymmetric roll bending and the asymmetric roll shifting was determined by analysing the coupling effect of the benchmark bending and shifting rollers on their asymmetric shape control characteristics. The on-site application shows that optimizing the amount of preset asymmetric shape control can significantly improve the asymmetric situation of the shape, providing theoretical guidance for the asymmetric shape control of the S6-High cold rolling mill.

Roll profile electromagnetic control technology (RPECT) is a new strip flatness control technology. As the control element, electromagnetic sticks have a great effect on the control ability of RPECT. To improve control ability and extend service life, effective control ratio of electromagnetic stick is presented in this paper. The ratio is designed based on the structure character of electromagnetic stick, and can be used to evaluate the key parameter of electromagnetic stick. Based on the coupled FEM, the heat flux density of the roll inner hole and the temperature distribution of electromagnetic stick are analyzed for different effective control ratios; the average contact pressure between electromagnetic stick and electromagnetic control roll is studied to evaluate the change of force roll profile; the state of roll profile and the stress state of the roll are researched to analyze the comprehensive control ability. Through the verification on the roll profile electromagnetic control experimental platform, the reasonable selection range of effective control ratio, which can be used to expand the roll profile axial affected area, is from 0.5 to 0.583. In order to increase the roll crown, the selection of η d needs to consider the current density and the optimal selection range of effective control ratio.

In order to solve the problem of deviation in the continuous annealing unit of strip steel, the deviation section, deviation-sensitive process parameters, and deviation-sensitive incoming material parameters of the continuous annealing process were analyzed and judged from the perspectives of process unit characteristics, plate passing process characteristics, and continuous annealing incoming material characteristics. Based on the analysis results, an indicator set of deviation-sensitive parameters was established; Subsequently, based on the random forest (RF) algorithm and the unit’s historical production data, the RF continuous annealed strip deviation prediction model was established and compared with the same type of regression prediction algorithms to verify the accuracy level of the algorithm, and the particle swarm optimization (PSO) algorithm was used to further optimize the RF model, which greatly improved the model’s prediction capability; Finally, combined with actual production, verify the accuracy of the model involved in this study for predicting the deviation of continuous annealing units. The results indicate that during the continuous annealing process of strip steel, the loop section and rapid thermal furnace (RTF) section are prone to deviation, and the sensitive factors for deviation mainly involve the basic parameters of the strip, the normalized first-order coefficient integral value of the plate shape, and the correction amount of the correction roll from CPC 6.0 to CPC 9.1; Through comparative analysis, the PSO-RF continuous annealing strip deviation prediction model can not only accurately predict the deviation of the loop section and RTF section, but also has higher prediction accuracy than similar algorithm models, making it more suitable for strip deviation analysis in continuous annealing units; Through field application testing, it was found that when the model was introduced into the continuous annealing production process in this study, the prediction hit rates of deviated steel coils in the entrance loop section and RTF section were 95.00% and 94.12%, respectively, and the accuracy of deviation quantity prediction were 94.65% and 93.84%, respectively.

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.