Adaptive Control Research Of Electrode Jump Motion In Electro-discharge Machining

Non-conventional Machining plays an important role in our nation’s industrydevelopment. The advancement of the non-conventional machining embodies themanufacturing level. As an important method in non-conventional machining, electricaldischarge machining (EDM) has extensively used in aeronautic and astronautic machiningfield, vehicle industry, textile industry and military industry, etc.. However, the mostserious problem that unstable machining in poor debris removal conditions elicits arcingand shorts in the gap between machining tool and workpiece burning the workpiecesurface still exists. Meanwhile, low processing speed is another problem that has disturbedprocessors so many years since the birth of EDM. Both problems have impeded thefurther development of electrical discharge machining.The tool retraction movement used in EDM helps to remove the generated debris out ofthe gap in order to decrease the ratio of stable arc and short pulses and thus maintain a stablemachining process. However, the tool movements cost time. In order to improve themachining efficiency, it is necessary to propose a strategy to control the electrode jump heightshortening the time consumption in electrode jump process on the premise of stablemachining. The purpose of the paper is to establish an adaptive control system for autoadjusting the electrode jump height in EDM and achieve the aim of improving the EDMperformances.Firstly, the process experiments of electrode jump in EDM have been conducted.Through the extreme difference analysis and variance analysis of the experimental data,obtained the influence law of electrode jump height on EDM process under the open-loopcontrol system.Then, in terms of adaptive control theory, this paper designed the adaptive control systemfor EDM Process in which the electrode jump height was taken to be a control variable andgap state as output. Based on the real-time-estimated parameters of an established EDMprocess model and by using the minimum variance control strategy, this adaptive controlsystem can adaptively adjust the electrode jump height to keep the gap state following aspecified gap state.Upon the above research, realized the adaptive control algorithm on Visual C++platform,and developed the EDM measurement-control system software; meanwhile, implemented theelectrical circuit for data acquisition, and the serial communication of IPC and EDM machine.Thus far, the closed loop control of IPC and EDM machine was established. Finally, thecontrast experiments between open-loop system and the closed-loop system for verifying thesuperiority of the established adaptive control system were conducted. And the results showthat more stable EDM machining process is realized in conformance with a greatly highermachining efficiency. Further development of this adaptive control system was conducted toobtain a more stable machining process and higher machining rate by optimizing the other machine parameters concerned. Finally, the established adaptive control system not only hassuperior performances but also manifests its theoretical and practical values.