光纤激光焊接过程中缺陷的监测与诊断

为了识别激光焊接过程中间隙和错边缺陷，采用自身搭建的光纤激光焊接在线监测系统，实现不锈钢焊接过程中等离子体可见光信号及熔池红外光信号的实时监测，并利用滤波和短时傅里叶变换的信号处理方法对不同缺陷的光信号进行数据分析。得到了信号时域频域随焊接缺陷的变化规律，当出现间隙缺陷时，可见光信号时域幅值从1.5V降至0.2V，1000Hz~4000Hz频率成分缺失，红外光信号时域幅值由3.5V降至1.0V，2000Hz~7000Hz频率成分缺失；当出现错边缺陷时，可见光信号时域幅值从2.0V降至0.5V，红外光信号时域幅值由4.0V降至0.5V，两者0Hz~1000Hz频率成分均缺失。结果表明，可见光信号与红外光信号与激光焊接状态存在一定的相关性，利用光信号的幅值与频率的变化可以有效地识别激光焊接过程中的缺陷。这对实际生产具有一定的应用价值。

Monitoring and detecting of defects during fiber laser welding

In order to identify gap and edge defects in laser welding process , plasma visible light signal and infrared signal of molten pool during the process of stainless steel welding was monitored by a self -made optical fiber laser welding on-line monitoring system.And the signal processing methods of filtering and short time Fourier transform were used to analyze the optical signals with different defects and the variation law of time domain and frequency domain with welding defects was obtained.When a gap defect occurred , the time domain amplitude of the visible signal decreased from 1.5V to 0.2V without any components in the range of 1000Hz ~4000Hz.The time domain amplitude of infrared signal decreased from 3.5V to 1.0V without any components in the range of 2000Hz~7000Hz.When an edge defect occurred , the time domain amplitude of the visible signal decreased from 2.0V to 0.5V and the time domain amplitude of infrared signal decreased from 4.0V to 0.5V without any components in the range of 0Hz~1000Hz for both signals.The results show that there is a certain correlation between the visible signal, the infrared signal and the laser welding state.The defects in the laser welding process can be effectively identified by the change of amplitude and frequency of the optical signal.The study has certain application value for actual production.