Study On Machining Characteristics Of Glass Materials Based On Electrochemical Discharge And Picosecond Laser

In recent years,with the evolution of science and technology,micro-electromechanical system(MEMS)has been applied in more and more fields.Non-conductive and hard brittle materials such as glass have been widely used in MEMS devices,but their properties make it difficult to be micro-processed with traditional processing technology,which limit their further application.Electrochemical discharge machining(ECDM)and picosecond laser machining which have been developed in recent years have been proved to be effective for processing such materials.In this dissertation,the mechanism of electrochemical discharge machining and picosecond laser machining were discussed respectively,then the experimental investigations of the microchannel machining by these two methods were carried on.Finally,based on the previous research,the mechanism and experimental investigations of laser assisted ECDM were carried on.By using this method,poor morphology of the edge of microchannel processed by ECDM were improved.The main contents are as follows:1.The mechanism of electrochemical discharge machining was investigated.The voltage-current characteristics and the removal of material,which are important in this process,were discussed respectively.The static and dynamic characteristics of voltagecurrent were discussed respectively,and the current patterns in different stages of ECDM were described,then the dynamic current signals were analyzed.As for the removal of materials,two main mechanism were discussed: high temperature melting and high temperature chemical etching.The temperature distribution model in ECDM was established.The mechanism of heat transfer and the minimum temperature required for material melting were discussed.As for high temperature chemical etching,the effect of electrolyte type on machining efficiency was analyzed and the dissolution rates of glass materials under different temperatures of electrolyte were discussed.2.The experimental investigations of groove and microchannel machining on soda-lime glass by ECDM were carried on.The effects of different power supply voltage,pulse frequency,tool electrode rotation speed and tool electrode feed rate on the microchannel were investigated.The results indicate that,to a certain extent,increasing voltage and electrode rotation speed or reducing pulse frequency and electrode feed rate increase material removal efficiency and width of the microchannel,but it also cause poor edge quality and bottom surface morphology of microchannel.3.The experimental investigations of groove and microchannel machining by picosecond laser were carried on.The influence of laser power,pulse frequency,scanning speed and scanning times on the processing of groove was investigated,as well as the influence of scanning interval on the roughness and contour of the bottom surface of microchannel.The results indicate that,to a certain extent,the increase of laser power and scanning frequency or the decrease of laser frequency and scanning speed increase the groove width and groove depth,but exorbitant power or excessive low scanning speed lead to the deterioration of groove quality.The roughness of microchannel bottom deteriorates with the increase of scanning interval.Moreover,the bottom contour of microchannel presents obvious periodic crest and trough morphology when scanning interval is lager than 15?m under the conditions of this experiment.4.The mechanism and experimental investigations of laser assisted ECDM were carried on.Laser machining and electrochemical discharge machining are regarded as two steps.Firstly,picosecond laser were used to pre-process grooves on the workpiece and then electrochemical discharge machining was carried on.The results indicate that this method can effectively improve irregular edge and heat affected zone of microchannel in ECDM,and can also improve the overcut phenomenon of microchannel edge during electrochemical discharge machining.The research of this dissertation laid a theoretical and experimental foundation for the processing of higher quality microchannels on glass materials and promoted the development and application of MEMS technology.