Modeling And Experiment Of The General End Stiffness Of Automatic Horizontal Dual-machine Cooperative Drilling And Riveting System

Automatic aircraft panel drilling and riveting greatly improves the quality and efficiency of aircraft panel assembly.In the actual assembly processing,the automatic drilling and riveting system will produce elastic deformation under the cyclic application of the heavy load,resulting in a decrease in the quality of drilling and riveting.In order to solve the above problem,it is an effective method to realize the quantitative analysis of the end deformation of the automatic drilling and riveting system and then perform the crushing displacement compensation.Based on the kinematics models of multi-axis machines in horizontal double-machine combined automatic drilling and riveting system,theexperimental and analytical methods are used to obtain the stiffness matrix of each main deformation source,the general end stiffness model of the automatic drilling and riveting system are obtained by small elastic deformation theory,in the end of this paper,the accuracy of the general end stiffness model is proved by actual experiments.First,the relevant research background is introduced and the significance of this paper is shown.The development status of automatic rivet drilling technology at home and abroad is expounded,and the research status of machine tool stiffness and robot stiffness is briefly introduced.The research content of this paper is drawn up and the basic framework of this paper is given.The horizontal double-machine combined automatic drilling and riveting system is introduced,and the motion axis distribution of the multi-axis machine is given.Then,the kinematic models of the two multi-axis machines are given,and the coordinate transformation matrixes are established.The calculation method of the Jacobian matrix is introduced;the Jacobian matrixes of the multi-axis machines on both sides are given.Secondly,the stiffness identification of each deformation source of the multi-axis machines is carried out.The main deformation sources of the multi-axis machine are determined through analysis.For the flexible links and the end effector,the finite element analysis method is used to obtain the flexibility matrix in its own coordinate system.For the motion joint,the enumeration method and analysis are used.Then,two methods to obtain the maximum load attitude of the joint are given,and on this basis,the stiffness matrix in the joint space is obtained by the experimental method.Thirdly,the end stiffness model of the automatic drilling and riveting system is established.The elastic small deformation theory is briefly described,which shows that the end flexibility matrix of the multi-axis machine can be equivalent to the superposition of the flexibility matrixes of deformation sources;the point transfer method is used to establish the flexibility matrix of the flexible links in the end coordinate system;The enhanced joint stiffness matrix transforms the joint stiffness matrix in the joint space into the matrix in the end coordinate;The general end flexibility matrix of the multi-axis machines on both sides are established,and the general end stiffness model of the automatic drilling and riveting system are obtained.Finally,the general stiffness model verification test was performed.The relevant test conditions are briefly introduced.The test lattices in the common processing space are divided.Based on this,the experimental scheme is designed.By comparing the difference between the end deformation test value and the theoretical value,the accuracy of the end comprehensive stiffness model is verified.