Research On The Key Technologies Of Micro And Small Hole EDM

With the increasing miniaturization and precision of products in the whole world, as one of non-contact precision manufacturing methods, micro and small hole EDM technology receives much attraction from both academic and industrial circles. It becomes an important part of micro machinery manufacturing, and is widely used in manufacturing industry. However, because of the natural characteristics of the micro and small hole EDM, such as weak discharge energy, high pulse power supply frequency, unstable spark discharge states and small discharge gap, etc., there are still some key technical difficulties in its machining process need to be solved: the difficulties in real-time discharge states detection, in accurate control of machining process, in prediction of discharge states, in improvement of machining system precision and in on-line preparation of micro electrode, etc. This paper focuses on providing new thoughts and methods to the key technical difficulties mentioned above: the research and implementation of real-time discharge states detection, the research and application of machining process intelligent control strategy, the research and implementation of discharge states prediction theory, the development of high precise and fast response machining system.According to the actual characteristics of high frequency weak energy discharge, complex interference and severe distortion of discharge signal in micro and small hole EDM, we provide a successive mapping detection method of discharge states based on fuzzy logic. The outputs (discharge states ratios) of this method are used as the inputs of machining control system, double-closed-loop control system of micro and small hole EDM is designed, and a machining control strategy of micro and small hole EDM based on fuzzy logic is proposed. Thereafter, the deep research and investigation of the discharge states prediction method of micro and small hole EDM are conducted, based on local wave decomposition, the discharge states prediction model and implementation method of micro and small hole EDM are proposed. The experimental results indicate that, the prediction accuracy of the method is high and the prediction result is stable. The prediction model and method provide beneficial reference to the on-line prediction of discharge states of micro and small hole EDM and to the stable control of the machining process.Meanwhile, a micro hole EDM experimental facility based on linear motor drive is developed, which exhibits high precision and fast response speed. The micro holes machining test based on this experimental facility shows that, with comparing the detection method proposed in this paper to the traditional detection and control method, discharge machining efficiency is greatly improved. Moreover, the more the machining parameters close to the actual condition, the more obviously the machining efficiency is improved. So compared to the traditional methods, the successive mapping detection method of discharge states and machining control strategy based on fuzzy logic are more suitable for the real-time detection and stable control of micro and small hole EDM.Above all, the research results of discharge states detection, machining control and discharge states prediction in micro and small hole EDM in this paper provide beneficial theoretical reference to the micro EDM, and have certain value of reference in technique.