Fixed-length Compensation In Micro EDM Milling With Cone Electrode

Micro electric discharge (EDM) milling is one of the major methodsof processing high hardness materials and complicated three-dimensionalmicro cavities. But due to serious electrode wear under the micro-scaleprocessing, the compensation for electrode has always been a difficultyand a hot spot in this field. The thesis put forward fixed-lengthcompensation method based on the cone electrode in micro EDM milling,which aimed to get the EDM milling process of the three-dimensionalmicro cavity with high effectiveness and high precision.This thesis designed the wire electro-discharge grinding mechanismbased on image detection. Processed the detected electrode images withMATLAB, and analyzed the machining quality of micro electrodesautomatically.The fixed-length compensation model was established, and thecorresponding experiment researched on the impact of electrode rotationon the shape of micro-electrode and the stability of cone electrode’s shape.The research indicated that through a certain machining length under thefixed-length compensation, a stable cone electrode could be formed.Based on the cone electrode, the fixed-length compensation modelwas corrected. And the experiment verified the correctness of this modeland studied the influence of compensation length on base angle andmachining depth of cone electrode. Typical samples of complicated microgrooves are machined. Besides, it also presented an accurate measuremethod of relative volume wear ratio based on image processing. On the base of the experimental results, a fitting curve ofcompensation length and actual machining depth was obtained. To therequired machining surface with triangle section, the compensation methodwhich aims to processing wavy surface was proposed. The processingmethod of two steps in one layer and change of direction between adjacentlayer was put forward. Then the overall machining process of processingthree-dimensional micro cavities with fixed-length compensation methodwas established. A typical flat bottom micro cavity with high precision wasmachined to verify the validity of that technological method.