High Reflectivity Steel Production via Precision Cold Rolling
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Solution Overview
Problem
Current methods for producing flat steel products with high reflectivity for solar concentrators are costly and inefficient, requiring extensive polishing or multiple processing steps, which are not economically viable or mechanically robust.
Innovation Solution
A method involving multiple cold rolling passes with progressively decreasing deformation rates and the use of work rolls with extremely low surface roughness to achieve a surface roughness of less than 0.03 μm, followed by annealing and re-rolling, allowing for the production of flat steel products with high directional reflection without additional fine processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If polishing is used to achieve high reflectivity, then surface roughness is reduced and reflectivity is improved, but processing time and production cost increase significantly
Solution Approach 1:
The invention performs surface preparation in advance by controlling the cold rolling process to create a pre-smoothed surface before final product delivery. The work rolls are specifically designed with controlled roughness parameters (Ra ≤ 0.06 μm) to impart the desired surface quality during the rolling process itself, eliminating the need for subsequent polishing operations.
2Productivity
If cold rolling with highly polished work rolls is used to reduce surface roughness, then processing time is reduced, but the achieved surface roughness (Ra ≥ 0.05 μm) is insufficient for high reflectivity requirements
Solution Approach 1:
The invention changes the surface roughness parameter of the work rolls from conventional values (Ra ≥ 0.05 μm) to specifically controlled low values (Ra ≤ 0.06 μm, preferably Ra ≤ 0.03 μm). This parameter change in the rolling tool enables the cold rolling process to directly produce surfaces with Ra ≤ 0.03 μm that meet high reflectivity requirements without subsequent polishing.
3Manufacturing precision
If multiple processing steps including polishing are used to achieve high reflectivity, then surface quality is improved, but production cost and mechanical robustness are compromised
Solution Approach 1:
The invention extracts and eliminates the polishing step from the traditional multi-step production process. By incorporating surface smoothing functionality directly into the cold rolling process through specially designed work rolls, the method removes the separate polishing operation, thereby reducing production costs and simplifying the manufacturing process while maintaining high surface 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
The method produces flat steel products with reflectivity comparable to conventionally polished products, achieving gloss values over 1200 gloss units and directional reflection exceeding 90%, while being cost-effective and mechanically robust, suitable for solar concentrators without the need for polishing.
Implementation Method 1
cold rolling the respective steel substrate at least in a last rolling pass with a work roll whose peripheral surface that comes into contact with the steel substrate has an arithmetic mean roughness Ra of less than 0.06 μm
Implementation Method 2
the cold strip obtained is subjected to cold strip annealing
Data Source
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AI summary
The invention relates to a method for producing a steel flat product with high reflectivity, the surfaces of which have an arithmetic mean roughness Ra of less than 0.03 µm, and in which the steel flat product, which has an arithmetic mean roughness Ra < 2.5 µm on at least one surface, is cold-rolled in several passes, the total deformation rate achieved by cold rolling is 75-90%, the deformation rate decreases from pass to pass, the rolling pressure in the first pass is 200-800 MPa and the rolling pressure in the last pass is 1000-4000 MPa, the cold rolling is carried out with the addition of a rolling oil with a viscosity of 5-10 mm²/s at 40 °C, the rolling speed is > 200 m/min, and the cold rolling is carried out at least in the last pass with a work roll having a mean roughness Ra < 0.01 µm. The cold-rolled steel flat product is then annealed under a protective gas atmosphere and dry-rolled.The invention also relates to a correspondingly produced steel flat product and a solar concentrator made from such a steel flat product.