Optimization Of Multi-layer Scanning Path For Selective Laser Melting Based On Transient Finite Elements Analysis

Selective laser melting(selective laser melting,SLM)is a complex process,which involves the process of metal solid-liquid conversion,heat conduction,heat radiation,and so on,the warping deformation of molded parts has always been the main reason of influencing the forming precision of parts and restricting the development of SLM technology.Because of the fast heating and heat dissipation of thin-walled parts,the distribution of temperature field is very uneven,which is more prone to warping deformation.In order to ensure the normal process of SLM and improve the forming precision of thin-walled parts,the distribution of temperature field must be controlled effectively.It is necessary to study the scanning path of the thin-walled parts reasonably and to reduce the temperature gradient and warping deformation of the forming parts,so it is very important to research the multilayer scanning paths of SLM-oriented thin-walled components.Based on the APDL language of Ansys software,the transient finite element analysis of temperature field,stress field and warping deformation of the simple thin-walled parts in SLM machining process is carried out in this paper.The relationship between temperature gradient,internal stress and warping deformation is investigated,and the mechanism of influencing the forming accuracy of the parts is analyzed from the whole forming process,and a multilayer optimal scanning path for thin-walled parts is proposed.The specific work is as follows: Firstly,the numerical model of temperature field of single layer and multilayer forming specimen in SLM process was established by Ansys finite element analysis software,it is concluded that the forming layer has the function of re heating and stress releasing of the formed layer during the multi-layer forming process,and the thermal accumulation of the specimen becomes larger with the processing.Therefore,in the process of processing should be appropriate to increase the cooling time between the layers.Secondly,the stress and strain characteristics of the workpiece are calculated by combining the thermal-structural coupling analysis method.This paper probes into the variation of stress field and warping deformation of specimen in Single-layer and multilayer forming process,and analyses the mechanism of warping deformation caused by the change of temperature field and stress field.Finally,the model of thin-walled structure is established,and the influence of different scanning molding methods on the forming accuracy is analyzed.For the thin-walled structural parts,the temperature field and stress field of multi-layer forming in six kinds of scanning modes are compared,and the warping deformation of thin-walled structural parts under different scanning forming modes is analyzed,and the optimum scanning path of multilayer forming of thin-walled structure parts is obtained.The improvement of the forming precision of the thin-walled structural parts by optimizing the scanning path is discussed.