Finite Element Modeling And Machining Parameter Optimization Of Graphite Cutting Process

Graphite is widely used in the engineering field,and the study of its processing properties is of great importance.However,graphite is a typical brittle material,which is highly susceptible to cracking during processing and will form craters and microcracks of different sizes on the machined surface,and the generation and expansion of cracks have unique patterns.In this paper,the finite element model of graphite cutting process is established by finite element software ABAQUS.Firstly,the Voronoi structure of the model is established,and the cohesion model is selected as the constitutive model of graphite material.Through the tensile test of graphite and consulting related materials,the relevant material properties of graphite are obtained to modify the model parameters.After the completion of the modeling,the solution is calculated,and the finite element model is verified according to the chip morphology and machined surface morphology obtained from the experiment as well as the graphite cutting process model in the literature.The simulation results show that there are mainly three periodic material removal methods in the cutting process of graphite material,namely,large block,micro block and small block removal stage,and lead to the formation of many pits with irregular distribution and different sizes on the surface of the material.In addition,the simulation results also show that the larger the block chip is with the increase of the cutting thickness,which indicates that the chip size will increase with the increase of the cutting thickness.In addition,the use of larger cutting thickness will lead to larger pits on the machined surface.In this paper,the parameters of cutting force and machined surface roughness of graphite cutting process were optimized by using single factor analysis,in which the cutting force was tested by finite element simulation and the machined surface roughness was tested by orthogonal cutting experiment.The results of single factor analysis showed that the cutting force increased by 90% when the cutting thickness increased from 0.1 mm to 0.3 mm;the cutting force decreased by 77% when the cutting speed increased from 3 m/min to 15 m/min;the cutting force decreased by60% when the tool rake angle increased from 0° to 20°;the cutting force increased by133% when the tool rounded radius increased from 10 μm to 50 μm.The machined surface roughness increased by 181% during the increase of cutting thickness from0.16 mm to 0.48 mm;the machined surface roughness decreased by 56% during the increase of cutting speed from 2.7 m/min to 15.1 m/min;the machined surface roughness decreased by 37% during the increase of tool rake angle from 0° to 20°;the machined surface roughness increased by 100% during the increase of tool rounded radius from 10 μm to 50 μm.In addition,because graphite is a brittle material,the cutting force fluctuates greatly during the cutting process,and the reliability of the results obtained by only one optimization method is not high.To ensure the reliability of the results,a multi-factor analysis of cutting forces and machined surface roughness using S/N and ANOVA was performed to obtain the machining parameters with the lowest cutting forces and machined surface roughness during the graphite cutting process and the significance of each cutting parameter on the cutting forces and machined surface roughness.The S/N analysis of cutting force showed that the optimal combination of parameters was cutting speed 3 m/min,cutting thickness 0.15 mm,tool rake angle 20°and tool blunt radius 10 μm.The S/N analysis of machined surface roughness showed that the optimal combination of process parameters was cutting speed 6.3 m/min,cutting thickness 0.16 mm,tool rake angle 20° and tool rounded radius 10 μm.The results of ANOVA showed that the effects of cutting parameters on cutting force and surface quality were highly significant,while the effects of cutting speed on machined surface roughness were insignificant and the effects of other parameters were highly significant.All other parameters are highly significant.The influence of each cutting parameter on the cutting force in descending order is the rounded radius of the tool,the rake angle of the tool,the cutting speed,the cutting thickness;the influence of each cutting parameter on the roughness of the machined surface in descending order is the cutting thickness,the rake angle of the tool,the rounded radius of the tool,the cutting speed.