Rheological characterisation of abrasive media and finishing behaviours in abrasive flow machining

摘要

Flow field simulation of abrasive media in a constrained passage in abrasive flow machining (AFM) plays a decisive role in optimising process parameters and designing the core of a fixture. Based on the experimental rheological characterisation of various types of abrasive media, a model of flow field simulation of abrasive media was constructed by combining with the continuous medium hypothesis. Moreover, a pressure detection platform was built for the constrained passage and test and simulated data were compared and analysed. The results demonstrate that the diameter of abrasives slightly affects the rheological characterisation of abrasive media under the same mass fraction, and rheological characterisation of abrasive media before and after use obeys a power-law constitutive model. Simulated pressures in the flow field show a completely consistent trend with measured pressures although they deviate significantly in the inlet region. Pressure in the constrained passage increases with increasing extrusion pressure and gradually attenuates along the flow direction, so that abrasive finishing marks become shallower along the flow direction. In addition, the increased extrusion pressure increases the final surface roughness of the polished surface and extends the processing time required to stabilise the final surface quality.