| In recent years,free-form surface elements and micro structure elements with complex surfaces have been widely used in civil,military and space exploration fields,greatly improving equipment performance.The fast tool servo technology driven by piezoelectric actuators has high frequency response and motion accuracy,which can be an effective means to achieve the machining of such complex surface components,and it can achieve the efficient and high surface quality machining of such components.In view of the limitation of the small working stroke of the fast tool servo system driven by piezoelectric actuators,this paper designs a long stroke fast tool servo system driven by piezoelectric actuators,as well as carries out the research on theoretical model analysis,parameters design,finite element simulation,experimental verification and control algorithm.The specific research results are as follows:(1)In view of the small stroke of the current fast tool servo system,through the analysis of the flexible amplification mechanism and the motion guidance mechanism,the symmetrical two-stage lever amplification mechanism and the guiding mechanism are designed to realize the displacement amplification and the motion transmission of the system,which are compact in structure and can restrain the parasitic displacement.In addition,in order to meet the performance requirements of different machining conditions for the fast tool servo system,the stiffness adjustable mechanism is designed,which can make the system have two switchable working states of long stroke and high frequency response to coordinate the travel and frequency response performance of the system(2)The static and dynamic theoretical modeling of the mechanical structure is completed.Considering the deformation of the flexure hinges,the static analysis of the two-stage lever amplifier mechanism is carried out based on the pseudo rigid body model.Considering the coupling effect of the guiding mechanism on the motion of the amplifying mechanism,the static model of the whole mechanism is built.Finally,based on the Lagrange equation,the dynamic models of the mechanism in the long stroke state and the high frequency response state are established respectively,which provide the theoretical basis for the mechanism optimization and motion control of the system.(3)The main constraints in the mechanism design of the fast tool servo system are analyzed theoretically,which gives the theoretical guidance for the mechanism parameters design and optimization.In addition,the static analysis and modal analysis of the long stroke state and the high frequency response state of the fast tool servo mechanism are carried out by using the finite element method,as well as the performance evaluation of the system mechanism such as stroke output and parasitic error suppression is completed according to the simulation results,which verifies the accuracy of the mechanism design performance and the established theoretical model.(4)At last,the experimental test and control algorithm of the fast tool servo system are studied.The test of the system prototype effectively verifies the design performance of the long stroke output.On the other hand,in view of the need to accurately track the periodic signal and consider the time-delay characteristics of the system,a controller based on the repetitive control algorithm is designed and solved to realize the tracking of the periodic signal in the process of the complex profile machining. |
PDF Full Text Request