SLS Forming Process And Numerical Simulation Study Of Investment Casting Wax Pattern For The Compressor Casing

The structure of aeronautical parts is increasingly complex,and investment casting are often used to process complex aeronautical parts.Wax pattern molding is a crucial link in investment casting.However,it is becoming increasingly difficult for traditional pressure wax technology to process complex wax pattern.The forming process of selective laser sintering technology is not limited by the complexity of parts,and it is more convenient and fast.So it is increasingly used in forming the investment casting wax pattern of aeronautical parts.A compressor casing aeronautical parts of the Boeing company is focused in this thesis,and the SLS forming process of the investment casting wax pattern is studied.The main work is as follows:Firstly,the SLS forming of the investment casting wax pattern of the compressor casing is studied experimentally.A set of experimental programs is designed,and 6 sets of structural parts are obtained using SLS technology,and the deformation results are analyzed.It is found that the relative error is as low as 0.17%,so the process parameters of these structures parts are still used during wax pattern processing.In addition,the deformation of the circular convex platform is significant,so the process of adding high-temperature layer is adopted.The deformation results of the wax pattern are obtained by using three-dimensional measurement technology,which provides reference for numerical simulation.Secondly,using the investment casting wax pattern of the compressor casing as a prototype,the SLS forming process is numerically simulated.Based on the numerical simulation results of the wax pattern,the errors between the numerical simulation results and the experimental data of the three-dimensional measurement are analyzed,and the reliability of numerical simulation results is demonstrated.Then,the numerical simulation results are analyzed from three aspects including the cylindricity of the wax pattern,the flatness of the mounting surface and the deformation of the circular convex platform,and the reasons for large deformation are pointed out.Finally,according to the numerical simulation results,two process optimization schemes are proposed and the numerical simulation is studied again.In the scheme 1,the left and right half casing are fully connected.In the scheme 2,different angles of support structures are added to the circular convex platforms.Among them,using the scheme 1 to optimize the investment pattern can improve its radial forming accuracy,the cylindrical degree of the cross section of the Z=413.6mm is reduced from 1.45 mm to 0.05mm;In addition,using the scheme 1 can improve the flatness of its mounting surface through machining.By contrast,using the scheme 2 to optimize the circular convex platform can reduce its Z-direction deviation.