Structural Analysis Of Chisel Edge Pitch Circle Region Of Solid Twist Drill And Experimental Research On Drilling TC4 Titanium Alloy

As the main hole machining tool,the solid carbide twist drill usually has problems such as large axial cutting force,unstable cutting,high cutting temperature,and difficulty in chip breaking and chip removal,especially for difficult-to-machine materials such as titanium alloys.At present,the research on solid carbide twist drills at home and abroad mainly focuses on the main cutting edge,and the exploration of the chisel edge is less,and the chisel edge affects the centering performance and drilling life of the twist drill directly.Therefore,this paper will mainly do targeted exploration experiments and analysis on the chisel edge structure of the solid carbide twist drill made of TC4 titanium alloy materials.To analyze the influence of the chisel edge position on the drilling performance.Firstly,the chisel edge structure of the solid carbide twist drill is analyzed,and the processing and manufacturing parameters of the twist drill are taken as the research object,and the chisel edge cutting mechanism of the twist drill is preliminarily analyzed based on the drilling angle.According to the working state of the chisel edge and the sharpening parameters(over-center,eccentric distance),the concept of the chisel edge pitch circle is proposed,and the model between the chisel edge grinding parameters and the chisel edge geometry is established.Secondly,the cutting mechanism of the chisel edge is expounded according to the normal rake angle and chisel edge cutting model during drilling.Through the theoretical analysis of the cutting force of the chisel edge,a calculation model of the comprehensive strength of the chisel edge is established.The chip evacuation and chip breaking performance of the twist drill was analyzed by analyzing the chip morphology,chip breaking rate and compressibility,and the advantages and disadvantages of the chisel edge geometry were evaluated based on this.Thirdly,the drilling experiment of TC4 titanium alloy material was carried out.Based on comprehensive experiments,the influence of chisel edge geometrical parameters on cutting performance was preliminarily explored.Through single-factor experiments,the effects of chisel edge grinding parameters on cutting force,wear,life and chip morphology were analyzed by taking the chisel edge pitch diameter,over-center and eccentric distance,and axial rake angle as experimental variables.The effects of chisel edge grinding parameters on drilling temperature,stress and chip morphology were explored through finite element simulation,and the reliability of the simulation was verified by experiments.Finally,based on the experimental and finite element analysis results,the effects of the ratio of over-center to eccentricity,axial rake angle and gash root arc on chisel pitch circle,axial cutting force,stress and life were investigated.The optimal grinding parameters and chisel edge geometry for machining TC4 titanium alloy are obtained.