EAAI Journal 2026 Journal Article
Integrated modeling and modal layered control strategy for flatness regulation in variable crown temper rolling
- Ji Zhang
- Zhixuan Wang
- Zhuo Wang
- Haibo Yuan
- Renhao Wu
- Hyoung Seop Kim
- Zhenhua Bai
Strip flatness is a critical indicator of product quality, strongly influencing downstream processing and the final performance of rolled products. Temper mills equipped with variable-crown (VC) rolls offer superior flatness control by combining hydraulic bulging with inner and outer roll bending. This study presents a novel framework characterized by the unique integration of a comprehensive VC roll physical model with a hierarchical multi-objective optimization strategy. The proposed model integrates metal plastic deformation theory, roll elastic deformation behavior, and the complex mechanical interactions within the roll-stack system. A Particle Swarm Optimization algorithm is employed to identify and optimize the key input parameters of the prediction model. Furthermore, an intelligent layered flatness control strategy is designed using the Non-dominated Sorting Genetic Algorithm III for multi-objective optimization. The strategy operates in two stages: first, inner and outer bending forces are prioritized for rapid coarse adjustment; subsequently, as flatness deviation approaches a defined threshold, hydraulic crown control is activated to work in coordination with the bending forces, enabling fine and precise regulation. The proposed methodology was validated through industrial application on 2503 actual production coils, encompassing a wide range of steel grades. Industrial results confirm that this strategy reduces the average flatness deviation by 61. 4 % and narrows the standard deviation by 56. 3 %, while achieving an exceptional quality compliance rate of 99. 4 %. This framework establishes a robust theoretical foundation and provides highly effective practical guidance for high-precision flatness regulation in modern manufacturing.