Optimization Of Permanent Casting Technology For Aluminum Alloy Large Sync Belt-Wheel

Large sync belt-wheel is one of the most important parts in CT machine, material is ZL111, now usually using sand casting. Due to Al alloy castings have serious tendencies of oxidization and air-breathing, in the meanwhile, the alloy is hypoeutectic alloy, it has obvious tendency of shrinkage porosity in the process of freezing. These defects can seriously influence Al alloy castings' properties, so products have low percent of pass.In order to resolve the difficult problem of producing large sync belt-wheel, the subject regards large sync belt-wheel, as subject investigated. It adopts metal-model foundry, according to flowing features of permanent casting filling, it uses Z-Cast foundry numerical simulation software to study casting filling and freezing processes of large sync belt-wheel , and realizes optimization of casting filling by computer simulation. Its purpose is to improve castings' percent of pass, inherence and appearance quality and comprehensive mechanical property.At first, in order to guarantee filling process smoothly and preventing Al alloy from generating defects of oxidization and air-breathing, and so on, bottom gate and setting separately three runners has been adopted. In the meanwhile, adopting vertical gate to fill casting body has been adopted. It is difficult to feeding through feeder, due to the edge of casting top is far from vertical gate, therefore, setting three feeding heads on casting top.Filling and freezing simulation results show that casting is filled well and has no flaws such as under priming, serious slay and so on, vertical gate and feeder heads have a good effect on feeding in process of cooling and freezing.According to simulation results, analyzing reasons of flows in freezing process and raising predicted methods of flaws, in order to define reasonable processing parameters: T_mold=240℃, T_sand=25℃, T_pour=710℃,t_pour=25s.Adopting technology after optimization in this subject to produce Sync Belt-Wheel, 535(±5℃)×5h+170℃(±5℃)×6h, after cooling treatment in the air,σ_b=295MPa,δ=2% and HB=86 in ZL111 alloy large sync belt-wheel, products have no obvious flaws, and meet requirements of mechanical property. It shows that the technology after simulation optimization meets actual production; it can be used to direct exploitation process of large shape of annulus aluminum casting.