Rolling Mill Shape Control Gain for Wide Steel Sheets
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Solution Overview
Problem
Existing methods for controlling steel sheet shape in rolling mills are ineffective in preventing breakage, particularly for wide steel sheets over 1200 mm, as they lead to overcontrol and shape distortion due to constant control gain settings.
Innovation Solution
A method and device for shape control in rolling mills that measure the steel sheet's shape and adjust the control gain based on the sheet width, setting a smaller gain for sheets wider than 1200 mm to prevent breakage without equipment modifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a constant control gain is used for shape control in rolling mill, then the control system is simple and easy to operate, but wide steel sheets (over 1200 mm) are prone to breakage due to overcontrol and shape distortion
Solution Approach 1:
The control gain is changed from a constant value to a variable value that changes dynamically based on the steel sheet width. The control gain setting unit sets different control gains according to the measured sheet width, making the control system adaptive rather than static. This resolves the contradiction by allowing simple operation (automatic adjustment) while preventing breakage through width-appropriate control parameters.
Solution Approach 2:
The control parameter (control gain) is changed based on the sheet width parameter. When the sheet width exceeds 1200 mm, a smaller control gain is set to prevent overcontrol and shape distortion. This parameter change strategy allows the system to maintain simplicity while adapting to different sheet widths to prevent breakage.
2Manufacturing precision
If existing shape control methods are used, then sheet thickness can be controlled within allowable range, but they are ineffective in preventing sheet breakage especially for wide steel sheets
Solution Approach 1:
The control gain is adjusted locally based on the sheet width category. For wide sheets (over 1200 mm), a specific smaller control gain is applied, while standard control gain is used for narrower sheets. This local quality approach allows thickness control precision to be maintained while adding breakage prevention for wide sheets through targeted parameter adjustment.
Solution Approach 2:
The control system uses feedback from the sheet width measurement to automatically adjust the control gain. The shape measuring device measures the actual shape, the control gain setting unit adjusts the gain based on width, and this feedback loop ensures both thickness control and breakage prevention without requiring manual intervention or equipment modifications.
3Manufacturing precision
If control gain is increased to improve shape control responsiveness, then shape control precision improves, but wide steel sheets become more prone to overcontrol and breakage
Solution Approach 1:
The control gain parameter is changed based on sheet width to optimize both precision and reliability. For wide sheets over 1200 mm, a smaller control gain is set to prevent overcontrol and breakage, while maintaining adequate shape control precision. For narrower sheets, a larger control gain can be used for more aggressive correction. This parameter adaptation resolves the contradiction between precision and breakage resistance.
Data Source
Figure 1(a)~1(b)
Figure 2~3
AI summary
A method for shape control in a rolling mill according to the present invention includes: a measurement step of measuring a shape of a steel sheet on a delivery side of the rolling mill; and a control step of controlling the rolling mill in a manner that the shape of the steel sheet falls within an allowable range, based on the shape of the steel sheet measured at the measurement step, wherein the control step includes a step of setting a control gain smaller than a control gain for a width of a steel sheet as a target for rolling being equal to or smaller than the predetermined value when the steel sheet as the target for rolling has a width greater than a predetermined value.