Automated electrochemical milling of complex surfaces with integrated path planning and gap control strategy

Abstract

Leveraging their multi-degree-of-freedom motion capabilities and adaptive machining advantages, industrial robots present an innovative approach to the efficient manufacturing of complex curved components. Because electrochemical milling is so good at precisely shaping materials that are hard to work with, robotic electrochemical milling technology has become a research hub in the field of advanced manufacturing. However, the structural flexibility and dynamic errors of industrial robots can cause the inter-electrode gap (ieg) to change in a way that isn't linear during electrochemical milling. This has a big impact on the accuracy of the machining and the quality of the surface. In this paper, we first propose a complex trajectory planning method with variable posture for tool-electrodes, and then simultaneously integrate the inter-electrode gap (ieg) servo control method with dynamic compensation in the seventh axis. By constructing a current signal-gap error mapping model, we analyze the characteristics of processing current fluctuation in real time and generate axial compensation commands and drive the end effector to realize the dynamic correction of the gap error. Finally, the electrochemical milling of the surface was verified by a self-built experimental platform. The experimental outcomes indicate that the milling method with variable posture can significantly improve the matching degree between the milling slot width and the inner diameter of the tool-electrode, and at the same time, the closed-loop feedback control of the machining gap is realized through the machining gap adaptive adjustment strategy, which maintains the machining gap in a stable range, and at the same time, reduces the surface roughness of the workpiece to 0.28 μm, which significantly improves the consistency of the forming of the complex curved surface and the surface integrity of the complex curved surface structure.