Research On Ultrasonic Vibration Assisted Milling Process Of Titanium Alloy

Titanium alloy has the characteristics of low density and light weight.This material is one of the important materials for processing aircraft parts.However,the reasons that severely restrict the improvement of the processing quality of titanium alloy materials are mainly due to the material characteristics of titanium alloy materials with small elastic modulus and good activity.In the actual cutting process,the cutting force is large and the chips are difficult to separate from the workpiece.It is caused by phenomena such as poor surface quality.Although the development of vibration cutting has improved the above drawbacks to some extent,the current research on vibration cutting is mainly focused on the fields of turning and grinding,and there is little research on vibration milling.In view of the above problems,this document has initiated the optimization study of ultrasonic vibration-assisted milling of titanium alloy.Reasoning through theory three-dimensional simulation of finite elements and experimental comparison methods,the grinding force and surface quality are analyzed in depth.The research content is as follows.First,based on the analysis of the tool's axial vibration trajectory,the intermittent cutting characteristics,impact characteristics and net cutting time models of ultrasonic milling are studied.Secondly,based on the coordinate change of the tool tip motion trajectory in space,a very accurate instantaneous undeformed cutting thickness theoretical model was established,and the mathematical model of chip forming force and friction force under different cutting angles was established through the instantaneous cutting thickness mode.When establishing the impact force model in the axial direction of the tool,the relationship between the milling force and the area of the undeformed chip section was used to establish an axial impact force model considering the instantaneous depth of cut model.Combine the chip formation force model,the friction force model and the axial impact model to obtain the axial ultrasonic vibration-assisted milling force model.The research results show that the predicted trend for change of milling force corresponds to the experimentally measured trend for change of milling force.Thirdly,I use ABAQUS to model the three-dimensional finite element simulation model of the ultrasonic milling titanium alloy material considering the axial vibration,and then extract the obtained simulation results in the postprocessing module,and obtain the surface of the workpiece during the cutting simulation process.Mises stress diagram and waveform diagram reflecting the change of milling force.At the same time,an axial ultrasonic milling platform for measuring milling force was built,and the milling force experiment was carried out through the same processing conditions as the simulation parameters.It is obtained through comparative experiments that the relative error of the peak force obtained by simulation and actual is within the allowable range,and the established simulation model is accurate.Finally,In the process of studying the surface roughness,a variety of influencing factors orthogonal experiment method,analysis of variance method and response surface method are used.Through the above analysis method,it is concluded that the most important interaction on the surface roughness is between the feed speed and the spindle speed.Through the analysis,the optimized milling process parameters and the empirical model that can predict the surface roughness are also obtained.At the same time,the experimental verification of the model proves the accuracy of the built model,which has guiding significance for actual processing.