Research On The Deviation Recognition Method Of Narrow Gap P-GMAW Welding Gun Based On Arc Sound

Small groove cross-section area of narrow gap welding can reduce welding material loss,save welding time,reduce heat input and improve joint mechanical properties,so as to reduce welding deformation and improve production efficiency.The welding gun swinging in the process of welding,can promote the side wall flision.However,due to the small side wall angle and narrow welding seam,the distance between the arc and the two side walls needs to be controlled to ensure the welding quality.The deviation of the welding gun's swing center from the weld center will cause arc sound changes in the process of narrow gap welding.Experienced welders can identify the deviation state of the welding gun through arc sound signals to adjust the welding position and parameters timely.Therefore,arc acoustic signal can be used as a potential signal source for welding process monitoring,and its research is of great significance to promote the development of welding automation.This paper studies the relationship between arc sound signal and welding gun deviation in narrow gap welding.Firstly,an arc sound signal acquisition device is designed on the basis of the original experimental platform and its reliability was verified by experiments.The noise of arc sound signal mainly comes from the ambient noise and its own pulse interference.Spectrum analysis of arc sound signal before and after noise reduction processed by wavelet packet de-noising,it shows that the interference signal at high frequency is significantly suppressed.Secondly,(1)based oin the mechanism of human speech generation,the mechanism of arc sound signal generation and its influencing factors are analyzed.It is found that the change of arc energy is the main cause of arc sound signal generation,and the occurrence of short circuit transition will cause the amplitude and vibration frequency of arc sound signal to increase sharply.(2)Through the comparison experiment,due to the influence of the side wall of welding seam,it is found that the time and frequency domain characteristics of arc sound signal are different when the welding gun swings to different positions.When the distance between the welding arc and the side wall of the xweld is reduced to a certain extent,the phenomenon of magnetic bias blown will occur,the arc is affected by the side wall of weld and the side wall of weld and the bottom of weld jump back and forth.The arc is affected by the side wall of the weld,So the are sound track system changes constantly,and thus affects the time-frequency domain characteristics of the arc sound signal.(3)The welding gun deviation experiment was designed in order to exploore the relationship between the welding gun deviation and the arc sound signal,which intercept the arc sound signal at the left and right oscillation limits of different welding gun deviations of 60ms and extract the tlime and frequency domain characteristics.By comparing the distribution of same characteristic signal with different deviation on the left and rightswing limits of welding gun,found that the time domain characteristics including mean,standard deviation,short-time energy and frequency domain characteristics of the short-time power density distribution can both reflect to some extent welding gun cdeviation information.But the distribution of the frequeney domain characteristic signal according to the interval is not convenient to characteristic laws of statistics.(4)the time domain characteristic signal difference value at the left and right swing limits of the welding gun.It is taken as the characteristic parameter to establish the linear relationship between the difference and the welding gun deviation.Through analysis and comparison,the sample concentration and sensitivity of short-time arc sound energy were the highest,and the identification law of the transverse deviation of the welding gun was established accordingly.Finally,a tracking program based on DSP was written according to the linear relationship between the arc sound short-time energy and the deviation of the welding gun,the welding seam tracking experiment was carried out.When the tracking program is started,the deviation of the torch is 48.6%of the total data of the data warfare between ±0.2mm;the deviation of the torch is 97.1%?of the total data of the data warfare between ±0.6mm.It can be proved that it is feasible to identify the transverse deviation of welding torch based on the short-term energy characteristic parameters of arc sound.