Simulation Analysis Of Shell Deformation During Firing In Investment Casting And Research Of Optimization Method

Investment casting is suitable for high temperature alloy casting partswith complex structure such as thin-wall, cavity. Take the aero-engine castfor an example, it is hard to be made using machining process technology forits streamlined profile and cavity for cooling. Investment casting manufacturetechnology can ensure size consistency of casting, avoid stress concentrationcaused by residual tool lines in machining process. Thus, it is widely used incomplicated parts manufacturing industry.The process of investment casting is complex with a lot of effect factors,which leads to unstability of casting quality. So it’s significant to improvemanufacture precision of investment casting by studying and controlling theeffect factors. Among the different stages, shell deformation during firingprocess is more significant. However, the traditional firing parameters are setby experience, which couldn’t establish digital model. This method couldn’treveal the principle and law of shell deformation with long design cycle. Sohow to predict the shell deformation by digital technology, and choosereasonable firing parameters have become a problem to be solved urgently ininvestment casting.To solve problems above, this paper studied the microstructure andmacroscopic composition change during shell firing process. We proposed touse the pore structure containing phase change referencing the soil mechanics.We designed characteristic part according to the aero-engine casting featurewith plate constraining inner and outer circles’ deformation. We simulatedthe deformation of shell in firing process, then used the response surfacemethod to robust design. Finally we got optimized shell firing parameter. Then we got the mathematical model between shell shrinkage and theroasting process parameters by this method, the model can be used for theestablishment of error flow in investment casting process.In this paper, the main research include:(1)The shell deformationmechanism at high temperature was studied. we put forward to use the porestructure model containing phase change referencing the soilmechanics.(2)we simulated a series of plate deformation with differenttemperature and load. Then a series of plate experiments were carried outwith the same firing parameters. Then, we compared the simulation andexperiment results and found that the simulation error was under15%, whichvalidated the model.(3)The simulation analysis of characteristic parts withplates constraining inner and outer circle and large casting were carried out,then we did experiments using the same parameters with simulations. Wefound that shell deformation was small where there was a plate, and carriedout the function between shell shrinkage ratio and size.(4)Robust design wascarried out for shell firing process, which offering reference for actual firingprocess.