Study On Chip Formation And Its Effects On Cutting Process In Elliptical Vibration Cutting

Elliptical vibration cutting(EVC)is a machining method that developed on the basis of vibration-assisted cutting,which not only can process complex microstructure on the workpiece surface,but also greatly improves the machining performance and hard and brittle materials such as titanium alloys and silicon carbide are effectively processed by this method.Chip is the important product during the cutting process,and its formation process is accompanied by various chemical phenomena(such as graphitization of diamond tools)and physical phenomena(such as tool wear and cutting heat,etc.).The variation of the geometric characteristics of the chip that caused by these phenomena has a major influence on the cutting process,especially the cutting force and the surface quality of the work-piece during the cutting process.However,the research on EVC chip is still rare.Most scholars only observe the chip after the experiment,and lack of in-depth theoretical research on EVC chip.Therefore,this thesis focuses on the study of the formation of EVC chip,taking into account the effects of EVC chip on the cutting process.The cutting force and the surface topography of the work-piece are also studied in this thesis.The content of this paper is expanded from the following aspects:1.Analyze the movement process of the EVC tool,identify the boundaries of the formed chips,fully consider the relative motion relationship and positional relationship between the tool and the workpiece,and re-establish the tool motion equation.According to different depth of cut ratios,mathematical models were established for geometric features such as thickness,cross-sectional area and volume of EVC chip.2.Most scholars use experimental methods to study the influence of relevant parameters on the surface quality of EVC,and lack the mathematical model of surface topography of EVC.In this paper,the geometrical modeling of the surface topography and surface residual height of the workpiece after chip removal is performed by using the geometric method to find relevant parameters that affect the residual height of the workpiece surface.3.The calculation of cutting force using the existing EVC force model requires a lot of calculations.However,according to the characteristic of variable depth of cut of EVC,the existing cutting force modeling is improved in this thesis and the chip cross-sectional area is introduced into the cutting force model to obtain the empirical EVC force.4.Use FEM analysis software to perform finite element simulation of the EVC process to obtain the chip geometry and cutting force after EVC process.By changing the relevant parameters,the changes of the chip geometry(mainly focus on thickness of chips)and the cutting force with the relevant parameters are verified.Using Matlab to simulate the established EVC surface model,an ideal three-dimensional surface topography is obtained and the effects of relevant parameters on the surface residual height are verified.5.The diamond cutting experiments are conducted,and the produced chip,surface of workpiece and cutting force are collected and measured.The corresponding interpretation of the experimental phenomena is made.The experimental results further verify the correctness of theoretical deduction and simulation conclusions.The research content of this thesis is developed from EVC chip formation,and the surface topography of the workpiece and cutting force are also studied by mean of EVC chip formation.By studying the influence of related parameters on the three,this thesis can provide reference for the selection of cutting parameters in the future.