Research On Rapid Prototyping Technology And Performance Of Mold For Casting

In this paper,the selective laser sintering process and post-treatment process of polystyrene powder were studied,which is designed to replace the sand mold used in casting mold.(1)The research status of selective laser sintering(SLS)is reviewed.The forming principle of SLS process,forming equipment,molding material,forming advantage and application in casting mold are introduced.(2)By analyzing the forming mechanism and process of polystyrene powder,four sintering process parameters(scanning speed,laser power,powder delivery cylinder temperature and preheat temperature)were selected,and the orthogonal design of L16(45)was designed.The optimal combination of process parameters was concluded through carried out analysis of range and variance on experimental results which included porosity,tensile strength and impact strength.The result showed that PS sintered parts had best molding quality when scanning speed was 2200mm/s,laser power was 32%,the temperature of powder delivery cylinder was 70? and the preheat temperature was 75?.(3)By orthogonal analysis,combined with the effect curve,the influence of process parameters on mechanical properties and the warping deformation of PS sintering parts were stressed and summarized,and the method of restraining the warping deformation was put forward by analyzing the mechanism of the warping deformation of polystyrene powder.Results indicated that the forming quality of PS sintered parts increased with the increase of laser power,while the increase of scanning speed decreased the forming quality.Effect on mechanical properties of sintered parts by powder delivery cylinder temperature and preheating temperature was not obvious,and warping deformation decreases with increasing degree of powder delivery cylinder temperature and preheat temperature.The reason of the warping deformation was the uneven shrinkage of the sintered layer caused by the change of the properties and the state of PS and the movement of the sintering layer by the laser energy source which is moving at the sintering time.Therefore,by setting reasonable process parameters and taking appropriate insulation measures,the temperature difference between the upper and lower parts of sinter powder layer can be reduced to reduce the warping deformation of PS sintered parts.(4)The mechanism of the interface between PS sintered parts and the sintered parts with epoxy resin was discussed.After the post-treatment,the density,surface hardness and impact strength of PS sintered parts were greatly enhanced.The good compatibility and wettability were the main reasons for the performance of PS sintered parts after treatment.