Numerical And Experimental Study Of Laser Assisted Machining Process Of Titanium Alloy Ti6Al4V

Titanium alloys are metals that contain a mixture of titanium and other chemical elements. Because of their high strength/weight ratio, good strength at high temperature and resistance to corrosion, titanium alloys are widely used in aerospace, medical and chemical fields. However, their poor thermal conductivity and high chemical activity make titanium alloys ver y difficult to be machined. The phenomena such as high cutting temperature and fast cutting tool abrasion can be observed during the conventional machining of titanium alloys, which has limited their application. Therefore, it is meaningful to search new m achining methods of titanium alloys and to improve its machinability. Laser-assisted machining(LAM) is a novel hybrid machining technology, which can reduce cutting force and cutting energy, extend cutting tools’ lifetime as well as improve the machined surface quality. At present, the research on LAM is mainly concentrated on ceramic materials and the research approach is limited to experimental method. This paper combines the finite element method and experimental method to study the laser-assisted turning method on the widely used Ti6Al4 V titanium alloy. The main content of this paper includes:First of all, a three dimensional finite element model based on classical thermal theory for laser heating is built and the simulations under different laser para meters are conducted. The absorptivity of laser energy is determined using the method of comparing the simulation and experimental results. The influence of the laser power, moving speed, spot radius and tool/spot distance on the laser heating temperature are analyzed. The appropriate cutting parameters are chosen for later cutting process simulation and experimental study.The finite element model for orthogonal cutting of Titanium alloy based on the Johnson-Cook material constitutive equation and corresponding damage law is then built. The temperature and stress fields are completely coupled in this finite element model. Simulations of conventional and laser-assisted machining under different cutting parameters are conducted. The stress and temperature fie lds as well as cutting force obtained in the simulation are analyzed and the mechanism of LAM is uncovered. Furthermore, the influences of the cutting parameters on the LAM effect are also analyzed.Finally, the experimental studies of orthogonal cutting o f titanium alloy are conducted. A experimental system of LAM is designed and the tests cover different cutting parameters. The cutting force during the cutting process is measured. The microstructure of Ti6Al4 V material after the laser heating process is o bserved, so as the chip morphology. Then the experimental and numerical results are compared to demonstrate the accuracy of the numerical model is thus proved.