Hybrid Spray Bar Cooling for Upper Work Roll Coolant Pools
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Solution Overview
Problem
Existing roll stands face challenges in achieving uniform and efficient cooling of upper work rolls due to the formation of coolant pools and the inefficiencies of current nozzle designs, which can lead to inadequate heat removal and potential damage from improper water tank positioning.
Innovation Solution
The roll stand incorporates lower spray nozzles designed as solid jet nozzles, which emit a focused coolant jet with higher impact pressure, capable of penetrating coolant pools, combined with upper and middle spray bars featuring flat or full jet nozzles, optimizing coolant distribution and pressure to enhance cooling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If flat jet nozzles are used in the upper spray bar, then coolant distribution is improved, but coolant pools form on the upper scraper element reducing cooling efficiency
Solution Approach 1:
The cooling system is segmented into multiple spray bars (upper, middle, lower) with different nozzle types positioned at different locations. The upper spray bar uses flat jet nozzles for broad distribution, while the lower spray bar uses solid jet nozzles to penetrate coolant pools, dividing the cooling function into specialized segments that address different problems.
Solution Approach 2:
Different nozzle types are assigned to different locations based on local requirements. Flat jet nozzles are used where broad coverage is needed (upper spray bar), while solid jet nozzles are used where high penetration power is needed to cut through coolant pools (lower spray bar). Each location has the specific nozzle quality needed for its function.
2Reliability
If water boxes are positioned close to work rolls for efficient cooling, then cooling efficiency is improved, but risk of damage to work rolls and water boxes increases
Solution Approach 1:
The spray bars with nozzles act as intermediaries between the coolant supply system and the work rolls. Instead of positioning water boxes directly against the rolls (which creates damage risk), the spray bars deliver coolant through controlled jets from a safe distance, maintaining cooling efficiency while eliminating direct contact damage risks.
Solution Approach 2:
The system uses hydraulic pressure to deliver coolant through spray bars and nozzles. The pressurized liquid jets can reach the work rolls effectively from a distance, providing efficient cooling without requiring physical contact or close positioning that would create damage risks.
3Power
If a single cooling beam with full jet nozzles is used, then intensive cooling is achieved, but uniform cooling over the entire width of work rolls becomes difficult
Solution Approach 1:
The single cooling beam is segmented into multiple spray bars (upper, middle, lower) arranged vertically. Each spray bar targets a specific region of the work roll width, ensuring that the entire surface receives uniform cooling coverage. This segmentation allows intensive cooling to be distributed uniformly across the roll width.
Solution Approach 2:
The cooling system transitions from a single horizontal cooling beam to a multi-level vertical arrangement of spray bars. By adding the vertical dimension with multiple spray bars at different heights, the system achieves both intensive cooling (through multiple nozzles) and uniform distribution (through vertical spacing that covers the entire roll width).
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
This configuration ensures highly efficient and uniform cooling of the upper work roll, effectively managing coolant pools and improving heat removal, while being simple to implement and retrofitting existing systems.
Implementation Method 1
at least some of the lower spray nozzles—usually all the lower spray nozzles—are designed as solid jet nozzles. Solid jet nozzles are spray nozzles that emit an essentially straight coolant jet. The coolant jet usually has a circular or almost circular cross-section.
Implementation Method 2
Solid jet nozzles generate a significantly higher impact pressure on the work roll than flat jet nozzles. The higher impact pressure not only causes a higher cooling effect.
Implementation Method 3
Flat jet nozzles, on the other hand, have a spray pattern in which the discharged coolant jet expands like a fan. The opening angle of the fan is at least 20°. The coolant discharged from a fan jet nozzle thus impinges on the upper work roll substantially in the form of an elongated line.
Implementation Method 4
Intensive cooling is therefore necessary in order to withdraw the heat supplied via the flat rolling stock, in particular from the work rolls.
Data Source
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AI summary
A rolling stand (1) for rolling a flat workpiece (2) has an upper work roll (3) and a lower work roll (4) which form a roll gap (5) between them. The flat workpiece (2) passes through the roll gap (5) in a transport direction (x) during the rolling process. An upper cooling device (8) is arranged at the exit end of the rolling stand (1) by means of which the upper work roll (3) is cooled. The upper cooling device (8) has an upper spray bar (17) which extends parallel to the upper work roll (3) and has a plurality of upper spray nozzles (22) by means of which a liquid coolant (12) is sprayed onto the upper work roll (3).The upper cooling device (8) further comprises a lower spray bar (18) extending parallel to the upper work roll (3) and having a plurality of lower spray nozzles (23) by means of which the liquid coolant (12) is sprayed onto the upper work roll (3). The lower spray bar (18) is arranged between the flat rolled material (2) and the upper spray bar (17). At least some of the upper spray nozzles (22) are designed as flat jet nozzles, and at least some of the lower spray nozzles (23) are designed as full jet nozzles.