Hot Strip Rolling Control Using Force-Guided Induction Heating
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Solution Overview
Problem
Hot Strip Mills face issues with temperature non-uniformity due to 'skid marks' on the slabs, leading to thickness control problems and quality defects in finished products, as existing pyrometric temperature measurement methods are inaccurate and surface-based, failing to represent the average temperature of the bar effectively.
Innovation Solution
A new generation rolling plant with a rapid heating device and mechanical deformation detection means to apply localized heating based on rolling force variations, ensuring uniform temperature across the bar length by activating thermal induction modules strategically to compensate for temperature differences caused by skid marks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pyrometric temperature detectors are used to measure surface temperature, then temperature measurement is possible, but the measurement accuracy is insufficient because surface temperature does not represent average section temperature
Solution Approach 1:
The patent replaces pyrometric temperature detection with mechanical deformation detection. Load cells measure rolling force variations, which indirectly indicate temperature differences in the bar section. This mechanical measurement system provides more accurate information about average section temperature compared to surface pyrometric measurement.
Solution Approach 2:
The patent introduces rolling force as an intermediary parameter to infer temperature distribution. Instead of measuring temperature directly, the system measures rolling force variations caused by temperature differences, using force as a mediator to obtain temperature information that better represents the average section temperature.
2Temperature
If inductors are activated based on surface temperature readings, then heating can be applied, but the heating effectiveness is reduced because skid marks are on the lower surface while measurement is on the upper surface
Solution Approach 1:
The patent replaces pyrometric temperature measurement with mechanical deformation detection using load cells. By measuring rolling force variations, the system directly detects temperature differences in the bar section including skid mark areas, enabling accurate identification of heating needs regardless of surface orientation.
Solution Approach 2:
The patent implements a feedback control system where rolling force measurements continuously inform inductor activation decisions. The command and control unit uses real-time rolling force data to dynamically adjust inductor operation, ensuring heating is applied precisely where temperature uniformity needs to be maintained.
3Temperature
If additional heating is applied to compensate for skid marks, then temperature uniformity improves, but energy consumption increases
Solution Approach 1:
The patent applies heating locally and selectively based on detected rolling force variations. Instead of uniform heating of the entire bar, the command and control unit activates specific inductors only in zones where temperature non-uniformity is detected, optimizing energy usage while achieving temperature uniformity.
Solution Approach 2:
The system uses continuous feedback from rolling force measurements to control inductor operation. Heating is applied dynamically and only when and where needed, based on real-time detection of temperature variations, minimizing unnecessary energy consumption while maintaining temperature uniformity.
4Measurement precision
If rolling force detection is used to identify temperature variations, then temperature measurement accuracy improves, but device complexity increases
Solution Approach 1:
The patent uses the rolling process itself to generate measurement information. The rolling force variations, which are inherent to the rolling process, serve as the measurement signal for temperature detection. This eliminates the need for separate temperature measurement devices, reducing overall system complexity while improving measurement accuracy.
Solution Approach 2:
The patent uses rolling force as an intermediary parameter that is already present in the rolling process. By leveraging this existing mechanical parameter, the system obtains temperature information without requiring additional complex temperature measurement equipment, thus avoiding increased device complexity.
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 solution effectively maintains uniform average temperature of the bar, improving the dimensional and microstructural quality of the finished product while maintaining high productivity, up to 6 million tons per year, by precisely tracking and compensating for temperature variations, thus enhancing the thickness control and uniformity of the rolled products.
Implementation Method 1
a rapid heating device (28) consisting of selectively activatable thermal induction modules (41, 42), interposed between the last pre-finishing stand (26) and the finishing stands (31)... to apply localized heating based on rolling force variations
Implementation Method 2
mechanical deformation detection means (40), associated with the last pre-finishing stand (26), to constantly detect the rolling force applied on the pre-finished rolled product (52)
Data Source
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AI summary
Rolling plant (10) and method for producing a strip (P) starting from a slab (50) having a certain starting thickness, comprising at least one walking beam heating furnace (16) configured to heat at least the slab (50) to a starting temperature, and a rolling train (25) operatively disposed in line with at least one roughing stand (23) and configured to reduce the thickness of an intermediate rolled product (51) at exit from the roughing stand (23), until the final strip (P) is obtained; the rolling train (25) comprising at least one pre-finishing stand (26) for obtaining a pre-finished rolled product (52), and a plurality of finishing stands (31) for obtaining the final strip (P); the plant (10) comprising load cells (40) directly associated with the pre-finishing stand (26) for detecting the rolling force applied on the pre-finished rolled product (52), a rapid heating device (28), interposed between the pre-finishing stand (26) and the finishing stands (31), for heating the pre-finished rolled product (52), and a command and control unit (44) connected both to the load cells (40) and also to the rapid heating device (28) and configured at least to selectively activate the latter (28), at least as a function of the rolling force detected by the load cells (40).