Effects Of Magnetic Abrasive Finishing On Surface Integrity Of TC4Titanium Alloy

In order to improve aircraft engine thrust-weight ratio, mosttypical engine parts use of titanium alloy material. The high speed milling wasgenerally used as the final machining process about the parts of complex shape suchas the vane-integrated disk of titanium alloy, the using performance of parts aredecided to the quality of surface that is ensured by milling parameters. Titanium alloyhas many excellent features such as high specific strength, corrosion resistance, nonmagnetic, well heat resistant performance, well low temperature performance, highfatigue strength and so on. However, Titanium alloy owing to excellent materialperformance caused great difficulty to its molding processing. When millingprocessing, titanium scraps are easily to adhesive the tool and accelerate the toolabrasion, and it is difficult to obtain a higher surface integrity. Therefore, the newadvanced high efficiency and quality processing technology is needed urgently toadopt the finishing processing.As a kind of non-traditional finishing processing, magnetic abrasive finishingtechnology can use the function of magnetic field to attract the magnetic abrasivetogether to form magnetic abrasive brush with a certain flexibility and viscoelasticity.By apply relative movement between the magnetic abrasive brush and the parts, themagnetic abrasive in the magnetic abrasive brush can make relative motion ontitanium alloy surface, such as slide, rolling, cutting and so on. So that magneticabrasive can realize machining on the surface of the workpiece. This study throughTC4titanium alloy materials after milling with the magnetic abrasive finishingprocess and concretely analyses the factors that influence the workpiece surfaceintegrity on the basis of research which has been made at home and abroad. Theexperiment studied the formation mechanism of the surface defects during machiningprocess by simulating the final milling titanium alloy parts related to the millingparameters. Magnetic abrasive finishing obtain the optimal processing scheme byorthogonal experiment with abrasive particle size, magnetic rotation speed, machininggap as experimental indexes and the surface roughness, micro-morphology, themicrostructure and residual stress as experimental factors. The surface integritycharacteristic parameter of TC4titanium alloy workpiece is collected after the millingtechnology and the magnetic abrasive finishing process, analyzing relatively theintegrity change of the workpiece surface before and after the magnetic abrasive finishing. Traditional BP neural network and evolutionary neural network were usedrespectively to establish the magnetic abrasive finishing parameters prediction modelof the workpiece, and analysis and comparison the prediction results.The study found that the workpiece value is larger after high speed milling, theaverage surface roughness Ra2.5μm; Surface micro-morphology of the cutting toolpath is clear and the shape of the tool cutting edge was copied by workpiece surface;The lattices inside the surface of the material is squeezed and some changes happenedlike stretched, twisted, broken. It formed different material surface of the basemetamorphic layer on the surface; Residual tensile stress value is larger after milling,it is easy to produce fatigue crack on material surface. After the Magnetic abrasivefinishing, it is able to see that the surface roughness of the parts is greatly reduced, theaverage surface roughness value can reach Ra0.07μm after analyzing the optimalprogram of surface integrity data; the remnant texture was basically removed afterMilling; the metamorphic layer in the surface layer is removed, the surface is moreclose to the original organizational structure material; residual stress value is reducedobviously by detecting. The evolutionary neural network based on genetic algorithmin convergence speed and prediction accuracy is superior to traditional BP neuralnetwork, and it effectively avoid the local minimum which has a certain referencevalue in magnetic abrasive finishing process, which has a certain reference value inmagnetic abrasive.