Study On Forming Process Of Vacuum Counter-pressure Casting Thin-wall Electric Box Castings Using Impregnation Post-processing SLS Resin Coated Sand Mold

The complex thin-walled castings can be quickly produced by combination of selective laser sintering resin coated sand mold(core) and Vacuum Counter-Pressure Casting, but there are many problems such as low initial strength and poor surface quality of SLS coated sand mold, which difficult to directly used in vacuum Counter-Pressure pressure casting, and vacuum Counter-Pressure pressure process parameters is more difficult to determine. Therefore, the SLS coated sand mold(core) the reprocessing reinforcement, explore the vacuum Counter-Pressure casting of SLS coated sand process, forming lay the theoretical and practical value for the SLS coated sand vacuum Counter-Pressure casting complex thin-walled castings.In this paper, taking a model casting of aeronautical thin-walled electrical box for the study, strengthening SLS coated sand mold by infiltration of silica sol, study on influence of infiltration silica sol and post curing temperature and time on the properties of SLS coated sand, analysis impregnated silica reinforced strengthening Mechanism for SLS coated sand, optimize pressure parameters of the SLS coated sand vacuum counter-pressure casting. Experimental results show, The influence of the silica sol and the post curing temperature and time on the strength, surface roughness and air permeability of SLS coated sand were significant. With infiltration temperature and time increase, the SLS coated sand strength, permeability increases at first and then decreased, the surface roughness decreases first and then increases, get the best infiltration temperature of 30℃, infiltration time is 15 h. With the infiltration post curing temperature and time increase, the SLS coated sand strength, permeability increases at first and then decreased, the surface roughness decreases first and then increases, get the best infiltration after curing temperature of 180 ℃, the curing time is 15h; get the best process LS coated sand vacuum counter-pressure casting with thin-walled box process parameters, for vacuum 20 kpa, filling pressure35 kpa, holding pressure time160 s, solidification pressure300 kpa, mold temperature of 120℃ and pouring temperature 680℃. And using optimal parameters to cast a certain type of aerospace Thin-walled electrical box of the casting air tightness and good surface quality by SLS coated sand vacuum counter-pressure.Through cast a certain type of Aerospace Thin-walled electrical box which infiltration of silica sol and curing process of strengthening SLS coated sand and vacuum counter-pressure casting combined, get the best strengthening SLS coated sand and vacuum counter-pressure casting forming technology for complex thin-walled castings rapid precision casting production provided the theoretical guidance and technical support.