Steel Plate Inner Defect Detection via Dual Magnetic Flux Directions

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Solution Overview

Problem

Existing steel plate defect detection methods, such as the magnetic flux leakage inspection method, cannot effectively distinguish between surface and internal defects, making it difficult to detect internal defects exclusively.

Innovation Solution

An apparatus and method that utilize two distinct magnetic flux directions – one for overall defect detection and another for surface defect detection – allowing for the subtraction of surface defect data from overall defect data to isolate internal defects, employing magnetizing units and magnetic sensor arrays to measure leakage magnetic flux strength.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If magnetic flux leakage inspection is performed in the transfer direction to detect overall defects, then both surface and internal defects are detected, but it becomes impossible to distinguish and detect only internal defects

Engineering Contradiction:
Improvedefect detection capabilityVSAvoiddefect location information
Core Design Contradiction:
Measurement precisionVSLoss of information

Solution Approach 1:

The inspection system is segmented into two independent detection units: an overall defect detection unit that detects both surface and internal defects, and a surface defect detection unit that detects only surface defects. By segmenting the detection functions and combining their results, the system can identify internal defects exclusively while maintaining comprehensive detection capability.

Inventive Principle:
Principle #1Segmentation

2Adaptability or versatility

If a single detection system is used to detect all defects, then detection coverage is comprehensive, but the system complexity increases and internal defects cannot be isolated

Engineering Contradiction:
Improvedefect detection coverageVSAvoiddetection system structure
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The detection system is divided into two separate units with distinct functions. The overall defect detection unit provides comprehensive coverage, while the surface defect detection unit focuses specifically on surface defects. This segmentation allows the system to maintain versatility while managing complexity through functional separation.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

A data processing unit acts as an intermediary that receives detection results from both detection units, processes the data by comparing and subtracting surface defect information from overall defect information, and outputs isolated internal defect detection results. This intermediary component manages the complexity of data integration and analysis.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Measurement precision

If magnetic flux is generated in the thickness direction to detect surface defects, then surface defect detection accuracy is improved, but internal defects cannot be detected

Engineering Contradiction:
Improvesurface defect detection accuracyVSAvoiddefect detection range
Core Design Contradiction:
Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The system segments detection functions into two specialized units: one optimized for overall defect detection (including internal defects) and another optimized for surface defect detection. Each unit uses magnetic flux generation in the thickness direction, but by combining their results, the system achieves both specialized accuracy and comprehensive coverage.

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

Enables the precise detection of internal defects by differentiating between surface and internal defects based on leakage magnetic flux strength, improving the accuracy of defect identification in steel plates.

Implementation Method 1

a magnetic sensor array 120 arranged along the width of the steel plate S for measuring leakage magnetic flux when magnetic flux passes through defects of the steel plate S

Methodology Applied
Scientific EffectMagnetic flux leakage: Magnetic Field

Implementation Method 2

a magnetic sensor such as a Hall element capable of converting magnetic flux into an electric signal

Methodology Applied
Scientific EffectHall effect: Hall Effect

Data Source

PatentEP2940464B1Apparatus and method for detecting inner defects of steel plate
Publication Date: 2021.08.18 POHANG IRON & STEEL CO LTD
  • EP2940464B1 patent drawingFigure 1~2
  • EP2940464B1 patent drawingFigure 3~4
  • EP2940464B1 patent drawingFigure 5(a)~5(b)

AI summary

An apparatus and a method for detecting inner defects of a steel plate are provided. The apparatus for detecting inner defects of a steel plate comprises: an all-defect detection unit for detecting all defects including surface defects present on the surface of the steel plate and inner defects present inside the steel plate on the basis of the intensity of leakage flux, which is measured by generating magnetic flux in a strike direction of the steel plate; a surface defect detection unit for detecting surface defects on the basis of the intensity of leakage flux, which is measured by generating magnetic flux in the thickness direction of the steel plate, for a predetermined detection region including all the defects detected by the all-defect detection unit; and a data processing unit for detecting only inner defects present in a detection region by excluding the surface defects detected by the surface defect detection unit from all the defects detected by the all-defect detection unit, for the detection region, thereby detecting only the inner defects of the steel plate.