Research On Weld Tracking Technology Based On The “wall Jumping” Behavior Of Narrow Gap P-GMAW Ar

Narrow gap welding has the advantages of small filling amount,low line energy and welding in all positions,and has obvious advantages when welding thick plates.In order to solve the problem of unfused sidewalls in narrow gap welding,the welding torch is often driven to swing in the groove during actual welding.In the automatic welding process,in order to ensure that the heat input by the swing arc to the two side walls of the groove is the same,the center of the groove can be tracked by the arc sensor.However,the narrow gap automatic welding equipment based on the arc sensor still has high requirements on the machining accuracy and assembly accuracy of the groove,and the welder still needs to make fine adjustments during the welding process.Therefore,the arc tracking accuracy of narrow gap welding still needs to be further improved.Aiming at the problem that the welding seam tracking accuracy of the narrow gap automatic welding equipment is low,this paper starts from the narrow gap P-GMAW arc "jump wall" behavior found in the test,and studies the method of applying it to the welding seam tracking.Attempts to improve the welding seam tracking accuracy from the point of arc physics.Firstly,in view of the problem that the interference factors in the welding process affect the normal operation of the test system,an anti-interference design is carried out for the control module of the swing welding torch test system,which enhances the stability and reliability of the system and ensures the smooth progress of the test.Secondly,by analyzing the arc image and welding electrical signal during the narrow-gap P-GMAW process,the causes of the arc "jump wall" and the laws affecting the changes of the welding electrical signal are studied: When the welding torch is close to the side wall of the groove,it will cause the arc "jump wall" behavior,which will cause the arc to continue to heat the side wall of the groove,resulting in the change of the groove shape.When the arc passes the location again,a special arc signal signature is created.Thirdly,the feasibility of applying the welding electrical signal characteristics caused by the narrow-gap P-GMAW arc "jump wall" behavior to arc tracking is verified:This feature changes approximately linearly with the change of the torch deviation value: Comparing the peak value,base value and average value of welding current and voltage in pulse welding mode to reflect the sensitivity of welding torch deviation,selecting the average welding current as the tracking signal can obtain higher accuracy and reliability.Fourthly,the law of the welding process parameters affecting the arc signal characteristics of the narrow-gap P-GMAW is studied: the swing amplitude of the welding torch,the wire feeding speed of the welding machine,and the correction coefficient of the arc length have obvious influences on the arc signal characteristics.Finally,a welding seam tracking control strategy based on the narrow-gap PGMAW arc "jump wall" behavior is formulated,including the welding torch deviation extraction algorithm and the welding torch deviation correction algorithm;the performance of the welding seam tracking control strategy is verified through experiments,and to a certain extent It shows higher reliability than the original tracking control strategy.The research results provide a new idea and establish a corresponding theoretical basis for improving the arc tracking accuracy of narrow gap welding.