Modeling And Experiment Investigation Of The Flow Field During The Free Abrasive Machining

Grinding is one of the most important technologies used by manufacturing today. Used to machine and finish materials, grinding is a effective manufacturing method available to engineers, particularly when ceramic or new composite materials are involved. In order to meeting the requirement for these new materials, many novel grinding and polishing methods have been development. Some of them which the working principle is not totally mechanical treatment, and some of them no longer use the traditional polishing tools and abrasive medium, but use free abrasive. The two phase flow field during the free abrasive machining have been simulated and experimental investigated in this paper.By our research work, main topics have achieved the following results:Firstly, by using the FLUENT, the abrasive flow shape during abrasive flow machining was simulated by the Spalart-Allmaras model which was a Mixture turbulent flow model for solid-fluid two phase flow system. The simulation results clearly show that the main parameters how to influence the abrasive flow machining efficientcy, so it can offer a valuable reference for parameter selection during abrasive flow maching.Secondly, the numerical model of fluid flow during precision lapping and polishing is set up by the commercial software of Computational Fluid Dynamics- FLUENT.The numerical model can predict pressure and velocity distributions beneath the workpiece. After that, the relations between the rotate speed, the slurry viscosity, the pad surface roughness and the pressure distributions were discussed, which provide a guide and reference for the design and optimization of the precision lapping and polishing. The complete numerical study provides a method to predict the effects of slurry flow at any pad speed, and help improve the efficiency and uniformity of workpiece polishing.Thirdly, a device has been designed to measure the pressure of the workpiece-pad interfacial film during precision lapping and polishing. Measurements have been collected where the workpiece was held stationary. Pressure trials results shows that an asymmetrical pressure distribution, there are a large sub-atmospheric pressure range, and some positive pressure region at the trailing edge of the workpiece. It also can be seen from the pressure experimental results that as the pad velocity increases, both the magnitudes of the positive and negative fluid pressures increases. The pressure distributions are affected by the viscosity of the slurry. While the slurry viscosity is larger, the difference of the pressure values in the interfacial film is also larger, and the flow field is more unsteady, it was not good for the workpiece planarization. The pressure distributions of the numerical simulations were compared with the available experimental data and good agreement was found.