Research On The Impact Of Discharges In Micro-edm

Due to the Size-Effect,Micro-EDM can't be regarded as an Non-Traditional Machining Technology without force,just like in macro scale.The micro-electrode used in Micro-EDM,is a big length-diameter ratio and low rigidity electrode.In the process of machining,there will be unnecessary vibration,which increases the size and accuracy error of the workpieces.As a result,the impact of discharge between electrode and workpiece can't be ignored.Firstly,aiming at the instability of low rigidity electrode in micro-EDM,a vibration displacement measurement experiment of micro electrode is designed.The experiment is carried out by using single pulse discharge,using low rigidity brass electrode with a diameter of 500 ?m and a length of 80 mm and 304 stainless steel wire workpiece with a diameter of 0.3mm.The laser displacement sensor is used to measure the displacement amplitude of the electrode during the discharge process.In terms of electrical parameters,six energy levels are selected,and there are six different combinations of electrical parameters under each level,a total of 36 combinations of electrical parameters.In other parameters,four different dielectrics are selected as experimental parameters.The experimental vibration results under the combination of these parameters were measured,and 144 amplitude values were obtained.Secondly,in order to quantitatively obtain the impact of discharge action under different working conditions,the Euler Bernoulli beam model is established and the theoretical calculation is carried out.A cantilever beam is regarded as an infinite number of two order underdamped oscillation links,the relationship between the vibration displacement of the cantilever beam and the impulse of the impact action is established,and the impulse value corresponding to the experimental amplitude value is calculated.Then,based on the finite element analysis of workbench,the vibration model of cantilever beam with impulse as input is established.Taking the impulse value as the input load,the electrode vibration results in different media are simulated.Finally,it is found that the simulation value in air is about 10% larger than the experimental value,while the shallow oil is 30%larger and the deep oil is 38% larger.Further analysis of the vibration curve shows that the simulation results are highly similar to the experimental results.Finally,the experimental calculation value was adjusted to get the final corrected equivalent impact force value.It is found that the electric parameters is the determining factor for the changes of impact force in Micro-EDM,while the energy absorption of liquid,bubbles in liquid and erosion products are the three important factors affecting the impact of discharges.