Cold Rolling Leveling Control for Asymmetric Elongation Stability
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Solution Overview
Problem
Existing cold rolling methods struggle to stabilize the sheet passing property of difficult-to-roll materials, particularly thin hard materials, leading to shape defects and potential fractures due to uncontrolled asymmetry in elongation difference rates at the transverse direction ends.
Innovation Solution
A cold rolling method that calculates a leveling target value based on an asymmetric component of elongation difference rate distribution using a third-order power function correlation, applied across all stands except the last, to control leveling and bender operations, ensuring symmetrical delivery shapes and reducing fracture risk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If first-order power function correlation is used for asymmetric component control, then calculation simplicity is maintained, but control precision of asymmetric component at transverse direction ends deteriorates
Solution Approach 1:
The patent changes the mathematical parameter from first-order power function to third-order power function for the asymmetric component correlation. This parameter change enables precise control of asymmetric elongation at transverse direction ends while maintaining the automated control system structure, thereby resolving the contradiction between calculation simplicity and control precision.
2Productivity
If automated control is applied to cold rolling, then productivity is improved, but ability to accommodate bends at joined portions deteriorates
Solution Approach 1:
The patent applies different control strategies to different regions of the rolled material. For the asymmetric component at transverse direction ends, third-order power function correlation is used to achieve precise local control, while the overall automated control system maintains high productivity. This local quality approach allows the system to handle bends at joined portions while preserving automated efficiency.
3Weight of moving object
If thin hard material is used to reduce weight, then fuel efficiency is improved, but sheet passing property stability deteriorates
Solution Approach 1:
The patent implements feedback control using shape meter data to calculate elongation difference rate distribution and apply appropriate leveling target values. This feedback mechanism allows the automated control system to adapt to the specific characteristics of thin hard material, maintaining sheet passing property stability while enabling the use of lightweight materials for fuel efficiency improvement.
Data Source
AI summary
Provided are a cold rolling method, a method of producing a steel sheet, a cold rolling line, and a steel sheet production line that can suppress the occurrence of fracture. The cold rolling method includes: a process of calculating a leveling target value for a cold mill (10) that carries out cold rolling on rolled material, the calculation being based on an index of an asymmetric component of an elongation difference rate distribution of the rolled material after cold rolling at delivery of the cold mill; and a process of executing leveling control of the cold mill. The index of the asymmetric component of the elongation difference rate distribution is calculated based on a correlation between the elongation difference rate distribution and an odd function, where the odd function is obtained by multiplying a first-order power function by an absolute value power function that is greater than zero-order.