Metal Strip Flatness Control via Tension Segmentation
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Solution Overview
Problem
Existing methods for improving the flatness of hot strips, particularly those rolled and coiled under tension, face challenges in maintaining sufficient flatness measurements and are hindered by limitations in tension levelers and cooling sections that affect strip quality.
Innovation Solution
Applying a method where the metal strip is subjected to varying tensile stresses between the rolling mill and the bend-stretcher, with a higher tension in the bend-stretcher section, controlled by drivers to optimize flatness, and excluding cooling downstream of the bend-stretcher to prevent flatness distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the strip is cooled in a cooling section between the rolling mill and the bend-stretcher, then the strip temperature is reduced, but the flatness of the strip is negatively affected
Solution Approach 1:
The patent segments the processing line into distinct zones: a cooling section upstream of the bend-stretcher and a no-cooling zone downstream. This segmentation allows cooling to occur only where it does not interfere with the straightening process, thereby preserving flatness while still enabling temperature reduction.
Solution Approach 2:
The cooling section performs the temperature reduction action preliminarily, before the strip enters the bend-stretcher. By completing the cooling function upstream, the subsequent straightening process can proceed without thermal interference that would compromise flatness.
2Manufacturing precision
If stretch levelers are used downstream of hot strip mills, then flatness is improved, but the tension control and cooling section limitations affect strip quality
Solution Approach 1:
The patent changes the tension parameter dynamically by employing multiple drivers (first driver upstream, second driver downstream) that can independently adjust tension levels. This allows optimization of both flatness improvement and tension control without requiring overly complex single-system designs.
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 approach enhances the flatness of the strip by maintaining optimal tension levels and temperature control, reducing constriction and maintenance costs, while ensuring consistent coiler temperature and improved straightening process efficiency.
Implementation Method 1
the strip being subjected to a straightening process in a bend straightener
Implementation Method 2
The strip is preferably subjected to cooling in a cooling section between the rolling mill and the bend-stretcher
Data Source
Figure 1
Figure 2
AI summary
The invention relates to a method for producing a metal strip (1), wherein the strip (1) is rolled in a rolling mill (2), wherein the strip (1) is subjected to a tension-levelling process in a tension-leveller (3) at a location after the rolling mill (2) in the conveying direction (F), and wherein the strip (1) is wound onto a reel (4) at a location after the tension-leveller (3) in the conveying direction (F). In order to increase the degree of flatness of the strip, according to the invention, the strip (1) is retained at least for a period of time under a first tensile stress (σ1) between the rolling mill (2) and the tension-leveller (3), the strip (1) is retained at least for a period of time under a second tensile stress (σ2) behind the tension-leveller (3) in the conveying direction (F), and the strip (1) is retained at least for a period of time under a third tensile stress (σ3) in the region of the tension-leveller (3), wherein the third tensile stress (σ3) is greater than the first tensile stress (σ1) and the second tensile stress (σ2). The invention also relates to a system for producing a metal strip.