Experiment study on low stiffness electrode vibration in air under the impact of discharge

Abstract

For micro-scale workpiece or tool electrode, it can no longer be considered there is no macro force and deformation between them during machining because of the low stiffness structure. This nonnegligible force will cause vibration, thus reduce the machining accuracy. Therefore, the study of the magnitude and influencing factors of this impact reaction becomes the basis of relevant research. This paper presents a low-cost method to get the impact reaction in EDM machining. The vibration displacement of low stiffness brass tubular detected electrode with size of φ500μm × 80mm under single pulse discharge was measured by laser displacement sensor. In order to study the key factors for the impact reaction, six energy levels were selected, and there were six combinations of electrical parameters for each energy level. For each set of measurement condition, at least 3 experiments were tried. A collection of detected electrode vibration under different machining conditions were recorded and presented in this paper. After low-pass filtering with FFT on the platform of Matlab, three kinds of unexpected waveform were analysed, and two among them were abnormal and discarded. This paper presents the occurrence distribution of the two abnormal signals and discusses the possible relationship with electrical parameters. For valid data from normal signals, this paper gives the correlation between energy levels and vibration amplitude. And this paper tris to discuss the contribution of peak current and pulse-on time to vibration amplitude within the same energy level.