Study On Adhesive Wear Behavior During High-Speed Milling Of Beryllium Copper Alloy

Beryllium copper alloy had been widely selected as high-precision parts in aerospace and other fields due to its high strength,high hardness,and excellent wear resistance,and higher requirements were proposed for machining beryllium-copper alloy in processing accuracy and surface quality.However,the processing quality was seriously affected by its high-temperature heat softening processing to produce a series of sticking substances and adhesive wear on the tool-chip contact surface in the traditional milling beryllium-copper alloy process.Therefore,the high-performance beryllium-copper alloy was adopted in this paper to analyze the tool adhesive wear behavior in the high-speed milling process.Based on the empirical orthogonal test method,the effect of cutting parameters on cutting force,cutting efficiency,cutting temperature,and surface topography was investigated,and the main wear behaviors were analyzed in milling and idle periods.An analysis method considering the elastoplastic deformation and slip theory and surface stress analysis was selected to describe the adhesive effect on the contact force of the tool surface.Besides,a series of physical quantities were adopted in this paper to analyze the relationship between sticking substances,tool adhesive evolution,and tool geometry by cutting experiments,numerical calculation,and theoretical analysis.In the end,a series of theoretical calculations and the experimental scheme was attempted in this paper based on two types of thermodynamic equation(including the cutting model and the principle of minimum energy consumption)to analyze cutting parameters’effect on the adhesive environment to indicate the mechanism of tool adhesive wear behaviors.The experimental investigation was conducted to analyze the environmental effect on the tool failure process,and results showed that the milling temperature of beryllium copper alloy is positively correlated with the cutting speed,and reaches the peak value of 250.7℃ at v=600 m/min.By observing the surface morphology and energy spectrum of the tool,it is found that there are a lot of workpiece and tool elements such as Cu,W,Co,and A1 near the cutting edge.With an increase in plastic deformation,the normal force on the surface can be effectively reduced with the huge movement of sticking substances to protect the tool surface in the early processing.Besides,the evolution of cutting force,cutting temperature,and cutting chatter were investigated for the negative correlation among the adhesive process,the contact area,the heat distribution coefficient,and the cutting energy,which stabilize the contact state between tool and chip under high adhesive environment.In the end,the cutting entropy and its corresponding tool surfaces were investigated under different cutting parameters in milling beryllium-copper alloy.It was found that the tool damage was more serious under high friction entropy at the early stage of machining.But the cutting distance increased the adhesive effect on the tool wear process,which lead to the tool surface in a high adhesive environment entering the severe wear stage faster than the low adhesive environment.The tool damage mechanism of adhesive behavior was investigated based on experimental and theoretical calculations to indicate that the cutting temperature is a main affecting factor on the tool-chip contact state to directly affect the tool adhesive wear process.Violent adhesion and slippage were found on the tool surface perpendicular to the direction of the cutting edge in machining periods due to the effect of the adhesive degree and the discontinuous cutting process,and it has a certain protective effect on the cutter surface in the cutting process.The more microscopic heterogeneous contacts were observed on the tool surface to increase the escape of Co elements and the generation of micro-cracks in a high adhesive environment under cyclic thermal-mechanical load,which eventually intensifies the adhesive wear behavior in the high adhesive environment.In addition,the rapid shedding of the adhesion on the tool surface made the cutting edge and the surface bears more complex and variable stress states to amplify the influence of the adhesive on the matrix material,which indicated that the proliferation of the surface crack was an important reason for the severe adhesive wear.