Clamping Force Optimization For Robotic Drilling Of Stacked Structure

During the process of automatic drilling, burr can form and grow due to the gap in the stacked structure, which deteriorates the quality of drilling and assembly. At present, one-side clamping is widely used to eliminate the gap between interlayer in automatic drilling in aircraft manufacturing. However, if the clamping force is too small, it is difficult to eliminate the interlayer gap. On the contrary, larger deformation of the workpiece will be induced. Both will affect the final fastening hole quality. Therefore it is necessary to predict and optimize the clamping force used in the robotic drilling. Meanwhile, considering the effects of spindle feed and spindle rotating speed on the interlayer gap, the clamping force, spindle feed and spindle rotating speed should be optimized together in drilling.Clamping force and other process parameters are optimized based on the robotic automatic drilling system. The effect of the clamping force on the interlayer gap induced by the drill trust by using Finite Element Method. Considering the integrated influence of initial interlayer gap and drill trust, the clamping force are predicted based on the elastic mechanics. The clamping force, the spindle feed and the spindle rotating speed are optimized together by the Taguchi method.In chapter 1, the development of automatic drilling technology in China and abroad is introduced. Then research on burr control is summarized. Finally, the background and significance of the thesis are presented.In chapter 2, we describe the structure of robotic automatic drilling system and components of drilling end-effector, analyze the function of the pressure foot, and introduces the formation of burr in the interlayer gap in robotic drilling and its contributors.In chapter 3, a finite element model of the drilling of laminated aluminum is established. The formation of interlayer gap, and the impact of the clamping force on the gap between the layers are analyzed.In chapter 4, we analyze the formation of gap in a aircraft panel, and present a prediction method of clamping force based on the principle of elasticity and influence coefficient method considering the initial gap and the gap induced by the drill trust.In chapter 5, The Taguchi method is used to optimize the process parameters in robotic drilling to minimize the interlayer burr, which is verified by experiments.In chapter 6, The thesis is summarized, and the future research issues are given.