| In the shipbuilding industry,aluminum alloy materials have been widely used.Aluminum alloys have the advantages of high specific strength and good corrosion resistance,and can be used as a new structural material.At present,GMAW is the main welding technology of aluminum alloy,which has the advantages of high quality,low cost and strong adaptability,but the welding efficiency is low.The cable-type welding wire(CWW)has a special twisted structure,which can accelerate the melting speed of the welding wire and rotate the arc so as to realize efficient,high-quality and low consumption welding.In this paper,the combination of CWW technology and aluminum alloy GMAW can improve the welding technology of aluminum alloy in shipbuilding.The numerical simulation method is mainly used to study the physical behavior of the arc in the CWW-GMAW welding process of 5083 aluminum alloy and the influence of the arc of CWW-GMAW on the flow in the weld pool.It can provide a theoretical basis for aluminum alloy CWW-GMAW process.First,a three-dimensional aluminum alloy CWW-GMAW arc numerical model was established,and the distribution of welding arc physical quantities under different welding parameters was studied.The results show that when the welding current increases(125A,175 A,225A,275A),the arc of CWW-GMAW is in a "bundle" shape.The arc shape first becomes larger and then gradually shrinks,and the arc radius decreases.In addition,the peak arc temperature is from 14587.13K increases to 22266.48K,the temperature increases more and more,the plasma flow speed increases from 51.15m/s to 244.34m/s,the change is large,the peak pressure of the workpiece surface is from 72.72Pa to 554.65Pa,and the anode potential increases from 9.37V to 11.81V,the potential gradient becomes larger.When the shielding gas flow rate increased,the maximum temperature,plasma flow velocity and pressure field in the cable GMAW arc showed an increasing trend,and the arc shape contracted slightly.An aluminum alloy single wire GMAW arc model has also been established for numerical simulation calculations.The results show that the arc of CWWGMAW has significantly contracted and rotated compared to the arc of single wire,changing from a "bell" arc to a "beam" arc.The arc of CWW-GMAW will concentrate the arc energy,and the effective arc radius of the arc on the surface of the workpiece is increased from 1.7mm to 3.8mm.In addition,the peak temperature of the arc of single wire at the center of the arc is slightly higher,the difference is 348.3K,and the peak speed is 1.71 times that of the arc of CWW-GMAW.The peak pressure at the cathode is 1.75 times,and the anode is 1.61 times,the anode potential is slightly higher than the cable arc,about 0.193 V.Secondly,the numerical simulation calculation of the 5083 aluminum alloy CWWGMAW,using the double ellipsoid heat source model,to define the electromagnetic force,buoyancy,rotation force and other forces on the molten pool.The flow fields of aluminum alloy cable welding wire pool melting under 150A,200A and 250A are calculated.Due to the change of current,the droplet transfer mode changes,which are large particle transition,small particle transition,and droplet transition.The impact force on the molten pool gradually increases.In addition,the arc rotation speed increases,and the rotational force generated on the molten pool increases.The force also increases with increasing current.The change of the combined force of the above forces and buoyancy,gravity and other forces makes the size of the two circulations inside the molten pool change.The upper circulation is from large to small,which can expand the melt width,which is 7.82mm,9.03mm,10.36mm,and the bottom circulation is If there is no further increase,it can deepen the molten pool,respectively1.94mm,2.45mm,3.20mm,the filler metal increases,and the residual height increases,it is1.95mm,1.94mm,2.06 mm.In addition,the single wire GMAW molten pool is numerically calculated,and then compared with the CWW welding pool,it can be found that under the action of rotating force,the width of the molten pool is 9.03mm greater than the single wire molten pool of 8.72mm,and the length of the molten pool tail is also greater than the single Welding wire.Affected by different electromagnetic force and droplet impact force,the single-wire welding depth of 3.04mm is greater than that of CWW 2.45mm.Due to the different amount of filler metal in the welding wire,the residual height of the single-wire welding seam is 2.24mm greater than the CWW 1.94mm.Finally,an aluminum alloy GMAW test was conducted.Collecting the welding arc signal,you can see that the CWW arc rotates and shrinks.As the current increases,the arc radius becomes smaller,and the ratio of the upper and lower diameters is 1.21,1.16,1.09,1.07,and the arc stiffness increases.And the calculation results were verified,and found that the calculation results and the GMAW arc shape is almost the same,which proves the rationality of the numerical simulation results.Collect the arc spectrum information to calculate the actual temperature of the arc,and compare it with the temperature obtained by numerical simulation.The change trend of the two is the same.The error range of the two is2.87%～7.51%,which can prove the rationality of the numerical simulation.A macro-analysis of the weld cross section reveals that the shape of the GMAW molten pool of the CWW and the single welding wire is similar to the results obtained by the numerical simulation,which verifies the accuracy of the simulation results.The numerical simulation of the 5083 aluminum alloy cable welding wire and single wire GMAW arc and molten pool shows that after the cable welding arc is coupled,rotated,and contracted,the heat is more concentrated,which can effectively reduce the volume of the heat affected zone and expand the melting.The width of the pool and the cladding rate of the welding wire are increased,which is more suitable for high-efficiency welding.The results of this study can provide a theoretical basis for the actual production and use of the GMAW method of aluminum alloy cable welding wire. |
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