Research On Mechanism And Experiments Of Electrochemical Abrasive Jet Combined Machining For Difficult To Machine Materials

Electrochemical abrasive jet machining(ECAJM) is a newfashioned processing method, that electrolyte jet machining(ECJM) is composited with abrasive water jet machining(AWJM). ECJM is effective, however, the surface quality is not so good in the micrometer extent. AWJM has a wonderful surface quality but an inefficient machining when under the condition of low pressure. ECJM has a low efficiency, especial y in some materials which is passivated easily, whereas this composite machining has an obvious advantage over it. Injecting abrasive makes the workpiece surface passivation film remove. It contributes to continue ECJM and improve the processing efficiency. At the same time, the processing surface is further leveling under the percussive action of the abrasive. So the surface quality is improved. Based on the Inconel 718 and the steel bond hard alloy GT35, this thesis got down to research about ECAJM.Firstly, the removal model of AWJM was established. Then the removal model of ECAJM was established composed with the removal model of ECJM. What′s more, The removal model of ECAJM was verified and simplified via experiments. The research showed that ECJM dominated in the electrochemical abrasive jet machining process and AWJM was subsidiary. However, abrasive promoted electrochemical machining and increased the ECAJM speed. According to the removal model analysis result, either increasing voltage or decreasing jet distance could improve the material removal rate of ECAJM. On the basis of comparison method of the volume electrochemical equivalent, the material removal amount of the Inconel 718 was bigger than the steel bond hard al oy GT35 in the electrochemical abrasive jet machining process when other conditions were same.Secondly, aimed at the Inconel 718 and the steel bond hard alloy GT35, the influence of material removal mechanism was obtained on the process of AWJM, ECJM, ECAJM composed with surface appearance analysis. Research showed that the material remove of AWJM was based on a large amount of abrasive impact cumulative effect but its processing efficiency was very low. Electrochemical machining area cracks at the pit were generated by stress corrosion of passivation film, while the pit was caused by anisotropic etching. In the process of ECAJM, the abrasive not only promoted anisotropic homohenization that improved the surface quality but also removed the passivation film of the electrochemical reaction which facilitated electrochemical processing. Surface topography analysis lay the foundation for further application of composite processing methods.Finally, a large number of process experiments were carried out via single factor method. The effect on both the Inconel 718 material removal rate and the surface roughness in ECAJM was analyzed by researching ECAJM process parameters, which mainly contain voltage, jet distance, electrolyte concentration, and so on. The experiment results showed that electrochemical machining parameters on material removal rate was large, and the AWJM parameters had litter effect. At the same time, the process parameters had relatively litter influence. Experimental study of ECAJM lay foundation for a wide range of applications.