Research On The Stability Of Robot Boring System Of The Aircraft Landing Gear’s Junction Hole

The industrial robot with a special designed end-effector is a new way to perform the finish boring procedure of the aircraft landing gear’s junction hole in the aircraft assembly field. However, due to the low stiffness of the six-joint industrial robot, chatter limits the choosing of machining parameters including spindle speed and cutting depth, which reduces the efficiency and quality of boring process. By applying a pneumatic pressure foot system between the workpiece and the end-eddector of the robot, chatter of the system can be depressed. Based on the above-mentioned background, this paper researches on the stability of the robot boring system and especially focuses on how pressure foot system influences the dynamics of the whole system and the mechanism of the pressure foot system can enhance the robotic boring stability. Theoretical analysis and experimental research has been carried out. The main contents include the following aspects: The first chapter summarizes the research on the robot machining system and chatter worldwide.In the second chapter, a robot boring system is built according to the machining requirements of the main intersection hole. After describing the overall structure and its control system, the sub-system’s mechanical structure and its function characteristic is illustrated in detail. At last, the robotic boring process is given based on the characteristic of the workpiece.In the third chapter, a dynamic model of the robot boring system is deprived by the rational simplification on the whole system. The whole dynamic model includes the robot model and pneumatic pressure foot model. At last, the mechanism of pressure foot that changes the dynamics of the whole system is studied.In the forth chapter, an analytical model for stability limit prediction considering dynamical characteristics with and without pressure foot structure of the robot boring system is proposed. First of all the relationship between the dynamic chip thickness and the cutting forces are modeled. Then, the dynamic force equation is formulated which is shown to reduce to an eigenvalue problem. According to the regenerative chatter mechanism, the analytical stability of the system is studied its stable parameter region is achieved through stability lobes.In the fifth chapter, the experimental robot boring system is built and robotic boring experiments are conducted to verify the rationality of the theoretical modeling under different pressure foot parameter condition. The analytical model and experiments show that the stability of the robot boring process can be enhanced by applying pressure foot system and choosing a rational pressure value.The last chapter summarizes the research work and prospect the further studies.