Study On The Technology Of Long Stroke Fast Tool Servo System Driven By Piezoelectric Actuators

With the advancement of modern precision optical processing and measurement technology,microstructure arrays that can achieve special optical effects play an increasingly important role in the optical design process.The fast tool servo(FTS)technology enhanced single-point diamond turning can achieve high precision and high surface quality processing.With high response speed,high rigidity and high positioning accuracy,it is considered of one of the most promising technology for cost-effective processing of microstructure arrays.However,there are few mature FTS products at present,because the only possible way for now to realize efficient processing of microstructure arrays is using piezoelectric ceramics as an actuator,and it still has several drawbacks.On the one hand,the piezoelectric actuators usually have a stroke of only tens of microns or less,thus increasing demand for microstructures in optical design cannot be met.On the other hand,the severe nonlinearity of piezoelectric actuators still lacks suitable control methods under high frequency operating conditions.Therefore,it is of great significance to study the large-stroke fast tool servo system driven by piezoelectric actuators.By comparing the research results and products of such FTS among the world,this thesis focuses on the key technologies,and a bi-piezocer-driven FTS device with displacement amplification structure was designed.In addition,the control system was built and the open-loop feedforward control algorithm was studied.Moreover,the microlens array processing experiment was carried out to verify the processing capability of the FTS system and test the correctness of the theoretical research.The main work of this thesis includes the following aspects:Firstly,the characteristics of the corresponding vibration system under different piezoelectric ceramic arrangements were compared,and the basic composition of the FTS device was determined.The displacement amplification structure was designed by finite element simulation analysis,and the appropriate piezoelectric actuators were matched;The kinematics model was established to analyze the influence of the oscillating motion of the FTS.The corresponding solution was given and the output of the device was verified with a sinusoidal drive signal.Secondly,according to the actual functional requirements,the host computer control software was designed.Based on the microcontroller,the FTS driver was developed,and the FTS control system that can communicate with the CNC machine tool was built and tested accordingly.Considering the special periodic drive signal corresponding to the microstructure array,an open-loop feedforward control algorithm was designed to correct the nonlinearity of the piezoelectric actuator.The effect was tested through experiments.Finally,on the one hand,the theoretical calculation of microstructure processing was completed by studying the geometric principle of the vibration cutting microlens array.On the other hand,the influence of each control parameter on the performance of the FTS was clarified by the no-load experiment,and the working limit was tested.Cylindrical microlens arrays were fabricated on ultra-precision lathes,and the results confirmed the processing capabilities of the fast knife system.