Numerical Simulation And Experimental Research Of Titanium Alloy Artificial Joint Curved Surface Abrasive Flow Machining

The roughness of artificial joint surface has an important effect on its function and lifetime. Titanium alloy has been widely used because of high strength and low modulus, but the polishing of artificial joint surface is artificial and the quality is unstable because of the complex curved surface.Abrasive flow precision machining is a new method that machining the surface of workpiece with abrasive flow in turbulence state, it has a good shape adaptation and nice effect when used to polish complex curved surface. This paper puts forward an improved method named complex curved surface abrasive flow based on gas compensation, simulate the characteristics of abrasive flow based on VOF model, proved the effectiveness by experiment. The main works and results of this paper are as follows:1. A method of complex curved surface abrasive flow based on gas compensation is put forward. Abrasive flow channel is build up based on hydrodynamic theory. The Reynolds number is calculated which affirmed the flow state in flow channel is turbulence. The material removal model is deduced from the stress analysis of single abrasive particle and the statistical distribution of abrasive particles in the flow channel, add the influence of curvature and gas compensation.2. The flow state of abrasive flow in flow channel is simulated by FLUENT. How the different entry position and absolute pressure of gas compensation affect the flow state of abrasive flow in channel is researched. The results indicate that the distribution of kinetic characteristic of abrasive flow is more uniform when gas compensation entry been set in inlet region. The higher the absolute pressure, the stronger the improvement is.3. The PIV observe experiment is conducted. The velocity vector and vorticity is got by image processing techniques. The results indicate that the contact chance between abrasive and curved surface is increased when gas compensation is used. The turbulence characteristic of abrasive flow in channel is proved.4. The processing unit and technic are developed. Through the machining experiment, the roughness of curved surface drops to 134.97 nm from 865.82 nm after 16 hours processing. The feasibility and effectiveness is proved.