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

Adopting a method and device that measure the steel sheet shape on the delivery side and adjust the control gain for rolling mills based on sheet width, setting a smaller control gain for sheets wider than a predetermined value to prevent breakage without equipment modifications.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a constant control gain is used for shape control in rolling mill, then the shape control is simple and consistent, but wide steel sheets (over 1200 mm) are prone to breakage due to overcontrol and shape distortion

Engineering Contradiction:

Improvesteel sheet breakage preventionVSAvoidcontrol gain adjustment complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The control gain is made dynamic rather than constant. The control gain changing unit adjusts the control gain based on the measured shape data and steel sheet width, making the control system adaptive to different sheet widths and conditions. This dynamic adjustment prevents overcontrol of wide steel sheets while maintaining effective control for narrower sheets.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The control gain parameter is changed based on steel sheet width and shape measurement results. For wide steel sheets (over 1200 mm), a smaller control gain is applied to prevent breakage, while for narrower sheets, a larger control gain can be used. This parameter change resolves the contradiction by adapting the control strength to the specific sheet characteristics.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If existing shape control methods are used, then equipment cost is low, but wide steel sheets break easily due to shape defects

Engineering Contradiction:

Improvesteel sheet breakage preventionVSAvoidequipment modification cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The system uses feedback from shape measurement devices (such as laser scanners or contactless gauges) that measure the actual shape of the steel sheet during rolling. This feedback information is fed back to the control gain changing unit, which adjusts the control gain in real-time based on the measured shape deviations, preventing breakage without requiring expensive equipment modifications.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The invention replaces complex mechanical modifications with a control system that uses measurement feedback and adaptive gain adjustment. Instead of modifying the physical rolling equipment to handle wide sheets, the system uses intelligent control algorithms that adapt to different sheet widths and shapes, avoiding the need for costly equipment changes.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Manufacturing precision

If control gain is increased to improve shape control precision, then shape accuracy improves, but wide steel sheets become more prone to breakage due to overcontrol

Engineering Contradiction:

Improveshape control precisionVSAvoidsteel sheet breakage prevention

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The control gain parameter is dynamically changed based on steel sheet width and measured shape deviations. For wide steel sheets, the control gain is reduced to prevent overcontrol and breakage, while for narrower sheets or larger shape deviations, the control gain can be increased to maintain precision. This resolves the contradiction by making precision and reliability context-dependent.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

Different control gains are applied locally based on steel sheet width categories. The system divides steel sheets into width categories (e.g., narrow vs. wide) and applies appropriate control gains to each category. This local quality approach ensures that each sheet receives the appropriate level of control aggression based on its specific characteristics.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS20230133751A1Method for shape control in rolling mill and device for shape control in rolling mill

Publication Date: 2023.05.04 JFE STEEL CORP

AI summary

A method for shape control in a rolling mill 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.