Investigation On The Cutting Technology And Tool Wear Control Methodology In Diamond Cutting Of Titanium Alloy

Titanium alloys with low density,good corrosion resistance,high specific strength and corrosion resistance and other excellent properties,are widely applied in aerospace,biology and other fields.However,due to the characteristics of low thermal conductivity,low elastic modulus and high chemical activity of Titanium alloys,it is difficult to achieve high surface quality in the machining of titanium alloys,which has restricted the application and the development of Titanium alloys.With the development of the biomedical industry,there is a need to produce micro-structureon the medical implants with higher and higher machining accuracy and surface quality.Ultra-precision manufacturing technologies can directly produce micro-structure array with nanometer scale surface roughness and sub-micron form accuracy,which has gained an increasing application.Diamond tools are considered as the best tool for ultra-precision machining,while in the cutting of Titanium alloys,it is easy to cause serious tool wear and induces lower surface quality.Therefore,in this thesis,a comprehensive investigation is conducted to decrease the cutting force so as to improve surface quality and control diamond tool wear.The main research contents are as follows:(1)The factors of cutting force variation,chip formation and surface quality are analyzed according to the mechanism of ultra-precision cutting,and the finite element simulation of the cutting of Ti6Al4 V is established using ABAQUS software to study the effect of cutting parameters to the cutting force and cutting temperature in the turning process.Through the experiments about ultra-precision turning of titanium alloys,the effects and primary and secondary factor of cutting parameters to the surface roughness and the cutting force are studied,theoretical analysis and finite element simulation are verified.The experiment results provide a basis for the optimization and selection of ultra-precision machining parameters of titanium alloy,and lay a foundation for subsequent theoretical analysis and experimental design.(2)The wear mechanism and wear characteristics of diamond tools in ultra-precision cutting of titanium alloys are analyzed,and finite element simulations on tools with different wear levels on the tool rake face are conducted to explore the impact of tool with different levels of wear to the cutting force,cutting temperature and chip generation.The relationship between the cutting distance and tool wear are established to explore the relationship between the cutting force,surface roughness and cutting distance in ultra-precision cutting of titanium alloy,the diamond tool wear experiments in turning of titanium alloy are carried out to obtain the effect of cutting distance to the cutting force and machined surface roughness,and establish a diamond tool wear judgment mechanism that meets the requirements of different machining accuracy.(3)The influence of micro-structure surface which is designed on processed surface is studied to reduce the tool wear caused by cutting force and cutting heat in the diamond cutting process of titanium alloy,and the finite element simulation model of ultra-precision cutting with micro-structure surface is established.The effect of micro groove structure surfaces with different geometric characteristics on chip generation,cutting force,cutting temperature and tool temperature are experimental and simulated studied to obtain the optimal micro groove structure.A better chip edge quality can be obtained with the optimal micro-groove structure,which can effectively reduce cutting force and improve surface quality,providing experimental basis for ultra-precision turning research.Diamond turning experiments of titanium alloy are conducted on micro-structure surface and smooth surface to study the influence of cutting distance on cutting force and surface roughness,and obtain the relationship between cutting distance and tool wear.It can be found when comparing the processing results of smooth surface and micro-structure surface: lower cutting force,better surface quality,less wear on diamond tools can be obtained in ultra-precision turning of surface with micro-structure.The results prove that the micro-structure surface has a positive effect on reducing the wear of diamond tools.The study of cutting force,surface roughness and the tool wear in different cutting distance can play an important role in the prediction and reference of the diamond tool life,through establishing the law of influence of micro-structure surface on the cutting force and surface roughness can make a positive effect on improving surface quality and reducing tool wear,and the cutting experiment and finite element simulation based on the micro-structure surface play a certain guiding role for diamond cutting of titanium alloy.