Study On Visual Inspection And Control Technology Of Fusion Hole TIG Single Side Welding With Back Formation

Fusion hole in the single side welding with back formation can ensure that the base metal on both sides of the reserve gap is melted during the welding,so as to ensure the welding penetration.During the operation,welders often adjust the arc length and position of the torch in time by observing the state of the fusion hole to obtain a better welding penetration and weld forming quality.Therefore,the study of the fusion hole is of great significance for the penetration prediction and forming control of single side welding with backside formation.The wire filling TIG working platform is improved,and a passive vision sensor system composed of dual CMOS cameras on the two sides and a filter system is built.The front and back images of the fusion hole are collected online in real time.The three-dimensional motion platform and the wire feeder are controlled;at the same time,the data acquisition card is used to control the welding current.Based on the respective characteristics of the front and back images of the fusion hole,differen image algorithms designed by MATLAB software are used to extract the edge of the front fusion hole,the arc edge in the fusion hole,and the contour of the back fusion hole.The cameras of the two sides were calibrated through the pinhole imaging model,and three image eigenvalues:the width of the front fusion hole,the length of the arc in the fusion hole,and the area of the back fusion hole were defined and extracted to characterize the size of the fusion hole.Constant parameter filler wire TIG backing welding tests are designed,analyze the fusion hole evolution process and formation mechanism are analyzed.At the same time the influence of the main welding parameters on the fusion hole are explored.Experiment results show that in a certain welding parameters,when the wire speed is lower and the reserve gap is wider,the easier the fusion hole forming and growing.The fusion hole is affected by the heat input and arc pressure.When the welding current is higher,the welding arc can melt more metal and exclude more molten pool,larger the fusion hole is.Extracting and analyzing the image eigenvalues in the experiment,it is found that the arc length in the fusion hole and the area of the back fusion hole can reflect the dynamic change process of the fusion hole more accurately and sensitively than the width of the front fusion hole.Design step change in welding parameter experiment and quantitatively analyze the relationship between the image eigenvalues values of the fusion hole and the welding parameters.Experiment results show that the fusion hole behavior cannot be affected stably and controllably by adjusting the welding current and welding speed;however the fusion hole size can be steadily adjusted in both directions by adjusting the wire speed,and the rate of the image eigenvalues values change and change of wire speed is positive correlation.Based on the correlation between wire speed and fusion hole size and experimental experience,a MISO fuzzy control system is designed,the arc length deviation value and the change rate of the arc length deviation value are imported as the input,the wire feeding speed is imported as the output,Variable gap welding experiment are carried out.Carry out the automatic control experiment on variable gap panels,it was found that the control strategy can automatically adjust the wire feeding speed to stabilize the fusion hole size.The controlled groups only keep fusion hole for about 30 seconds before the fusion hole collapsed,and the controlled groups keep fusion hole for the entire welding process.And fusion hole size maintain stable during the welding process.A fuzzy-PID controller which was designed to control the size of the fusion hole also achieved a good control effect.