Long-Material Magnetic Change Detection with Closed Axially Symmetric Yoke
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Solution Overview
Problem
Existing methods for detecting magnetic characteristic changes in long materials, such as steel pipes, suffer from dead zones at the ends and inaccuracies in detecting fine poorly quenched portions due to open magnetic paths and potential surface scratches, making it difficult to accurately inspect the entire length of the material.
Innovation Solution
A device using an encircling coil type with a yoke member that encloses the exciting and detecting coils, providing a closed magnetic path and axial symmetry, allowing for uniform magnetization and accurate detection of magnetic flux changes along the material's length, even with variations in the pass-line.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If an open magnetic path configuration is used for detecting magnetic characteristics, then the device structure is simple, but dead zones occur at the ends of the material and detection accuracy is reduced
Solution Approach 1:
The yoke member is divided into multiple segments (first yoke member and second yoke member) that can be assembled around the material. This segmentation allows the magnetic path to be closed while maintaining ease of device construction and adaptation to different material sizes, resolving the contradiction between structural simplicity and detection accuracy.
Solution Approach 2:
The yoke member acts as an intermediary component that bridges the gap between the exciting coil/detector and the material surface. By providing a closed magnetic path through the yoke member, it eliminates dead zones at the ends of the material while maintaining a relatively simple device structure, thus improving detection accuracy without excessive complexity.
2Measurement precision
If a contact-type detecting method is used, then detection accuracy is high, but surface scratches may occur on the material
Solution Approach 1:
The yoke member serves as a non-contact intermediary that carries the magnetic field to the material surface. The detecting coil is positioned within the yoke member structure, allowing magnetic flux to reach the material without physical contact between the detecting components and the material surface, thereby eliminating surface scratches while maintaining high detection accuracy.
Solution Approach 2:
The invention replaces direct mechanical contact between the detecting components and the material with a magnetic field-based detection system. The yoke member guides and concentrates the magnetic flux to the material surface without requiring physical contact, substituting a mechanical detection system with an electromagnetic one that avoids surface damage.
3Device complexity
If the detecting coil size is large, then the device structure is robust, but fine poorly quenched portions cannot be detected accurately
Solution Approach 1:
The yoke member is designed with localized magnetic flux concentration at the detection point. By shaping the yoke member to concentrate magnetic flux in a small area corresponding to the detecting coil position, the system achieves high spatial resolution for detecting fine poorly quenched portions while maintaining a robust overall device structure.
Solution Approach 2:
The detection system is segmented into discrete components (yoke member segments, detecting coil positioning) that can be configured to achieve appropriate detection resolution. This segmentation allows the detecting coil to be positioned and sized appropriately for detecting fine portions while the overall yoke member structure remains robust and mechanically sound.
4Ease of manufacture
If the yoke member has asymmetric shape, then it can be easily manufactured, but detection accuracy varies with pass-line position
Solution Approach 1:
The invention employs a symmetric yoke member design (both first and second yoke members have symmetric configurations relative to the material centerline). This symmetry ensures that the magnetic path length and magnetic flux distribution remain consistent regardless of pass-line position variations, thereby maintaining high detection accuracy while the modular symmetric design still allows for relatively easy manufacturing and assembly.
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
The device reduces dead zones and ensures accurate detection of magnetic characteristic changes over the entire length of the material, enabling continuous inspection with reduced sensitivity to pass-line variations.
Implementation Method 1
an exciting coil into which the long material is inserted and which magnetizes the long material in a longitudinal direction
Implementation Method 2
a detecting coil into which the long material is inserted and which detects a magnetic flux generated in the long material due to magnetization by the exciting coil
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 2C~3A
AI summary
A device of detecting magnetic characteristic change for a long material includes: an exciting coil into which the long material is inserted and which magnetizes the long material in a longitudinal direction; a detecting coil into which the long material is inserted and which detects a magnetic flux generated in the long material due to magnetization by the exciting coil; and a yoke member which has a first opening portion which is positioned on one side of the long material in the longitudinal direction and into which the long material is inserted and a second opening portion which is positioned on the other side of the long material in the longitudinal direction and into which the long material is inserted, and has a shape which is substantially axially symmetrical about an axis passing the first opening portion and the second opening portion, and the exciting coil and the detecting coil are surrounded by the yoke member, the first opening portion, and the second opening portion.