放電加工操作參數適應控制

ADAPTIVE CONTROL OF OPERATING PARAMETERS OF EDM’ING

本研究針對放電加工電腦數值控制器（EDM CNC）的系統架構，加入一操作參數的適應控制策略。此策略能在直深孔（deep-sinking）粗加工之前適應自調 放電電源參數，也能在粗加工中適應調整間隙電壓參考輸入（reference gap voltage）與跳躍排渣頻率（jump frequency）。而在擴孔細加工（orbiting）時隨半徑改變能自動調整放電電源參數以滿足實際加工的需求。本適應控制器能在表面粗糙度（Rａ）與電極消耗（Wｐ）的限制下找到具有最大金屬去除率（MRR）的放電電源參數。間隙電壓參考輸入與跳躍排渣頻率則跟據外接的電弧訊號來調整，而擴孔加工時的放電電源參數則跟據擴孔半徑改變所需不同的粗糙度條件來調整。尋找放電電源參數、間隙電壓參考輸入與跳躍排渣頻率的適應性調整的控制策略如何應用在放電加工電腦數值控制器的軟體流程在本文中將有介紹。由實際放電加工實驗可驗證本方法在實際加工中的改進。

The adaptive control strategy for the operating parameters that govern electric discharge machining (EDM’ing) is installed on the computerized numerical controller (CNC) for EDM. The strategy can deliver adaptive switching of the generator parameters before undertaking a deep-sinking roughing process; the adaptive regulation of the reference gap voltage and jump frequency during roughing, and the auto switching of the generator parameters during the orbital finishing process. Discharge generator parameters can be obtained by finding the maximal metal removal rate (MRR) under the constraints on surface roughness (Ra) and electrode wear percentage (Wp). The reference voltage may be regulated or the jump frequency be changed according to the arc signals that occur in the discharge gap. The adaptive generator parameters can be adjusted according to the linear change in the roughness in the radial direction during orbital finishing. Block diagrams of the software are presented to search for the generator parameters and adaptively regulate the reference gap voltage and the jump frequency in a practical CNC EDM. The software installed in a CNC EDM shows the improvement of MRR through the practical experimental test.