Research Of Process Parameters For Machining Nickel-Base Super Alloy IN718 With Middle Speed WEDM

With the rapid development of aerospace,the requirements for high temperature components such as engines are getting higher,and the materials should have good mechanical properties at high temperature.Nickel-base super alloy IN718 is a typical high-temperature alloy with excellent high temperature creep strength,fatigue resistance,anti-oxidation and thermal corrosion resistance,which plays an important role in the field of aviation and aerospace.Nickel-based super alloy has great plastic deformation resistance,so it is very easy to make the tool damaged and chilled in the cutting process.Therefore,it is a suitable processing method to use WEDM to process Nickel-based super alloy IN718 in the manufacture of some parts.WEDM is a process which treats moving metal electrode and adopts CNC technology to control the electrode to discharge the workpiece,so as to cut the forming surface.Therefore,the Nickel-based super alloy IN718 can be processed by WEDM to meet the manufacturing accuracy requirements.The research of cutting speed and surface roughness of specimen on the effects of the factors,which are pulse-on time,discharging gap,walking wire speed and duty cycle,is studied by using middle speed WEDM machine tool DK7740Z to cut Nickel-base super alloy.The aim of the research is to optimize the processing parameters,discuss the new method of Nickel-based super alloy and then improve the productivity.The effects of pulse-on time,discharging gap,walking wire speed and duty cycle on the cutting speed and surface roughness of specimen of IN718 in WEDM are studied by single factor experiment.By adopting orthogonal experiment,the experiment factors and the level of each factor are reasonably selected,the orthogonal table L₁₆?4⁵?is also used to form the test plan table.By means of the range analysis and variance analysis,the prominence effect of the following four factors on cutting speed and surface roughness of specimen,pulse-on time,discharging gap,walking wire speed and duty cycle are showed in this thesis.Quantitative analysis is used to analyze the significance of these factors as well.On the premise of orthogonal experiment,the numerical value of cutting speed and surface roughness of specimen are treated through the method of grey correlation analysis.By calculating their value,the maximum level of grey correlation degree of each factor is obtained according to the same level of different factors,and then the optimal parameter combination of pulse-on time,discharge gap,walking wire speed and duty cycle is obtained.That is,the experiment processing condition is that the pulse width time is 24?s,the discharging gap is 8?m,walking wire speed is 2 gear,and duty cycle is 0.1428.Experimental results show that the optimal parameter combination achieves the expected machining effect.By using the response surface method,the fitting model is established,and then the data processing is through Minitab software to get the analytic formula of the independent variable and the objective function.That is,the function analytic formula of the pulse-on time,discharging gap,walking wire speed and duty cycle to the cutting speed and the surface roughness of specimen.Based on the variance analysis,it can be seen that the model fitting effect is pretty good.Two dimensional equivalent image and three-dimensional response graph are used to observe the range of the optimum point.At the same time,it is possible to do the target prediction by fitting analytic formula,which provides a strong basis for the selection of the technological parameters in the process of Middle Speed WEDM cutting Nickel-based super alloy IN718.