Hot-Dip Coating Stabilizers for Strip Vibration and Dross Control

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Solution Overview

Problem

The existing hot dip coating processes suffer from zinc evaporation and contamination due to surface dross, leading to coating defects and uneven surfaces in metal strips, particularly in automotive applications, due to mechanical disturbances and vibrations of the moving metal strip.

Innovation Solution

A hot dip coating device with stabilizers on either side of the metal strip within the snout, which dampen vibrations and prevent surface dross pickup, using stabilizers that form a first container within a second container, allowing for a dual metal bath system with different or same chemical compositions for the coating materials.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the metal strip is allowed to move freely through the snout, then the coating process is simple and fast, but the strip vibrates and picks up surface dross leading to coating defects

Engineering Contradiction:
Improvecoating qualityVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

Stabilizers are introduced as intermediary elements between the metal strip and the liquid metal bath. These stabilizers act as mediators that dampen strip vibrations and prevent direct contact between the vibrating strip and the bath surface, thereby eliminating dross pickup while maintaining the simplicity of the overall coating process

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The harmful vibrations and dross pickup are extracted or removed from the system by introducing stabilizers that specifically target and eliminate these problematic elements, allowing the coating process to proceed with high reliability without the need for complex vibration control systems

Inventive Principle:
Principle #2Taking out (Extraction)

2Manufacturing precision

If stabilizers are added to reduce strip vibrations, then coating quality improves, but the device structure becomes more complex

Engineering Contradiction:
Improvecoating uniformityVSAvoiddevice complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

Instead of attempting to control vibrations throughout the entire coating line, stabilizers are placed locally at the critical point where the strip enters the liquid metal bath. This localized intervention provides the necessary vibration damping and dross prevention exactly where needed, achieving manufacturing precision without requiring system-wide complexity

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

Stabilizers serve as local intermediary elements that specifically address the vibration and dross issues at the strip-bath interface, providing targeted improvement in coating uniformity without the need for complex overall device design

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If a single liquid metal bath is used, then the device is simple, but coating performance and corrosion resistance are limited

Engineering Contradiction:
Improvecorrosion resistanceVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The single liquid metal bath is segmented into multiple separate baths, each containing different coating materials or alloys. This segmentation allows for multi-layer coating application where each layer provides specific functional properties, thereby improving corrosion resistance and overall coating performance while maintaining reasonable device complexity

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Multiple liquid metal baths with different compositions are used to create composite coating layers on the metal strip. Each bath contributes different alloying elements or coating materials that combine to form a composite structure with enhanced corrosion resistance and tailored performance characteristics

Inventive Principle:
Principle #40Composite materials

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

Reduces strip vibrations and prevents surface dross contamination, ensuring a homogeneous coating with reduced defects and improved wettability, suitable for high-quality steel production.

Implementation Method 1

The at least two stabilisers are placed as opposing stabilisers on both sides of the metal strip so that they rely on the pressure built up by the flow induced by the moving metal strip

Methodology Applied
Scientific EffectPressure built up by flow: Pressure Increase

Implementation Method 2

The at least two stabilisers are placed as opposing stabilisers on both sides of the moving metal strip in such a way that on usage, the pair of stabilisers dampen vibrations

Methodology Applied
Scientific EffectVibration damping: Damping

Implementation Method 3

This creates an oxide layer that limits the zinc evaporation

Methodology Applied
Scientific EffectEvaporation limitation by oxide layer: Evaporation

Implementation Method 4

The at least two stabilisers form a first container within the second container. The first container holds a first liquid metal bath of a first metal coating material

Methodology Applied
Scientific EffectPhysical containment: Physical Containment

Data Source

PatentEP4624621A1A hot dip coating device with stabilizing means and a method of coating using a hot dip coating device
Publication Date: 2025.10.01 TATA STEEL IJMUIDEN BV
  • EP4624621A1 patent drawingFigure 1
  • EP4624621A1 patent drawingFigure 2~3
  • EP4624621A1 patent drawingFigure 4~5

AI summary

A hot dip coating device 19 for providing a metal coating on a metal strip 2, comprising, a second container 22 comprising a second liquid metal bath 18 of a second metal coating material in use; a snout 50 for guiding the metal strip 2 into the second liquid metal bath 18 comprising a lower opening 39 immersed in the second liquid metal bath 18 wherein the hot dip coating device 19 further comprises at least two stabilisers 100 on each side of the metal strip such that the at least two stabilisers form a first container 220 within the second container 22. The first container 220 comprises a first liquid metal bath 180 of a first metal coating material in use. The lower opening 39 of the snout encloses the upper portion 100a of the pair of stabilisers.