Moving Metal Strip Temperature Imaging in the Roll Wedge Zone
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Solution Overview
Problem
Current methods for measuring the temperature of a moving steel strip in an annealing furnace are inaccurate due to emissivity variations and interference from furnace walls, and existing solutions are either costly or difficult to install and maintain, particularly when measuring over the full width of the strip.
Innovation Solution
Employing infrared or visible light cameras to measure the temperature in the wedge shaped opening between the strip and the roll, using two cameras positioned on either side of the roll to capture the full width of the strip, which provides a 2D image and allows for accurate temperature measurement with reduced emissivity interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a scanning pyrometer is used to measure temperature over the full width of the strip, then measurement coverage is improved, but the system becomes costly and complex to install and maintain
Solution Approach 1:
The patent divides the measurement task into segments by using multiple spot pyrometers positioned at different locations. Each pyrometer measures a specific spot on the strip, and the measurements are combined to obtain the temperature distribution across the full width. This segmentation approach achieves full-width coverage without requiring a single complex scanning system.
Solution Approach 2:
The patent combines multiple simple spot pyrometer measurements to achieve the functionality of a complex scanning pyrometer. By merging the data from multiple stationary pyrometers positioned at different transverse locations, the system achieves full-width temperature measurement coverage while maintaining simplicity in individual components.
2Object-affected harmful factors
If a water-cooled cone is used to shield the strip surface, then radiation interference from furnace walls is reduced, but the risk of cooling water leakage increases and installation becomes difficult
Solution Approach 1:
The patent extracts the pyrometer from the hot furnace environment by positioning it outside the furnace and using the wedge-shaped opening to access the strip surface. This eliminates the need for water-cooled shielding cones inside the furnace, removing the leakage risk while still achieving accurate temperature measurement by measuring in the wedge-shaped opening where emissivity is high and radiation interference is minimized.
Solution Approach 2:
The patent uses the wedge-shaped opening between the roll and strip as an intermediary measurement zone. This opening provides a natural shielded path for infrared radiation from the strip to reach the pyrometer, eliminating the need for artificial water-cooled shields. The wedge-shaped opening acts as a passive intermediary that blocks furnace wall radiation while allowing strip radiation to be measured.
3Ease of operation
If a spot pyrometer is used to measure temperature at a single point, then measurement simplicity is maintained, but measurement precision is reduced due to emissivity variations
Solution Approach 1:
The patent transitions from measuring a single point to measuring across the transverse dimension by positioning multiple spot pyrometers at different transverse locations. This dimensional expansion allows the system to capture temperature distribution across the strip width while maintaining the simplicity of spot pyrometer operation. The wedge-shaped opening ensures high emissivity measurements at each location.
4Stability of the object's composition
If the pyrometer is attached to the furnace wall to maintain fixed position, then measurement stability is improved, but the measuring spot shifts due to furnace thermal expansion and contraction
Solution Approach 1:
The patent replaces mechanical attachment to the furnace wall with optical alignment through the wedge-shaped opening. The pyrometer is positioned to measure through the opening defined by the roll and strip geometry, which remains stable relative to the strip. This substitution of mechanical mounting with geometric alignment eliminates the problem of thermal expansion-induced position shifts.
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 method enables accurate temperature measurement over the full width of the strip with a deviation of no more than 10°C, is easier to control, and is less expensive than traditional scanning pyrometers, while also detecting shape and surface defects.
Implementation Method 1
Infrared radiation coming from the surface of the strip is collected by using a rotating mirror
Implementation Method 2
The radiation from the strip is reflected in this mirror and focussed on a single point detector
Implementation Method 3
the emissivity of the strip is rather low in comparison to the emissivity of a black body... in the wedge shaped opening the emissivity of the steel strip is not affected by infrared radiation noise from the surrounding, and the emissivity is almost the emissivity of a black body, so the emissivity value is close to unity
Data Source
Figure 1
AI summary
The invention relates to a method for measuring the temperature of a moving strip, wherein the strip is in contact with a roll such that a wedge shaped opening is present between the strip and the roll where the strip and the roll depart and a wedge shaped opening is present between the strip and the roll where the strip and the roll meet. According to the invention, the temperature of the strip is measured along at least part of the length of at least one of the wedge shaped openings using an infrared or visible light measuring camera. The invention also relates to a system for measuring the temperature of a moving strip.