Rolling Strip Flatness Control Through Hot Mill Thickness Profiling
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Solution Overview
Problem
Current flatness control methods in rolled material production lines often result in flatness errors and a risk of strip break due to mismatched thickness profiles between hot and cold rolling mills, leading to inefficiencies and reduced yield.
Innovation Solution
A method that determines a thickness profile target for the hot rolling mill based on flatness data from cold rolling mills, allowing for adjustments that match the incoming thickness profile and reduce flatness errors, using mechanical actuators to compensate for flatness corrections and minimize the risk of strip break.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the roll gap of cold rolling mill is controlled according to flatness target, then flatness control is improved, but very large corrections are required which may cause strip break
Solution Approach 1:
The patent applies preliminary action by determining the thickness profile target in the hot rolling mill before the strip enters the cold rolling mill. By pre-adjusting the thickness profile to match the cold rolling mill's roll gap capabilities, the system avoids requiring large corrective actions downstream that would risk strip break. This proactive approach prepares the material in advance to be compatible with subsequent process constraints.
Solution Approach 2:
The patent changes the parameter being controlled from flatness (in conventional approaches) to thickness profile in the hot rolling mill. By adjusting the thickness profile parameter to match the cold rolling mill's roll gap characteristics, the system achieves flatness control without requiring extreme corrections downstream. This parameter transformation allows the system to work within the mechanical constraints of the cold rolling mill actuators.
2Manufacturing precision
If mechanical actuators are used to correct flatness errors in cold rolling mill, then flatness control is improved, but the actuators have limited range and cannot achieve required corrections
Solution Approach 1:
The system performs preliminary action by adjusting the thickness profile in the hot rolling mill before the strip enters the cold rolling mill. This pre-adjustment ensures that the thickness profile is compatible with the limited correction range of the cold rolling mill actuators, allowing them to operate within their capabilities while still achieving the desired flatness control.
Solution Approach 2:
The hot rolling mill thickness profile acts as an intermediary that mediates between the upstream process and the cold rolling mill actuators. By shaping the thickness profile in the hot rolling mill to match the roll gap characteristics of the cold rolling mill, the system creates a compatible interface that allows the limited-range actuators to achieve effective flatness control without exceeding their correction capabilities.
3Ease of operation
If different process steps are operated in isolation, then process control is simplified, but flatness errors accumulate across multiple cold rolling mills
Solution Approach 1:
The patent merges the control of multiple cold rolling mills into a unified system by determining a single thickness profile target that accounts for the roll gap characteristics of all subsequent cold rolling mills. This combined approach replaces isolated control of individual mills with an integrated strategy that prevents flatness error accumulation while maintaining operational simplicity through centralized coordination.
Data Source
AI summary
A method of controlling flatness of a strip of rolled material in a production line including a hot rolling mill and at least one cold rolling mill, downstream of the hot rolling mill, the method including determining flatness data of the strip in one or more of the at least one cold rolling mill and/or following passing of the strip through one or more of the at least one cold rolling mill; determining a thickness profile target of the strip for the hot rolling mill based on the flatness data; and passing the strip through the hot rolling mill and adjusting the thickness of the strip based on the thickness profile target. A control system and a production line are also provided.