Research On Technology Of Titanium Alloy Grille By Abrasive Flow Machining

With its outstanding performance,the grille structure is widely used in the field of aerospace.The titanium alloy grille used in a stealth fighter is machined by EDM.Recast layer appears on the surface of the inner hole,which seriously affects the fatigue performance of the grille.As a surface finishing technology,abrasive flow machining technology has unique advantages in removing recast layer and polishing inner hole.In this paper,the research on titanium alloy grille by abrasive flow machining technology was carried out.The main work and achievements are as follows:(1)The study on the surface integrity by abrasive flow machining was conducted by preparing the EDM sample of titanium alloy.The results showed that the surface roughness decreased with the increase of the abrasive grain size and machining pressure.With the increase of the processing times,the surface roughness presented a declining trend on the whole,and finally tended to be stable.The residual stress of the surface changes from the original tensile stress to the compressive stress after abrasive flow machining.With the increase of processing times,the surface microhardness decreases first and then increases on the whole.In addition,the uniformity of microhardness is also enhanced.(2)For titanium alloy grille workpieces,special fixture design was carried out according to the steps of workpiece analysis,abrasive path planning,fixture structure design,fixture simulation,fixture strength check and fixture effect verification.Through numerical simulation and comparative analysis,it was concluded that the grille does not produce large orifice chamfers without the trap clamp.And compared with the double-sided drainage plate fixture,the finishing process is more efficient under the same processing pressure.(3)The numerical simulation method was used to limit the machining pressure,and it was concluded that the grille will not undergo plastic deformation when the machining pressure is less than 7.3MPa.By means of numerical simulation and experimental verification,it was concluded that the chamfer angle of the orifice increases with the increase of grain size and machining pressure.(4)Using the surface roughness reduction rate and the orifice chamfering as the evaluation indexes,the optimized technological parameters for titanium alloy grille by abrasive were obtained through orthogonal test: the particle size is 320 microns,the machining pressure is 7MPa and the machining times is 20.