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The system of robotic boring, mainly involving an industrial robot and an end-effector, is prone to chatter during the boring process of intersection hole, which not only affects the machining surface quality, but also restricts the boring efficiency. To improve the quality and the efficiency of the intersection hole, a new approach to identify and forecast the chatter of a robotic boring system based on the measured force signal of the dynamometer is presented. The proposed approach consists of three steps. First, the measured force signal is decomposed a series of intrinsic mode functions (IMF) and a residue by empirical mode decomposition (EMD). Secondly, Hilbert transform is invoked for each IMF to obtain the instantaneous frequencies and the instantaneous magnitudes, which comprise the Hilbert-Huang spectrum of the original signal. Finally, the chatter feature is extracted by analyzing the Hilbert spectrum of each IMF and a statistical method is used to detect the chatter symptom. The experiment results show that the extracting chatter feature from the signal can gain the chatter symptom at most 0.6 s ahead of the chatter outbreak, which is beneficial to guarantee for follow-up chatter suppression and improve the surface quality of workpiece. [ABSTRACT FROM AUTHOR]

Robotic boring, mainly involving an industrial robot and an end effector, is an effective way to implement the final machining of intersection holes. Although the capacity to resist vibration has been greatly improved by the pressure foot, the robotic boring system is still easily subjected to chatter during the boring process due to the series structure of the robot, which seriously affects the boring efficiency and the surface quality of the workpiece. In this article, the chatter mechanism and the stability of robotic boring with a pressure foot are analyzed. First, the cutting force model based on a multi-dimensional method and the forced model of the system with pressure foot are presented. The chatter and stability models of robotic boring with pressure foot are then established. Next, the stability lobe diagram is plotted. Finally, orthogonal experiments were performed twice using an ABB IRB6600-175/2.55 robot on high-strength steel to verify the chatter mechanism and stability. The result shows that the two most significant factors that affect the stability of the system are the feed rate and the depth of cut. This finding is beneficial for parameter selection, chatter suppression, and improving efficiency of the robotic boring. [ABSTRACT FROM AUTHOR]

In this paper, a new approach based on industrial robotic boring is proposed to solve problems associated with intersection holes during aircraft assembly. A model is established to predict the dynamic cutting force of a robotic machining system. The robot stiffness coupling, chip deformation, and plowing interference affecting the cutting force are considered using the principles of cutting mechanics and the Oxley orthogonal cutting model. By solving a numerical solution of motion differential equation, the cutting force components in the radial, tangential, and feed directions are obtained by the model. In addition, an advanced curve intersection method is developed to identify the instantaneous uncut chip area and cutting edge contact length. Verification tests were performed on an ABB-IRB6600-175/2.55 robot for titanium alloy TC4 to determine the accuracy of the predictions. The results show that the simulated and measured cutting forces were in good agreement under different cutting conditions. By analyzing simulated and experimental results, we show that the model can be applied to predict the occurrence of vibration and has application value in terms of suppressing vibration during robotic boring. [ABSTRACT FROM AUTHOR]