Fundamental Research On Additive Manufacturing Forming Of Thin Wall Parts By High Energy Pulse Cold Welding

In recent years,additive manufacturing technology as a revolutionary technology for parts,has been rapidly developed in automotive,aerospace,medical and other fields.Arc additive manufacturing technology is favored by researchers with low cost,no size limitation,high deposition efficiency.However,this technology has a large heat input during surfacing,and it is easy to generate large thermal stress,which causes hot deformation and internal defects of the parts,and it is difficult to ensure the forming accuracy of the parts.High-energy pulse cold welding has a small heat input amount during the surfacing process,and can realize accurate forming of parts,and can be used for precision repair and remanufacturing of various metal parts,scratches and cracks.However,there are few reports on the use of this technology in the field of additive manufacturing of metal parts.In this paper,the fundamental research on additive manufacturing forming of the thin wall parts forming by high-energy pulse cold welding was studied,which enriches and develops the control theory and method for forming parts of high-energy pulse cold welding additive manufacturing technology.Based on high energy pulse cold welding manufacturing technology as the research object,the pulse arc discharge under no-load experiment was carried out under different welding process parameters,the spot weld,long weld,multi-layer cylinder and other parts of the welding deformation test,according to the pulse arc current and voltage waveform,analysis the process of pulsed arc discharge and the characteristics of pulse arc.The additive manufacturing tests of parts under different welding parameters were carried out to reveal the influence of welding process parameters on the forming rule,geometric size and surface morphology of spot weld,long weld and multi-layer cylinder.The research results show that the output of high-energy pulse cold welding is pulse square wave,which produces intermittent pulse arc,the pulse time is short,the arc energy density is high,the cooling time is long,the heat input is small,and the substrate is in a cold state,the molten pool has a short existence time,and there is no flow phenomenon in the weld pool,which can realize surfacing welding of different inclined angle parts,and this technology has the ability to create and shape complex parts.With the increase of pulse current,the maximum height of the spot weld decrease,and the width increase.Under different diameter welding wires,as the pulse current and pulse time increase,the height of the spot weld decreases and the width increases.In the same number of layers,the diameter of the stacked forming singlepoint cylindrical part increases and the height decreases.With the increase of the gap between two poles,the height of the spot weld increases,while the width decreases.With the pulse current and pulse time increase,the width of the long weld increases and the height changes less.As the pitch of the solder joint increases,the width of the long weld decreases and the surface flatness becomes worse.As the diameter of the wire increases,the height and width of the thin wall increase.