Study On Ultrasonic Vibration Assisted Micro Wire Electrochemical Discharge Machining Technology

Insulating materials are widely applied in micro electromechanical system,wearable equipment,intelligent mobile terminal and other fields with the rapid development of society.In insulating materials,such as glass and ceramic,it is difficult to be machined because of its hard and brittle characteristics.While electrochemical discharge machining is a non-contact machining,which can be competent for the fabrication of hard and brittle insulating materials.In this thesis,ultrasonic vibration was introduced to wire electrochemical discharge machining.The mechanism of ECDM and the effect of ultrasonic vibration,machining voltage,feed rate and other main machining parameters on the cutting quality have been studied.Firstly,the formation gas film in ECDM was analyzed theoretically.The thickness model of gas film and the energy model of micro slit were established.Through the simulation analysis of the flow field,it was found that the ultrasonic vibration on the tool electrode can refine the gas film,make the gas film distribution more uniform,and then reduce the critical voltage of spark discharge.In addition,through the simulation of temperature field,it was found that with the aid of ultrasonic vibration,the depth of pit produced by single discharge can be reduced,and then the surface roughness after machining can be reduced.Then,the effect of ultrasonic amplitude on the cutting quality was analyzed by using the helical electrode with a diameter of 100 ?m.When the amplitude was 5.25 ?m,the average silt width was 128.63 ?m,and the surface roughness was 0.235 ?m.Compared with that without ultrasonic assistance,the average silt width and surface roughness were reduced by 20.78%and 52.9%respectively.At the same time,the effect of machining voltage,duty factor,pulse frequency and feed rate on the average slit width and the surface roughness of side wall were analyzed by combining the current signal graph and the energy model of micro slit.Combined with the effect of each parameter on the machining quality,the three slit array,closed structure Archimedes spiral curve were fabricated by optimized parametersFinally,the wire electrode with a diameter of 50 ?m was used for cutting experiment.The experimental results show that the ultrasonic vibration applied on wire electrode was more easily to refine the gas film.When the vibration was applied to wire electrode and the optimal amplitude is 7.5 ?m,the average silt width was 56.2 ?m and the surface roughness was 0.265 um.Compared with that without ultrasonic assistance,the average silt width and surface roughness were reduced by 17.63%and 54.23%respectively.The effect of machining voltage,duty factor,pulse frequency and feed rate on cutting quality were investigated by applying ultrasonic vibration on the wire electrode.Combined with the effect of each parameter on the machining quality,the micro gear structure with high aspect ratio was completed by parameter optimization.