Hot-dip Galvanizing Cooling Apparatus for Edge Defect Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge is to reduce comb-patterned surface defects on the edges of hot-dip plated steel sheets, which occur due to non-uniform solidification and surface tension differences, especially in highly-corrosion resistant plated steel sheets manufactured through continuous hot-dip galvanizing processes.
Innovation Solution
A cooling apparatus is introduced, featuring a gas knife for controlling plating thickness and a defect prevention portion that sprays a cooling gas to the center of the steel sheet, moving to address the comb-patterned surface defects by ensuring uniform solidification and reducing surface tension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the plating amount is increased to achieve high corrosion resistance, then corrosion resistance is improved, but comb-patterned surface defects occur on the edge of the steel sheet
Solution Approach 1:
The patent applies local quality by differentiating the cooling treatment between the center and edges of the steel sheet. The cooling apparatus is positioned to selectively cool the center region, creating a uniform solidification layer there, while the edges are allowed to solidify naturally. This localized differential cooling resolves the contradiction by improving surface quality at the critical edge regions without compromising the overall corrosion resistance achieved through adequate plating amount.
Solution Approach 2:
The patent applies preliminary action by implementing cooling treatment during the solidification process itself, before the steel sheet leaves the plating bath. The cooling apparatus is activated in advance to control the solidification rate and create a uniform solidification layer, preventing comb-patterned defects from forming in the first place rather than correcting them after occurrence.
2Manufacturing precision
If cooling treatment is applied to the entire steel sheet, then surface uniformity is improved, but productivity is reduced due to extended processing time
Solution Approach 1:
The patent applies local quality by providing cooling treatment only to the center region of the steel sheet where it is most needed for uniform solidification, rather than cooling the entire sheet uniformly. This selective cooling approach achieves the necessary surface uniformity and prevents comb-patterned defects at the edges while minimizing the total cooling time and energy consumption, thereby maintaining productivity.
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 solution leads to improved surface quality and productivity by forming a uniform solidification layer, thereby reducing comb-patterned surface defects and enhancing the aesthetic appeal and corrosion resistance of the steel sheets.
Implementation Method 1
a defect prevention portion installed downstream of the gas knife and cooling the steel sheet by spraying a cooling gas onto the steel sheet
Implementation Method 2
a gas knife for adjusting a plating thickness by spraying a wiping gas onto a steel sheet passing through a plating bath
Data Source
AI summary
Provided is an apparatus for cooling a hot-dip plated steel sheet, the apparatus being capable of reducing comb-pattern surface defects occurring on the edge portion of the hot-dip plated steel sheet. The apparatus includes: a gas knife for spraying wiping gas to a steel sheet that has passed through a plating bath, thereby adjusting the plating thickness thereof; a defect prevention portion installed downstream of the gas knife so as to spray cooling gas to the steel sheet, thereby cooling same; and a moving portion for driving the defect prevention portion such that same moves.