等离子焊接熔池小孔尺寸的电弧信号检测  

Detection of Keyhole Size by Arc Signal Processing

作　　者：王海燕[1] 陈强[1] 孙振国[1] 王耀文[1] 

机构地区：[1]清华大学,北京100084

出　　处：《焊接学报》2000年第3期24-26,共3页Transactions of The China Welding Institution

基　　金：国家自然科学基金资助项目(59975050);国防科技重点实验室基金资助项目(97-104-14);国家863专题资助项目(9913-02)

摘　　要：为了开发可行的实时检测等离子焊接过程中熔池小孔尺寸的传感技术 ,采集了对应于不同熔池小孔尺寸的电弧电压和电弧电流信号存入计算机 ,采用快速傅里叶变换 (FFT)和短时Fourier变换对电弧信号进行了分析 ,发现位于频率区间f=2 .5～ 3 .5kHz的电弧谱峰信号幅值的局部最大值pf随着熔池小孔尺寸的增大波动速度逐渐减慢 ,pf所对应的频率pff单调递减。在此基础上设计了合适的算法 ,从而得到pf和pff信号与熔池小孔尺寸之间的定量关系。用厚度渐变试样进行了焊接试验 ,检验了pf和pff信号对熔池小孔尺寸的检测效果 ,并初步分析了pf和pff信号与熔池穿孔的物理关系。最后选取pff信号作为熔池小孔尺寸传感信号 ,该检测技术可为实现中厚板的等离子焊接精密熔透自动控制提供必要的反馈信息 ,适用于以逆变焊机为热源的等离子焊接过程。To explore the proper sensing techniques which should be able to tell the size of the keyhole in real time during the plasma welding processes,the signals of arc voltage and current under the conditions of different keyhole sizes were sampled into the computer,and processed to find characteristics related to keyhole size using`FFT'and`STFT'techniques on the signals.After analyzing of the data gained the features of the local maximum of the spectrum peeks were correspondent to the keyhole size when the frequent region of spectrum was form 2.5kHz to 3.5 kHz.It was found that the fluctuation of the amplitude of the local maximum of the spectrum peeks slows down as the keyhole expands and the relevant frequency gradually shifts.Proper arithmetic have been bevised to quantify the relationship between the amplitude`pf'and the frequency`pff'of the local maximum of thespectrum peeks and the keyhole size.Then welding experiments were carried out using the work pieces of thickness changing to test the validity of the detection of keyhole size by`pf'and`pff'signals.The physical relationship between the arc signals of `pf'and `pff'and the `keyholeeffect'has been explained preliminarily.At last,`pff'signal has been selected to act as the sensing signal of the keyhole size,and this technique can provide the necessary feedback information for the automatic control system on the precise plasma welding of work pieces of great and modest thickness.

关 键 词：等离子焊接 小孔尺寸检测 电弧信号 

分 类 号：TG456.2[金属学及工艺—焊接]