Research On Design Scheme Of Eccentric Control System For Helical Milling End Effector

Helical milling technology,as a new type of hole making process that combines traditional drilling and milling,shows the advantages of high quality,high efficiency and low cost when machining difficult-to-machine materials.Zhejiang University aircraft digital assembly technology team developed a new helical milling equipment combined with drilling and reaming.The eccentricity adjustment system uses semi-closed-loop structure,the transmission path from the motor output to the spindle eccentric movement is complex,the accuracy is difficult to ensure.In this thesis,based on the characteristics of the transmission chain length and error of eccentricity adjustment mechanism,a full closed-loop control scheme of eccentric adjustment system based on real-time measurement data of eccentricity is established,and the synchronous and differential control methods of eccentric shaft and revolution shaft are further proposed,the foundation of technology for the real-time compensation of the aperture in the process of helical milling is established.The main contents of this thesis are as follows:The first chapter is the introduction,which mainly introduces the background and significance of the thesis research,and summarizes the development overview of helical milling technology at home and abroad,the research status of multi-axis synchronous control technology.The second chapter describes the basic mechanical structure and hardware and software of end effector of helical milling hole,analyzes its mechanical structure and control method of eccentricity adjustment system in detail,and analyzes the problems of accuracy,efficiency and timing in the adjustment of eccentricity.In the third chapter,the system of eccentricity real-time feedback control based on the length meter and the motor rotation angle measurement data is constructed based on the position relationship between the eccentric skateboard and the length meter in the mechanism of eccentricity adjustment.The simulation results verify the system's positioning accuracy and position retention.The fourth chapter establishes the linear relationship between the eccentric shaft,the difference of the rotation angle of the revolving shaft and the eccentricity,and designs the two-shaft synchronous and differential control strategy.The simulation research of two-axis synchronous and differential control system under the environment of MATLAB/Simulink shows that the steady-state error of eccentricity is within 0.002mm when the two axes move synchronously;when in the differential motion,eccentricity changes gradually,the steady-state error is 0.006mm.The fifth chapter build helical milling end effector experimental platform,identify the eccentric sliding plate surface conditions.Real-time reading of length meter and revolving shaft motor angle are used to carry out real-time feedback test of eccentricity.The experimental results show that the real-time feedback error of eccentricity is within 0.01mm at revolution of 10r/min.The sixth chapter summarizes the research work of the dissertation,and looks forward to the contents that can be further studied.