Study On The Wet Cluster Phenomenon In The Process Of Mixing Clay-bonded Moulding Sand

Clay-bonded moulding sand is easily obtained and shaped.resourceful and low-cost,which is the most commonly used molding material in casting production.In order to prevent the chemical scab phenomenon of the casting,to improve the surface property and reduce the subsequent clean-up workload,we usually add pulverized coal in clay green-sand.But when during casting and the disposal process of sand waste,coal and clay sand will pollute the environment,waste energy and be high-cost,and it will bring pollution to the factory,affect the health of workers and increase production costs.Given the shortcomings of the pulverized coal clay sand,Donghua University develops a kind of natural clay sand without pulverized coal.This kind of green sand can avoid the occurrence of the phenomenon of sticky sand which doesn't need the pulverized coal additives.Also it is less polluting and can save energy and be reused.What's more,the production of surface quality and size accuracy of iron castings made of the green sand are extremely excellent.But there is a certain agglomeration phenomenon during the mixing process of the natural clay sand without pulverized coal.This phenomenon will lead some kinds of disadvantages,Just like:a)Affect the overall uniformity of this kind of clay sand and make its intensity decreased,b)lower the surface finish of mold cavity of the clay sand and affect the surface quality of castings,c)may cause waste of the sand and porosity and sand hole defects,d)affect the sand mobility and not conducive to the production of complex casts,e)because it needs screen mesh to remove the clay group of the clay sand so that production efficiency is reduced and labor intensity is added.So researching and resolving phenomenon of agglomeration is important to improve the quality and mixing efficiency of the pulverized natural clay sand,and it is also significant to solve such problems during mixing process of other kinds of clay sand.Understanding of the bonding mechanism of clay sand and analyzing the mechanism of agglomeration phenomenon in sand-mixed process let us find that uneven distribution of moisture content and clay sand is an important cause of phenomenon of agglomeration.This shows that uniform distribution of moisture in the clay sand or use of additive may reduce the agglomeration phenomenon in the process of clay sand mixer.During the process of mixing sand if we change the way of adding water we can use the way of water spray to make the moisture evenly distributed.The results show that it is not ideal to spray water mist.Although the affect of spraying drops is not very notable,it can help improve the situation of agglomeration.It can evenly distribute moisture if we change the water added order during the process of mixing sand and use the measure of adding water and adding soil step bu step.The results show that it can slightly increase compressive strength and greatly reduce sand agglomeration degree when we use the way mentioned above.Though the way of adding the type of YZ-1 lubricant we want to promote the blending of sand to decrease agglomeration degree.The results show that it is effective to improve agglomeration degree of the clay sand when we add YZ-1 lubricant.It will promote strength degree to a certain extent while we add in small amounts of YZ-1 lubricant;but if the content of YZ-1 lubricant is increasingly added,the strength degree will be gradually decreased or even to the content of not being shaped.So it will be best when we keep the amount of YZ-1 lubricant within a certain range.To ensure that the strength degree is not reduced,we could attain the minimum agglomerate degree when the percent of dosage of YZ-1 lubricant is 0.35%,because thus can make the natural clay sand keeps compressive strength and can resolve the harm of agglomeration so that the clay sand can be shaped without the affect of agglomeration.In summary,we could use these measures to improve the agglomeration of clay sand:change the order of adding water and add YZ-1 lubricant.To ensure that clay sand can be reused for many times when its agglomeration has been decreased,we should repeat mixed texts.The texts show that when we re-mixed the clay sand which has been improved the agglomeration phenomenon,its agglomeration degree is still low and its compressive strength is promoted slightly,so the clay sand can be re-mixed for many times.The more time is used to mix sand,the compressive strength of clay sand is more enhanced.So adding YZ-1 lubricant when the clay sand is reused,the agglomeration degree will be increasingly decreased.