Theoretical Analysis And Experimental Research On Abrasive Flow Machining

Abrasive Flow Machining (AFM) is a non-traditional finishing process, which processes component by using a flowable viscoelastic abrasive mixture. AFM possesses excellent capabilities for finishing of complicated surface and inaccessible regions of a component, such as narrow slits of component, micro- voids, cross holes, shaped holes and cavity, and so on. The process can achieve radiusing, deburring, and polishing simultaneously. The AFM can be used for a wide range of materials including metals, ceramic and hard plastics. This paper presents theoretical analysis and experimental results of an investigation into some aspects of the mixture performance, AFM process mechanism, parametric relationships, surface integrity, and abnormal process.First, new formulas, applied in different areas, were developed by improving the properties of flowable mixture. The method of classification for viscosity of flowable mixture on the basis of the fuzzy mathematics theory was indicated. The membership functions of viscosity were founded to provide a way of selecting flowable mixture. The accurate method of measuring viscosity of flowable mixture based upon the integrative technology of mechanics and electrics was also presented to establish the foundation for emulational research.Secondly, the rheological behavior and processing properties of flowable mixture were studied in detail. The velocity formula of flow with a boundary condition of nonzero was derived. In during of investigateing the effect of primary process parameters on the size of radiusing, the characteristic of quasi-radiusing was found and inferred to result from elastic turbulent flow of flowable mixture by investigating the formation mechanism. Then the deburring mechanism of AFM was analyzed. The effects of deburring of single direction process and to-and-fro process were discussed. The load of small and single abrasive was estimated using the microcosmic method, and the polishing mechanism of microscopic and uneven surface was analyzed. The process mechanism that grinding and rolling coexist in during AFM was revealed. The effects of processing cycle times on the surface roughness and the sustaining length ratio of profiles were evaluated. It was found that the first few processing cycles were crucial to improve the quality of surface. It was shown that AFM made the surface of component more wearable and the useful life of component longer.The mechanisms of some abnormal processes, such as corrugated surface and serious wearing surface due to leakage flow, were analyzed. It is thought that the corrugated surface results from the elastic deformation of flowable mixture exceeding allowance because of AFM process parameters. According to the mechanism, much more abnormal phenomenona which appeared possibly were forecasted. The serious wearing occurs at the place of leakage flow between component and fixture because the flowable mixture flows at a high speed through the place which presents the configuration of small hole with short length. These provided theoretically support for insuring process quality and preventing wasters from producing.The equipment of real-time detecting and controlling temperature was developed. Using the equipment, the variation of temperature was revealed during the process of AFM, and the inevitability of the variation was testified corresponding to the process mechanism. The influence of temperature on the surface roughness processed was investigated. The results showed that the temperature was important to stabilize the processing quality, enhance the processing efficiency and predict the processing outcomes.With the ultimate aim of obtaining excellent processing surface through process controll in the thesis, the surface appearance and energy dispersive spectrum (EDS) were investigated. The micro-hardness of surface was measured. The results indicated that the surface was integrated, not tearing. Moreover, the micro-hardness of surface slightly increased. It was found that the surface of AFM was antirust and this was the intrinsic characteristic of the technology for AFM by analyzing the trait of technology and the hypostasis of flowable mixture. In view of the structural limitation in the existing apparatus, the special position adapting to AFM such as narrow cracks, micro-voids, shaped cavity etc can't be detected. Accordingly, a novel detecting method based on computer vision was developed and applied in some experiments.Finally, the rationality and correctness of the theoretical results were proved by processing some components,such as mould, hot runner, gear, ceramic tube of optical fiber linker, stator of cycloid motor, nozzle, long stainless pipe, bent pipe, and so on.