Numerical Simulation Research Of Abrasive Flow Machining Based On The Finite Element Method

Abrasive flow machining (AFM) is a nontraditional finishing method, which is also called extrusion honing. The machining principle of the technology mainly is that viscoelastic high polymer carrying abrasive particles is forced to flow the workpiece surface at certain pressure, and during this process the abrasive particles create relative slipping with workpiece surface and produce scraping action on the workpiece to remove microscopic uneven rough material. AFM is particularly suitable to polishing and burring complex surface, cavity and relatively hidden parts, such as micropores, narrow slits, cross-holes etc. And it has high machining efficiency, excellent processing quality, and wide range of machined materials. Therefore AFM has been widely applied to various industries.However, due to many influencing factors for machining effect, the study of machining mechanism of AFM becomes very difficult. Currently the study for AFM still relies on experimental method. A great numbers of experiments are needed for establishing and improving the theory of AFM mechanism and finding out the influences of various factors on AFM processed results. And then summaries and comparisons are done based on these experimental data; in addition, due to the objective conditions restrictions, experiments lack of operability, all of reasons above will delay research period. In recent years people can achieved the analysis of various flow on the computer with the development of Computational Fluid Dynamics and related numerical simulation software. And because using numerical simulation method is not limited by physical and experimental conditions, saves money and time, and has visualization results, it is more and more used to analyze flow problems.In this paper, on the basis of previous theory studies and experiments, numerical simulation method of AFM is preliminary explored by using fluid analysis software--LUENT, trying to find a kind of effective finite element method to realize numerical simulation of AFM in order to save research costs, shorten research period and provide a feasible method for quantitative analysis of AFM. And the main contents are as follows:Firstly, taking a common round-hole workpiece as example, flow field of abrasive media in practical processing of AFM is simplified as a two-dimensional axisymmetric physical model based on knowing about machining process and principle of AFM. And then the structural model is meshed through GAMBIT and a finite element model for AFM numerical simulation is created.Next, preliminary study on numerical simulation method of AFM is made by using flow analysis software FLUENT. In the simulation analysis, the above finite element model is adopted and the material modle of Non-newtonian-power-law from FLUENT software is used to described abrasive media property, and then experimental study of numerical simulation of AFM is performed by different combination settings of the solution parameters. Final solution parameter setting is as following:using steady implicit solution of two-dimensions single precision based on pressure and RNGκ-εmodel in turbulence model; applying enhanced wall treatment method near to the wall and solution parameter combinations of non-slide boundary condition in stationary wall. Later the numerical simulation analysis of AFM under pressure-inlet and velocity-inlet conditions is carried out by using the solution settings established above respectively. The simulation result shows that one under pressure-inlet condition is more suitable to the actually machine. It is proved that this method can be used to forecast the total pressure drop between inlet and outlet of round hole workpiece by comparing simulation results with experiment ones, and the conclusion can offer reference basis for further study of AFM numerical simulation method.Finally, because the total pressure drop between inlet and outlet of round hole workpiece is one of the leading causes affecting on effect of AFM in the theory research, three factors of viscosity of abrasive media, abrasive media working pressure and hole diameter of workpiece are analyzed separately by numerical simulations method. The regulations of abrasive media pressure and velocity distributions in round hole channel influenced by different factors are obtained, and the conclusion can offer reference basis for AFM parameter selection.