TOF Flatness Measurement for Hot-Rolled Steel Strip
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Solution Overview
Problem
Existing methods for determining flatness deviations in strip-shaped materials, particularly during hot-rolling of thin metal sheets, face challenges such as heat-sensitive piezo sensors being compromised by elevated temperatures and complex calibration requirements for non-contact measurement systems, leading to reduced accuracy and increased effort in industrial settings.
Innovation Solution
The use of Time-of-Flight (TOF) cameras with a Photonic Mixing Device (PMD) sensor, an illumination source, and control electronics to measure transit times of electromagnetic waves, allowing for high-temperature measurements and simplified calibration, enabling accurate flatness deviation determination and automation of material treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If force transducers designed as heat-sensitive piezo sensors are used in measuring rollers, then flatness deviations can be measured during hot-rolling, but the roller body heats up and the sensors are compromised by elevated temperatures
Solution Approach 1:
The patent replaces mechanical force transducers (piezo sensors) with an optical measurement system consisting of a camera and projector. This substitution eliminates heat-sensitive mechanical sensors from direct contact with the hot strip, allowing flatness measurement during hot-rolling without sensor compromise from elevated temperatures.
2Reliability
If non-contact measurement systems with projector and camera are used, then flatness can be measured without heat-sensitive sensors, but the spatial arrangement requires six-parameter definition and significant calibration effort
Solution Approach 1:
The patent merges the projector and camera into a vertically arranged configuration where both components share a common optical axis. This unified arrangement eliminates the need for complex six-parameter spatial definition and reduces calibration effort while maintaining measurement reliability in hot-rolling conditions.
3Measurement precision
If conventional measuring rollers are used, then flatness measurement is possible, but the roller body heats up making sensor use difficult
Solution Approach 1:
The patent replaces conventional contact-based measuring rollers with an optical measurement system using camera and projector. This eliminates the heating issue inherent in mechanical rollers while maintaining flatness measurement precision, as the optical system does not require physical contact with the hot strip.
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 solution provides a robust and efficient method for determining flatness deviations under challenging conditions, ensuring high accuracy and reduced calibration effort, while enabling real-time automation of material treatment processes.
Implementation Method 1
The measuring principle of a TOF camera consists in measuring the transit time of electromagnetic waves, for example light, from a transmitter (the illumination source) to the measurement object and from the measurement object to a PMD sensor (photonic mixing device).
Implementation Method 2
The source of illumination may consist of one (or more) LEDs, one (or more) lasers or one (or more) similar sources, preferably in the near infrared range.
Implementation Method 3
An optical bandpass filter in front of the sensor can suppress external influences.
Data Source
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AI summary
The invention relates to a device for determining flatness deviations during the processing of a strip-shaped material, in particular during the hot rolling of a steel strip, wherein the device comprises a TOF camera and the TOF camera can be arranged above the strip-shaped material in such a way that an image of an area of the material can be captured by means of the TOF camera transversely and/or longitudinally to the direction of movement and the TOF camera is designed in such a way that a flatness deviation can be determined from the image, wherein the device has a synchronizing device which is designed in such a way that the TOF camera takes images taking into account the speed of movement of the strip-shaped material, which enables a sequence of areas to be used to determine flatness deviations of the material.