Hot Strip Descaling Layout for Uniform Secondary Scale Thickness
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In hot rolling mills, uneven scale layer thickness on the upper and lower sides of metal strips leads to thrust rolling effects, ski formation, and rolling torque issues, which affect strip running stability and quality, as the existing methods fail to maintain optimal scale formation conditions.
Innovation Solution
The method involves determining and optimizing the thickness of secondary scale layers on both sides of the metal article by adjusting the distance between descaling nozzles and roll stands, using a process model to calculate and set the scale thickness difference to within 15% and temperature difference to within 3% to ensure symmetrical scale formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the strip is descaled using high-pressure water jets in a scale washer, then the scale is removed from the strip surface, but a secondary scale layer immediately forms again during transport and the scale layer thickness becomes uneven between upper and lower sides
Solution Approach 1:
The patent applies preliminary action by positioning the upper row of nozzles closer to the roll stand than the lower row, so that the upper side of the strip receives descaling treatment earlier in the transport path. This preliminary timing difference compensates for the faster secondary scale formation on the upper side, ensuring both sides have uniform scale thickness when reaching the roll stand.
Solution Approach 2:
The patent changes the spatial parameter (distance from roll stand) of the nozzle rows asymmetrically. The upper row is positioned at a first distance while the lower row is at a second distance, creating intentional asymmetry in the descaling process to achieve symmetric scale thickness results by accounting for different secondary scale formation rates on each side.
2Temperature
If symmetrical temperature distribution is maintained from upper to lower side in the scale washer region, then temperature control is improved, but scale formation behavior is not optimally influenced and scale layer thickness remains uneven
Solution Approach 1:
The patent deliberately introduces asymmetry in the nozzle positioning (different distances from the roll stand for upper and lower rows) to compensate for the symmetrical temperature distribution. This asymmetric geometric arrangement creates different exposure times to the descaling medium, which compensates for the symmetric thermal conditions and achieves uniform scale thickness.
3Reliability
If different scale layer thicknesses exist on upper and lower sides of the strip, then thrust rolling effects and ski formation occur, but these are consequences rather than direct controllable parameters
Solution Approach 1:
By positioning the upper nozzles closer to the roll stand, the system performs preliminary descaling on the upper side earlier in the process. This timing adjustment ensures that when the strip reaches the roll stand, both upper and lower sides have developed uniform secondary scale thickness, preventing thrust rolling effects and maintaining strip running stability.
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 approach enables targeted control of scale formation, improving strip quality and stability by maintaining equal scale layer thickness and temperature across both sides, thereby reducing secondary scale effects and enhancing rolling mill performance.
Implementation Method 1
the article is subjected in the scale washer to at least one upper row of nozzles, which descales the upper side of the article, and to at least one lower row of nozzles, which descales the lower side of the article
Implementation Method 2
a secondary scale layer immediately forms again during further transport
Data Source
AI summary
A method for producing a metal article, in particular a slab, a pre-strip, a strip, or a sheet, in which the article is first conveyed in the conveying direction through a scale washer and then through a rolling mill, wherein the rolling mill has at least one roll stand, in particular a first roll stand in the conveying direction. The article is subjected in the scale washer to at least one upper row of nozzles, which descales the upper side of the article, and to at least one lower row of nozzles, which descales the lower side of the article.