AC Magnetic Field Cast Piece Surface Temperature Measurement
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Solution Overview
Problem
Existing methods for measuring the surface temperature of cast pieces in severe conditions, such as those with high water and vapor presence, are prone to inaccuracies due to environmental interference and scatter, making it difficult to prevent break-out issues in slab continuous casting.
Innovation Solution
A system comprising a magnetic field exciting device applying an AC magnetic field perpendicular to the cast piece surface, a detecting device to measure the induced electromotive force, and a deriving device to calculate the surface temperature using a predetermined relation data, with a solenoidal excitation and detection coil configuration to minimize interference from temperature variations near the cast piece corners.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a radiation thermometer is used to measure the surface temperature of cast pieces immediately under the mold, then the surface temperature can be detected to prevent break-out, but the measurement is extremely difficult due to severe conditions with great quantities of water, vapor, powder and scales scattered in the space between the thermometer and cast pieces
Solution Approach 1:
The patent introduces a magnetic field as an intermediary medium to indirectly measure the surface temperature of the cast piece. Instead of directly measuring temperature with a radiation thermometer in the severe environment, the magnetic field interacts with the cast piece's magnetic properties which change with temperature, allowing temperature inference without direct contact through the interfering medium of water vapor and scales
Solution Approach 2:
The patent replaces the optical/mechanical radiation thermometer system with a magnetic field-based measurement system. The excitation coil generates a magnetic field that penetrates the cast piece, and the detection coil measures magnetic flux changes that correlate with temperature, substituting the direct optical measurement approach with an indirect magnetic measurement approach that is immune to water vapor and scale interference
2Object-affected harmful factors
If a radiation thermometer with short wavelength range is used, then the measurement is relatively robust in severe conditions, but stable measurement is still difficult due to scatter in measurement data
Solution Approach 1:
The magnetic field serves as an intermediary that is not scattered by water vapor, powder, or scales in the same way optical radiation is. The magnetic flux changes detected by the detection coil directly reflect the cast piece's magnetic properties at its surface, providing stable and scatter-free measurement data even in severe environmental conditions
3Measurement precision
If thermocouples are installed into the mold copper plate to monitor surface temperature changes, then the surface temperature near the meniscus level can be measured with high sensitivity, but precise measurement is difficult due to air gap formation between the cast piece surface and mold copper plate
Solution Approach 1:
The patent replaces the mechanical contact-based thermocouple system with a non-contact magnetic field measurement system. The excitation and detection coils are positioned to generate and measure magnetic fields that penetrate through any air gaps between the mold copper plate and cast piece surface, eliminating the reliability issue of air gap formation while maintaining high sensitivity to temperature changes through magnetic property variations
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
Enables stable and precise measurement of cast piece surface temperature over a long time, even under severe conditions, effectively preventing break-out by accurately controlling the surface temperature within the desired range.
Implementation Method 1
a magnetic field exciting device which applies an AC magnetic field substantially perpendicular to a surface of a cast piece
Implementation Method 2
a magnetic field detecting device which detects the AC magnetic field to detect a magnetic flux varied in response to a surface temperature of the cast piece
Data Source
Figure 1
Figure 2A~2B
Figure 3~4
AI summary
A cast piece surface temperature measuring device includes: a magnetic field exciting device which applies an AC magnetic field substantially perpendicular to a surface of a cast piece; a magnetic field detecting device which detects the AC magnetic field to detect a magnetic flux varied in response to a surface temperature of the cast piece; and a surface temperature deriving device which derives the surface temperature of the cast piece based on an induced electromotive force obtained by detecting the AC magnetic field by the magnetic field detecting device and a predetermined relation data. The magnetic field exciting device includes a solenoidal excitation coil, the magnetic field detecting device includes a solenoidal detection coil interposed between the surface of the cast piece and the excitation coil, and the relation data indicates a correspondence relationship between the surface temperature of the cast piece and the induced electromotive force in a temperature range including a predetermined Curie point.