Modeling Of Variable Groove Weld In Rotating Arc Narrow Gap MAG Welding

Rotating arc narrow gap MAG welding is an efficient welding method,which has a good prospect in the welding of medium and thick plates.The difficulty of narrow gap welding is to ensure the sidewall penetration.In the past,arc sensing or visual sensing was used to ensure that the rotating arc was located in the center of the groove to ensure the depth of the sidewall fusion.However,when the groove is irregular(hereinafter referred to as variable groove),the traditional welding seam tracking based on a single sensing method is not enough to guarantee the weld depth on the sidewall of the groove.Therefore,a variety of sensor information fusion is needed to conduct modeling research on the weld formation of variable groove to improve the welding quality.In this paper,it is first to build the welding system and the corresponding data acquisition,image acquisition system.In order to ensure the correspondence between the multi-sensor information and the sidewall melting depth,and to address the shortcomings of the marking method of the marking needle in the past.In this paper,the software and hardware of laser marking is builded to mark the central position of the arc where data collection begins and ends so that the data collected can be synchronized with the position of welding workpiece.The multifunctional PCI-6251 data acquisition card is selected to simultaneously collect welding current,arc voltage and in front of the arc three signals,and the isolation module is used to improve the accuracy of data transmission.The welding current signal of each rotation cycle was extracted by the pulse signal of the position in front of the arc.CCD camera is used to trigger the acquisition of arc center and bevel edge images,and the image coordinates of arc center and bevel edge are obtained according to the existing passive vision sensing algorithm,and then the coordinate value is calculated to obtain the distance between the arc center and the left and right side walls.According to the position of the laser mark,the workpiece is cut,polished,corroded,image human-computer interaction processing and data fitting,and the sidewall penetration synchronized with the collected data is obtained.In order to build an effective prediction model of variable groove sidewall penetration.First of all,three kinds of groove forms were designed for test.The groove structure is the slope mouth,the width of the groove is changed,and the height of the groove is changed.Secondly,the distance from the end of the wire to the side wall is changed through the cross slider.Finally,correlation analysis is carried out on data of different groove morphologies.The input feature vector is composed of the groove morphology,welding current I,and the shortest distance from the wire end to the sidewall w,and the sidewall penetration depth P is taken as the output feature vector.By using kernel function in support vector machine,the prediction model of the lower side wall melting depth of variable groove is obtained.The related research lays a foundation for further control of weld forming under variable groove.