Press-Hardened Sheet Metal Zinc Flake Coating for Full Corrosion Coverage

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Solution Overview

Problem

Existing methods for producing sheet metal parts from high-strength sheet steel with metallic anti-corrosion coatings face challenges such as damage during forming, incomplete coverage, and reduced corrosion protection, especially in areas difficult to access.

Innovation Solution

A method involving press-hardening of bare sheet steel followed by application of a zinc flake coating in a liquid form, which is then baked to form a compact and abrasion-resistant layer, ensuring complete coverage and retention of mechanical properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a metallic anti-corrosion coating is applied before hot forming, then corrosion protection is provided, but the coating is damaged during forming

Engineering Contradiction:
Improvecorrosion protectionVSAvoidcoating integrity
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The metallic anti-corrosion coating is applied to the starting sheet metal material before hot forming. This preliminary coating application ensures that the coating is in place before the forming process, and the hot forming parameters are optimized to prevent coating damage while still achieving the desired shape.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The hot forming parameters (temperature, pressure, time) are optimized to balance the need for shaping the metal with the need to preserve the coating. By controlling these parameters, the coating remains intact despite the severe deformation involved in hot forming.

Inventive Principle:
Principle #35Parameter changes

2Manufacturing precision

If a metallic anti-corrosion coating is applied after hot forming, then the coating remains intact, but areas difficult to access are not completely covered

Engineering Contradiction:
Improvecoating integrityVSAvoidcorrosion protection
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The metallic anti-corrosion coating is applied to the starting sheet metal material before hot forming. This preliminary coating application ensures that the coating is in place before the forming process, and the hot forming parameters are optimized to prevent coating damage while still achieving the desired shape.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The hot forming parameters (temperature, pressure, time) are optimized to balance the need for shaping the metal with the need to preserve the coating. By controlling these parameters, the coating remains intact despite the severe deformation involved in hot forming.

Inventive Principle:
Principle #35Parameter changes

3Manufacturing precision

If a metallic anti-corrosion coating is applied after hot forming, then the coating remains intact, but the corrosion protection is reduced

Engineering Contradiction:
Improvecoating integrityVSAvoidcorrosion protection
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The metallic anti-corrosion coating is applied to the starting sheet metal material before hot forming. This preliminary coating application ensures that the coating is in place before the forming process, and the hot forming parameters are optimized to prevent coating damage while still achieving the desired shape.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The hot forming parameters (temperature, pressure, time) are optimized to balance the need for shaping the metal with the need to preserve the coating. By controlling these parameters, the coating remains intact despite the severe deformation involved in hot forming.

Inventive Principle:
Principle #35Parameter changes

4Ease of manufacture

If spraying is used to apply coating, then the process is simple, but areas difficult to access are not completely covered

Engineering Contradiction:
Improvecoating application simplicityVSAvoidcoating coverage
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The conventional spray coating method is replaced with an immersion coating method. The shaped sheet metal part is immersed in a coating bath containing the metallic anti-corrosion coating material, allowing the coating to uniformly cover all surfaces including hard-to-reach areas through direct contact and capillary action.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 allows for simple forming without damaging the coating, provides excellent corrosion protection, and maintains the strength and purity of the sheet metal, making it suitable for both functional and visible applications.

Implementation Method 1

The applied zinc flake coating is then baked in an oven or similar at a controlled temperature (the liquid phase is evaporated and the flakes bond or crosslink to form a film)

Methodology Applied
Scientific EffectEvaporation: Evaporation

Implementation Method 2

Press-hardening a provided starting sheet metal material to form a sheet metal part

Methodology Applied
Scientific EffectHeating: Heating

Data Source

PatentEP2890821B2Method and production facility for producing a hot-formed or press-hardened shaped sheet metal part with a metallic corrosion protection coating, shaped sheet metal part produced therewith and motor vehicle body with such shaped sheet metal part
Publication Date: 2023.05.10 BAYERISCHE MOTOREN WERKE AG
  • EP2890821B2 patent drawingFigure 1
  • EP2890821B2 patent drawingFigure 2

AI summary

The invention relates to a method for producing a shaped sheet metal part (P), which is provided with a metallic corrosion protection coating and made from a higher-strength sheet metal material. Said method comprises the following steps: hot-forming a provided basic sheet metal material to form a shaped sheet metal part; and coating the shaped sheet metal part with a zinc flake coating (C). The invention further relates to a production facility for producing such a shaped sheet metal part, and such a shaped sheet metal part itself and a motor vehicle body having at least one such shaped sheet metal part.