Hot-Rolled Steel Strip Cooling System with Flexible Guide
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Solution Overview
Problem
Conventional cooling systems for hot-rolled steel strips are insufficient in cooling capacity and scale, making it impractical to industrially produce high-tensile steel with a fine-grained structure at a low cost without alloy elements, due to inadequate cooling rates and nozzle arrangements.
Innovation Solution
A cooling system with a guide and roll cooling nozzles that jet a large amount of cooling water directly to the rolled material through numerous jet holes, supported by a flexible separating member to prevent water from hitting the material, allowing for rapid cooling and adaptation to varying work roll diameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional cooling systems are used, then the cooling capacity is insufficient, but increasing the cooling capacity requires larger scale equipment which increases cost
Solution Approach 1:
The cooling system is segmented into multiple nozzle rows (first, second, third, and fourth rows) arranged at different positions relative to the work rolls. Each row serves a specific cooling function: the first row cools the rolled material immediately after rolling, the second row cools the work rolls, the third row provides additional cooling to the rolled material, and the fourth row cools the work rolls again. This segmentation allows achieving high cooling capacity without requiring a single large-scale cooling apparatus.
Solution Approach 2:
Different nozzle rows are positioned to provide localized cooling to different areas. The nozzles are arranged to jet cooling water to specific locations: some nozzles jet water to the rolled material while others jet water to the work rolls. This local quality approach ensures that cooling is applied precisely where needed, maximizing cooling efficiency without increasing overall system scale.
2Manufacturing precision
If high reduction rolling is applied to achieve fine-grained structure, then grain refinement is achieved, but the equipment cost increases
Solution Approach 1:
The system utilizes the working heat generated during high reduction rolling itself to achieve grain refinement. The intensive cooling applied immediately after rolling exploits the thermal energy already present in the rolled material, eliminating the need for external heating equipment or additional energy input. This self-service approach allows achieving fine-grained structure (3-4 μm or less) without increasing equipment cost.
3Temperature
If multiple nozzle rows are arranged close to work rolls, then cooling capacity increases, but water may hit the rolled material causing quality issues
Solution Approach 1:
A flexible separating member is introduced as an intermediary between the nozzles and the rolled material. This separating member prevents cooling water from directly hitting the rolled material while still allowing the nozzles to be positioned close to the work rolls for effective cooling. The flexible nature of the separating member allows it to adapt to the rolling process while maintaining the barrier function.
Solution Approach 2:
The separating member is designed to be flexible rather than rigid, allowing it to dynamically adapt to the changing conditions during rolling. This flexibility enables the separating member to maintain its protective function while accommodating the dynamic nature of the rolling process and the proximity of the nozzles to the work rolls.
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 system achieves a high cooling rate of approximately 1000 °C/s, enabling the industrial production of high-tensile steel with a fine-grained structure at a low cost without additional alloy elements, by ensuring efficient water distribution and adaptation to rolling mill configurations.
Implementation Method 1
a large number of jet holes are formed in the guide, and rolled material cooling nozzles are provided to jet cooling water directly to the rolled material through the jet holes
Implementation Method 2
jetting a large amount of cooling water directly to the rolled material through the jet holes of the guide
Implementation Method 3
a flexible separating member to prevent water from hitting the material
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
Provided is a cooling system for a hot-rolled steel strip capable of increasing the cooling rate for rapidly cooling a rolled steel immediately after rolling and suitable for an apparatus for manufacturing a hot-rolled steel strip having a fine-grained structure. For this purpose, guides (16A, 16B) having guiding surfaces (16a, 16b) to guide a rolled steel (W) exiting work rolls (12A, 12B) in the conveyance direction are provided at exits of the work rolls in a final stand (Sn) of a finish rolling mill line in a manner that the guides can follow a change in the diameter of the work rolls, a number of injection holes (21A, 21B) are formed in the guides, and a number of rolled steel cooling nozzles (23A, 23B) are provided to spray a large amount of cooling water through the injection holes directly onto the rolled steel.