Hot Rolling Friction Control via Dynamic Lubrication
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Solution Overview
Problem
Current hot rolling methods fail to continuously regulate the coefficient of friction effectively during the process, leading to issues like excessive energy consumption, roll deterioration, surface defects, slippage, and productivity losses, especially when dealing with high-strength steels or varying strip thicknesses.
Innovation Solution
A method that calculates the forward slip ratio and estimated coefficient of friction using real-time measurements of screwdown force and speed, allowing for dynamic regulation of lubrication parameters to maintain optimal friction levels throughout the rolling process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lubricating emulsion is injected continuously during hot rolling, then the coefficient of friction is reduced preventing slippage and threading issues, but the beginning and end sections of the strip must be scrapped due to lack of lubrication, reducing productivity
Solution Approach 1:
The patent applies preliminary action by deactivating the lubricating emulsion injection before the strip enters the rolling stand and after it exits. This prevents lubricant contamination at the beginning and end sections that would cause threading issues, while maintaining continuous lubrication during the critical rolling process to prevent slippage and maintain friction within the optimal range.
Solution Approach 2:
The patent implements periodic action by cyclically activating and deactivating the lubricating emulsion injection system. The injection is activated during the main rolling process when friction needs to be controlled, and deactivated during transition periods (before strip entry and after strip exit) to prevent contamination. This periodic operation optimizes both reliability and productivity.
2Reliability
If the coefficient of friction is too high during hot rolling, then lubrication is insufficient, but this leads to excessive energy consumption, rapid roll deterioration, and surface defects on the strip
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the coefficient of friction through controlled injection of lubricating emulsion. By modifying the lubrication parameter (emulsion injection rate), the system maintains friction within the optimal range of 0.15-0.35, preventing both excessive friction (which causes energy loss and surface defects) and insufficient friction (which causes slippage).
Solution Approach 2:
The patent implements feedback control by continuously monitoring the coefficient of friction and adjusting the lubricating emulsion injection rate accordingly. The system measures actual friction conditions and modifies lubrication parameters in real-time to maintain optimal friction levels, thereby preventing energy waste while ensuring adequate lubrication throughout the rolling process.
3Loss of energy
If the coefficient of friction is too low during hot rolling, then energy consumption is reduced, but slippage problems and guidance issues occur
Solution Approach 1:
The patent applies parameter changes by controlling the lubricating emulsion injection to maintain the coefficient of friction within the optimal range of 0.15-0.35. By adjusting the lubrication parameter, the system prevents friction from becoming too low (which would cause slippage) while also preventing it from becoming too high (which would waste energy).
Solution Approach 2:
The patent implements feedback control by monitoring friction conditions and adjusting lubrication in real-time. When friction approaches the lower limit, the system increases emulsion injection to maintain adequate friction for proper strip guidance and prevent slippage, while still reducing energy consumption compared to inadequate lubrication.
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 ensures stable and efficient hot rolling by continuously adjusting lubrication to prevent slippage and threading issues, reducing waste and maintaining consistent output across varying conditions.
Implementation Method 1
Regulation of the coefficient of friction is assured, in particular, by the lubrication process. Currently, the lubrication is generally carried out at the level of each stand of the rolling mill by the injection of an emulsion composed of water and a lubricating fluid, conventionally oil, on the roll at the level of the gap.
Implementation Method 2
During the hot rolling of steel strips, in each stand of the finishing line, the steel strip is subjected to a precisely determined sequence of thermal and mechanical operations (reduction, temperature) which is influenced by the friction between the work rolls and the strip in the gap between the rolls.
Data Source
AI summary
A method for the regulation of at least one of the parameters (α) of a hot rolling process of a semi-finished metal product in at least one rolling mill stand having at least two work rolls is provided. The regulation method includes calculating a forward slip ratio (FWS) with the following equation:FWS=|vexit-vstand|vstandwhere vexit is the speed of the semi-finished product at the exit of the respective stand and vstand is the linear velocity of the work rolls; calculating an estimated coefficient of friction (μreal) as a function of a measured value of the screwdown force (F) of the work rolls in the stand and of the forward slip ratio (FWS); and regulating at least one of the parameters (α) based on the calculated estimated coefficient of friction (μreal).