Rolling Mill Tail-End Leveling Using Thrust-Force Compensation
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Solution Overview
Problem
Conventional differential-load type zigzagging control methods for rolling mills fail to accurately account for inter-roll and material-roll thrust forces, leading to inaccurate leveling corrections and potential damage from buckling due to insufficient consideration of overturning moments and material-roll thrust forces, especially at low rolling reduction rates.
Innovation Solution
A method for a four-high or more rolling mill that estimates inter-roll and material-roll thrust forces based on measured or estimated cross angles and friction coefficients, and uses these parameters to correct rolling-load-difference information for precise reduction leveling control during the rolling of the workpiece tail portion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional differential-load type zigzagging control is used without considering thrust forces, then the control system is simple, but the leveling correction accuracy deteriorates due to unaccounted overturning moments
Solution Approach 1:
The patent applies preliminary action by estimating the inter-roll thrust force and material-roll thrust force before performing the differential load measurement. This allows the system to pre-calculate the overturning moments and compensate for them in advance, thereby improving the accuracy of leveling correction without adding complex real-time measurement systems.
Solution Approach 2:
The patent introduces an intermediary calculation step that estimates thrust forces based on measurable parameters (rolling load, reduction rate, friction coefficients) and uses these estimates to correct the differential load measurement. This intermediary process bridges the gap between simple measurement and accurate control.
2Measurement precision
If thrust forces are estimated and considered in leveling control, then the accuracy of centerline deviation correction is improved, but the device complexity increases due to additional measurements and calculations
Solution Approach 1:
The system uses self-service by leveraging existing measurements (rolling load, reduction rate) and material properties (friction coefficients) that are already available or easily obtainable. The thrust force estimation is performed using these existing data, avoiding the need for additional complex measurement equipment while still improving correction accuracy.
Solution Approach 2:
The patent changes parameters by introducing estimated thrust forces as correction factors to the differential load measurement. This parameter change allows the system to account for overturning moments without requiring direct measurement of these forces, thereby improving accuracy while limiting complexity growth.
3Ease of manufacture
If inter-roll thrust force and material-roll thrust force are not considered, then the control method is simpler, but the risk of buckling and roll damage increases due to uncorrected differential loads
Solution Approach 1:
By estimating thrust forces and calculating their overturning moments before the rolling operation, the system prepares compensation values in advance. This preliminary action ensures that the differential load caused by thrust forces is corrected, preventing buckling and roll damage while maintaining relative simplicity in the control implementation.
Solution Approach 2:
The patent applies preliminary anti-action by calculating the overturning moments from estimated thrust forces and using these calculations to counteract the harmful differential loads before they cause buckling or damage. This proactive compensation approach prevents reliability issues without requiring complex real-time intervention systems.
Data Source
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AI summary
There is provided a zigzagging control method for a workpiece in which a rolling mill includes a plurality of rolls that include at least a pair of work rolls and at least a pair of backup rolls, the zigzagging control method including: an estimation step of, before rolling of a tail portion of the workpiece, acquiring at least any one of an inter-roll thrust force estimated based on an inter-roll cross angle and an inter-roll friction coefficient that are acquired through measurement or estimation and a material-roll thrust force estimated based on a material-roll cross angle and a material-roll friction coefficient that are acquired through measurement or estimation; and a tail control step of measuring work-side and drive-side rolling loads, correcting a rolling load difference or a rolling load difference ratio based on any two of acquired parameters including a roll-axis-direction thrust counterforce at the measurement of the rolling loads, the inter-roll thrust force, and the material-roll thrust force, and performing reduction leveling control on the rolling mill based on the corrected rolling load difference or rolling load difference ratio, the tail control step being performed during the rolling of the tail portion of the workpiece.