Research On The Posture Change And Chatter Analysis Of Articulated Robot In Milling

The popularization of industrial robots is an important link in realizing industrial modernization and intelligence.Improving control accuracy,system stiffness and processing capability plays an important role in high-precision manufacturing for robots.This paper mainly focuses on the stiffness model,milling analysis,kinematic and stiffness performance evaluation index,flutter analysis and machining method optimization of the articulated tandem robot.First,for the KUKA articulated robot model KR60-3,the MD-H method is used for structural modeling,so as to obtain the kinematics and dynamic models of the robot.According to the stiffness of each joint,the stiffness matrix is obtained,and the static stiffness model of the robot（stiffness ellipsoid model）is established.Through the milling processing parameters,the three-direction average milling force is obtained,and the influence of different milling parameters on the surface processing quality is analyzed.The above provides a theoretical basis for kinematic and stiffness performance evaluation indexes,flutter analysis and machining method optimization.Secondly,in order to improve the machining performance of the robot,and for the possible singular pose and low stiffness problems of the robot,the robot kinematic performance index and stiffness performance index are established in the joint space and Cartesian space respectively,so as to obtain a relatively ideal machining.Spatial extent,and try to avoid singular poses and states of low stiffness during processing.In terms of improving the stiffness performance of the robot,a stiffness optimization strategy for the arm span and redundant angular attitude of the robot is obtained.Thirdly,based on Simulink,the kinematic model of two-degree-of-freedom regenerative chatter was compiled,and the influence of milling force on the real-time motion trajectory of the machining end of the low-stiffness robot was obtained.The limit depth of cut curve of robot milling is analyzed,and the limit depth of cut under different spindle speeds is obtained.The amplitude of the no-load vibration of the robot is analyzed,and it is obtained that with the increase of the robot’s arm span,the average amplitude of the vibration increases,and the average amplitude of the vibration shows a certain regularity with the change of the redundant angular attitude of the robot.Finally,for the chatter and stiffness of robot machining,a measure is proposed to change the milling direction to suppress chatter.When the angle between the direction of milling force and the projection vector of the maximum stiffness vector of the robot end stiffness ellipsoid on the machining platform is smaller,the chatter will be reduced.The smaller the average amplitude,the better the quality of the milled surface.The above research has a certain guiding role in enhancing the milling processing ability of the robot,suppressing chatter vibration,and improving the surface processing quality.