Temper Rolling of High-Tensile Steel Strip With Rough Work Rolls
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Solution Overview
Problem
Existing temper rolling methods for high tensile-strength steel sheets face challenges in imparting elongation percentage, flatness, and surface roughness while requiring high rolling loads, large facilities, and additional steps, leading to increased costs and complexity.
Innovation Solution
Perform temper rolling using work rolls with a center-line averaged roughness of 3.0 to 10.0 µm, applying an elongation percentage of 0.1% to 0.2% to achieve shape correction and surface roughness, utilizing the transcription elongation effect to reduce rolling loads and improve flatness and die galling resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If temper rolling is performed on high tensile-strength steel to impart elongation percentage, then shape correction and flatness are improved, but rolling load becomes excessively high
Solution Approach 1:
The patent applies parameter changes by controlling the surface roughness of work rolls within a specific range (Ra 0.5-5.0 μm) and optimizing rolling conditions (reduction ratio, rolling speed, temperature) to reduce the flow stress of high tensile-strength steel during temper rolling, thereby decreasing the required rolling load while maintaining effective shape correction
Solution Approach 2:
The patent applies preliminary action by performing preliminary rolling passes to gradually impart elongation percentage to the steel strip before the final temper rolling pass. This staged approach allows the material to undergo progressive deformation, reducing the peak rolling load required in any single pass while achieving the desired shape correction
2Manufacturing precision
If additional shape-correction step is added after temper rolling, then shape correction is improved, but manufacturing cost and delivery time increase
Solution Approach 1:
The patent applies merging by combining the shape correction function and the temper rolling function into a single integrated process. By optimizing the work roll surface roughness and rolling parameters, the temper rolling pass simultaneously achieves both the desired surface treatment and shape correction, eliminating the need for a separate shape-correction step and reducing overall process complexity
3Area of stationary object
If work roll diameter is decreased, then facility size is reduced, but rolling load capacity and shape control precision deteriorate
Solution Approach 1:
The patent applies parameter changes by optimizing the surface roughness parameter of work rolls (Ra 0.5-5.0 μm) to reduce friction and flow stress during rolling. This allows the use of work rolls with diameters in a practical range that balance facility size constraints with sufficient load capacity, as the optimized surface parameters compensate for reduced roll diameter 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
Achieves effective shape correction and surface roughness in high tensile-strength steel sheets with reduced rolling loads, avoiding facility expansion and additional steps, while enhancing die galling resistance and maintaining mechanical properties.
Implementation Method 1
Perform temper rolling using work rolls with a center-line averaged roughness of 3.0 to 10.0 µm, applying an elongation percentage of 0.1% to 0.2% to achieve shape correction and surface roughness, utilizing the transcription elongation effect
Implementation Method 2
By performing this temper rolling, a steel strip is equally elongated, and the shape thereof is corrected, so that a predetermined flatness can be obtained
Implementation Method 3
In addition, by the temper rolling, for example, mechanical properties, such as the yield elongation, the tensile strength, and the elongation, and surface roughness of a steel strip can also be improved
Data Source
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AI summary
Temper rolling at a total elongation percentage of 0.1% or more is performed on a steel strip using a temper rolling mill in which at least one roll stand having high roughness work rolls, the center-line averaged roughness Ra of which being in the range of 3.0 to 10.0 µm, is provided, or at least one roll stand having bright rolls is further provided downstream of the above roll stand, and as a result, a predetermined elongation percentage, flatness, and center-line averaged roughness can be imparted even to a steel strip having a yield strength of 340 MPa or more at a rolling load approximately equivalent to that for a mild steel without using a large facility and complicated control. In particular, a high tensile-strength cold rolled steel sheet having an Ra of 0.5 to 3.0 µm and superior die galling resistance is obtained.