| The ultra-narrow gap welding using flux pieces constraining arc method has obtained many periodical achievements through constant development.The main research question at present is(1)How to realize the automatic production of flux piece and flux chain;(2)How to make flux pieces convey into the groove to complete stable welding process,and achieve weld joint with good performance.Based on the summary of the advantages and disadvantages of flux band(flux piece chain)manufacturing process and applicable performance,designing the structure of flux piece again and making it through squash technique.In order to solve problem of single flux piece easy to rotate around the fiberglass string,this paper presents fiberglass mesh type flux chain,the structure of this flux chain not only retained advantages of fiberglass mesh type flux chain but also has excellent elasticity.When the flux piece chain was conveyed into the groove,it was close to the side wall to ensure two sides wall and the root fuse well.The author produced a single set of fiberglass mesh braiding machine to woven the fiberglass mesh designed in this paper,and research the binder ratio of fiberglass mesh at the same time.Test found that fiberglass mesh binder not only had good elasticity but also uneasy to be broken down when the ratio of the epoxy resin and diluent was 1:2.In order to realize the automation of the ultra narrow gap welding,the author designed a set of four degrees of freedom ultra narrow gap welding experiment device.This set of device consists of ultra narrow gap welding torch with conveying flux piece chain,welding rig and travel mechansim.The ultra narrow gap welding torch with conveying flux piece chain not only realized automatic transmission of flux piece chain but also welding torch wire conductive part adopted the integration of the design reducing the number of the welding torch parts for the convenience of welding torch assembly and disassembly.Welding work fixture is composed of four square steel,using strength bolt and two positioning bolt to clamp welding specimen.This welding rig travel agency with four degrees of freedom,can move along the X,Y,Z axes and around the Z axis rotation.Finally,using the ultra narrow gap welding rig performed process test,this paper explore the ultra narrow gap welding process stability from three aspects,namely the dropping external characteristic power source,wire offset,groove width variation.Under the same welding process parameters,by comparing welding sample cross section morphology and waveform changes in the welding process under the dropping external characteristic power source mode and the flat external characteristic power source mode,found that the dropping external characteristic power source mode could increase the stability of arc,making the ultra narrow gap welding had better adaptability.The former welding process test had confirmed that the distance between the wire and flux played an important role in constraining arc,weld forming,and the distance between the two was 0.35 ~ 0.5 mm,the weld quality was best.In this paper,through the diameter of the fiberglass mesh longitudinal line controlled the distance between the wire and fluxes.When the wire deviated from the center line of the groove,the wire and fiberglass mesh longitudinal line would produce a force,resulted in the tip of wire produce trace amounts of deformation,ensured enough distance between the wire and fluxes,so as to the sides wall and root fused well.During the period of actual industrial production,the welding groove width would produce a certain amount of change in the same path.In this paper,under a certain welding process parameters,through the v-shaped weld specimen simulated this phenomenon.Test found that with the increase of groove width,melt dripping transition frequency reduced,the volatility of welding current and arc voltage increased. |
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