Hot Rolling Pass Control for Stable Strip Center Flatness
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Solution Overview
Problem
In hot rolling metal strips, the existing methods for controlling center flatness lead to fluctuations, particularly in thin and high-strength strips, resulting in increased rolling pressure, work roll wear, and undesirable edge sharpening, which negatively impact rolling stability and product quality.
Innovation Solution
The method involves specifying pass-specific interval ranges for target center flatness and using a technological model to calculate control variables for profile and flatness control elements, ensuring that the center flatness remains within predetermined thresholds, thereby preventing fluctuations and optimizing rolling stability and product quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If existing methods for controlling center flatness are used, then center flatness control is achieved, but fluctuations occur particularly in thin and high-strength strips leading to increased rolling pressure and work roll wear
Solution Approach 1:
The patent applies preliminary action by calculating and specifying target center flatness values and interval ranges for each individual pass before the rolling process begins. The technological model pre-determines the control variables for profile and flatness control elements for all passes, allowing the system to proactively maintain center flatness within thresholds rather than reacting to fluctuations after they occur.
Solution Approach 2:
The patent implements dynamics by making the control variables adaptive to each specific pass conditions. Instead of using fixed control parameters, the system calculates pass-specific control variables based on the actual strip characteristics and rolling conditions for each pass, allowing the control system to dynamically adjust to varying conditions and prevent fluctuations.
2Manufacturing precision
If existing center flatness control methods are applied, then flatness is maintained, but edge sharpening and center waviness increase negatively impacting product quality
Solution Approach 1:
The patent applies feedback by using a technological model that continuously calculates and adjusts control variables based on the actual state of the strip. The system monitors center flatness values and uses this information to adjust the control variables for profile and flatness control elements in subsequent passes, creating a closed-loop control system that prevents edge sharpening and center waviness.
Solution Approach 2:
The patent implements local quality by applying different control strategies to different areas of the strip. The system specifically targets center flatness control while separately addressing edge profile control, allowing optimized control for each region. The control variables are specifically tailored to prevent center waviness while maintaining appropriate edge characteristics.
3Manufacturing precision
If conventional profile control is used, then profile values are maintained, but fluctuations in center flatness occur from pass to pass
Solution Approach 1:
The patent applies segmentation by dividing the rolling process into individual passes and treating each pass separately with its own specific control variables. Instead of applying a uniform control strategy across all passes, the system segments the control approach to address the specific requirements of each pass, thereby preventing center flatness fluctuations while maintaining profile control.
Data Source
AI summary
A method ascertains control variables for active profile and flatness control elements for at least one rolling stand for hot rolling metal strip with a plurality of i=1 . . . I successive passes and for ascertaining profile and center flatness values for the hot-rolled metal strip. The occurrence of fluctuations in the center flatness of the metal strip after the individual passes and the resulting disadvantages for the rolling stability and the product quality are prevented. The method provides that, also for the target center flatness of the metal strip after a predetermined pass k with i=1 . . . <k< . . . I and for the target center flatness after the subsequent passes, pass-specific interval ranges are also specified in each case, and in that the successive calculation of the control variables and profile values is then carried out taking into account such additional specifications as well.