Induction Preheating of Work Rolls for Thermal Profile Control
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Solution Overview
Problem
Existing rolling processes in metallurgy face challenges in achieving consistent flatness and thickness control of metal strips due to thermal expansion and mechanical stress-induced defects in work rolls, often requiring multiple sensors and leading to material loss and post-defect detection.
Innovation Solution
A method for preheating work rolls using electromagnetic induction to achieve a predefined thermal expansion profile, utilizing a thermal control device with inductors and a processing unit to iteratively adjust thermal power based on predefined physical models, ensuring the work rolls have a stable thermal state matching the target profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple sensors are used to measure roll temperature and thermal expansion, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent extracts the measurement function from separate sensors and integrates it into the inductor system itself. The inductor serves dual purposes: heating the work roll and measuring its thermal expansion through impedance changes, eliminating the need for separate measurement sensors and reducing system complexity while maintaining measurement precision
Solution Approach 2:
The inductor is designed to perform multiple functions simultaneously: it acts as both a heating element (delivering thermal power) and a measurement sensor (detecting thermal expansion via impedance changes). This multi-functionality reduces the number of components needed in the system while achieving both thermal control and precise measurement
2Manufacturing precision
If thermal control device with inductors is used to modify thermal expansion profile, then manufacturing precision is improved, but use of energy increases
Solution Approach 1:
The patent applies local quality by distributing multiple inductors along the longitudinal axis of the work roll, each controlling the thermal expansion in its specific zone. This localized approach allows precise thickness profile control in different regions of the roll while minimizing unnecessary energy consumption in areas that don't require thermal adjustment
Solution Approach 2:
The system uses feedback control where the impedance changes of the inductors (which reflect thermal expansion) are continuously monitored and used to adjust the thermal power delivered by each inductor. This closed-loop control ensures the target thermal expansion profile is achieved while optimizing energy usage by adjusting power delivery based on actual roll condition
3Stability of the object's composition
If iterative adjustment of thermal power is performed, then stability of thermal profile is improved, but time consumption increases
Solution Approach 1:
The patent implements continuous useful action by performing iterative thermal power adjustments during the preheating phase before production rolling begins. The system continuously monitors impedance changes and adjusts thermal power delivery in real-time iterations, ensuring the thermal profile stabilizes to the target profile before actual metal rolling starts, thus achieving stability without extending production time
Solution Approach 2:
The iterative thermal profile stabilization is performed as a preliminary action during the preheating phase before the actual rolling operation begins. By completing all necessary thermal adjustments and stabilizing the roll profile in advance, the system ensures optimal rolling conditions are achieved without causing time loss during production rolling
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
The method enables efficient and precise thermal expansion of work rolls, reducing defects and ensuring the rolled metal strip achieves desired thickness and flatness without the need for additional sensors, thereby improving production efficiency and material utilization.
Implementation Method 1
a thermal control device comprising Ni spray nozzle inductors distributed along the longitudinal axis of the working roll opposite the Ns longitudinal segments
Implementation Method 2
the working roll has a target thermal expansion profile determined along Ns longitudinal segments of the working roll
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3
AI summary
The invention relates to a method for preheating at least one working roll for rolling, involving phases of: - determining a target thermal expansion profile, - determining an effective mean temperature profile of longitudinal segments of the working roll and for determining a target mean temperature profile; - activating a plurality of inductors distributed along the working roll in order to reduce a difference between the effective mean temperature and the target mean temperature.