Forming Quality Analysis And Process Numerical Calculation Of Wire And Arc Additive Manufacturing

Wire and Arc Additive Manufacturing,as one of the 3D printing technologies,has the advantages of uniform chemical composition,good mechanical properties,high utilization rate of welding wire and low cost,but poor stability,low surface quality and dimensional accuracy in the forming process.By analyzing the forming morphology of the wire and arc additive manufacturing shaped parts,it is helpful to improve its utilization rate.In this paper,Q235 low carbon steel plate is selected as the base plate and 304 stainless steel as the welding wire for wire and arc additive manufacturing experiment.The process experiments were carried out with different welding direction,thickness of substrate and current type,and the experimental results were analyzed to summarize the influence of various variables on the forming quality.The experimental results show that in the process of additive manufacturing,the forming height of the weldment is lower on both sides and higher in the middle,and obvious flow and collapse appear at both ends,which are gradually intensified with the increase of the number of welding layers,and the forming height of the arc starting end of the weld bead is higher than that of the arc extinguishing end.The forming effect of reciprocating welding between layers is better than that of unidirectional welding,and the height difference between the end and the middle of the formed part is small.When the thickness of the substrate is 8mm,the arcing end of the bottom layer weld will tear under the action of tensile stress,and the more the number of welding layers,the more obvious the tearing and warping.The formed parts made of pulse current additive have good forming quality and smooth vertical wall.It is difficult to study the forming dynamic evolution process of the formed parts in the process of wire and arc additive manufacturing through process experiments,and it is impossible to analyze the distribution of temperature field and stress field of the formed parts in the manufacturing process.In this paper,visual environment simulation software is used to calculate the temperature field and stress field in the process of wire and arc additive manufacturing.It is found that there is a deviation between the time when the peak temperature of one-way welding and reciprocating welding reaches in even layers.In the process of welding,the weld area is subject to compressive stress,and the edge of base plate is subject to tensile stress;at the end of welding,the weld area is subject to larger tensile stress,and the edge of base plate is subject to compressive stress.Under the influence of the clamping point,the deformation difference between them is small.When the thickness of the base plate is different,the heat dissipation speed of the thin plate is fast,it bears more stress and produces large deformation.With the increase of the number of welding layers,the forming height of the weldment increases,the distance between the top weld and the base plate increases,and the heat is mainly transferred between the welds.The stress of the weldment decreases with the increase of the number of welding layers,and the deformation of the weld area is large.