Study On Process Experiment And Mechanism Of Nozzle-type ELID Grinding

As a high efficiency ultra-precision machining technology, Electrolytic In-Process Dressing (ELID) mirror grinding is widely applied in high accuracy machining of hard and brittle materials. In this paper, nozzle-type ELID grinding method was discussed, experiment investigations were conducted, and grinding mechanism was also analyzed. It provided technical foundation and theoretical support for the machining of micro parts in the future, and also provided evidence for the expansion of application scope of ELID grinding.Firstly, based on analyzing and summarizing the principle of nozzle-type ELID grinding method, the structure of nozzle electrode and the anode brush of ELID system were developed. To establish the experimental table for nozzle-type ELID grinding, the existing grinding machine was improved. The special power supply and grinding fluid of ELID grinding and metal bond diamond wheel were used. Before the experiments, the wheel was balanced by three-point balance method and electro-discharge trued by choosing different power parameters to meet the requirements of nozzle-type ELID grinding. The roundness error of the grinding wheel reached less than 1～2μm.Then, three kinds of cemented carbides were selected as workpiece materials and the experiments were conducted by using nozzle-type ELID grinding system installed on MGK7120×6 precision surface grinder. By changing the parameters of power supply and grinding process, the variation of the grinding force, specific grinding energy and surface roughness were analyzed and the electrolytic parameters achieving best surface quality were obtained. Meanwhile, under the same grinding parameters, the grinding force, specific grinding energy and surface roughness of nozzle-type ELID grinding and ordinary grinding were compared. The results showed that nozzle-type ELID grinding can significantly improve the surface quality of the workpiece and reduce the grinding force. So, nozzle-type ELID grinding can realize the high quality grinding for cemented carbides.Finally, according to brittle-ductile transition theory, the maximum undeformed chip thickness of cemented carbides was obtained.. Combined with surface topography of workpiece and the variation rules of grinding force, specific grinding energy and surface roughness, cemented carbides were mainly removed by sliding and plowing in the nozzle-type ELID grinding. Therefore, the removal way of cemented carbides in nozzle-type ELID grinding was mainly ductile removal mode.