Research On Key Technology Of Microwave Hardening For Sodium Silicate Sand Mold 3D Printing

Water glass sand is one of the most environmentally friendly molding sand.Among foundry sands,sodium silicate sand is most likely to be pollution-free,which meets the needs of environmentally friendly green production and manufacturing in the 21 st century.In the traditional sand casting process,the design and processing process of complex molds is more complicated,the product development cycle is long,and the production cost of the enterprise is high.With the rapid development of microwave equipment and three-dimensional printing,the practical application of microwave moldless hardening sodium silicate sand technology has become possible.The principle of three-dimensional printing-microwave hardening printing : pave the raw sand layer by layer,use liquid water glass as a binder and bond the raw sand layer by layer through a nozzle,and then microwave harden.Through repeated sanding,selective injection of liquid water glass,and repeated microwave hardening,the shape that requires a sand mold is finally realized.Among them,a powder system mixed with solid water glass and silica sand is used,the binder system is diluted water glass,and fluidity,compactness,and microwave targeted absorption are key technologies.This paper studies the influence of different reagents on the fluidity of sand grains.The results show that the increase of the added amount of liquid reagent will reduce the fluidity of sand grains,and the change of the added amount of fine crystals or powder reagents has a weak effect on the fluidity of sand grains.Solid water glass does not affect the fluidity of sand particles.Through the three-dimensional printing of sodium silicate sand mold-microwave hardening process,the influence of different addition amount of solid sodium silicate,different microwave time,the quality of the microwave hardening layer of the sand mold,the number of hardened sand layers,the concentration of the diluted water glass used for spraying and other parameters on the strength of the sodium silicate sand mold is studied.Impact.The results show when preparing a sample with a size of Φ30mm×30mm,the solid water glass is added in 2.5%.Microwave for 60 s after finishing modeling,and microwave for 90 s again after demolding.When the weight of the hardened sand layer is 0.5g,the hardened sand The number of layers is 1 layer,and the integrated microwave effect of undiluted water glass is better.By experimenting with different modifier adding methods and different dosages to improve the compactness of the water glass sand mold.The results show that:polyquaternium-7,polyquaternium-10,silane coupling agent KH-602,silane coupling agent KH-570,titanate coupling agent CS-201,titanate coupling agent CS-101,potassium ricinoleate,ethylenediaminetetraacetic acid,graphene,etc.are all effective in improving the compactness of water glass sand molds.Among them,the improvement effect of the two measurement indicators of the instant strength and density of the sand mold after microwave curing is more obvious.When the 2% polyquaternium-10 modified sodium silicate sand,the instantaneous effect of the sand mold The increase rate of strength is 63.07%,and the increase rate of density is 3.2%.By experimenting with different adding methods and different amounts of absorbing materials to improve the targeted absorbing performance of the water glass sand mold.The results show that: flake graphite,graphene,titanium oxide,yttrium oxide,ferroferric oxide magnetic nanospheres,nano-zirconia dispersion,nano-magnesium oxide dispersion,nano-zinc oxide dispersion,etc.for improving the targeting of water glass sand The wave absorbing performance has a significant effect.Among them,the amount of graphene added is the least.When the amount of graphene added is 1%,the instant strength of the sand mold is increased by 45.80%,the surface temperature is increased from the unmodified 64.9°C to73.5°C,and the microwave utilization efficiency is increased by 12.86%.