Research On Thin-Walled Parts Dual-Robot Mirror Milling Speed Coordination And Vibration Suppression

Based on the current demand of aircraft manufacturing for large thin-walled parts,this paper made a research on mirror milling.A mirror milling platform is built with Tri Mule,a 5-DOF hybrid robot.The end of the two robots is equipped with a milling cutter and a support head respectively,making mirror image collaborative movement relative to the thin-walled part to suppress the vibration phenomenon in milling process.The structure and physical parameters of the support head,as well as the accuracy of the robot speed control in the mirror milling system directly affect the quality of the thin-walled parts in the milling process.Based on the above research objectives,the following creative achievements have been achieved:In the aspect of robot speed planning,based on the structure of Tri Mule hybrid robot,the Jacobian matrix of the parallel part and the serial part of robot are derived respectively,and the simulation model is built in Simulink.The speed of each joint of the machining robot and the supporting robot under different feed rates is simulated on a specific trajectory,and the accuracy of the theory is verified.By comparing the speed changes of the joints under different feed rates,the feed rate of the end actuator is modified.In the aspect of forced vibration of plate thin-walled parts and cylinder thinwalled parts,firstly,the structure of the pneumatic multi-point following support head used in this study is introduced,and the supporting force equation is derived.Then,the dynamic model of milling cutter,thin-walled part and support head is established based on the plate theory and shallow shell theory,and the simulation is carried out in Matlab.The vibration suppression effect of two kinds of thin-walled parts under different support points,support forces,damping conditions and eccentricity direction caused by speed error is compared,and the vibration suppression ability of pneumatic multi-point following support head is verified in the two kinds of thin-walled parts.In order to verify the above research contents,the experiments of hammering and triangular grids machining are carried out on the dual-robot mirror milling platform.The frequency response function and dynamic stiffness of thin-walled parts under different support conditions,the following error of robot joint velocity,the processing amplitude of thin-walled parts under different support conditions are tested through the analysis of the experimental data,the accuracy of the robot speed planning in the process of experimental machining is verified,and the effect of the pneumatic multipoint following support head on the vibration suppression of thin-walled parts and the improvement of machining quality is verified.