The drilling operation occupies an important position in the aircraft assembly workload, and it accounts for a large proportion of the assembly cost. Previous reports show that drilling quality affects aircraft safety factor such as the probability of fatigue failure accidents. This paper proposes an automatic machining system for curved surface drilling. In this scheme, the self-adaption normal direction is realized by using the secondary positioning strategy (primary positioning and precise positioning). An elastic structure and the key positions smooth processing are applied to enhance the positioning guidance. The active variable stiffness mechanism satisfies the different requirements for system stiffness during the positioning stage and the drilling stage. Expansion sleeve locking and state switching of drilling assistance pneumatic cylinder lead to changes in the actuator's DOF and external forces, thereby achieving active control of the stiffness. Vibration-assisted machining technology is introduced to improve drilling quality. Compared with conventional drilling, the results show that this drilling system produces thin and slender chips, smaller burrs, and better internal surface quality.

钻井作业在飞机组装工作中占据重要位置，并且占组装成本的很大一部分。先前的报告显示，钻孔质量会影响飞机安全系数，例如疲劳失效事故的机率。本文提出了一种用于曲面钻孔的自动加工系统。在该方案中，通过使用次级定位策略（初级定位和精确定位）来实现自适应法线方向。采用弹性结构和关键位置平滑处理，以增强定位指导。主动变刚度机构满足定位阶段和钻孔阶段对系统刚度的不同要求。膨胀套筒的锁定和钻井辅助气缸的状态切换会导致执行机构的自由度和外力发生变化，从而实现对刚度的主动控制。引入了振动辅助加工技术以提高钻孔质量。与常规钻孔相比，结果表明该钻孔系统可产生细而细长的切屑，较小的毛刺和更好的内部表面质量。