Rolling Mill Thickness Control for High-Frequency Strip Deviations
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Solution Overview
Problem
Existing methods for compensating entry-side thickness deviations in metal strips during rolling processes are inadequate, particularly for higher frequency deviations, leading to significant residual thickness variations in the final product.
Innovation Solution
An operating method for a rolling mill that utilizes a control device to determine control values based on final thickness deviations and the inverse frequency response of the rolling stand, feeding device, and measuring device, employing models or frequency-response characteristics to adjust the rolling gap and entry speed for precise compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If aggressive feedback control is applied to correct high-frequency deviations, then manufacturing precision improves, but system stability deteriorates
Solution Approach 1:
The invention changes the control parameters by introducing frequency-dependent correction factors. These correction factors modify the control response based on the spectral characteristics of thickness deviations, transforming the control system from a static gain approach to a dynamic frequency-selective approach that optimizes compensation for different deviation frequencies.
Solution Approach 2:
The control device implements a refined feedback mechanism that incorporates inverse frequency response correction. By analyzing the frequency characteristics of thickness deviations and applying appropriate correction factors, the system provides targeted feedback control that corrects high-frequency deviations without inducing oscillations or instability in the rolling process.
Data Source
AI summary
A roll stand of a rolling mill is supplied with a metal strip by an upstream supply device at an in-feed speed (v), with said metal strip being rolled in the roll stand. A measuring device between the supply device and the roll stand detects a respective thickness value (d) of the metal strip for consecutive sections of the metal strip and supplies said value to a control device of the rolling mill. The control device determines final thickness deviations based on the preliminary thickness deviations. The control device determines a respective control value (A2, A3) for the roll stand and/or the supply device for the sections of the metal strip based on the final thickness deviation of the respective section of the metal strip and the final thickness deviations of multiple preceding and/or subsequent sections of the metal strip.