Research On Manufacturing Technology Of Cold Welding Additive With Preset Welding Wire

After decades of development,additive manufacturing technology has made great progress in the fields of aerospace,medical equipment,automobile mold and art.Compared with other metal additive manufacturing technologies,arc additive manufacturing technology has great potential,due to its advantages of low cost,high material utilization rate and unlimited forming size,it has attracted the attention of researchers.However,in the process of welding forming,the heat input is large,the molten pool is prone to collapse,the forming quality is unstable,resulting in the final forming parts with internal defects and poor forming accuracy.In this paper,the method of cold welding additive manufacturing after pre-welding wire remelting is adopted.Each layer is pre-assembled with corresponding length of wire to form the shape of the layer,and then the layer of pre-welding wire is remelted,and then the metal parts can be accumulated by pre-welding wire and remelting layer by layer.In order to improve the forming accuracy of additive manufacturing parts,this paper studies the additive manufacturing process of cold welding prefabricated wire,which is beneficial to the application of the technology to practice and to improve the theory.In order to study the influence of cold welding additive manufacturing process of preset welding wire on part forming,we developed a three dimensional numerical control welding device,conducted the remelting preset layer test under different welding process parameters and remelting trajectory,complete the forming of ring parts and complex structural parts.The results show that the pulse current and welding time in welding parameters have the greatest influence on the size of bead forming,and the weld width increases with the increase of pulse current and pulse time.Spot spacing and weld spacing have a great influence on the flatness of weld seam and surfacing layer.With the increase of spacing,the flatness of surfacing layer tends to increase,but with the decrease of spacing,the overall heat input increases,and the stress and deformation of surfacing layer increase.In addition,welding process parameters have little influence on the thickness of remelted layer,and the thickness of remelted layer is consistent with that of the preset layer.After the completion of welding wire presetting,the remelting trajectory has a great impact on the forming quality of the surfacing layer.Compared with the remelting parallel to the direction of the preset wire,the remelting weld perpendicular to the direction of the preset wire is better formed and the overlap is more uniform,and the surface flatness of the remelting layer is better.Remelting the edges and then remelting the inside ensures the shape and size of the remelting layer.The method of remelting after presetting welding wire can control the height of each layer and the amount of fuse at each position,so as to ensure the forming accuracy of parts accumulated layer by layer.It is applicable to the structure with different tilt Angle,can adopt the support structure and be removed easily,suitable for the additive manufacturing of complex parts.