Experimenatal Study On TC4 Titanium Alloy External Surface By Fluid Magnetic Abrasive Finishing

With its outstanding physical and mechanical properties,TC4 titanium alloy is widely used in defense industry and civil industry,such as aerospace,automotive,marine and biomedical fields.However,titanium alloy is a typical difficult-to-machine material.Titanium alloys have low thermal conductivity,small modulus of elasticity,and large deformation in machining processes such as grinding,which may cause problems such as excessive surface temperature rise,adhesion,and even surface burns,burns,etc.Thermal stress and micro-cracks and other thermal damage problems greatly affect the accuracy and performance of TC4 titanium alloy parts surface processing.Typical parts include jet engine brakes,tail vertebrae,and rocket engine nose cones.The Fluid magnetic abrasive is a suspension,which can play a cooling and lubricating role,and at the same time effectively avoid the phenomenon of burnt workpiece surface during grinding processing and surface ablation during grinding.Therefore,this paper uses Fluid magnetic abrasive finishing technology to process it.The project was supported by the National Natural Science Foundation of China(51075294),the Natural Science Foundation of Shanxi Province(201601D011060),the Open Project of the Key Laboratory of Precision and Special Processing of the Ministry of Education(JMTZ201603),Key R & D Project of Shanxi Province(201903D121091),and the 2019 Graduate Education Innovation Project(RC1900001671)of the Shanxi Education Department.The main contents of this paper are as follows:(1)Aiming at the difficulty of processing TC4 titanium alloy,a scheme for processing the outer surface of TC4 titanium alloy using Fluid Magnetic Abrasives finishing technology was proposed.(2)Based on the rheological mechanism of the magnetorheological fluid combined with the Preston material removal formula,the main factors affecting the finishing of the titanium alloy outer surface are analyzed and obtained;a processing experimental bench is set up based on a vertical CNC drilling machine,and The magnetic field generating device,workpiece fixture,power supply model,grinding tool composition and configuration process involved in the design were selected and selected,and a preliminary test of Fluid Magnetic Abrasives finishing was performed on the outer surface of TC4 titanium alloy to verify The feasibility of processing.(3)A test scheme for Fluid Magnetic Abrasives for finishing TC4 titanium alloy outer surface was designed,and the surface quality of the workpiece before and after finishing was tested,including surface roughness Ra,Rz and surface micro-morphology.The effects of main process parameters(workpiece speed,abrasive particle size,abrasive type,magnetic field strength,and processing time,etc.)on the finishing of TC4 titanium alloy by Fluid Magnetic Abrasives were analyzed.(4)The Taguchi method is used to design and carry out experiments.The best parameter combination for finishing the external surface of TC4 titanium alloy with Fluid Magnetic Abrasives is obtained.The abrasive type is white corundum,the abrasive particle size is 2000 mesh,and the speed is 700 r / min,current strength is 2.0 A.The influence rules and order of the various factors on the processing effect are: abrasive type> abrasive particle size> workpiece speed> current intensity.The influence law of each process parameter on the processing effect was thoroughly explored,and the process parameters were optimized.The optimal process parameters were selected to carry out machining experiments on the typical part of the revolving curved surface "nose cone".The surface quality of the workpiece was greatly improved,and the relative reduction rate of surface roughness reached 87.55%.(5)The BOX-Benhnken test design in the response surface analysis method was adopted,and the relative reduction rate of surface roughness %?Ra was used as a characteristic parameter to screen out three factors that are significant to the outer surface of the TC4 titanium alloy: processing time,abrasives Particle size and workpiece speed,explored the relationship between process parameters and their interaction with the above characterization parameters.A surface roughness prediction model for the outer surface of TC4 titanium alloy was established,and the accuracy of the model was verified by designing random experiments.