Numerical Simulation Optimization Of Casting Processes And Structure Of Ductile Iron Casting For Wind Power

With the fossil energy shortage and more and more serious pollution of environment,wind power as a kind of clean renewable energy has attracted more and more people's attention.Under this background,the wind power industry in our country develops very quickly.The wind power castings,such as wind wheel,base,shaft,etc,have large bodies and their weight of single casting is more than 10t.So if the kind of casting has a high reject rate,the enterprises will suffer great losses.The work condition of wind power casting is usually very poor and the altitude of the working place is more than tens of meters.So the casting must have high mechanical performance requirements.For this,the national standard has strict requirements for microstructure and properties of the casting.Some defects appear in the ductile iron for wind power in the process of practical production which is connected with casting processes.So it is important to estimate Whether the casting processes are reasonable.This improve the casting's reject rate greatly.In this paper,the author applied simulation software of MAGMASOFT to the production of casting and determined the parameters required by simulation at every stage.This provides theoretical foundation for the reasonable design of casting processes.Then numerical simulation of the current foundry process of wind wheel was carried out by the software.The simulation results show that there are some defects at the top of the casting which match the location of the defects in the process of actual production.The two reasons are the defects-early to seal of riser neck and unreasonable arrangement of chill.Changing arrangement of chill and the form of riser can eliminate these defects.Wind power equipment belongs to the typical thick section ductile iron.In order to study the relationship between wall thickness and microstructure property,the author designed wedge block in this study.The results show that the density of graphite nodule become less and less,and the size of graphite nodule become bigger and bigger with the increase of wall thickness.When the wall thickness reaches a certain degree,some chunky graphite appears.Chunky graphite can reduce the performance of the castings greatly.When the wall thickness is large,the cooling speed is slow and the silicon will gather around some graphite nodule this area.When the content of silicon around graphite nodule is more than 2.25%,the graphite nodule will rupture more easily.In this paper,the author studied the relationship between the amount of pearlite and cooling speed.The results show that the amount of pearlite relies on linear growth with the increment of cooling speed.The relationship show that when the cooling rate is larger than 4.1?/min,the amount of pearlite is more than 10%;when the cooling rate is less than 1.4?/min,the amount of pearlite is 0.What is more,according to the experimental data,the author established mathematical model of the decomposition of pearlite.