Metal Strip Thermal Imaging for Accurate Emissivity Measurement

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Solution Overview

Problem

Current metal strip production lines face challenges in accurately measuring temperature and emissivity due to varying emissivity changes during processing, leading to erroneous measurements and poor product quality, especially in temperature-sensitive applications like high-strength steel production.

Innovation Solution

A system utilizing thermal imaging cameras to generate wide-angle images of the metal strip, allowing for real-time determination of temperature and emissivity by identifying and subtracting reflected radiation components, with feedback control signals to adjust processing parameters and minimize waste and energy consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If spot thermometers are used to measure temperature based on assumed emissivity values, then temperature measurement is simple and direct, but measurement accuracy deteriorates due to varying emissivity during processing

Engineering Contradiction:
Improvetemperature measurement accuracyVSAvoidmeasurement system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent introduces an intermediary calculation process that uses measured radiated flux and reflected flux components to determine emissivity and temperature. Instead of directly measuring temperature with assumed emissivity, the system first measures total radiated flux, calculates reflected flux from known background temperatures and geometry, then uses these as intermediaries to derive accurate temperature and emissivity values through iterative calculation.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the mechanical/physical spot thermometer measurement system with an optical radiation measurement system using thermal imaging cameras. This substitution allows non-contact measurement of radiated flux from multiple points simultaneously, enabling the calculation of both temperature and emissivity without physical contact or assumption of emissivity values.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Manufacturing precision

If emissivity is assumed to be constant, then temperature measurement is straightforward, but product quality deteriorates due to erroneous measurements in temperature-sensitive processes

Engineering Contradiction:
Improveproduct qualityVSAvoidsetup and measurement time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent implements continuous measurement and calculation of temperature and emissivity throughout the processing line. The thermal imaging camera continuously captures radiated flux data, and the system continuously calculates reflected flux and iteratively determines accurate temperature and emissivity values for each processing stage, ensuring real-time quality control without interruption to the production process.

Inventive Principle:
Principle #20Continuity of useful action

Solution Approach 2:

The patent incorporates feedback mechanisms where the measured radiated flux and calculated reflected flux are fed back into the iterative calculation process to continuously refine temperature and emissivity determination. The system uses feedback from background temperature measurements and geometric relationships to adjust and improve measurement accuracy throughout the processing sequence.

Inventive Principle:
Principle #23Feedback

3Measurement precision

If thermal imaging cameras capture wide-angle images of the processing line, then real-time temperature and emissivity measurement is achieved, but reflected radiation from background objects increases measurement complexity

Engineering Contradiction:
Improvereal-time measurement capabilityVSAvoidradiation component separation complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the total radiated flux into distinct components: flux directly emitted by the metal strip and flux reflected from background objects. By separating these components through geometric analysis and background temperature measurement, the system can isolate the strip's emitted radiation and calculate accurate temperature and emissivity values despite the presence of reflected radiation in wide-angle images.

Inventive Principle:
Principle #1Segmentation

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 provides accurate and real-time temperature and emissivity measurements, ensuring high-quality product production by minimizing waste and energy usage, and enabling precise control of processing stages like annealing and coating.

Implementation Method 1

A thermal imaging camera is provided at a location to generate a wide-angle image including temperature information for a large number of positions, corresponding to pixels within the camera

Methodology Applied
Scientific EffectThermal radiation: Thermal Radiation

Implementation Method 2

By identifying and subtracting reflected components of radiation it may be possible to determine a radiated component, emitted directly from the metal strip

Methodology Applied
Scientific EffectReflection: Reflection

Data Source

PatentEP3729026B1Measurement system for metal strip production line
Publication Date: 2021.08.04 LAND INSTRUMENTS INTERNATIONAL LTD
  • EP3729026B1 patent drawingFigure 1
  • EP3729026B1 patent drawingFigure 2
  • EP3729026B1 patent drawingFigure 3

AI summary

A metal strip production line measurement system is disclosed comprising a thermal imaging camera (8) configured to receive thermal radiation from a plurality of positions on a metal strip being conveyed along a production line and to generate an image based on the thermal radiation received. A temperature or emissivity calculation unit (34) is also provided within a processor (36) to determine temperature and/or emissivity for the plurality of positions which includes identifying and subtracting a reflected component in the radiation received at the thermal imaging camera from a position on the metal strip.