Investigation on orbital EDM for double-hole thin wall of integrated flexible joint

The thin neck structure of integrated flexible joint is the key factor to realize high-precision navigation in dynamically tuned gyroscope. The components of the thin neck structure include two adjacent circular holes and a thin-walled structure between the two holes. The thin wall is vulnerable to be deformed under the external loading which is generated by the tool when using traditional machining methods such as drilling and boring. Simultaneously, pronounced fabrication cost will occur as the cutting tools are also ready to be damaged for machining small holes based on superhard materials. To resolve above problems, a machining method is proposed for the structure of double-hole thin wall in the step-by-step orbital electrical discharge machining (EDM) by using a high rotation speed electrode. The procedure for EDM of double-hole flexible thin wall is designed, and the processing parameters of each step machining are optimized though orthogonal experiment and signal-to-noise ratio analysis. The machining experiments of double-hole thin wall of 3J33B material are proceed using the optimized parameters. The results show that the hole diameter of the double-hole flexible thin wall is 2 mm, the hole depth is 8 mm, and the average thickness of the thin wall is about 46.5 μm. The thickness range between the measured point and the average is 1.55 μm. Comparing with average thickness of 46.5 μm, the error is less than 3%, and the overall thickness is uniform relatively.