Differential Cooling Control for Rolled Strip Flatness
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Solution Overview
Problem
Metal strips often emerge from rolling and coating processes with center waves or distortions, reducing their flatness, which existing technologies have not effectively addressed.
Innovation Solution
A system and method that apply differential cooling across the width of a hot metal strip using a cooling unit and feedback control loop to create a non-uniform temperature gradient, increasing tension at the edges and relieving stress through yield, thereby improving flatness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional rolling and coating processes are used, then production efficiency is maintained, but the strip develops center waves and distortion that reduce flatness
Solution Approach 1:
The patent applies differential cooling to specific regions of the strip - greater cooling at the edges and less cooling at the center. This creates non-uniform temperature distribution across the strip width, which generates differential thermal contraction and tension to eliminate center waves and improve flatness.
Solution Approach 2:
The patent changes the temperature parameter non-uniformly across the strip width by applying variable cooling rates. By controlling the temperature gradient (higher at edges, lower at center), the system induces differential thermal stress that counteracts the center wave distortion and improves flatness.
2Manufacturing precision
If differential cooling is applied to improve flatness, then manufacturing precision improves, but device complexity increases due to feedback control requirements
Solution Approach 1:
The patent incorporates a feedback control system that measures strip flatness and uses this information to automatically adjust the differential cooling application. The control system monitors the strip condition and modifies cooling rates in real-time to maintain optimal flatness, thereby managing the complexity through intelligent control.
3Manufacturing precision
If non-uniform temperature gradient is applied through differential cooling, then flatness improves by increasing edge tension, but energy consumption increases
Solution Approach 1:
The patent applies cooling energy non-uniformly - concentrating greater cooling at the strip edges where it is most needed to generate tension for flatness improvement, while applying less cooling at the center. This targeted approach optimizes energy utilization by directing cooling resources to the specific regions that require correction.
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
The differential cooling method effectively reduces center waves and maintains improved flatness by temporarily increasing edge tension, allowing the strip to elongate and relieve stress, resulting in a more uniform and flat metal strip.
Implementation Method 1
applying differential cooling across the width of a hot strip to improve the flatness of the strip
Implementation Method 2
create a desired non-homogenous temperature gradient across the width of the metal strip
Implementation Method 3
The imposed tension distribution is not equalized soon after being applied, and the strip is sufficiently hot to yield slightly under the differential tension
Implementation Method 4
A feedback control loop can be implemented including a flatness measurement device and a control system that controls the differential cooling
Data Source
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AI summary
System and method for improving the flatness of a rolled sheet or strip (102) by the application of differential cooling. A cooling agent can be selectively applied along the width (202) of the strip. More cooling can be applied to the edges of the strip, where tension is greatest, to increase tension at the edges. The strip can be allowed to lengthen at these edges, which can improve flatness. In some embodiments, a closed loop flatness control system is used to measure the flatness of a strip and automatically adjust the differential cooling based on the measurement.