Rolling Mill Feed-Forward Speed Control for Stable Strip Entry
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Solution Overview
Problem
Speed and mass flow disturbances during the initial rolling process in rolling mills, particularly in the first roll stand of multi-stand systems, lead to tension changes and material accumulation, which can negatively impact the casting process and result in reduced output and quality issues.
Innovation Solution
The method involves setting the roll gap height smaller than the entry thickness of the rolling stock and operating the driven work roll at a pilot rotational speed that varies monotonically from the initial contact until the roll gap is filled, with the pilot speed either increasing or decreasing to compensate for expected disturbances, ensuring minimal tension and mass flow changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the work roll is operated at target rotational speed immediately after rolling stock enters the roll gap, then the rolling process can proceed efficiently, but speed disturbances and material accumulation occur in front of the roll stand
Solution Approach 1:
The control device performs preliminary action by operating the work roll at pilot rotational speed before the rolling stock fully enters the roll gap. This preliminary speed adjustment prevents material accumulation and tension changes that would otherwise occur when transitioning to target rotational speed, thereby maintaining mass flow stability while preserving rolling efficiency
2Strength
If the work roll rotational speed is reduced to accommodate rolling force build-up, then material deformation can be achieved, but tension changes and mass flow disturbances occur
Solution Approach 1:
The control device applies preliminary anti-action by adjusting the work roll speed to pilot rotational speed in advance, counteracting the harmful tension changes and mass flow disturbances that would result from sudden rolling force build-up. This prevents the harmful effects before they occur while still enabling the necessary deformation
3Stability of the object's composition
If pre-control of rotational speed is applied to eliminate material accumulation, then mass flow stability improves, but the complexity of speed control increases
Solution Approach 1:
The control device uses preliminary action by implementing a structured pilot rotational speed phase with specific criteria for transition. This approach maintains mass flow stability through advance speed adjustment while managing complexity through clear transition criteria based on rolling stock position and rolling force thresholds
4Manufacturing precision
If the roll gap height is set smaller than entry thickness, then the rolling stock can be properly deformed, but the timing precision for speed control must be highly accurate
Solution Approach 1:
The control device employs feedback mechanisms to detect when the rolling stock has reached the roll gap and when the pilot rotational speed phase should transition to target rotational speed. This feedback-based timing control ensures precise deformation while managing the timing precision requirements through continuous monitoring of rolling stock position and rolling force
Data Source
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AI summary
The invention relates to a method for rolling a rolling material (3) in a rolling mill (1) comprising at least one roll stand, wherein a gap height of a rolling gap arranged between working rolls (2) of the roll stand is set to be smaller than an in-feed thickness (h1) of the rolling material (3) before contact of the rolling material (3) with said working rolls (2), wherein at least one driven working roll (2) of the roll stand is driven at a desired rotational speed (v0) once the rolling material (3) has reached the rolling gap, and wherein the driven working roll (2) is operated at a feed-forward rotational speed (vV) deviating from the desired rotational speed (v0), until the rolling material (3) reaches the rolling gap. In order to reduce as much as possible the change in the tension in the rolling material (3) during entry of a leading edge of the rolling material (3) into the roll stand, the invention proposes that the feed-forward rotational speed (vV) is varied after contact of the rolling material (3) with the driven working roll (2) in such a way that the feed-forward rotational speed (vV) increases or decreases monotonically.