窄间隙MAG焊电弧声与电弧作用位置的相关性

电弧-侧壁距离控制是保证窄间隙熔化极活性气体保护焊(Narrow gap metal active gas welding, NG-MAG)侧壁熔合良好的关键。通过对NG-MAG脉冲立焊过程中电弧声的预处理和分析，发现其时域波形呈周期性“振铃”衰减特性，频率与焊接电源脉冲频率相同；电弧声能量的频域分布范围为0.3～12.0 kHz，且能量主要集中在0.3～3.0 kHz和9.0～12.0 kHz两个频带，频谱分布与电弧-侧壁距离高度相关。在此基础上，采用小波变换(Wavelet transform, WT)和联合时频分析(Joint time-frequency analysis, JTFA)实现对电弧声信号的降噪处理和时频分析，结果发现，伴随电弧-侧壁距离的逐渐增大，电弧声能量的低频分布始终存在，呈现“断续-连续-断续”分布特征；而高频分布出现在电弧-侧壁距离2.6 mm以上，呈现“断续-连续”分布特征。利用NG-MAG脉冲立焊电弧声的时频分布规律可实现对电弧作用位置的监测预警，为NG-MAG焊接过程状态监控提供一种途径。

Correlation of Arc Sound and Arc-sidewall Position in Narrow Gap MAG Welding

The control of arc-sidewall distance is the key to ensure good sidewall fusion in the process of narrow gap metal active gas welding(NG-MAG) welding. Through pretreatment and analysis of arc sound in NG-MAG pulse vertical welding, it is found that there exists periodic “ringing” attenuation phenomenon in the time-domain waveform, and its frequency is equal to the pulse frequency of welding power. The frequency distribution of arc sound energy varies from 0.3 kHz to 12.0 kHz. And energy mainly concentrates in two bands, range of 0.3-3.0 kHz and 9.0-12.0 kHz. Spectrum distribution of arc sound is highly relevant to arc-sidewall distance. On this basis, noise reduction and time-frequency analysis of arc sound are achieved by use of wavelet transform(WT) and joint time-frequency analysis(JTFA). The results show that low-frequency energy distribution of arc sound is always present, show “intermittent-continuous-intermittent”, with gradually increasing of arc-sidewall distance. While high-frequency energy distribution of arc sound only present arc-sidewall distance more than 2.6 mm, show “intermittent-continuous”. The monitoring and early warning of arc-sidewall distance can be realized based on time-frequency distribution of arc sound in NG-MAG pulse vertical welding, which provides a new way for condition monitoring in the process of NG-MAG welding.