Experimental Investigation On Tool Failure And Machined Surface Quality For High Speed Milling Titanium Alloy

Titanium alloy has been widely applied in various industrial fields, especially in the aerospace engineering because of its excellent physical and mechanical characteristics such as high specific strength, heat resistance and corrosion resistance. However, titanium alloy is considered as a typical difficult to machine material due to it has low thermal conductivity, low elastic modulus, high chemical reactivity and very small tool-chip contact area during its machining, which will easily lead to serious tool wear and poor surface quality. High speed milling Ti6A14V is taken as the investigation subject in the thesis, systematical investigation on milling fore, cutting temperature, tool wear, tool life and surface integrity were carried out.Experiments on high speed TC4 with indexable coated carbide milling cutters were carried out and variation of milling force with the milling parameters was studied systematically and empirical formulas for cutting were established by use of regression analysis, which have significant theoretical and practical application value in revealing the cutting deformation mechanism of high speed milling and improving surface quality and increasing tool life etc.Temperature data was obtained by using infrared thermal imager. the effects of cutting parameters and tool flank wear on milling temperature were analyzed. Tool wear situation and their formation mechanism for high speed milling TC4 were studied by means of tool wear tests and SEM observation. Empirical model for tool life was established, which provides support for prediction of tool life and optimization of cutting process.The machined surface integrity and its relationship with processing parameters when high speed milling titanium alloy TC4 were discussed in terms of machined surface roughness, machined surface residual stress and microstructure changes etc. The effects of milling parameters on machined surface integrity were analyzed, and the results show that high speed milling can improve machined surface integrity to some extent, which is of great significance for improving the quality of workpiece and the machining efficiency.