Some Key Techniques Of Dual-robot Pneumatic Riveting And Applications In Fuselage Panel Assembly

At present,in the field of aircraft assembly,traditional manual riveting technology is being replaced by automatic ones.Automatic riveting technology and equipment directly affected on the assembly quality of aircraft components,which represented reliability and fatigue life of an aircraft.As a supplement of automatic squeeze riveting machine,electromagnetic rivet gun and other riveting equipment,dual-robot pneumatic riveting system,which fostered the main advantages of pneumatic rivet gun and industrial robot,can be used to finish the majority of riveting tasks in fuselage panel assembly.In this paper,an extensive investigation is carried out on the dual-robot pneumatic riveting technology and its application on fuselage panel assembly.The main contents include:In the background of flight safety and manufacturing requirement,the present state and development trend of automatic riveting technology and equipment are introduced.Based on a project of dual-robot pneumatic riveting system for fuselage panel assembly,research content and framework of this dissertation are presented.Task object and layout design of the dual-robot pneumatic riveting system is introduced.Stress wave propagation and reflection in pneumatic riveting process are also analyzed.The system is designed by considering vibration reduction for tools and isolation for robots.Automatic process flow is drawn up and the successfully implemented system is presented.For determining the normal vector of drilling/riveting point,a linear approach based on measuring the coordinates of four points in the area around the point by four non-contact displacement sensors is proposed.Accuracy estimation of the method is also presented based on the theory of differential geometry.Elastic-plastic formation of rivet shank and cold expansion of rivet hole are approximated as cylindrical upsetting and thick-wall cylinder forming processes,respectively.An approximate analytic solution associated with the amount of interference is proposed for obtaining the total riveting energy.The phenomenon of bending shank at the initial stage is attributed to an elastic-plastic buckling problem.Based on the analysis,the control method of riveting energy is presented.Nonlinear multi-body dynamic model including clearance and collision is established for investigating the dynamic performance and the systemic sensitivity.Semi-implicit Runge-Kuta algorithm is used for solving the dynamic equations and shop experiments are implemented to verify the effectiveness.In order to ensure the stability of riveting process and realize the quality monitoring and feedback over the aircraft's lifetime,possible riveting defects are analyzed for obtaining corresponding signal characteristics.Peak detection algorithm is implemented on the denoised vibration signal of bucking bar for evaluating the impact frequency,impact times and total impact energy.The effectiveness is also verified by shop experiments.Lastly,the whole work in this dissertation is summarized,and the future work is discussed.