Research On Abrasive Flow Polishing And Material Removal Mechanism Based On Discrete Element Method

With the rapid development of engineering technology,machining has progressed from rough machining to precision and ultra-precision machining.More and more ultra-precision machining technologies have emerged,and abrasive flow polishing technology is one of the fields of ultra-precision machining.Variable-diameter pipe parts have extremely wide applications in aerospace,automotive,machining,and other industrial production.Due to the special nature of variable-aperture pipe parts,it is difficult for traditional machining methods to perform effective finishing on their inner surfaces.Abrasive flow polishing technology can reduce the surface roughness of parts,and the vibration of the fluid in the variable-diameter tube will be decreased,the dynamic and static characteristics of the system can be ensured.Therefore,it is of great significance to prolong the life of the variable diameter pipe parts and ensure the stability of the system.Consequently,the study of abrasive flow polishing technology has extremely important engineering application value and academic significance for improving the performance of variable-diameter pipe parts.Based on the discrete element theory and method,through the numerical simulation of the dynamics,the interaction between the abrasive particles、the abrasive particles and the workpiece surface during the polishing process is analyzed,and the collision,deburring,and rounding of the abrasive particles against the workpiece surface are thoroughly discussed.The material removal mechanism of multi-grain impact on wall collision and single abrasive particle to wall sliding are analyzed.The material removal effect of the abrasive particle on the inner surface was studied.As a result,the material removal mechanism of the abrasive grain on the workpiece wall surface was revealed.Based on the discrete element theory and method,a numerical model for solid-liquid two-phase flow was constructed.The fourth-order variable bore tube was used as the research object.In the CFD-DEM coupling field,different inlet velocities,different abrasive concentrations and different abrasive particle sizes were used to study the solid-liquid two-phase in the fourth-order variable-diameter tube.The influence of the coupling field of the fluid turbulent kinetic energy and the kinetic energy of the abrasive particles on the polishing quality of the fourth-order variable-diameter tube was discussed.Taking the fifth-order variable-aperture pipe parts as the research object,under the CFD-DEM coupled field conditions,the solid-liquid two-phase in the fifth-order variable-diameter tube was studied from different inlet velocities and different incidence angles.The influence that coupling fields such as fluid dynamic pressure and total particles energy to the fifth-order variable-diameter tube were discussed.Finally,the abrasive flow polishing test was performed and the surface roughness and surface topography were tested.The surface roughness values of the fourth-order variable-diameter tube and the fifth-order variable-diameter tube were respectively analyzed through orthogonal test and comparative test.The multi-regression mathematical model was used to optimize the process parameters,and the ideal polished surface quality was obtained.The accuracy of the optimized model and the mathematical model and the orthogonal test method were verified.It is confirmed that the experimental measurement results are in accordance with the theoretical calculation results and can provide technical support for actual production and processing.