Granular Chromium Work Roll Surface for Stable Skin Pass Rolling
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Solution Overview
Problem
Existing rolling work rolls for high-strength steel strips face issues with surface roughness degradation and crack growth due to abrasion, leading to unstable rolling operations, especially when performing skin pass rolling on high-tensile-strength steel sheets.
Innovation Solution
A rolling work roll with a recess and projection layer formed on its outer surface using granular chromium, achieving an arithmetic average roughness of 2.0 µm to 10.0 µm, which inhibits surface roughness decrease and crack growth, thereby stabilizing the rolling operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If shot blasting processing or discharge dull texturing process is used to obtain surface roughness, then the surface roughness can be achieved, but surface roughness decreases due to abrasion and crack growth with increase in rolling distance
Solution Approach 1:
The invention uses a composite structure consisting of a roll barrel made of cemented carbide (WC-Co) and a surface layer containing granular chromium. This composite material combination provides both the required surface roughness (Ra: 2.0-10.0 μm) and high abrasion resistance, preventing surface roughness degradation and crack growth during extended rolling operations on high-strength steel strips.
Solution Approach 2:
The invention changes the material parameters of the work roll surface by using granular chromium with specific grain size distribution and high chromium content (≥70% by mass). This parameter change results in a surface layer with both the required arithmetic average roughness (2.0-10.0 μm) and enhanced durability, maintaining surface integrity over increased rolling distances.
2Productivity
If conventional work rolls are used for high-tensile-strength steel sheets, then rolling can be performed, but significantly high rolling load is necessary to achieve required elongation ratio
Solution Approach 1:
The invention optimizes the surface roughness parameter to a specific range (Ra: 2.0-10.0 μm) and uses granular chromium with controlled grain size (0.1-10 μm). These parameter changes enhance the elongation effect during skin pass rolling, enabling achievement of required elongation ratios (0.1-1.0%) with reduced rolling loads compared to conventional smooth rolls or rolls with different surface treatments.
3Reliability
If work roll surface roughness decreases due to abrasion, then rolling operation becomes unstable, but maintaining high surface roughness requires frequent repair or replacement
Solution Approach 1:
The composite structure of cemented carbide roll barrel with granular chromium surface layer provides exceptional abrasion resistance. The high chromium content (≥70% by mass) and specific grain size distribution create a surface layer that resists wear and prevents crack initiation, maintaining surface roughness stability and enabling continuous rolling operations without frequent repairs or replacements.
Solution Approach 2:
The granular chromium surface layer acts as a protective cushioning layer that absorbs and distributes mechanical stresses during rolling. This beforehand protection prevents stress concentration that would lead to crack growth, thereby extending work roll service life and maintaining operational stability over extended periods.
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 allows for stable rolling operations by reducing rolling load and maintaining surface roughness, even with increased rolling distance, without requiring equipment modifications, thus enhancing the operational stability and longevity of the work rolls.
Implementation Method 1
it is possible to inhibit problems occurring in a work roll such as a decrease in surface roughness due to abrasion
Implementation Method 2
a recess and projection layer which is formed on the outer peripheral surface of the roll barrel, which has an arithmetic average roughness of 2.0 μm to 10.0 μm, and which contains granular chromium
Data Source
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AI summary
[Object] To provide a rolling work roll with which it is possible to effectively perform rolling with stable product qualities even with an increase in rolling distance when skin pass rolling is performed on a high-strength steel strip, and a skin pass rolling method using the roll. [Solution] A rolling work roll 2 includes a roll barrel 2x made of a cemented carbide having a Young's modulus of 450 GPa or higher, and a recess and projection layer 2y which is formed on the roll barrel 2x, which has an arithmetic average roughness Ra of 2.0 µm to 10.0 µm, and which contains granular chromium.