Design and Performance Evaluation of Hydraulic Fixing System for Aircraft Skin Milling Flexible Jigs

Abstract

Manufacturing aircraft skin components requires high precision and structural integrity because of the process complexity. Traditional bolt friction brake fixation methods have resulted in inadequate stiffness, leading to suboptimal machining accuracy and surface finish. To address these issues, this study proposes a hydraulic fixation system to improve the stiffness of flexible jigs in CNC milling of aluminum plates. The hydraulic system's performance was assessed via stiffness tests and repeated precision measurements, demonstrating significant improvements over conventional methods. The horizontal stiffness increased to 11.6 N/μm, marking an 830% improvement over that of bolt friction brakes, and the vertical stiffness reached 190 N/μm. Furthermore, the hydraulic system achieved an axial precision of 1 μm and radial precision of 5 μm under a working pressure of 30 MPa. These results underscore the effectiveness of hydraulic fixation systems for enhancing machining quality and fixture reliability in aerospace manufacturing.