Abstract: In order to study the effect of abrasive grain size on abrasive flow polishing, common rail pipe was selected as the research object. By calculation the state of abrasive grain flow under different grain sizes, the discrete phase analysis of the flow field was carried out from the dynamic pressure, the velocity field, the abrasive grain trajectory and the turbulent kinetic energy. From the numerical analysis shows that, with the increase in the grain size, the dynamic pressure, the velocity and the turbulent kinetic energy are reduced and the grinding effect is weakened. The trajectory of the abrasive grain can be used to predict and theoretically guide the optimal control of the abrasive grinding path and the production process, thus achieving effective and accurate polishing. The surface roughness and the surface topography of the common rail pipe were measured before and after abrasive flow grinding. The surface roughness was 3.401 μm before the grinding and was 1.138 μm after the grinding. This verifies the effectiveness of abrasive flow polishing workpiece with inner channel structure, and confirms the correctness of the numerical analysis. This work may provide theoretical support for the development of abrasive grinding technology.

Key words: machinery manufacturing technology and equipment, common rail pipe, discrete phase, abrasive particle size, polishing quality