Tin-Plated Steel Coating Removal by Selective Tin-Layer Melting

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Solution Overview

Problem

The existing methods for removing organic coatings from tin-plated sheet steel are complex and costly, requiring chemical cleaning to remove residues left after laser burning, which complicates the welding process in can production.

Innovation Solution

Applying electromagnetic radiation with a predefined wavelength that is transparent to the organic coating, causing the tin layer to melt and detach the coating, which can then be easily removed without chemicals, using a pulsed laser to control energy density and prevent overheating.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If laser burning is used to remove polymer coating from welding areas, then the organic coating is removed from the tinplate surface, but burned polymer residues are left on the surface requiring chemical cleaning

Engineering Contradiction:

Improvecoating removal qualityVSAvoidburned polymer residues

Core Design Contradiction:

Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

The patent changes the parameters of electromagnetic radiation by selecting a specific wavelength range (9.7-10.6 μm) that is absorbed by the polymer coating but not by the tinplate. This parameter selection allows the radiation energy to be selectively converted to thermal energy in the coating material, causing it to carbonize and detach without leaving residues on the metal surface.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces mechanical or chemical removal methods with electromagnetic radiation. The CO2 laser provides non-contact, residue-free removal through controlled carbonization, eliminating the need for subsequent chemical cleaning processes that were required with traditional laser burning methods.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Ease of operation

If chemical cleaning is used to remove burned residues, then the tinplate surface is cleaned, but the process becomes more complex and costly

Engineering Contradiction:

Improvesurface cleaningVSAvoidcleaning process complexity

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The patent converts the harmful effect of polymer carbonization into a beneficial process. By controlling the electromagnetic radiation parameters, the carbonized coating material is made to detach completely from the surface, and the radiation wavelength is selected so that the tinplate surface does not absorb the energy, preventing any harmful effects on the base material while achieving complete coating removal without residues.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Manufacturing precision

If electromagnetic radiation with wavelength absorbed by organic coating is applied, then the coating can be removed, but the tin layer may be damaged or overheated

Engineering Contradiction:

Improvecoating detachmentVSAvoidtin layer damage

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent applies the principle of local quality by selecting a wavelength that creates different absorption characteristics in different materials. The polymer coating has high absorption at 9.7-10.6 μm while the tinplate has low absorption at this wavelength. This creates localized heating in the coating material only, allowing precise control of the removal process without affecting the underlying metal substrate.

Inventive Principle:

Principle #3Local quality

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 method efficiently creates residue-free blocked-out areas on tin-plated sheet steel, allowing for seamless welding without chemical cleaning, while maintaining the corrosion resistance of the tinplate.

Implementation Method 1

electromagnetic radiation with a predefined wavelength, to which the organic coating is at least primarily transparent

Methodology Applied

Scientific EffectAbsorption (EM radiation): Absorption (EM radiation)

Implementation Method 2

the tin layer of the tin-plated sheet steel is completely or at least incipiently melted

Methodology Applied

Scientific EffectMelting: Melting

Implementation Method 3

using a pulsed laser to control energy density and prevent overheating

Methodology Applied

Scientific EffectLaser: Laser

Implementation Method 4

the energy density produced by the electromagnetic radiation in the predefined areas is selected to ensure that in the irradiated areas, the tin layer is completely or at least incipiently melted

Methodology Applied

Scientific EffectHeating: Heating

Data Source

PatentUS10894301B2Method of removing a coating of organic material adhering to the surface of tin-plated sheet steel

Publication Date: 2021.01.19 THYSSENKRUPP RASSELSTEIN

AI summary

A method of removing a coating made of an organic material, in particular an organic lacquer or a polymer coating, which adheres to the surface of tin-plated sheet steel. In a first step, the tin layer of the tin-plated sheet steel is completely or incipiently melted by exposure to electromagnetic radiation with a predefined wavelength, to which the organic coating is at least primarily transparent, with the organic coating becoming detached from tin layer, and in a second step, the organic material of the coating which detached from the tin layer is removed.