Research On Dynamics Characteristics Of Milling Titanium Alloy Thin-walled Structure With Air Jet Assistance

In the aerospace industry,titanium alloy thin-walled parts are extensively used due to their excellent characteristics,such as light weight and high structural strength.A titanium alloy thin-walled part needs to remove large amounts of material from a single billet because of the titanium alloy component’s design to reduce its weight as much as possible while maintain the necessary strength and rigidity.But one disadvantage of the titanium alloy component is that its relative rigidity will be low.Therefore,titanium alloy thin-walled parts are difficult to machine as a fact of easy deformation and vibration during the cutting process,which will lead to aggravated tool wear and degradation of the machined surface,because of the comprehensive influence of different factors like clamping force,cutting force and cutting heat,etc.Finaly,it will difficult to effectively guarantee the machining quality and precision.The instability of cutting force is the main reason for severe vibrations during high-speed cutting of titanium alloy thin-walled parts.Therefore,it is of great significance to reduce the cutting force and suppress the vibration while machining the titanium alloy thin-walled parts by exploring new methods.Because it will also make sense to improve the machining quality and precision,thus realizing the high quality and high efficiency machining of the titanium alloy thin-walled parts.In this paper,the influence of air jet assistance on milling performance of titanium alloy thin-walled parts is studied.Firstly,the simulation of flow field of air jet inside and outside the nozzle is carried out based on the relevant theory of fluid finite element analysis.So the flow field characteristics inside and outside the nozzle could be investigated by studying the pressure field and velocity field.Secondly,single factor tests and orthogonal experiment were designed to analyze the influence of different air jets on the impact force and deformation of titanium alloy thin-walled parts.Thirdly,milling experiments of titanium alloy thin-walled parts with and without air jet assistance were carried out and the influence of the impingement on processing stability,machining quality and precision of the side wall of the titanium alloy thin-walled parts were compared and investigated.The air jet flow field inside and outside nozzle is simulated by the use of Ansys Fluent software.The influences of geometric parameters of the nozzle structure on the pressure field,the velocity field and the radial velocity of the nozzle outlet,as well as the influence of the inlet pressure on the inner and outer pressure fields and the velocity field of the nozzle,are all analyzed to provide a reasonable basis for optimizing the geometric parameters of the nozzle structure.The ANSYS Workbench coordinated simulation platform is applied for the fluid mechanics analysis by using the obtained Fluent fluid simulation results.The influences of the geometric parameters of the nozzle structure and external parameters on the impact force and deformation of the titanium alloy thin-walled parts by air jet are studied.The nozzle structure parameters are optimized based on the air jet impact force.inlet pressure and target distance.The experiments on the milling of titanium alloy thin-walled parts with and without air jet assistance were carried out.The vibration acceleration,cutting force,the thickness error and surface roughness of the finished side wall are all compared and analyzed.It is proved that the machining quality and precision of the side wall can be improved by the auxiliary support of the air jet.