Research On Expandable Polystyrene Pattern High-quality And Efficience Machining Process

In 21st Century,the lost foam foundry industry is a green foundry technology,which is widely used in complex and high-quality castings in recent years.Machining equipment and craft of lost foam foundry is monopolized by foreign countries and the technology is blockaded,the equipment is expensive.Besides,the demand of single and small batch flexible LFC castings in domestic market is becoming stronger ever.The most urgent problem is to solve NC forming technology as soon as possible.Thus,in this paper the NC forming technology--which is green manufacturing--of expandable plastic pattern is researched.Firstly,according to the processing experiments and reference to the dodecahedron pentagonal foam model,bead releasing is found as the main machining defect.And cutting tool and parameters of the machining is main factors in the machining.After the analysis of the movement and cutting force of the tool,we found that bead releasing made by the tool often happens on the rake face and chip flutes,radial rake angle is the main factor result the bead releasing on the rake face.The smaller the radial rake angle is,the lesser of the phenomenon of bead releasing happens,When the number of the blades up to 6,the cutting force tends to a constant value,from 6.68N tends to 2N.When the helix angle is about 35°,there is the smallest cutting force(as the value of 2.26N),and chips is throwed well.Secondly,we research the influence of the structure parameters of the tool to the forming quality of model,in order to reducing the machining deviation caused by the structure parameters of the tool.And the deformation of the tool in the machining is researched,too.At last,we know that radial rake angle is the most important factor,the fitting helix angle is 35°,the number of the blades is more than 6,good forming quality turns.Thirdly,on the foundation of the tool research,we want to know the relationship between the machining parameters and the forming quality of the expandable plactic pattern,to know the machining law of the different kinds of expandable plactic pattern.We analysis the relationship of factors like spindle speed,feed rate,depth and feed speed to the forming quality like dimensional accuracy,surface roughness and dimples accounting on the STMMA and EPS.The study show that when the machining condition is same,the machining character of STMMA is better than EPS.The forming law of the factors to the two material is basically same.To improving the efficiency,the spindle speed should be set as 7800r/min,variable feed rate in side milling and variable depth in end milling shoule be used in rough machining.Finally,in order to reducing the deform of the castings in the current LFC technology and in full use of LFC and No Mold Sand Casting technology,we put forward a compound forming technology of LFC and NMSC.We make a car wheel hub with the compound forming technology.At the same time,we get the changing law of the forming quality that is dimensional accuracy is controlled in 6 times from the expandable plactic pattern model to the casting model,surface roughness in 3 times and dimples accounting in 4 times.We can get the good quality by the compound forming technology and provide a new craft to the castings.