Dynamic Observer Modeling and Minimum-Variance Self-Tuning Control of EDM Interelectrode Gap

Abstract

Featured Application: Applying on electric discharge machining. Abstract:The electric discharge machining (EDM) interelectrode gap directly determines the discharge state, which affects the machining efficiency, workpiece surface quality, and the tool wear rate. The measurement of the real-time varying interelectrode gap during machining is extremely difficult, and so obtaining an accurate mathematical model of the dynamic interelectrode gap will make EDM gap control possible. Based on p-type single-crystal silicon EDM, a flat-plate capacitance model is introduced to analyze the time-domain characteristics of the inter-electrode voltage in the breakdown delay phase. Further, we theoretically established a physical model of the interelectrode spacing d and the charging time constant τ of the plate capacitor. The least-squares fitting of the experimental data was used to determine the model coefficients, and in combination with the actual machining process, a minimum-variance self-tuning controller was designed to control the interelectrode gap in real time. The experimental verification results show that the established physical model can correctly predict the interelectrode gap in the actual machining process. The minimum-variance self-tuning controller improves machining stability, and eliminates the occurrence of the short-circuit state.

Experimental Research on Discharge Forming Cutting-Electrochemical Machining of Single-Crystal Silicon

“…Figure 5 shows that the current and voltage signals in the discharge forming cutting process of the copper foil electrode are similar to those of WEMD and EDM [16], the current signal is not synchronized with the voltage signal, and the voltage signal has a noticeable breakdown delay [16]. After the breakdown delay, the voltage signal drops rapidly (drops from 100 V to approximately 24 V and remains unchanged), the current signal rises rapidly (rises up to approximately 17 A and remains unchanged), and there is obvious negative resistance between the electrodes [18].…”

“…us, it is an ideal choice for brittle and hard materials that are difficult to process [10][11][12][13][14]. In particular, it is suitable for processing brittle and hard single-crystal silicon [15][16][17][18] and polycrystalline silicon [19,20]. Although WEDM has certain advantages in cutting brittle and hard single-crystal silicon (no contact and high machining efficiency), there are still two main problems: (1) the vibration of the electrode wire can easily produce a workpiece with poor surface quality and cause wire breakage [21,22].…”

Multi-Response Optimization of Electrical Discharge Machining Using the Desirability Function

“…Therefore, the presented disturbances will not have a significant impact on the quality of the treated surfaces. Nevertheless, unfavorably selected ranges of the set parameters will significantly affect the efficiency of the process [56]. The following are examples of stable U ( t ), I ( t ) waveforms, which enabled the selection of the range of variability of parameters used in the experimental research (Figure 4).…”

The Effect of TiC Additive on Mechanical and Electrical Properties of Al2O3 Ceramic

“…The conductivity of the deionized water was 0.1 µS•cm −1 ; electric voltage V o = 270 V; and current intensity I e = 0.05 A. The frequency of the working impulses was f w = 0.2 MHz [49,50].…”