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Method for quantitatively detecting resistance spot welding nugget and nucleation quality through acoustic emission signal frequency spectrum

An acoustic emission signal and resistance spot welding technology, which is applied in the field of quantitatively detecting the nucleation quality of resistance spot welding nuggets by using the acoustic emission signal spectrum, can solve the problems of large amount of information and calculation, and achieves a simple evaluation method, easy realization, Practical effect

Active Publication Date: 2014-08-27
CHONGQING UNIV OF TECH
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

This patented technology needs to extract the acoustic emission signals of multiple physical stages in the welding process, the amount of information and calculation is large, and it is necessary to establish and train an artificial neural network

Method used

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  • Method for quantitatively detecting resistance spot welding nugget and nucleation quality through acoustic emission signal frequency spectrum
  • Method for quantitatively detecting resistance spot welding nugget and nucleation quality through acoustic emission signal frequency spectrum
  • Method for quantitatively detecting resistance spot welding nugget and nucleation quality through acoustic emission signal frequency spectrum

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Embodiment 1

[0044] The workpiece to be welded is the overlap of two 2024 aluminum alloy sheet structures with a thickness of 2mm. The main welding process parameters used are: welding current is 18000A, welding current duration is 8 cycles, and electrode pressure is 0.1MPa.

[0045] During welding, the structural load acoustic emission signal of the resistance spot welding process is collected in real time, and the dynamic curve of the structural load acoustic emission signal is drawn by the analysis software, as shown in figure 1 shown.

[0046] Different stages of the welding process can be identified from the waveform diagram, and the nugget nucleation signal waveform can be extracted, such as figure 2 shown.

[0047] The last five signal periods are extracted from the acoustic emission signal of the nucleation stage, such as image 3 shown.

[0048] Compute the magnitude spectrum of the last five signal cycles of the nucleation stage and plot the spectrogram as Figure 4 shown. ...

Embodiment 2

[0055] The workpiece to be welded is the overlap of two 2024 aluminum alloy sheet structures with a thickness of 2mm. The main welding process parameters used are: welding current is 24000A, welding current duration is 8 cycles, and electrode pressure is 0.1MPa.

[0056] During welding, the structural load acoustic emission signal of the resistance spot welding process is collected in real time, and the dynamic curve of the structural load acoustic emission signal is drawn by the analysis software, as shown in Figure 8 shown.

[0057] Different stages of the welding process can be identified from the waveform diagram, and the nugget nucleation signal waveform can be extracted, such as Figure 9 shown.

[0058] The last five signal periods are extracted from the acoustic emission signal of the nucleation stage, such as Figure 10 shown.

[0059] Compute the magnitude spectrum of the last five signal cycles of the nucleation stage and plot the spectrogram as Figure 11 sho...

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Abstract

A method for quantitatively detecting the resistance spot welding nugget and nucleation quality through an acoustic emission signal frequency spectrum includes the following steps of collecting structural load acoustic emission signals of the resistance spot welding process in real time, drawing a signal dynamic oscillograph, extracting acoustic emission signals of the nugget and nucleation stage, extracting out the last five signal cycles, calculating and drawing out a frequency spectrogram, extracting frequency spectrogram lines with the frequency ranging from 500 Hz to 5000 Hz, calculating a peak value, carrying out test through at least five sets of different welding parameters, obtaining five experimental test points, corresponding resistance spot welding nugget diameter and the nugget tension shear load, obtaining a fitting mathematic model through fitting calculation with the peak value of the frequency spectrogram lines as the X-axis and the nugget diameter or the nugget tension shear load as the Y-axis, and detecting and evaluating the nugget diameter and the nugget tension shear load of resistance spot welding nuggets obtained by welding in the technical range according to the model. By the method, the size and tension shear loads of the resistance spot welding nuggets can be detected and evaluated in a rapid and nondestructive mode.

Description

technical field [0001] The invention relates to a non-destructive detection method for evaluating nucleation nucleation quality, which is suitable for rapid detection of resistance spot welding nugget quality of commonly used metal sheet structural materials. Background technique [0002] Resistance spot welding is a welding method widely used in automobile manufacturing. There are about 3000-6000 resistance spot welding spots on a modern car. Therefore, the detection of the quality of resistance spot welding solder joints is very important. High-efficiency solder joint quality sensing and its detection and evaluation during the welding process are of great significance for optimizing the production process, improving production efficiency and welding quality. However, in the process of resistance spot welding, the nucleation process of nugget cannot be directly observed, which makes it difficult to judge the quality of resistance spot welding joints. The size of th...

Claims

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Application Information

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IPC IPC(8): G01N29/14
Inventor 罗怡
Owner CHONGQING UNIV OF TECH