Study On Core Injection Process Of Sodium Silicate Sand

Foundry industry is the foundation of equipment manufacturing industry,and sand casting is the most important casting method.Among the three most commonly used types of sand,namely clay sand,resin sand and sodium silicate sand,sodium silicate sand has the most advantages in terms of green environment,so the development potential of sodium silicate sand is very large.However,although sodium silicate sand has many advantages,it has poor dispersion and other problems,which still seriously restrict its large-scale use and promotion.The root cause of poor dispersion of sodium silicate sand is due to the large amount of sodium silicate added(4% and above),so reducing the amount of sodium silicate added should be an important way to solve the problem.In addition,due to the serious environmental pollution problem of resin sand core,the machine core making of sodium silicate sand is receiving more extensive attention.In this paper,the authors intend to add modifiers to improve the performance of sodium silicate sand,reduce the sodium silicate sand addition level to 1.5%,and study the sodium silicate sand core injection process with brake disc cores,which are quite complicated to make cores,in order to promote the practical application of sodium silicate sand machine core making technology.The research in this paper is mainly as follows:First,to improve the quality of sand core.The proportioning experiments were conducted with modified sodium silicate sand with 14% modifier G6 and 10% with agent ester E4 as binder and four additives ZL-1,ZL-2,ZL-3 and ZL-4 were added respectively.The results showed that when ZL-1,ZL-2 and ZL-3 were added at 0.3%,0.15% and 0.5%,the fluidity of sodium silicate sand increased by 30%,20% and 11%,respectively,and the surface stability decreased by 25%,50% and 16%,respectively.the addition of ZL-4made the bonding between sodium silicate sand more solid.When ZL-4 was added at0.5%,the surface stability of the sodium silicate sand increased by 17% and the fluidity decreased by 34%.Then,the core shooting process was investigated.After adding 14%modifier G6,10%having agent ester E4,and 1.5%sodium silicate mixed in the original sand,respectively.By comparing multiple experiments,the sand cores made with single blowing of CO2 for 200s and single blowing of hot air for 110s(gas temperature 120°C,blowing pressure 0.3Mpa,sand injection time 2s)under cold core box conditions were improved in terms of sand drop.Under the condition of hot core box(200℃),single blowing 90s of CO2 and 15s of hot air(gas temperature 120℃,blowing pressure 0.3Mpa,sand injection time 2s);compound blowing using 15s of hot air(gas temperature 120℃,blowing pressure 0.3Mpa,sand injection time 2s)and then blowing 90s of CO2,the appearance of the sand cores made is good and the sand drop situation is improved.certain improvement.The effect of sand core placement was also studied.The study showed that the sand core would absorb moisture and carbon dioxide in the air,so it is better to place the sand core in isolation after demolding;the placement method also has an effect on the sand core placement after molding,and it is better to choose a placement method that is not affected by the gravity of the sand core itself to prevent the sand core from breaking during the curing process due to the influence of the gravity of the sand core itself.Next,four additives were added to the modified sodium silicate sand for core shooting process research.The results of the study showed that ZL-4 additive had the greatest effect on the core forming of sodium silicate sand,and the improvement of surface stability of the core was very obvious.In the orthogonal experiment of sodium silicate sand after adding ZL-4,the optimal core shooting process parameters were obtained as hot air(gas temperature 120℃,blowing pressure 0.3Mpa)blowing for 10 s and then CO2 blowing for 70 s,sand shooting time of 1.5s,mold temperature of 200℃,complete core molding,smooth top and bottom surface without sand loss.Finally,In order to verify the modification effect of the modifier on the sodium silicate sand,experimental casting was carried out.The experimental results show that the modified sodium silicate sand can obtain.