Energy Accumulation Effect And Process Optimization Of PA6 Powder In Selective Laser Sintering

During the process of adding layer by layer in selective laser sintering,the continuous input of laser energy results in the accumulation of energy in sintering area,which affects the properties of polymer samples.In this paper,the transient temperature field of PA6 powder sintering was modeled and simulated.Combined with the yellow-blue index which can reflect the aging degree of thermal oxygen,the energy change in sintering process was analyzed.The thermal oxygen aging caused by the high energy of the sample was reduced by the optimization of the process,and the sintering quality is improved.Firstly,the input,transformation and dissipation of energy in the process of laser powder interaction was analyzed.The quantitative relationship between energy change and temperature in sintering zone was established.A numerical model of sintering temperature field of PA6 powder was established by finite element method.Secondly,the energy changes in the process of single layer scanning and multilayer layer by layer addition were calculated.The results show that the energy accumulation is relatively obvious when the input energy is small and the preheating temperature is lower;the energy accumulation is faster under 10 layers when the continuous sintering in 20 layers,with an increase of 11.66%and only 0.67%in 10?20 layers.The yellow-blue index b*value of the surface of the experimental sample is measured according to the change of appearance color caused by PA6 thermal oxygen aging.The yellow-blue index b*value of 4?20 layers sintered samples increases from 6.81 to 31.02,which indicates that the aging degree of thermal oxygen increases with the increase of layer number.Finally,the experimental conditions and parameters were analyzed and optimized.The effects of different technological parameters on the quality of sintering were studied by single layer sintering experiment.A reasonable range of areal energy density is 0.15?0.24 J/mm2;based on the accumulation of energy in sintering zone during the increase of layer number,the energy density of input was reduced by changing process parameters,and the degree of thermal oxygen aging of sintered samples was reduced.The energy accumulation in the selective laser sintering process is simulated and experimentally studied.The influence of energy accumulation and related technological parameters on the sintering samples is obtained.The sintering quality is improved by reducing the thermal oxygen aging of the sample by changing parameters in sintering process,which provides a reference for the optimization of the process.