Research On Tool Friction And Wear Mechanism In Micro Cutting Of Titanium Alloy Ti6Al4V

With the widely application of Ti6Al4 V parts in the aerospace,ship,automotive,biotechnology and many other fields,higher demands have been made toward Ti6Al4 V in industry,which attracts more attention from researchers worldwide to the study of the phenomena and mechanisms of tool wear in cutting process.The study is mainly focused on friction and tool wear.Friction and wear in the cutting process are significantly different from those in the conventional case,and there is material retention in in the titanium alloy Ti6Al4 V process.The reason is that the thermal conductivity of titanium alloy is small,the temperature rise higher;and chemical characteristics of titanium is lively,so easy to react with air.The worn tool in known to create poor surface qualities with high tensile surface residual stress,machining induced surface hardening,and undesirable surface roughness.It is essential to develop a methodology to determine how and to what extent the friction is built up on the tool.Therefore,friction mechanics theory and cutting parameters have to be put forward for simulation analysis and experimental research.Firstly,through the study of friction mechanism and wear mechanism in cutting process,the rules of mechanism was been found that sticking friction and mechanical friction are the main friction mechanism in cutting process,and sticking wear diffuse wear and abrasive wear are the main wear mechanism.The most important element in diffuse wear is Co.Secondly,this study facilitates a determination methodology to estimate the stress distributions on the rake and flank surfaces and tool edge of the tool and resultant friction coefficients between the tool and chip on tool face.The methodology is applied to various tool edge radii and also utilized in solving stagnation point(40°-50°)and minimum uncut chip thickness.And the results are further validated with comparison of predicted stress distributions from FE simulations with AdvantEdge for machining of titanium alloy Ti-6Al-4V.The classical simulation model is based on a series of cutting depths,and the gradual changes of the cutting depth are taken into account and the new model decrease the error.It was found that the minimum uncut chip thickness would increase with the increase of rake angle.Finally,the theoretical analysis is applied to discuss various cutting parameters and tool parameters,and tool wear is largely affected by cutting depth and slightly affected by cutting speed.During the chip formation process,the material flows slow around the edge radii,so we must take this phenomenon into consideration and build the modified tool wear model.Comparing with the experimental results,the simulation results based on the tool wear model can agree well with the experimental results.