Thermographic Basis Weight Mapping for Coated Metal Sheet Lines
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Solution Overview
Problem
Existing on-line measurement systems for sheet materials, such as coated metal foils used in lithium-ion batteries, face challenges in accurately measuring basis weight and thickness due to variations in the machine and cross directions, limited measurement coverage, and the inability to provide real-time data across the entire sheet width and length.
Innovation Solution
A system that combines thermal imaging with online scanning basis weight measurements and temperature sensing to correlate thermographic image data, allowing for more accurate and comprehensive basis weight and thickness calculations across the cross direction by using a thermal imaging camera, a beta gauge, and an infrared temperature sensor, which computes the areal weight and accounts for sheet cooling conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a scanning sensor is used to measure basis weight across the sheet width, then measurement coverage is improved, but measurement precision deteriorates due to sheet velocity causing diagonal scanning paths and zig-zag patterns
Solution Approach 1:
The patent replaces the mechanical scanning sensor system with a thermographic imaging system that uses infrared radiation detection. Instead of physically scanning across the sheet with a sensor that suffers from velocity-induced diagonal paths, the system uses a stationary or synchronized thermographic camera to capture temperature distributions across the entire sheet width simultaneously, eliminating the mechanical scanning problem while maintaining comprehensive measurement coverage
Solution Approach 2:
The patent changes the measurement parameter from direct basis weight measurement to temperature measurement. By measuring the temperature distribution across the sheet and using the known relationship between temperature and basis weight (cooler areas indicate heavier coating), the system achieves precise basis weight measurement without the mechanical limitations of scanning sensors
2Loss of information
If scanning sensors traverse back and forth across the sheet, then cross-directional variations can be detected, but measurement time increases to twenty to thirty seconds per scan
Solution Approach 1:
The patent transitions from one-dimensional sequential scanning to two-dimensional simultaneous imaging. The thermographic camera captures the entire cross-directional profile of the sheet in a single frame, providing complete cross-directional variation data instantaneously rather than requiring sequential traversal that takes twenty to thirty seconds
Solution Approach 2:
The thermographic imaging system provides continuous real-time measurement of the moving sheet, eliminating the intermittent nature of scanning measurements. The system continuously monitors temperature distributions across the sheet width as the sheet moves, providing uninterrupted data for cross-directional variation detection without the stop-start scanning process
3Device complexity
If fixed-point sensors are positioned across the sheet, then measurement cost and space requirements are reduced, but measurement coverage is limited and cannot measure the full width and length of the sheet
Solution Approach 1:
The thermographic camera serves multiple functions simultaneously: it measures temperature distribution across the entire sheet width, provides basis weight information through temperature-basis weight correlation, and captures data for both cross-directional and machine-directional variations. This single device replaces what would otherwise require multiple fixed-point sensors positioned across the sheet width
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 enables continuous, accurate quality control of lithium-ion battery electrodes by providing early-stage quality measurement data, reducing scrap rates and improving process control through enhanced measurement precision and coverage.
Implementation Method 1
a thermal imaging device, such as an infrared imaging camera, that is configured to capture a thermal image of the sheet material along a cross direction
Implementation Method 2
means for measuring an areal weight of the traveling sheet of material
Data Source
AI summary
Areal weight or thickness of a moving coated metal sheet along its entire cross directional width is derived by correlating thermographic image data to online, scanning basis weight measurements. Thermal imaging camera captures thermal images of a heated moving coated metal sheet material along a cross direction at a first position along the machine direction to generate sequential temperature profiles. Scanning beta gauge measures the areal weight of the moving coated metal sheet downstream at a second position. An infrared temperature sensor also measures the temperature of the moving coated metal sheet which is at a lower temperature at or near the second position. The temperature differential between the cross directional thermographic image data and the latter infrared temperature is a function of the basis weight. Basis weight measurements from the beta gauge is used to extrapolate cross directional basis weight data.