Ultrasonic Welding Microstructure Imaging via Signal Processing
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Solution Overview
Problem
Conventional quality evaluation methods for welding areas face challenges such as destructive testing, unreliable indirect measurements, and difficulty in obtaining clear nondestructive ultrasonic images due to weak reflected waves and noise amplification.
Innovation Solution
A method and apparatus that use an ultrasonic beam with a small beam size to scan the welding area, enhance the reflected wave by subtracting a moving average waveform, and amplify only the extracted signal to improve image clarity, reducing noise and 'darkness areas' in the image.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a focused ultrasonic beam is used to scan the welding area, then the resolution of the imaging is improved, but the reflected wave from the microstructure becomes too weak to obtain a clear image
Solution Approach 1:
The patent applies preliminary action by performing moving average processing on the received ultrasonic signals before amplification. This preprocessing step removes slowly varying components and enhances the reflected waves from the welding microstructure, ensuring that when the signal is subsequently amplified, the useful signal components are strengthened while noise is suppressed, resolving the contradiction between signal strength and imaging resolution
Solution Approach 2:
The patent introduces an intermediary processing step (moving average filtering) between signal reception and amplification. This intermediary process acts as a mediator that selectively enhances the weak reflected waves from the welding microstructure while suppressing noise, allowing the focused beam's resolution advantage to be maintained while overcoming the weak signal problem
2Reliability
If the received signal is amplified to enhance the reflected wave, then the signal strength is improved, but noise and ultrasonic tailing are also enhanced making it difficult to obtain a clear image
Solution Approach 1:
The patent applies preliminary action by performing moving average processing on the received ultrasonic signals before amplification. This preprocessing step removes slowly varying components and enhances the reflected waves from the welding microstructure, ensuring that when the signal is subsequently amplified, the useful signal components are strengthened while noise is suppressed, resolving the contradiction between signal strength and imaging resolution
Solution Approach 2:
The patent extracts the useful signal components from the noisy received signal through moving average processing before amplification. By separating and enhancing only the reflected waves from the welding microstructure while leaving noise components untouched, the subsequent amplification step strengthens only the useful signal, avoiding the problem of noise amplification that plagues conventional methods
3Measurement precision
If destructive inspection is performed to evaluate welding quality, then measurement precision is improved, but productivity decreases due to time-consuming sample preparation and testing
Solution Approach 1:
The patent replaces the mechanical destructive inspection process (cutting, polishing, etching) with a nondestructive ultrasonic imaging method. By using high-frequency ultrasonic waves to visualize the welding microstructure in situ, the system achieves comparable measurement precision to destructive inspection while eliminating time-consuming sample preparation and enabling rapid inspection of actual products
Solution Approach 2:
The patent changes the inspection parameters by using extremely high frequency ultrasonic waves (20-50 MHz) with a focused beam, enabling nondestructive inspection to achieve the same level of microstructural detail as destructive inspection. This parameter change allows the system to obtain clear images of welding microstructure without physically destroying the test object, thereby maintaining measurement precision while dramatically improving productivity
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 approach allows for clear visualization of the welding microstructure, enhancing the signal-to-noise ratio and reducing blurry areas, thereby improving the accuracy of welding quality evaluation without destructive testing.
Implementation Method 1
scanning a cross section of a test object orthogonal to a welding direction with an ultrasonic beam, and receiving a reflected signal from the inside of the test object
Implementation Method 2
The ultrasonic frequency is set as high as 20 MHz to 50 MHz. Then, while a cross section orthogonal to a welding direction is being scanned with an ultrasonic beam
Data Source
Figure 1
Figure 2
Figure 3(A)~3(B)
AI summary
A microstructure form of a welding area is quickly and accurately (or clearly) imaged in a nondestructive inspection. Specifically, while a cross section of a test object S orthogonal to a welding direction is being scanned with an ultrasonic beam B, a reflected signal from the inside of the test object is received. On the basis of the received reflected signal, the scanned cross section is imaged to inspect a microstructure of a welding area 2. In imaging the welding area, a reflected wave from the microstructure of the welding area is enhanced by subtracting a moving average waveform Ra at an average score m to remove a slowly varying component of the received signal, extracting the reflected signal from the microstructure of the welding area, and amplifying only the extracted reflected signal. Alternatively, a reflected wave from the microstructure of the welding area is enhanced by scanning a cross section of the test object orthogonal to the welding direction with a focused ultrasonic beam at a plurality of different positions in the welding direction, imaging the scanned cross sections on the basis of the resulting ultrasonic received signals, superimposing a plurality of images obtained by scanning at the plurality of positions in the welding direction, and retaining a maximal value of superimposed pixels.