Surface Bonding Sand Of Sand Casting Cylinder Block

This paper is aiming at the high rejection rate of thin-walled cylinder casting caused by surface adhering sand sintering.Through the analysis of the factors influencing the surface adhering sand,optimizing sand casting technology and coating spraying technology to solve the problem of surface adhering sand sintering.Using a multimeter measuring method and concentrated hydrochloric acid chemical reaction method to study thin-walled cylinder castings surface adhering sand categories.Using metallographic microscope to analyse the microstructure of sand castings and adhering sand state.The study of sand mold shows that using MCS,FS powder instead of pulverized coal can make the reduction of sand moisture and gas production.Using the natural sodium bentonite which had a swelling value of more than 95% to replace the artificial activated sodium bentonite can reduce the surface adhering sand.Under the condition of high bentonite and absorbing methylene blue,the sand mold has good quality and the casting has good surface quality.The higher the expansion coefficient of the wet sand,the higher the expansion of the sand,the more obvious the defect of the casting.Reducing the sand grain size can reduce the sand sticking.In the process of cylinder casting,the amount of core sand increases gradually,which results in the increase of the sand grain size and the serious sand sticking.The hardness of the sand mold is controlled in the range of 85 to 90 g/mm2.The coating spraying shows that the pouring temperature of the thin-walled cylinder is high,and the sand sticking of the cylinder body is mainly mechanical sand sticking,chemical bonded sand and mechanical and chemical mixed sand accounted for less than 10%.Spray coating is beneficial to prevent mechanical sticking.Graphite,corundum and zirconium powder coating are the same as to prevent sand sticking.HA zirconium powder coating,although slightly better than the current state of production,the bottom of the cylinder casting is still stuck at the corner of the sand.Foseco coating with high,low proportion of the two kinds of coatings,a layer of sand after ignition phenomenon,no abnormal phenomenon on casting surface.Ignition and non ignition of the cylinder,the surface quality has little difference.The use of sand casting process optimization,spray a layer of paint,then dipping451 anti veining coatings,and then coated with a layer of zirconium powder coating,the cylinder surface quality improved significantly,the waste rate caused by the cylinder surface quality fell below 1%,reduces the cylinder production costs and production cycle.