Dynamic Responses,Stability And Surface Topography Prediction In The Process Of Turning Thin-walled Inner Cavity Workpieces

Thin-walled inner cavity parts with light weight and high specific strength properties are widely acceptable in the field of high-end equipment manufacturing,such as aeronautics and aerospace structures.In order to improve the reliability of the structure and the performance of the engine in aero engine technology,the integral structure design is usually used for this kind of parts.The integral structure design of the core components of aero engine such as turbine disk and compressor disk can make the engine lose weight and greatly improve the stability and safety of the engine.However,turning these components is a challenging problem due to the complex structure and the low stiffness of the tool.For instance,the inner cavity structure of integral inner cavity parts can only be machined with non-standard bent-blade cutter.The depth of the inner cavity structure is usually 150 mm.The overhang of the bending tool is large and the structure is complex in the turning process.The challenge is that the tool produces serious deflection and vibration.In order to satisfy the high-quality and high precision requirements of thin-walled inner cavity parts,it is crucial to predict and control the vibration of bent-blade cutter.Firstly,a dynamic model of bent-blade cutter considering the combined bending and torsion deformation effect and its solution method are proposed.Based on the complex structure of bent-blade cutter,the dynamic model of bent-blade cutter is established by using Timoshenko beam model,three-dimensional rigid body theory and Hamilton principle.Then,the governing equations of bent-blade cutter is solved by the finite element numerical method(FEM)to study the static characteristics,modal characteristics and dynamic response of bent-blade cutter.Lastly,the bent-blade cutter of modal characteristics and vibration response are verified by simulation and the design experimentsSecondly,the dynamic model of bent-blade cutter turning is established to predict the stability of bent-blade cutter in turning process.Based on the dynamic model of bent-blade cutter,the stability lobes of bent-blade cutter are obtained by differential quadrature method(DQM).A series of turning experiments are designed to verify the correctness of the prediction model of turning stability of bent-blade cutter.At the same time,based on the movement path of the cutting edge of bent-blade cutter,the prediction method of the three-dimensional surface topography of bent-blade cutter turning is proposed,and the influence of the tool offset on the surface topography of turning is studied.The correctness of prediction model is also verified by observing and analyzing the surface morphology of workpiece after bent-blade cutter turning experimentFinally,based on the stability lobes and the surface topography prediction model of bent-blade cutter turning,the influencing factors of the turning stability and the surface topography of bent-blade cutter are studied respectively,the cutting parameters and radius of round insert of bent-blade cutter is optimized.At the same time,based on the analysis of the dynamic characteristics of bent-blade cutter,the structure of bent-blade cutter is optimized.The results show that the vibration of the cutting tool is reduced,the turning stability is improved,the surface quality of workpiece is greatly improved,and the surface roughness is reduced.