Study On The Influence Of Welding Parameters On CMT3D Molding

CMT(Cold Metal Transfer)welding 3D molding is based on cold-metal transition welding arc additive manufacturing technology,use the arc as a heat source,as welding wire melting after the formation of the weld as the additive material,according to a certain path,use the way of continuously layered,to achieve rapid processing technology of special parts.The main features of 3D molding technology include,saving processing materials,flexible production methods,restricted by less,and the production cycle of the product or the workpiece is very short,the cost in terms of time and material cost has a significant space savings,and can be flexible in the product shape.In 3D molding systems,designed a three-dimensional moving mechanism,it can carry a CMT welding torch move horizontally and vertically,Design the control system to meet the requirements of 3D molding process.The position error of the welding torch of the 3D molding system is not more than 0.1 mm,and the time error is not more than0.1s.CMT cold-metal transition welding with low heat input and stable welding process was selected as the 3D molding welding method.The effects of welding parameters such as welding current,welding speed and welding voltage on the shape of weld bead were studied.The influences of interlayer temperature,welding direction and welding current on the bead shape and dimensional accuracy in 3D welding process are studied.The 3D molding process accuracy index is the roughness of the weld bead side surface and the top weld bead flatness after the multilayer weld bead is superimposed.Through the mechanical property test of 3D formed specimens,it is found that the strength and toughness of specimens in vertical direction are lower than that of parallel specimens,and the weld layers are the weakest points in 3D molding specimens.Select the appropriate welding parameters can effectively improve the mechanical properties of 3D specimens.The welding process parameters also have a great influence on the microstructureof the weld bead.When the welding wire energy is very high,the molten metal in the weld bead will stay for a long time in high temperature and the cooling speed will be low.The weld bead will easily form coarse columnar crystal structure,Poor performance.Choosing the proper welding current and welding speed and controlling the reasonable temperature of the weld bead can obtain the fine equiaxed grain structure in the weld bead so that the 3D molding member can meet the process design requirements.