Hot-Dip Coated Metal Strip Waviness Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing processes for manufacturing metal strips for automotive parts result in surface waviness, which requires thick paint coats to compensate, leading to an unacceptable 'orange peel' appearance and hindering the reduction of paint thickness in industrial production.
Innovation Solution
A process involving a metal strip coated with a corrosion protection layer that is treated with a wiping gas of low oxidizing power and passed through a confinement zone with a specific atmosphere, reducing surface waviness and allowing for thinner paint coats.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If thick paint coats are applied to compensate for surface waviness, then the final appearance is satisfactory, but the total paint thickness increases and productivity decreases
Solution Approach 1:
The invention applies preliminary action by reducing surface waviness during the metal strip coating process itself, before the painting stage. By controlling the coating formation and applying wiping treatment with controlled atmosphere, the surface is prepared in advance to require minimal paint thickness, thereby improving productivity without sacrificing appearance quality
Solution Approach 2:
The invention changes physical parameters by controlling the atmosphere composition (oxygen content between 0.15-4% by volume) and temperature during the coating process. These parameter changes affect the surface waviness characteristics of the metal coating, enabling reduced paint thickness while maintaining appearance quality
2Productivity
If the number of paint coats is reduced to increase productivity, then manufacturing efficiency improves, but the final surface appearance becomes unacceptable
Solution Approach 1:
By performing surface waviness reduction during the coating process before painting, the invention prepares the substrate in advance to accept thin paint coats. This preliminary action enables reduced number of paint coats while maintaining appearance quality, thus improving productivity
Solution Approach 2:
The invention applies local quality by creating a specific controlled atmosphere environment (confinement zone with regulated oxygen content) during coating formation. This localized controlled environment produces uniform surface properties across the metal strip, enabling consistent appearance quality with reduced paint thickness
3Reliability
If conventional hot-dip coating is used for corrosion protection, then corrosion protection is achieved, but surface waviness occurs requiring thick paint coats
Solution Approach 1:
The invention changes physical parameters by controlling atmosphere composition (oxygen content between 0.15-4% by volume) and temperature during the coating process. These parameter changes affect the surface waviness characteristics of the metal coating, enabling reduced paint thickness while maintaining appearance quality
Solution Approach 2:
The invention introduces an intermediary element - a confinement zone with controlled atmosphere - between the coating bath and the cooling zone. This intermediary environment mediates the coating formation process, allowing corrosion protection to be maintained while surface waviness is reduced through controlled atmospheric conditions
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 process achieves a significant reduction in waviness, enabling the use of thinner paint coats while maintaining a satisfactory appearance, thus improving manufacturing efficiency and reducing material costs.
Implementation Method 1
wiping the coated metal strip by means of nozzles that spray a gas on each side of the strip, said gas having an oxidizing power lower than that of an atmosphere consisting of 4% oxygen by volume and 96% nitrogen by volume
Implementation Method 2
making the strip pass through a confinement zone bounded: at the bottom, by the wiping line and the upper faces of said wiping nozzles, at the top, by the upper part of two confinement boxes placed on each side of the strip, just above said nozzles, and having a height of at least 10 cm in relation to the wiping line and on the sides, by the lateral parts of said confinement boxes, the atmosphere in said confinement zone having an oxidizing power lower than that of an atmosphere consisting of 4% oxygen by volume and 96% nitrogen by volume and higher than that of an atmosphere consisting of 0.15% oxygen by volume and 99.85% nitrogen by volume
Data Source
AI summary
An installation for continuous hot-dip coating of a metal strip is provided. The installation includes a tank containing a bath of molten metal, a metal strip running through the bath and a confined wiping device. The confined wiping device includes at least two wiping nozzles placed on each side of a path of the strip after the strip has left the bath of molten metal. Each nozzle has at least one gas outlet orifice and an upper face. The confined wiping device also includes a confinement box adjacent each upper face. The confinement boxes are open on a face which faces the strip. Each box includes at least one upper part and two lateral parts.