| Metal surfacing technology has been developed from 3D printing rapid prototyping technology.On the one hand,it inherits the advantages of 3D printing technology,namely high molding efficiency,cost saving,flexible molding path for forming complex parts,and metal surfacing technology.The advantages of welding technology include good joint performance,good overall structural mechanical properties,and wide adaptability.At the same time,the metal surfacing technology also has the following shortcomings,such as poor quality of the molding surface and large residual stress.The experimental method can not meet the research needs.Nowadays,the research on the surfacing technology is not only limited to the experimental method.Instead,it combines the surfacing technology with the finite element analysis technology,and then compares it with the actual experimental results,and studies it more conveniently and intuitively through numerical simulation.In this paper,the arc is used as the energy input,and H08Mn2 SiA is used as the filler wire material to carry out finite element numerical simulation analysis on a single wall.This paper starts from the difference between the experimental and numerical simulation temperature curves.Firstly,the main types of heat transfer,namely convective heat transfer,conduction heat transfer and radiation heat transfer,are explained in detail,and the heat transfer mode under welding conditions is analyzed.Play a leading role.Then based on the previous theoretical analysis,the heat dissipation function model is compiled and the role of each parameter in the heat dissipation function is analyzed.The parameters of the blackbody coefficient and the convective heat transfer coefficient are mainly discussed.Finally,using the finite element software to call the completed heat-dissipation function program,after modifying the range variable in the heat-dissipation function,after a large number of simulation tests,the optimal set of parameters is found to make the result more consistent with the actual result.Therefore,the set of parameters is used as an optimization parameter of the heat dissipation model,and then applied to the subsequent numerical simulation.Using the optimized heat dissipation model for finite element analysis,combined with the surfacing test to explore the influencing factors of molding quality.First,the influence of the speed of the welding torch is discussed.It is found that as the surfacing speed increases,the surfacing members exhibit greater compressive stress,and the forming efficiency is higher,but the surface quality is worse.As the speed decreases,the surfacing members exhibit greater tensile stress,lower molding efficiency,but better surface quality.Then,the influence of the waiting time between the tracks is discussed.It is found that the molding quality has a tendency to become better as the waiting time is extended,and the waiting time between the channels has no influence on the residual stress.Finally,the influence of the forming trajectory is discussed.For the case of single wall molding,the arc at the same position is easy to cause the molding part to be poorly formed,and the staggered reciprocating arcing method can effectively avoid the collapse phenomenon,which greatly reduces the residual stress of the molded part. |
