Study On Milling Behavior Of Micro-Textured Ball-End Milling Cutters With Variable Distribution Density

The application of micro texture on the surface of the tool provides excellent friction and wear reduction and it is gradually being used for high-speed cutting of difficult-to-machine materials such as titanium alloys.However,as the depth of cut changes during the machining,the main wear interface between the rake and flank face of the tool evolves and the area where the micro texture acts on the tool surface transitions accordingly.There is no defined standard for the design of the anti-wear area at the micro texture interface in the corresponding region of the cutting depth,resulting in the micro texture tool not being able to give full play to its anti-wear and friction-reducing effect in the actual application process.At the same time,the distribution of micro texture on the tool surface affects the anti-wear and friction-reducing effect of the tool,the optimization of micro texture distribution parameters is the key to improve the cutting performance of such tools.In order to solve the above problems,this paper takes the design and preparation of micro texture as the starting point,the tribological properties of laser prepared micro textured on the cemented carbide surfaces are systematically analyzed,the critical cutting depth region of micro texture in the tool surface action area as a function of cutting depth is studied,and considering the effect of the micro texture parameters on the milling behavior of ball end milling cutter in the critical cutting depth region,the multi-objective optimization of the texture parameters of the micro texture ball end milling cutter with variable distribution density is carried out,which provides a diversified idea for the optimization design of the micro texture cutter.The tribological properties of laser processed micro textured cemented carbides are studied.Through friction finite element simulation,the friction properties of micro textured surfaces with different geometric shapes are obtained,and the optimized geometry of the micro texture is determined.Combined with theoretical analysis and friction and wear tests,based on the response surface methodology,the influence mechanism of laser processing parameters and texture distribution parameters on the surface friction properties of micro textured cemented carbides is studied and a prediction model of the friction coefficient is established,the sensitive relationship between the influence factors and their interactions on the friction coefficient is clarified,and the optimal laser processing parameters and micro texture layout parameters are obtained.At the same time,it is revealed that the main wear form of the micro textured surface is adhesive wear,and its anti-wear and anti-friction mechanism is explained.The theoretical placement area of micro texture on the rake and flank surfaces of ball milling cutter is analyzed,and the mathematical model of micro texture layout with variable distribution density is established.The friction characteristics of the rake and flank surfaces of ball milling cutter is analyzed by the two zone method.Based on the stick slip friction theory,a theoretical prediction model for the limit cutting thickness of titanium alloy is established under the influence of the blunt radius of the cutter edge,the geometric parameters of micro texture and other variables.Based on the machined surface quality of the workpiece,an experimental solution to the limit cutting thickness is proposed for milling titanium alloy with micro texture ball milling cutter of variable density.The theoretical prediction model of the limit cutting thickness is verified by finite element simulation and milling experiments,the results show that: the limit cutting thickness increases with the increase of the blunt radius of the cutting edge;the error between the theoretical value and the experimental result is less than 10%,which fully verifies the accuracy of the theoretical model of the limiting cutting thickness of the micro texture ball milling cutter with variable density.The concept of the critical cutting depth region of ball milling cutter is proposed based on the evolution of micro texture action region.A test platform for milling titanium alloy is built,the evolution laws of the wear of the rake and flank surfaces of ball milling cutter by changing the cutting depth are studied,signals of the milling force,the vibration acceleration in the three directions and the wear of the rake and flank surfaces as the number of tool passes increases are obtained.The multi domain eigenvalues of each group of signals are extracted by time-frequency analysis,and the Relief algorithm is compiled to optimize the eigenvalues that have strong correlation with the wear of the rake and flank faces.Based on BP neural network,prediction models of the wear about rake and flank surfaces of the ball milling cutter at different cutting depths are established respectively.Through the analysis of the wear rates of the rake and flank faces,the definition standard of the main wear concentration area is defined,and the critical cutting depth region when the main wear area of the tool surface transits from the flank surface to the rake surface is obtained.The milling behavior of micro texture ball milling cutter in critical cutting depth region is studied.A test platform for milling titanium alloy with micro texture ball milling cutter with variable density in dynamic cutting depth region is built,based on the theory of critical cutting depth region,experiments are conducted on milling titanium alloy in the wear depth region of the rake and the flank faces respectively.By changing the geometric parameters of micro texture,the dynamic evolution of milling behavior of micro texture ball milling cutter with variable distribution density is expounded from the aspects of micro texture placement area,distribution characteristics,size parameters,etc.Based on the improved particle swarm optimization algorithm and taking the cutting performance of the tool as the optimization objective,the multi-objective optimization models of the texture parameters of the micro texture ball milling cutter with variable distribution density in the critical cutting depth region are established respectively,and the optimal design method of the micro texture ball milling cutter with variable distribution density in the critical cutting depth region is obtained.This study provides a comprehensive and systematic theory for the development and design of micro textured tools with different cutting parameters.