Variable-Rate Cooling Bars for Uniform Steel Sheet Quenching
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Solution Overview
Problem
Conventional cooling devices in plate mills and hot strip mills often result in uneven cooling, leading to internal stresses and quality issues in rolled materials due to limitations in achieving both high and low cooling rates with uniformity.
Innovation Solution
A cooling device comprising two cooling bars with full jet and full cone nozzles arranged symmetrically, allowing for high and low cooling rates, and controlled by a system that adjusts coolant quantity and pressure individually for each nozzle, ensuring precise and uniform cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If water jet cooling is used to achieve high cooling rates, then cooling rate is improved, but cooling uniformity deteriorates
Solution Approach 1:
The cooling system is segmented into multiple nozzle types (full jet nozzles and full cone nozzles) arranged in alternating sequence along the cooling bar. This segmentation allows different zones to provide different cooling intensities, with full jet nozzles delivering high cooling rates and full cone nozzles providing gentler cooling, thereby achieving both high cooling rates and uniform cooling distribution across the strip width
Solution Approach 2:
Different nozzle types are assigned to different local positions along the cooling bar to match the local cooling requirements. Full jet nozzles are positioned where higher cooling rates are needed, while full cone nozzles are positioned where gentler cooling is required, creating a non-uniform nozzle configuration that produces uniform overall cooling效果
2Manufacturing precision
If air fan cooling is used to achieve low cooling rates, then cooling uniformity is improved, but cooling rate deteriorates
Solution Approach 1:
The cooling system includes full cone nozzles that are specifically designed to provide low cooling rates with good uniformity. These nozzles are segmented and distributed along the cooling bar to cover the entire strip width, ensuring that even at low cooling rates, uniform cooling is maintained across all zones
Solution Approach 2:
The system uses water spray through full cone nozzles instead of air fan cooling. The full cone nozzles are designed to create a conical spray pattern that distributes water evenly across the strip surface, achieving uniform cooling at low cooling rates (1-2 K/s) that is sufficient for cracking-sensitive steel grades
3Device complexity
If conventional single nozzle type is used, then device complexity is reduced, but adaptability deteriorates
Solution Approach 1:
The cooling bar is designed with multiple nozzle types (full jet nozzles and full cone nozzles) that can serve different cooling rate requirements within a single device. This multi-functional nozzle configuration allows the same cooling bar to achieve both high cooling rates (up to 150 K/s) and low cooling rates (1-2 K/s), making the system adaptable to different steel grades and product requirements without requiring multiple separate cooling devices
Solution Approach 2:
The system enables dynamic adjustment of cooling rates by controlling which nozzle types are activated and at what water flow rates. The alternating arrangement of full jet and full cone nozzles allows flexible combination and individual control, enabling the cooling rate to be dynamically adjusted across a wide range to match different production requirements
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
Enables seamless adjustment of cooling rates from 1 K/s to 150 K/s, ensuring precise control over material properties and minimizing internal stresses, thus enhancing the quality of rolled sheets.
Implementation Method 1
a water jet is directed in the form of a cylinder at the rolled stock to be cooled
Implementation Method 2
high cooling rates can be achieved with water jet cooling
Implementation Method 3
low cooling rates with air fan cooling (forced convection)
Data Source
AI summary
A cooling device with variable cooling rate for treating metal materials, in particular for cooling steel sheets in plate mills, hot strip mills or thermal treatment lines, by means of a spray nozzle cooling system. The cooling device consists of at least two cooling bars one of each two cooling bars being situated on the lower side and the other on the upper side transversely to the sheet travel direction of the sheet and centrally between two roller table rollers and includes a spray nozzle cooling system with which a plurality of full jet nozzles and a plurality of full cone nozzles are associated, the full jet nozzles being arranged symmetrically to the full cone nozzles. A method for operating the cooling device according to the disclosure.