Rolling Mill Strip End Stabilization via Differential Force Correction
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Solution Overview
Problem
The existing methods for stabilizing the threading out of metal strips at high rolling speeds and thin gauges in multi-stand rolling mills are inadequate, leading to unstable strip run and potential damage due to differential rolling forces, temperature differences, and hardness variations, which existing control systems fail to fully address.
Innovation Solution
Measuring differential rolling forces between the drive and operator sides of each roll stand to derive a correction value for roll adjustment, calculating a 'pivot value' to stabilize the strip end, and using adaptive evaluation to improve the process, with options for manual or automatic correction by the helmsman.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the rolling speed is reduced to stabilize the strip end, then the strip path stability is improved, but the final rolling temperature cannot be achieved and productivity decreases
Solution Approach 1:
The invention changes the parameter of strip tension dynamically during the rolling process. By increasing strip tension specifically when the strip end approaches the exit of the rolling stand, the system stabilizes the strip path without reducing the overall rolling speed. This parameter change allows maintaining both high productivity and strip path stability.
2Ease of operation
If the strip tension is released to allow the strip end to exit the stand, then the strip can be unthreaded, but the strip path becomes unstable and the strip end strays
Solution Approach 1:
The invention applies preliminary anti-action by detecting when the strip end approaches the exit of the rolling stand and preemptively increasing the strip tension. This counteracts the potential instability before it occurs, preventing the strip end from straying while still allowing it to exit the stand. The system monitors strip position and adjusts tension in advance to maintain stability throughout the unthreading process.
3Stability of the object's composition
If manual intervention is used to correct strip end position, then some stabilization is achieved, but rolling damage occurs and the process is interrupted
Solution Approach 1:
The invention implements a feedback control system that continuously monitors the strip end position using detection devices. When the strip end approaches the exit of the rolling stand, the system automatically increases strip tension through the backup roll drive mechanism. This closed-loop feedback control eliminates the need for manual intervention, preventing rolling damage and ensuring continuous operation without process interruptions.
4Productivity
If the strip end exits at rolling speed, then productivity is maintained, but unwinding and unthreading become problematic especially at high speeds and thin thicknesses
Solution Approach 1:
The invention applies dynamic control by adjusting the strip tension based on real-time detection of the strip end position. The backup roll drive mechanism dynamically increases tension only when needed (when the strip end approaches exit) and maintains normal operation otherwise. This dynamic adjustment enables successful unthreading at high rolling speeds and thin thicknesses while maintaining productivity, as the system adapts to the specific conditions during the unthreading phase.
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
A method for improving the running-out of a metal rolled strip (1), the rolled trailing strip end (1a) of which exits out of a respectively last roll stand (2) of a multistand rolling mill (3) at a rolling speed, wherein during rolling between two consecutive roll stands (F1, F2, F3 . . . Fn) the strip tension (a) is adjusted to stabilize the strip position, provides that shortly before the rolled trailing strip end (1a) exits the developing rolling force differences are measured separately for each roll stand (F1, F2, F3 . . . Fn), that from this the pivot value (16) and the pivot direction are derived for forming a corrective value for the adjustment of the rolls (10, 11) and that the adjustment is corrected.