Pressure-Force Optimization In The Process Of Robotic Automatic Obital Drilling

Service life of an aircraft is mainly determined by the life span of fuselage, and most of the fatigue failure occurred in the connection part of the fuselage structure. Holes quality therefore has a significant influence on the life of aircraft. In order to improve the quality of the connection holes and fill the technology gap, intensive research of robotic automatic orbital drilling technology has important significance. Against this background, a method of pressure-force optimization, which is based on the robotic automatic orbital drilling system, has been proposed to ensure the quality and accuracy of holes.The robotic automatic orbital drilling system consists of hardware and control system. The hardware devices include panel and tooling, moving platform, industrial robot, orbital drilling end effector, laser tracker, computer and so on. The communication between computer and industrial robot which is based on the SOCKET technology realizes the motion control of industrial robot. Based on the SynqNet network technology, the control of the moving platform, orbital drilling end effector and other numerical control devices is realized by motion controller’s secondary development, and the process of automatic orbital drilling is realized.The robotic automatic orbital drilling system strengths the dynamic stiffness and depresses drilling vibration by using press-foot device. The press-foot device which is installed at the end of orbital drilling end effector can offer one-side pressure-force to the panel. It is widely used in the process of automatic drilling. The relative position signal from press-foot device to spindle can be detected by using absolute grating ruler. Elastic deformation of panel which is caused by drilling can be compensated to the feed distance to ensure holes’ accuracy. A method which calculates the internal stress of the workpiece by using the Navier trigonometric series method is proposed and the range of allowable pressure-force is derived in order to ensure that there is no plastic deformation or failure in the panel.The finite element model of orbital drilling process is established by ABAQUS according to actual drilling parameters. A method of pressure-force optimization is proposed by comparing simulation results under different pressure-force. By using this method, the accuracy of holes is improved and the strength of panel is guaranteed.In the end, holes’ quality under different pressure-force is compared based on robotic automatic orbital drilling system. The experimental results show that the quality of holes which are drilled under optimized pressure-force is improved as well as exit burr and surface roughness. After pressure-force optimization, holes’ cylindricity is successfully controlled within 0.013mm, and holes’ surface roughness is controlled within Ra1.6.