Steel Sheet Rolling Coolant Control for Oil Spots and Shape Defects
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Solution Overview
Problem
Existing methods for manufacturing steel sheets fail to prevent defects in appearance and shape due to oil spots from coolant and thermal deformation of work rolls, as they either inadequately control coolant drainage or excessively reduce coolant feeding rates, leading to incomplete cooling and shape defects.
Innovation Solution
A method that dynamically adjusts the coolant feeding rate based on the amount of center buckles and edge waves in the steel sheet, keeping it below a predetermined rate initially, increasing to an upper constant rate when center buckles exceed a target value, and decreasing to a lower constant rate when they fall below a lower target value, while monitoring and controlling thermal deformation of work rolls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the coolant feeding rate is increased to control thermal deformation of work rolls, then shape defects are prevented, but oil spots appear on the steel sheet surface causing appearance defects
Solution Approach 1:
The coolant feeding rate is dynamically adjusted based on the rolling mill's operational state. During startup and shutdown periods when oil spots are likely to occur, the feeding rate is controlled at a first (lower) rate. During stable operation when cooling is critical, the feeding rate is increased to a second (higher) rate. This dynamic adjustment resolves the contradiction by adapting the coolant flow to the actual thermal needs while preventing appearance defects during vulnerable operational phases.
Solution Approach 2:
The system performs preliminary action by detecting operational states (startup, shutdown, stable operation) in advance and adjusting the coolant feeding rate proactively. Before oil spots can form during startup/shutdown, the system already controls the feeding rate at the lower level. This preventive approach allows the system to avoid appearance defects while maintaining shape precision through appropriate cooling when needed.
2Object-affected harmful factors
If the coolant feeding rate is reduced to prevent oil spots, then appearance defects are prevented, but thermal deformation of work rolls occurs causing shape defects
Solution Approach 1:
The coolant feeding rate is dynamically adjusted based on the rolling mill's operational state. During startup and shutdown periods when oil spots are likely to occur, the feeding rate is controlled at a first (lower) rate. During stable operation when cooling is critical, the feeding rate is increased to a second (higher) rate. This dynamic adjustment resolves the contradiction by adapting the coolant flow to the actual thermal needs while preventing appearance defects during vulnerable operational phases.
Solution Approach 2:
The system uses feedback from operational state detection to adjust coolant feeding. By monitoring whether the rolling mill is in startup, shutdown, or stable operation mode, the system receives feedback about the current thermal and operational conditions. This feedback mechanism enables the system to automatically select the appropriate feeding rate, preventing both oil spots during vulnerable phases and thermal deformation during high-load phases.
3Object-affected harmful factors
If a liquid drainer is disposed near nozzles to improve coolant drainage, then oil spots on the upper surface are reduced, but oil spots on the lower surface still occur and complete prevention is not achieved
Solution Approach 1:
The coolant feeding rate control system serves multiple functions: it prevents oil spots on both upper and lower surfaces, controls thermal deformation of work rolls, and adapts to different operational phases. By making the feeding rate control universal and responsive to operational state, the system achieves complete prevention of oil spots rather than just partial prevention on specific surfaces, thereby improving reliability.
Solution Approach 2:
The system uses feedback from operational state detection to adjust coolant feeding. By monitoring whether the rolling mill is in startup, shutdown, or stable operation mode, the system receives feedback about the current thermal and operational conditions. This feedback mechanism enables the system to automatically select the appropriate feeding rate, preventing both oil spots during vulnerable phases and thermal deformation during high-load phases.
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 effectively prevents defects in appearance and shape by ensuring appropriate coolant drainage and thermal deformation control, reducing oil spots and edge waves, and maintaining high yield in steel sheet production.
Implementation Method 1
prevent temperature rise of the work rolls due to frictional heat caused during rolling of a steel sheet
Implementation Method 2
frictional heat caused during rolling of a steel sheet
Implementation Method 3
the sprayed coolant 3 is desirably drained in an atomized form
Data Source
AI summary
Provided is a method for rolling a steel sheet and a method for manufacturing a steel sheet capable of preventing occurrence of defects in appearance of a steel sheet caused by oil spots of a coolant and preventing occurrence of defects in shape of a steel sheet by appropriately controlling thermal deformation of work rolls. The method for rolling a steel sheet according to the present invention is a method for rolling a steel sheet involving feeding of a coolant to rolls that form a rolling mill during the rolling. The method includes keeping a coolant feeding rate at or lower than a predetermined rate lower than an upper constant rate at a start of operation of the rolling mill, and increasing the coolant feeding rate to the upper constant rate in response to an amount of center buckles of the steel sheet reaching or exceeding an upper target value.