Study On The Tool Wear Under Thermo-mechanical Coupling In Ti6Al4V Cutting Process

Titanium alloy has been widely used in aerospace,petrochemical,biomedical and other fields because of their excellent strength-to-weight ratio,good corrosion resistance and their exceptional resistance to corrosion.However,titanium alloy has the characteristics of small elastic modulus,low thermal conductivity and high chemical activity at elevated temperature,which be considered as one of typical difficult-to-cut materials.At present,the tool materials commonly used in the processing of titanium alloy are mainly cemented carbide,polycrystalline diamond,polycrystalline cubic boron nitride,etc.Among them,cemented carbide is the most widely used among them because of its comprehensive cost performance.However,cemented carbide is prone to severe tool wear when processing titanium alloy,which not only affects the cutting efficiency,workpiece dimensional accuracy and surface quality,but also directly relates to the cost of production.Therefore,the study of the tool wear when machining titanium alloy with cemented carbide tools has important theoretical value and practical significance for actual production.In this paper,the experimental and simulation research on the processing of an important aerospace titanium alloy Ti6Al4 V is carried out.The thermo-mechanical coupling phenomenon in the cutting process is theoretically analyzed,and the thermo-mechanical coupling calculation model of the rake face and flank face in Ti6Al4 V orthogonal cutting is established;Two common coated carbide tools SP4019 and NL300 are used in the Ti6Al4 V cutting experiments at high,medium and low speeds,it is found that the cutting speed has a great influence on the tool wear,tool wear is severe in high speed cutting and the tools are easy to damage in a short time;The results of scanning electron microscopy analysis and energy spectrum analysis of the two coated tools show that the wear mechanism of the tool were adhesion wear,diffusion wear and oxidation wear,the adhesion-diffusion wear will occur simultaneously and promote each other,the oxidation wear and adhesion-diffusion wear are mutually inhibited;From the observation of the microscopic morphology of the flank face and the measured amount of tool wear,it can be seen that the SP4019 coated tool is more suitable for the processing of Ti6Al4 V than NL300;Based on the cutting special finite element analysis software AdvantEdge,the simulation of processing Ti6Al4 V by cemented carbide tool is carried out,it is concluded that the cutting force,tool peak temperature and tool stress will increase with the increase of tool wear.As the tool wear increases,the chip curled degree becomes less noticeable,and the chip serrated degree becomes more serious.