Endless Rolling Strip Flatness Control Using Periodic Tension Reduction
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Solution Overview
Problem
Endless rolling processes face challenges in achieving cost-effective and efficient flatness measurement and control due to the limitations of optical flatness measuring devices under tension, requiring costly and maintenance-intensive flatness measuring rolls, and often resulting in ineffective measurements.
Innovation Solution
Implement a measuring cycle that reduces tension in the conveyor section from nominal to reduced levels for flatness measurement using an optical device, followed by tension increase, with periodic repetition to correct parabolic and asymmetrical flatness components via work roll bending and swivel control, allowing for precise and simple detection of strip flatness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If an optical flatness measuring device is used in continuous rolling with the strip under tension, then the measurement can be performed continuously, but the measurement results are not usable due to tension interference
Solution Approach 1:
The patent implements periodic tension reduction cycles during continuous rolling, where the strip tension is temporarily reduced to a low tension state for a predetermined period to enable accurate optical flatness measurement, then restored to the normal tension state. This periodic switching allows continuous rolling to proceed while obtaining usable flatness measurement data at regular intervals.
Solution Approach 2:
The patent performs preliminary tension reduction before the optical flatness measurement is conducted. By reducing the strip tension in advance to a low tension state, the measurement conditions are prepared optimally before the actual measurement takes place, ensuring accurate results without interrupting the continuous rolling process.
2Measurement precision
If a flatness measuring roller is used to measure strip flatness in continuous rolling, then measurement can be performed under tension, but the device is costly and maintenance-intensive
Solution Approach 1:
The patent replaces the mechanical flatness measuring roller system with an optical flatness measuring device. By using optical methods instead of mechanical contact measurement, the system achieves flatness measurement capability while eliminating the costs and maintenance requirements associated with mechanical rollers.
Solution Approach 2:
The patent changes the physical state parameter of the strip by temporarily reducing tension during measurement. This parameter change enables the use of optical measurement methods that would otherwise be ineffective under normal operating tension conditions.
3Measurement precision
If the strip tension is reduced for flatness measurement, then accurate measurement can be obtained, but the measurement time increases and productivity decreases
Solution Approach 1:
The patent uses periodic tension reduction with predetermined, optimized durations to balance measurement accuracy requirements with productivity maintenance. The measurement cycles are scheduled at intervals that minimize disruption to continuous rolling while obtaining sufficient measurement data.
Solution Approach 2:
The patent applies partial tension reduction rather than complete tension release, maintaining just enough tension to keep the strip stable and positioned correctly during measurement while reducing it sufficiently to obtain accurate flatness readings.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enables cost-effective and precise flatness measurement and control in endless rolling by minimizing measurement time and maintaining stable strip tension, improving flatness without disrupting thickness control, thus enhancing sliver quality and reducing maintenance costs.
Implementation Method 1
Measurement of the flatness of the belt using an optical flatness measuring device
Implementation Method 2
improvement of parabolic or symmetrical flatness components is carried out by using work roll bending on at least one rolling stand
Implementation Method 3
improvement of the asymmetrical flatness components by changing the setting positions on at least one rolling stand
Data Source
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Figure 2
AI summary
The invention relates to a method for producing a metallic strip (1) by continuous rolling, wherein in the conveying direction (F) of the strip (1) behind the last rolling stand (2) of a rolling mill there is a conveying section for the strip (1) which extends to a shear driver (3) and/or a reel driver (4), wherein at least temporarily in the conveying section a nominal tensile stress is maintained in the strip (1).To further develop this method so that cost-effective flatness measurement and subsequent flatness control can be carried out with minimal effort even during continuous rolling, the invention provides that the following measurement cycle is performed at defined times to determine the flatness of the strip (1): a) Reduction of the tensile stress in the strip (1) located in the conveying section from the nominal tensile stress to a reduced tensile stress value; b) After performing step a): Measurement of the flatness degree of the strip (1) using an optical flatness measuring device (6); c) After performing step b): Increase of the tensile stress in the strip (1) located in the conveying section from the reduced tensile stress value to the nominal tensile stress.