Welding Magnetic Sensing for Nonuniform Current Distribution
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Solution Overview
Problem
In resistance welding, the current distribution at the joining surface is often nonuniform due to surface roughness and impurities, leading to poor welding quality, and existing techniques struggle to accurately detect defective welds with low variation in magnetic signal waveforms.
Innovation Solution
A welding management system comprising multiple first magnetic detection units and a second magnetic detection unit curved to surround the joining position, which generates information on the joining state by calculating differences in detection values to analyze current distribution and detect deviations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a detection range of magnetic sensors is set to match the variation width of the entire waveform, then the quantization width increases accordingly, but the accuracy of detecting defective welding decreases
Solution Approach 1:
The patent extracts and removes the background magnetic noise component from the detected signal by using a cancel coil to generate an opposing magnetic field. This separation allows the system to focus detection resources on the actual welding signal variations, improving the effective signal-to-noise ratio and enabling more accurate detection of defective welding portions without being constrained by the full dynamic range of the raw signal.
Solution Approach 2:
The system performs preliminary cancellation of magnetic noise before the actual welding detection process by pre-characterizing the background magnetic field and using the cancel coil to generate counteracting fields. This preliminary anti-action reduces the overall signal amplitude that needs to be processed, thereby reducing the required quantization width while maintaining detection accuracy for defective welding portions.
2Object-affected harmful factors
If magnetic noise is canceled by storing a normal state magnetic signal and canceling it, then the background noise is reduced, but the ability to extract defective welding waveforms deteriorates
Solution Approach 1:
The patent applies local quality by using multiple magnetic sensors positioned at different locations around the welding area. Each sensor detects local magnetic field characteristics, and by comparing these spatially-distributed measurements, the system can identify localized anomalies corresponding to defective welding portions while filtering out uniform background noise. This spatial differentiation preserves defective signal characteristics that would otherwise be lost in global noise cancellation.
Solution Approach 2:
The system dynamically adjusts the noise cancellation process by continuously monitoring the magnetic field and adapting the cancel coil current in real-time during welding operations. Rather than using a static pre-recorded normal state signal, the dynamic adjustment allows the system to maintain accurate noise cancellation while preserving transient signal variations that indicate defective welding, thereby resolving the contradiction between noise reduction and defect detection accuracy.
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 system effectively manages welding by accurately detecting deviations in current distribution, improving welding quality and reducing the likelihood of defective welds, even with small variations in magnetic signal waveforms.
Implementation Method 1
a magnetic detection unit includes a plurality of first magnetic detection units provided around a target joining position and a second magnetic detection unit curved to surround the target joining position
Implementation Method 2
the data processing unit generates information of a joining state of the target joining position based on a difference between a detection value of each of the plurality of the first magnetic detection units and a detection value of the second magnetic detection unit
Implementation Method 3
the resistance welding is a welding method in which members to be welded abut against each other (or are superimposed) and are energized in a pressurized state and a joining surface is fixed by Joule heat
Data Source
AI summary
Provided is a welding management system that appropriately manages welding. The welding management system (100) includes a plurality of local magnetic sensors (10a to 10f) provided around a target joining position (K) and a correction magnetic sensor (20) curved to surround the target joining position (K). A data processing unit (30) generates information of a joining state of the target joining position (K) based on a difference between a detection value of each of the plurality of the local magnetic sensors (10a to 10f) and a detection value of the correction magnetic sensor (20).