Research On The Process And Performance Of Frozen Sand Molding

In the case of increasingly serious environmental pollution,with the continuous progress of human society and the continuous improvement of the concept of green development,the development of green manufacturing technology has become an irreversible situation,and it has also become the only way for the modern manufacturing industry.The application of green and environmentally friendly frozen sand casting technology to the foundry industry will further promote the green development of sand casting technology.This paper mainly takes the frozen sand molding process as the main research object,selects silica sand and high-alumina sand as two kinds of raw sand,and adds different clay and water content to silica sand and high-alumina sand respectively to obtain the best ratio of clay and water content.The main conclusions are as follows:(1)When the water content is constant,as the clay content increases,the strength of the frozen sand mold decreases overall,but not obviously;when the clay content is constant,as the water content increases,the strength of the frozen sand mold increases.As the particle size of silica sand and high alumina sand increases,the strength of the frozen sand mold decreases;under the premise of adding the same clay content and water content,the average strength of sand particles with different meshes is approximately equal to the strength of the original sand mold.As the particle size of silica sand and high alumina sand increases,the air permeability of the frozen sand mold becomes higher;under the premise of adding the same clay content and water content,the average air permeability of sand particles with different meshes is approximately equal to that of the original sand mold.As the freezing temperature decreases,the strength of the frozen sand mold first increases and then becomes flat,and the air permeability decreases.(2)For the three coating processes,the spraying process of boron nitride coatings,inorganic high temperature resistant anticorrosive coatings and zinc oxide coatings is respectively 2:1,3:1,and 3:1;the spraying pressure is 0.16 MPa,0.16 MPa,and 0.12MPa;After spraying the coating,the surface of the casting is smoother and the surface has less sand sticking.The anti-sand sticking effect of the three coatings is better.Spraying the coating can improve the tendency of the casting to stick to sand.After spraying boron nitride coatings,the porosity of the casting is 9.2%,and after spraying inorganic high temperature resistant anticorrosive coatings,the porosity of the casting is 9.5%,while the casting porosity is almost zero when the coating is not sprayed and zinc oxide coatings is sprayed,and zinc oxide coatings can be used.(3)Different casting methods have almost the same crystal structure,and the castings have obtained a relatively uniform microstructure,all of which are cellular crystals.The measured grain size of the resin sand casting is 133.6±3.5μm,the grain size of the frozen silica sand casting is 87.9±1.5μm,and the grain size of the frozen bauxite casting is 88.0±1.5μm.In the cast state,yield strength(YS),tensile strength(UTS)and elongation(El)of the resin sand mold ZL205 A alloy are 115.25 MPa,196.54 MPa and 11.3% respectively;the frozen silica sand mold YS,UTS and El are 118.18 MPa,202.71 MPa and 12.3% respectively;the frozen high alumina sand mold YS,UTS and El are 116.36MPa、197.54 MPa 和 11.8% respectively.In the T6 state,the YS,UTS and El of the resin sand mold ZL205 A alloy are 385.53MPa、438.7MPa and 7%respectively;the frozen silica sand mold YS,UTS and El are 389.8MPa、440.6MPa and 9.8%respectively;the frozen high alumina sand mold YS,UTS and El are 390.2MPa、441.8MPa 和9.5%.The strength and elongation of frozen sand castings are slightly greater than those of resin sand castings.When the cooling rate increases,the strength and ductility of the alloy become better.