Textured Steel Sheet Surface for Paint Finish and Deep Drawing
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Solution Overview
Problem
Existing metal sheets for automotive body components face challenges in achieving optimal paint coating appearance and forming behavior, particularly with regular surface structures being difficult to produce reliably, especially on galvanized sheet steel, and requiring complex multi-layer paint systems to compensate for surface unevenness.
Innovation Solution
A metal flat product with a stochastic surface structure featuring steep flanks and defined depth in valleys, allowing for a delicate appearance and efficient lubrication during forming, achieved through a roller with a corresponding surface texture created using electro discharge texturing and superfinishing, enabling simplified coating processes and improved forming performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If regular surface structures with cylindrical elevations are produced on galvanized steel sheets, then the paint coating appearance can be optimized, but the manufacturing reliability is difficult to achieve with required consistency
Solution Approach 1:
The patent changes the fundamental parameters of the surface structure from regular cylindrical elevations to an irregular pattern characterized by ridge lines and transverse grooves. This parameter change includes modifying the geometric shape, arrangement, and depth distribution to create a stochastic pattern that is inherently more reliable to produce while maintaining the necessary surface properties for paint coating optimization
Solution Approach 2:
Instead of trying to produce perfectly regular structures that are difficult to manufacture reliably, the patent inverts the approach by deliberately creating an irregular, stochastic surface pattern. This inversion transforms the problem from achieving regularity through difficult manufacturing to achieving reliability through controlled irregularity that is easier to produce consistently
2Manufacturing precision
If multi-layer paint systems are applied to compensate for surface unevenness, then the visual appearance quality is improved, but the manufacturing effort and cost increase significantly
Solution Approach 1:
The patent applies preliminary action by creating the optimal surface structure (ridge lines with transverse grooves) during the steel sheet manufacturing process itself, before the painting process. This preliminary structuring of the surface eliminates the need for subsequent multi-layer filler coatings, as the surface is pre-conditioned to work optimally with simplified paint systems
Solution Approach 2:
The patent extracts the surface preparation function from the painting process and integrates it into the steel sheet manufacturing process. By incorporating the surface structuring directly into the rolling process through the textured roller, the need for complex multi-layer filler coatings is eliminated, simplifying the overall manufacturing system
3Quantity of substance
If the paint layer thickness is reduced to achieve cost savings, then the coating cost decreases, but the underlying metal may show through on insufficiently coated sheets
Solution Approach 1:
The patent applies local quality by creating specific surface features (ridge lines and transverse grooves) at different locations on the sheet surface. The ridge lines provide elevated areas that promote uniform paint distribution, while the transverse grooves capture and retain lubricant and paint materials, ensuring adequate coating even when overall paint thickness is reduced
4Ease of operation
If deep drawing is performed on sheets with surface depressions, then the forming process can proceed, but lubricant may collect in the depressions forming pockets that affect load-bearing capacity
Solution Approach 1:
The patent inverts the conventional approach by not creating deep isolated depressions, but rather a network of shallow transverse grooves that run across the surface. This inverted approach prevents lubricant pocket formation while still providing adequate lubrication channels, transforming the surface from one that traps lubricant into one that distributes it effectively
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 results in a surface that is optically and technically flawless even with reduced paint layer thickness, minimizing forming forces and ensuring uniform surface quality, allowing for efficient deep-drawing and high-quality paint finishes without the need for complex filler coatings.
Implementation Method 1
achieved through a roller with a corresponding surface texture created using electro discharge texturing
Implementation Method 2
a roller with a corresponding surface texture created using electro discharge texturing and superfinishing
Data Source
Figure 1~2c
Figure 3~4b
Figure 5~6
AI summary
The flat product is made from metal, particularly steel. The frequency distribution of the high values has two distinctive maxima, which stands for distinctive highest and lowest levels of the surface. The frequency of the highest point is larger than the frequency of the lowest point. The distance between the main maxima of the frequency distribution of the high values is amount from 1 micro meter to 5 micro meters. The 99.99 percent of the topography measuring points has a minimum distance from edge of the lowest point and the highest point. Independent claims are also included for the following: (1) roller for manufacturing flat product (2) a method for manufacturing a flat product.