Laser Textured Metal Sheets for Paint Appearance
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Solution Overview
Problem
Current methods for producing stochastic surface textures on metal sheets fail to independently control roughness and long-waviness values, leading to suboptimal paint appearance and formability, especially when using reduced paint layer thicknesses, and suffer from reproducibility issues.
Innovation Solution
A deterministic surface texture is created using a short-pulse laser to produce I-shaped, double-I-shaped, H-shaped, cross-shaped, or X-shaped depressions with specific roughness and waviness values, allowing for improved formability and paint appearance, achieved through a roll with a textured surface featuring overlapping dimples arranged in precise patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If stochastic surface textures are produced on metal sheets, then paint appearance and formability are improved, but roughness and long-waviness values cannot be independently controlled
Solution Approach 1:
The surface texture is segmented into two distinct components: roughness (controlled by depression depth of 2-14 μm) and long-waviness (controlled by depression spacing and shape). This segmentation allows independent control of each parameter through the laser texturing process, resolving the contradiction between manufacturing precision and device complexity.
Solution Approach 2:
The patent replaces conventional mechanical texturing methods (which cannot independently control roughness and waviness) with laser texturing technology. The laser system uses controllable parameters (pulse energy, duration, scanning speed, patterning) to independently adjust depression depth and spacing, achieving precise control of both surface roughness and long-waviness without complex mechanical mechanisms.
2Loss of energy
If reduced paint layer thickness is used, then process costs are reduced, but demands on surface quality of sheet metal increase
Solution Approach 1:
The surface texture is created in advance on the metal sheet before painting through laser texturing. This preliminary action prepares the surface with optimal roughness (2-14 μm depression depth) and long-waviness characteristics, enabling reduced paint thickness while maintaining high surface quality and ensuring proper paint adhesion and appearance.
Solution Approach 2:
The laser texturing creates localized depressions with specific depth (2-14 μm) and distribution patterns, providing local surface quality optimization. This localized texture modification allows reduced paint thickness overall while maintaining high surface quality where needed, balancing paint material consumption with surface quality requirements.
3Illumination intensity
If deterministic surface textures with high periodicity are used, then vivid paint appearance is achieved, but wavelength components with high intensity occur
Solution Approach 1:
The patent employs asymmetric depression shapes (I-shaped, double-I-shaped, H-shaped, cross-shaped, or X-shaped) in the surface texture. This asymmetry disrupts the high periodicity that causes strong wavelength components, while still maintaining a deterministic pattern for vivid paint appearance. The asymmetric geometry scatters light more uniformly, reducing harmful wavelength intensities.
Solution Approach 2:
Instead of using regular elevations projecting from the surface, the patent inverts the approach by creating depressions below the surface level. This inversion changes the light interaction pattern, achieving vivid paint appearance through the depression geometry while controlling the wavelength components by adjusting depression depth (2-14 μm) and spacing, thereby reducing harmful high-intensity wavelength effects.
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 resulting metal sheets exhibit enhanced tribological properties, including low abrasion, reduced slip-stick effect, and improved formability, with a stable lubricating film that supports high forming forces, while achieving visually and technically perfect paint coatings without the need for a filler layer.
Implementation Method 1
A deterministic surface texture is created using a short-pulse laser to produce I-shaped, double-I-shaped, H-shaped, cross-shaped, or X-shaped depressions
Data Source
AI summary
A flat product made of a metal material has been provided with deterministic surface texture which has a plurality of depressions which have a depth in the range of from 2 to 14 μm, wherein the depressions are designed to be I-shaped, H-shaped, cross-shaped, C-shaped or X-shaped, and wherein the surface texture has a peak count RPc in the range of from 45 to 180 1/cm, an arithmetic mean roughness Ra in the range of from 0.3 to 3.6 μm, and an arithmetic mean waviness Wsa in the range of from 0.05 to 0.65 μm. A roll which is particularly suitable for producing such a flat product has a deterministic surface texture which has a plurality of overlapping dimples, which are arranged such that they delimit a double-I-shaped, H-shaped, cross-shaped, C-shaped or X-shaped material texture in the roll surface, and wherein the surface texture of the roll, measured in the direction of the roll axis, is characterized by a peak count RPc in the range of from 80 to 180 1/cm, an arithmetic mean roughness Ra in the range of from 2.5 to 3.5 μm and an arithmetic mean waviness Wsa in the range of from 0.08 to 1.0 μm.