Research On Automatic Seam Tracking System Of CO₂ Welding Machine For Ventilation Duct

The research background of this subject is the automatic tracking problem of welding seam of straight longitudinal seam,annular seam and elbow non-circular seam of ventilation duct.When welding the girth seam,the welding path is the same as the cutting path,but after the secondary clamping of the pipe,there is a certain degree of deviation,which makes the angle of the welding torch deviate from the position of the welding seam;in the cold state,the welding gun will go along the welding seam,and after the arc starts,Due to the effect of arc heat,the welding seam changes its original position,resulting in leakage welding and undercut defects.It is necessary to manually adjust the position of the welding torch frequently,which in turn leads to the problems of low production efficiency and high rejection rate of ventilation ducts.Based on the above problems,the subject has carried out the research on the automatic welding seam tracking system based on laser vision.By improving the movement mode of the welding torch,the movement of the welding torch in the horizontal,vertical,lateral,swing and deflection directions can be realized.Aiming at the characteristics of arc light,smoke and spatter during CO₂welding,the system adopts a high-definition camera,a red light-line laser,and a narrow-band filter to form a laser vision sensor,and performs image processing on the collected images.After the machine receives the deviation information,it sends motion commands to control the movement of the welding torch to complete the real-time deviation correction of the welding torch during the pipeline welding process.In the study,Solid Works was used to design the pipe displacement device,the pipe clamping mechanism and the welding torch feeding mechanism,and the strength of the main shaft in the displacement device was checked.In addition,a set of control system based on CTSC-200 PLC is also designed,the electrical schematic diagram is drawn by Auto CAD,and a welding seam with high calculation efficiency and strong applicability,which can meet the requirements of the welding seam tracking system,is designed by using Visual Basic 6.0.The image processing program has written an interactive interface and a motion control program,which can automatically control the deflection of the pipeline and the movement of the welding torch according to the welding seam deviation information given by the image processing program,and realize the automatic welding seam tracking function.The experimental test shows that the automatic welding seam tracking system of the ventilation duct CO₂welding machine realizes the real-time image processing of the ventilation duct welding seam,which can give the position deviation of the welding seam of the girth weld and the straight weld,and can also detect the non-circular shape of the elbow.The position of the welding seam is accurately judged,and the deflection angle of the welding torch is given.Preliminary experiments on narrow-band laser light sources show that the position of the weld groove can be characterized by the strip laser,and the corresponding image processing algorithm can identify the weld position quickly and well.The designed VB and PLC programs can realize the motion control of the welding torch with four degrees of freedom,and initially achieve the design goal.The image processing algorithm in it also has certain reference significance in related fields.