Hot Rolling Mill Shape Control for Quarter Buckle Correction
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Solution Overview
Problem
Conventional hot rolling mills struggle to control complicated strip shapes, particularly quarter buckles, due to limitations in the ratio of work-roll diameter to strip width, restricting the control of higher-order shape components.
Innovation Solution
The implementation of a hot rolling mill with work rolls and backup rolls configured to satisfy a Dw/Lb ratio of 0.30 or less, allowing for parallel angle adjustments and combined bending forces to control both low-order and high-order shape components through precise actuator control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the work-roll diameter to strip width ratio Dw/Lb is set greater than 0.30 to perform strip shape control through work-roll bending, then second-order shape control is achieved, but complicated shapes like quarter buckle cannot be controlled
Solution Approach 1:
The patent segments the shape control function into two independent parts: pair cross angle control for low-order components and work-roll bending for high-order components. This segmentation allows each mechanism to operate in its optimal range, with the pair cross handling overall shape and bending handling local details, thereby achieving control of complicated shapes that neither mechanism could achieve alone
Solution Approach 2:
The patent introduces a new control dimension by reducing the work-roll diameter to achieve Dw/Lb ≤ 0.30, which fundamentally changes the bending control order from second-order to third-order or higher. This dimensional change in the Dw/Lb ratio enables the work-roll bending to control high-order shape components that were previously inaccessible
2Strength
If the work-roll diameter is increased to maintain structural stability, then roll strength is improved, but the ability to control complicated strip shapes is reduced
Solution Approach 1:
The patent segments the control functions between the pair cross mechanism (handling low-order shape components) and the work-roll bending mechanism (handling high-order components). This segmentation allows the use of smaller work rolls with Dw/Lb ≤ 0.30 for high-order control while the pair cross provides the necessary structural support and low-order control, eliminating the need for large-diameter rolls
Data Source
AI summary
A hot rolling mill1 includes a control apparatus 20 that adjusts an angle formed between an upper-side pair of an upper backup roll 120A and an upper work roll 110A and a lower-side pair of a lower backup roll 120B and a lower work roll 110B in a state where the upper-side pair is kept parallel and in a state where the lower-side pair is kept parallel. The hot rolling mill 1 is configured such that the work rolls 110A and 110B satisfy the condition that DW/Lb is equal to or smaller than 0.30 where DW is a diameter of the work rolls 110A and 110B, and Lb is the maximum strip width of a rolled material, and the hot rolling mill 1 performs rolling in a state where a bending force is applied to the work rolls.