Steel Sheet Shape Control via Electromagnetic Force
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Solution Overview
Problem
Existing methods for uniformizing coating thickness on steel sheets in continuous hot-dip metal coating processes face challenges such as warp and vibration issues, which lead to non-uniform coating thickness in both transverse and longitudinal directions, and are limited in suppressing high-frequency vibrations using electromagnetic correction technologies.
Innovation Solution
A steel sheet shape control method and apparatus that employs a series of electromagnets and sensors to apply electromagnetic forces, perform numerical analyses, and adjust control gains to correct the shape of the steel sheet in the transverse direction, setting target correction shapes to curved forms to increase rigidity and suppress vibrations, ensuring uniform coating thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If electromagnetic correction is used to correct steel sheet warp, then coating thickness uniformity is improved, but high-frequency vibrations cannot be sufficiently suppressed
Solution Approach 1:
The steel sheet shape control system is divided into multiple independent electromagnet units arranged along the transverse direction, with each electromagnet capable of independent control. This segmentation allows targeted correction of different warp and vibration patterns across the steel sheet width, enabling effective suppression of high-frequency vibrations that affect coating uniformity.
Solution Approach 2:
The electromagnet control system dynamically adjusts the magnetic field strength and timing based on real-time steel sheet position and shape measurements. By varying the electromagnetic force dynamically during the steel sheet passage, the system can suppress high-frequency vibrations and adapt to changing warp conditions, improving both vibration suppression and coating uniformity.
2Device complexity
If support rolls are used to flatten steel sheet shape, then device complexity is reduced, but coating thickness uniformity deteriorates due to insufficient shape correction
Solution Approach 1:
The patent replaces mechanical support rolls with an electromagnetic field-based correction system. Multiple electromagnets generate magnetic forces that act on the steel sheet to correct shape deviations without physical contact. This substitution eliminates the complexity of mechanical adjustment mechanisms while providing precise, contactless shape control that ensures uniform coating thickness.
Solution Approach 2:
The electromagnetic correction system changes the magnetic field parameters (strength, duration, distribution) to achieve optimal shape control. By adjusting electromagnetic force parameters rather than mechanical roll positions, the system achieves superior shape correction precision while maintaining relatively simple device structure, thereby improving coating thickness uniformity.
3Manufacturing precision
If electromagnets are positioned close to the steel sheet for effective correction, then shape control precision is improved, but the risk of contact and damage increases
Solution Approach 1:
The patent introduces an intermediate gap between the electromagnets and the steel sheet, filled with air or inert gas. This intermediate space allows the electromagnetic field to penetrate and exert force on the steel sheet without physical contact. The electromagnets can be positioned close enough for effective correction while the intermediate gap prevents contact damage, resolving the contradiction between precision and safety.
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 method effectively suppresses warp and vibration, achieving uniform coating thickness in both transverse and longitudinal directions by optimizing the steel sheet's shape and adjusting electromagnetic forces, thereby improving the uniformity and consistency of the coating process.
Implementation Method 1
controls a shape in a transverse direction of the steel sheet by applying an electromagnetic force in a through-thickness direction with respect to the steel sheet by the electromagnets
Data Source
AI summary
A steel sheet shape control method includes, (A) setting a target correction shape of the steel sheet at a position of an electromagnet to a curved shape, (B) measuring a steel sheet shape when electromagnetic correction is performed, (C) calculating the steel sheet shape in a nozzle position based on the steel sheet shape, (D) repeating (B) and (C) by resetting the target correction shape to a curved shape having a smaller amount of warp, (E) when the amount of warp of the steel sheet shape at the position of the nozzle is less than the upper limit value, (F) calculating vibration of the steel sheet at the position of the nozzle, and (G) adjusting a control gain of the electromagnet until amplitude of vibration is less than a second upper limit value when the amplitude of the vibration is equal to or more than the second upper limit value.