Study On The Ultrasonic Vibration Filing Of C_f/SiC Composites

C_f/SiC composites have been widely used in aerospace such as rockets,missiles,aircraft and other high technology fields due to their low density,high specific strength and modulus,strong design ability,excellent corrosion resistance,good fatigue resistance and excellent dimensional stability.However,as one typical kind of hard-brittle material,C_f/SiC composite is difficult to machine.It's easy to induce these phenomena like large cutting force,tool wear fast,severe fever and poor surface quality with the traditional method.In addition,for the complex shape parts,like abnormity,deep cavity components,the conventional machining methods will face greater challenges.When the handle is too long and cutting force is large,it's likely to cause the insufficient rigidity of handle stiffness and eccentric rotating of tool,which seriously affect the processing quality.In order to solve the problems that it's difficult to process abnormity,deep cavity and complex shape C_f/SiC parts,the method of ultrasonic vibration filing was applied in this paper.The shape of the cutting tool was designed to be consistent with processing surface.The tool didn't rotate and the ultrasonic vibration was applied in the axial.Meanwhile,it fed in the horizontal direction so as to realize the superposition of trajectories,thus achieving the purpose of removing material.Aiming at the innovation method of ultrasonic vibration filing,the main research work in this paper focuses on the following aspects:Firstly,research on the mechanism of ultrasonic vibration filing of C_f/SiC composites.Kinematic analysis of ultrasonic assisted filing was studied based on mechanism.The mathematical model of material removal rate and filing force of ultrasonic vibration filing hard brittle composite materials was derived.The mechanism of ultrasonic vibration filing was revealed.Secondly,the trajectory of ultrasonic vibration vibration filing was simulated and optimization analysed.On the basis of tool surface topography simulation,the research on trajectory simulation and optimization analysis in different grain grit,ultrasonic amplitude,and feed speed was achieved.Thirdly,the accessory ultrasonic vibration filing head was designed,which was mainly composed of an ultrasonic generator,a piezoelectric transducer,an ultrasonic tool,a special knife handle and a high speed slip ring.At the same time,ultrasonic machining head performance test was completed.Based on this,ultrasonic assisted filing C_f/SiC composites experiment platform was built.Finally,according to the experiment platform,the feasibility of ultrasonic vibration filing C_f/SiC composites was verified through comparing the filing force,surface morphology and surface quality with and without ultrasonic vibration.Besides,the influence of grain grit,ultrasonic power,filing depth and feed speed on filing force and surface quality was studied through single-factor test.Accordingly,the processing technology of ultrasonic vibration filing of C_f/SiC composites was obtained.