Downward Strip Coating with Aerodynamic Airlocks and Rapid Cooling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing coating methods for continuously moving metal strips, particularly those using solvent-based varnishes, face challenges such as solvent condensation leading to explosions, health hazards, and contamination of the coating chamber, especially when the strip is not fully dried, necessitating long drying lengths and increased installation height.
Innovation Solution
A method and installation for coating a continuously moving strip in a vertical downward strand, utilizing aerodynamic airlocks to isolate the baking unit, injecting and extracting hot gases to prevent contamination, and using rapid liquid cooling to avoid mechanical contact before the strip reaches ambient temperature, thereby preventing damage and ensuring safe operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the strip is cooled rapidly after coating to prevent adhesion to the top roll, then the coating may be damaged by mechanical contact, but if the strip is cooled slowly, then the installation height must be greatly increased
Solution Approach 1:
A water cooling unit is introduced as an intermediary device between the coating application and the top roll. This mediator rapidly cools the strip in a controlled manner, preventing adhesion to the top roll while avoiding mechanical contact damage to the coating. The water cooling unit acts as a buffer that enables fast cooling without direct mechanical interaction with the vulnerable coating.
2Object-affected harmful factors
If water cooling is used to prevent solvent condensation, then the coating chamber may be contaminated by solvent-laden air, but if air cooling is used, then the cooling length and installation height must be greatly increased
Solution Approach 1:
The harmful solvent-laden air is extracted and removed from the coating chamber through a dedicated extraction system. This separates the cooling function from the contamination problem, allowing water cooling to be used effectively without compromising chamber purity. The extraction system takes out the harmful byproduct of cooling, enabling the use of efficient water cooling.
Solution Approach 2:
An air curtain or barrier system is introduced as an intermediary between the water cooling unit and the coating chamber environment. This mediator prevents solvent-laden air from contaminating the chamber while allowing the water cooling to proceed efficiently. The air curtain acts as a protective interface that isolates the two zones.
3Productivity
If the strip travels in upward pass, then the coating can be applied and baked, but the coating may adhere to the top deflection roll causing clogging and damage
Solution Approach 1:
The conventional upward pass configuration is inverted to a downward pass configuration. By reversing the direction of strip travel, the coating is applied and baked while moving downward, which prevents adhesion to the top roll. This inversion fundamentally changes the interaction between the coating and the roll, eliminating the clogging and damage problems associated with upward pass systems.
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 solution effectively prevents coating damage and ensures safe operation by avoiding mechanical contact and solvent condensation, allowing for efficient application of viscous varnishes without the risks of explosion or fire, suitable for high-speed production of steel sheets for electric motors.
Implementation Method 1
cooling the coated steel strip in a water cooling unit
Implementation Method 2
cooling the coated steel strip in a water cooling unit
Implementation Method 3
A method and installation for coating a continuously moving strip in a vertical downward strand, utilizing aerodynamic airlocks to isolate the baking unit
Implementation Method 4
injecting and extracting hot gases to prevent contamination
Data Source
AI summary
An installation for coating a substrate comprising a steel strip with a liquid, the steel strip moving continuously and in a vertical downward strand, as a coated strip, the installation including, successively from top to bottom: a coating unit; a baking or drying unit including at least one oven; a re-treatment unit for continuously re-treating residual vapors emitted by the baking or drying unit; an entry aerodynamic airlock system and an exit aerodynamic airlock system located at an entrance and an exit, respectively, of the baking or drying unit; in the baking or drying unit, an entrance near the exit aerodynamic airlock for injecting hot gas and an exit near the entry aerodynamic airlock for extracting the hot gas towards the re-treatment unit; and a rapid liquid cooling unit. The coated strip does not come into mechanical contact with any part of the installation.