Research On Structure Analysis And Control Method Of Fast Tool Servo System Driven By Piezoelectric Ceramics

Elements with microstructured array surfaces play important functions in the fields of optics,mechanics,and communications.The processing of the surface of the precision microstructure array is relatively difficult,and traditional processing methods cannot simultaneously solve the problems of processing accuracy,efficiency,and cost.The machining method based on the fast tool servo can realize the high-efficiency and high-precision machining of the microstructure array surface.Therefore,this paper studies the mechanical structure and control method of piezoelectric ceramic fast tool servo,aiming to improve the actual machining accuracy.Firstly,it introduces the machining process of the fast tool servo,analyzes the cutting force generated,and introduces the mechanical structure of the piezoelectric ceramic type fast knife servo used in this topic.Analyze the three main factors affecting machining accuracy and efficiency in the mechanical structure,including stiffness,displacement sensor installation accuracy and resonance frequency.The stiffness of the mechanical structure is analyzed using finite element analysis and actual measurement,and combined with the previous cutting force to analyze the effect of stiffness on machining accuracy.In order to avoid the measurement error caused by the installation error of the displacement sensor,the displacement sensor is calibrated to improve the measurement accuracy.Finally,the resonant frequency of the mechanical structure is determined by theoretical calculation.The machining accuracy of the fast tool servo is mainly determined by the control system.The composition of the fast tool servo control system is introduced,and the calculation method of the maximum operating frequency of the fast tool servo control system is given.Then the input-output hysteresis nonlinear phenomenon of the fast tool servo in the open loop state is analyzed.In view of the uncertainty and error of the output displacement caused by the hysteresis nonlinear phenomenon,the traditional PID control is performed first,and the control effect is analyzed.Aiming at the limitations of Maxwell’s model,an improved Maxwell model and parameter calculation method are proposed;based on the improved Maxwell model,an inverse model is established for feedforward control and combined with feedback control for control to analyze the control effect.The test results show that the two control methods have different characteristics and are suitable for different processing requirements..Finally,the actual processing effect of the fast tool is tested,and the plane slope microstructure is selected as the processing microstructure.Give the shape and size of the plane slope microstructure to be processed.The shape and size of the tool are analyzed for the design of the plane slope microstructure.Then introduce the machine tools that need to be connected,give the processing steps,including the installation of the fast tool servo mechanical device,the connection of the machine tool and the fast tool servo control system and tool setting,and choose the appropriate control method.Finally,the processing results are analyzed based on the angle and bottom width of the two slopes of the plane slope microstructure,and the processing requirements are basically met without considering the phase.