The Study Of The Welding Pool Real-time Visual Sensing And Parameter-vontrol System In Bypass Coupling Arc Mig Welding

With the development of welding technology, the high-efficiency welding attracts the intention of more and more researchers in the welding field. The thesis proposes bypass coupling arc GMAW method which makes use of the bypass-flow of bypass arc to reduce current flowing through parent metal so as to reduce heat-input to the parent metal while ensuring high deposition rate. The thesis carries out researches on the process, signal detection and control system of non-melt pole single-bypass coupling MIG welding.Firstly, a set of signal detection and hard-ware platform applied to the non-melt pole single-bypass coupling arc MIG welding is established; the LadVIEW software is adopted to write programs for simultaneous collection, motion control and bypass current control of multichannel current, arc and welding-pool images of the bypass coupling arc MIG welding, so as to realize the real-time control to simultaneous high-speed collection, real-time display and storage of welding current, voltage and video images and work table, etc. hardware equipments.In addition, based on large amount of polytechnic test, with bypass coupling arc MIG welding method, clear imagines of welding-pool are obtained using common CCD camera accompany with compounding filters in the condition of constant heavy current. With digital image processing technology, images of welding-pools are processed in real time by means of IMAQ module of the software Lab VIEW. After comparing and analyzing the results of welding-pool edge detected by various image processing methods, the best morphological processing method is obtained and welding-pool width is also detected in real time. On the basis of that, considering welding process is a leaner, strong coupling, strong time-varying system. A fuzzy controller based on LabVIEW is designed to control welding-pool width in the welding process.Last, it is proposed that constant current source should be used in main pass MIG welding, pulse current should be used in non-melting bypass coupling arc MIG welding, and different base metal is used in welding polytechnic test with the welding method. In order to make welding process more stable and current regulation more concrete, welding process control system is designed based on MATLAB xPC Target.It is revealed that clear image of the welding pool can be obtained in constant large current of 270A with visual detection system designed by Chinese in bypass coupling arc MIG welding, which is deemed as a low cost while high efficient welding method. Programmed by Labview, the width of the welding pool which is obtained by visual detection system is measured automatically. The time for the measurement is about 40 ms. The result of the measurement is in accord with the actual welding pool width. It lays a foundation for penetration control in visual sensing. The welding process is controlled in which Constant current source is applied to both main pass and bypass in bypass coupling arc MIG welding. The welding process is stable. The welding seam is formed well. It lays a foundation for the precise current control in welding on the base metal which is sensitive to heat input.