Research On Optimizing Process Parameters In Selective Laser Melting

Selective Laser Melting(SLM)technology is an important branch of additive manufacturing technology.It has been developed for the purpose of producing full-density solid parts of any shape.There have been good developments in recent years,but there is room for improvement in the control of forming quality,mainly involving the optimization of process parameters.In this paper,water atomized iron powder is taken as the research object,and it is carried out by theoretical research,numerical simulation and experimental verification to optimize the process parameters related to the forming quality.The intrinsic mechanism analysis of spheroidization and warpage cracking is carried out,and the reasons for the formation of these two shaped parts are described.It is found that the spheroidization phenomenon is caused by the surface tension of the liquid phase,and the warpage cracking is caused by the temperature gradient.Inconsistent shrinkage is caused by some improvements in material and process parameters.The three-dimensional transient temperature field model of the optimized selective laser melting process was established by ANSYS finite element software.The characteristic analysis of the temperature field was carried out,and the temperature delay effect was found at the highest temperature of the molten pool.The effects of laser power,spot radius and scanning speed on the temperature field were studied and the sensitivity analysis of the parameters was carried out.The temperature value increases with the increase of laser power,and decreases with the increase of spot radius and scanning speed.The sensitivity of temperature field temperature level to parameters is from spot height to laser spot radius,laser power and scanning speed.Under the conditions of laser power,spot radius and scanning speed,the scanning pitch and the layer height are optimized based on the principle of minimum energy consumption,and the optimization of process parameters in selective laser cladding is further improved.Based on the simulation results of temperature field,a three-dimensional stress-strain analysis model was established.The thermal coupling analysis was carried out by means of indirect coupling.The generation process of continuous entities was simulated by the method of life and death unit.The stress field was analyzed and found in the molten pool.In the state of compressive stress,the sintered portion exhibits a tensile stress state,the X-direction tensile stress of the sintered portion is greater than the tensile stress in the Y direction,and a large stress concentration occurs at the junction of the sintered layer and the substrate;The standard finds that as the energy input of the powder bed increases,the residual stress increases,and within the range allowed by the practical conditions,when the laser energy input is constant,the larger scanning speed should be preferentially selected,and then the appropriate laser power and spot radius should be selected.The experimental prototype was set up,and the sintering experiment was carried out under the conditions of changing laser power,scanning speed,spot radius and high layer thickness.The effects of process parameters on the quality of the formed parts were explained from the aspects of density,residual stress and surface roughness.