Surface Integrity And Deformation Forecasting In High Speed Cutting Titanium Alloy Thin-walled Component

As the most important component of manufacturing industry, aerospace manufacturing industry represents national highest manufacturing standard and technical strength. Modern aircraft and spacecraft as well as other aerospace products use a large number of lightweight and high strength thin-walled components to reduce its weight, and increase the thrust weight ratio of engine. It can be predicted that along with the further development of aerospace industry, thin-walled components will be used more and more widely, and the demand of quality will also be further improved. Titanium alloy has many advantages, such as high temperature resistance, good corrosion resistance, and high strength, which has become one of the main structure materials of modern aircraft and engine, and its dosage proportion shows increasing trend. In some military aircraft of U.S, the dosage of titanium alloy material has reached over 40%, among them, TC4 titanium alloy (Ti-6A1-4V) as the representative ofα+βphase titanium alloy is used frequently.In order to meet the performance and reliability of components, aerospace titanium alloy thin-walled component has high demand on machined surface quality and machining precision as well as machining efficiency. Because of the titanium alloy material physical properties such as small deformation coefficient, low thermal conductivity, high chemical activity and high surface imperfection sensitivity and others, as well as the low stiffness and large cutting vibration, poor processing technology and other factors caused by thin-walled structure, the overall processing level of this kind component is not high in China currently; especially the component surface integrity and face shape precision are the most prominent problem which has become the important bottleneck to restrict aerospace product developing. With its high efficiency, high precision, high surface quality and other advantages, high speed machining technology has become the mainstream processing technology of titanium alloy thin-walled components in America Boeing, Hughes Company, the European Airbus Corporation and other large aircraft manufacturing enterprises, which has showed vigorous vitality. Accordingly, the following is researched in this paper:Considering tool vibration, surface topography model of high speed cutting titanium alloy diaphragm disk is established by analyzing the machined surface forming process of titanium alloy diaphragm disk after cutting, and the simulation of surface topography is also researched; by testing experiment of surface roughness and surface topography, the simulation results of the surface topography are validated. On the basis of surface topography modeling and simulating, using genetic algorithm, and taking machined surface roughness and cutting efficiency as the goal, high speed cutting titanium alloy diaphragm disk cutting parameters optimization is made, and the titanium alloy diaphragm disk cutting parameters optimization membrane and morphology simulation system are also established.On account of the titanium alloy diaphragm disk with different clamping means, titanium alloy diaphragm disk surface torsion deformation and bending deformation induced by clamping force and cutting force are calculated according to material mechanics, elastic-plastic mechanics and computational mechanics; meanwhile comparative analysis of the results with finite element simulation is made, which can achieve deformation precision prediction of titanium alloy diaphragm disk surface with different clamping method and clamping force as well as cutting force. At the same time, it offers mechanical theoretical basis for titanium alloy diaphragm disk clamping method optimization and tool profile design.Combined the experiment results with numerical simulation, the change law of surface residual stress is studied, and the deformation caused by the release of residual stress in the process is selective researched. Through researching on titanium alloy material surface micro-hardness experiments, the machined surface hardening evaluation index value changing range is obtained; Surface metamorphic layer depth and metallographic structure as well as lattice and hardness and microstructure changes are theoretical analyzed and tested with SEM; Based on the theoretical and experimental study of surface physical performance parameters change law mentioned above, the influence law of cutting parameters on physical properties of titanium alloy machined surface in high speed cutting is obtained, which has provided the theoretical basis and experimental data support for improving machined surface quality of titanium alloy material and titanium alloy thin-walled component.