Technology Research On The Secondary Sintering Of Porous Strucyure Based On SLS

Porous materials are the functional structure material having a great potential to be widely used, because of a large number of internal pores and both excellent physical and mechanical properties: lightweight, low density, high strength and sound absorption. For the existent domestic and foreign problems of using the first laser sintering to produce porous structure, the technology research on the secondary sintering of porous structure based on SLS is proposed and studied, combining with the technological advantages of SLS in this paper, which is very important to prepare the porous structure of any complex shape.Firstly, the problems of using the first laser sintering to produce porous structure are analyzed, and drawing up a technical route of the secondary sintering of porous structure by analyzing SLS principle and process parameters. And demonstrate the feasibility of the secondary laser sintering through preliminary experiments.And then the workability of the small size unit is researched by the experiments of spatial position and angle molding. It is concluded that if the two pillars unit body angle is in 45°~90°and the angle between pillars and horizontal is in 30°~90°, the workability of the small size unit can be improved. Construct a space geometry model of the unit combining with geometric analysis and the influence of the geometric parameters on the unit structure is researched. Established the parameter λ=0.8、α2=60° unit as the research object of the secondary sintering.Then with the experiments of measuring bulk desity, porosity, mobility and coordination number, the study gets the unit’s accumulation characteristics and the relationship between porosity and bulk density relationship; what’s more, using the PFC3 D simulation analysis software helps to prove the uniformity inside the structure of accumulation system with the normal distribution of the porosity. The averge pore size is 1.62 mm with ranging from 0.38 mm to 2.5mm.Finally, the study of sticky powder technology and building a heating device improved the unit secondary sintering properities. The laser power and secondary sintered density, the scanning speed and secondary sintered density, the power amount and secondary sintered density and the heating temperature and secondary sintered density are fitted by MATLAB, and the influence law of the experimental parameters to sintered density is quantitative analyzed. At last, the porous structure samples are sintered.