Preparation Of Working Fluid For EDM And ECM Composite Machining And The Study On Slotting Effect

Slotted pipe is sand control equipment commonly used in petroleum industry.In order to obtain the good surface quality and use it in long term,the electric discharge electrolytic?EDM/ECM?composite processing method is used for cutting research.At present,the poor safety and high cost are existed in oil-based fluids,and the poor processing efficiency is existed in pure water-based working fluid.Aiming at the above problems,a series of working fluids were designed and prepared by orthogonal test in this paper.The cutting specimen is Q235 steel plate of 6 mm.The slotting effect and processing parameters on the cutting process of self-made working fluid was investigated using electric spark electrolytic composite processing equipment with independent intellectual property rights,and compared with the processing effect of oil.In order to obtain a highly effective and environmentally friendly compound working fluid,pure water,oil and emulsifier as raw material adding to some rosin as blasting agent and a small amount of anti rust agent used in the preparation of oil in water working fluid.The results show that the emulsifier HLB value is 8.Under the condition of 55?and the proportion of water,oil and emulsifier 4:1.5:1 can obtain uniform and stable emulsion.In the same electrical parameters,adding 30 g rosin can improve processing efficiency,the kerf width and surface roughness.The solution has better dispersion stability and the security is improved compared with the oil processing.In order to further improve the effect of cutting processing with the processing parameters unchanged,in this paper,a kind of safe water based working fluid was developed by using pure water,NaCl,NaNO₃,polyvinyl alcohol?PVA?and emulsion as raw materials for composite processing.The results showed that the salt and the additive?PVA?in the working fluid had a great influence on the working efficiency of the combined process.The emulsion has a certain impact on the surface quality of the processing because of it can improve the surface tension of the composite working fluid.The order of the influence of the three factors on the efficiency of the compound processing is the salt content,the emulsion content and the PVA content.Adding 1%polyvinyl alcohol,50%self-made emulsion and 0.022%NaCl and NaNO₃ in the working fluid can get the best slotting effect.Compared with the developed water-based working fluid and traditional oil fluid,it can be found that the efficiency is increased by 7%,cutting surface roughness is reduced by 23.45%,the kerf width is increased by 11%.In the experiment,experimental study on cutting using water-based working fluid to complete.This paper determined the optimal combination of process parameters using the machining efficiency and cutting width as the evaluation index by the orthogonal test.The results show that increasing of the pulse width and current value will increase the processing efficiency,however,the width of the gap increases correspondingly,and the adjustment of the pulse gap and the rotation speed of the electrode will improve the state of the discharge gap.So that the processing can be carried out steadily.Under the experimental conditions,the optimum process parameters are as follows:the pulse width 48?s,pulse interval 30?s,electrode rotation speed 375 r/min,current value 50 A.Compared with oil processing,the machining efficiency is increased by 2.2%,the crack width is increased by a factor of 8%,and the surface roughness is reduced by a factor of 10.7%under the optimum process parameters.The research results of this paper have certain reference value to the research of the working fluid of the electro discharge electrolysis combined machining,and the working fluid which is prepared with economic high practicability ensure the safety of the cutting process.