Original Article

Development of technological principles for load-based reduction scheduling in multi-pass thin-sheet rolling^☆

¹ Ningbo Iron and Steel Co., Ltd. 168 Lingang 2nd Road, Beilun District, Ningbo City, Zhejiang Province, 315800, People's Republic of China
² Iron and Steel Institute of Z. I. Nekrasov of National academy of science of Ukraine, Academician Starodubov sq., 1, Dnipro, 49107, Ukraine

^* e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 16 April 2026
Accepted: 2 July 2026

Abstract

Multi-pass thin-sheet rolling requires rational distribution of reductions between passes, since reduction scheduling determines stand loads, energy-force parameters, rolling stability, and final strip quality, including longitudinal thickness variation and flatness. Many existing approaches rely on computational optimization techniques that are resource-intensive and poorly suited for real-time mill control. This study develops technological principles for load-based reduction scheduling aimed at practical implementation in industrial automation systems. A load-consistency criterion is formulated as a requirement to maintain a specified ratio of stand loads, and it is interpreted from a technological standpoint. Procedures are proposed for adjusting the distribution of reductions while preserving the required total deformation. Based on these principles, a computational tool was developed for iterative coordination of reductions with the target load distribution, using the engineering assumption of approximate proportionality between reductions and loads. The proposed approach achieves the required load distribution within 3–5 iterations, independent of the number of rolling passes, and the computational effort does not increase with schedule complexity. The results demonstrate that the method is suitable for Level-2 automation systems and enables rapid recalculation of rolling schedules under changing technological constraints, contributing to improved load uniformity, rolling stability, and conditions for thickness and flatness control. New regularities in the cold rolling process in a tandem mill have been established, demonstrating the alternative nature of the cold rolling process conditions for thin strips with minimal force level or minimal total power. The possibility of increasing the stability of the rolling process parameters has been established through the use of the proposed algorithm for optimizing reductions in the automatic strip thickness control system, which improves the accuracy, flatness, and uniformity of the surface roughness of the rolled product.