Research On Control System Design And Essential Technology Of Ultrasonic Polishing Machine For Optical Curved Face

Ultrasonic polishing of optical surface is a new polishing technology in recent years.This technology uses high-frequency ultrasonic vibration to cause the abrasive particles in the nano-suspension to collide with the surface of the workpiece to achieve the effect of material removal.It is an ideal process for polishing optical curved components.Therefore,research and development of the optical curved ultrasonic polishing machine tool has become an important issue.According to the requirements of five-axis motion and variable pressure control of the ultrasonic polishing machine tool,the main work of this thesis is as follows:(1)The control characteristics and requirements of the optical curved ultrasonic polishing machine tool was analyzed and the overall design and planning of its control system were carried out.Based on the PC+UMAC multi-axis motion controller,the upper and lower open control system of the machine tool was proposed.Then,the main hardware system and the upper software system were designed and planned.(2)The process and method of interpretation and development of the NC program of optical curved ultrasonic polishing machine in open CNC system were explored.The G code program with pressure control command was constructed,so that the pressure control requirements of the polishing can be sent with the five-axis motion NC program and recognized by the CNC system.This method can be used for the interpretation and development of CNC programs for the polishing machine.(3)A pneumatic polishing pressure loading method based on high-speed on-off valve was proposed by analyzing the polishing pressure model of optical curved surface.Then,the design,construction and mathematical modeling of the pneumatic pressure loading system were carried out.The control model of the pneumatic pressure loading system was obtained by offline identification.(4)The combination of numerical control system and pneumatic pressure loading system was realized.The communication,data transmission and electrical wiring between the numerical control system and the pressure loading system were carried out.Then,the PID control program was designed and programmed for system adjustment.The system was simulated and analyzed in MATLAB which verified that the PID controller can better adjust the dynamic characteristics of the system.(5)The pressure loading control experiments under different motion trajectories were carried out.The collected data proved that the system can effectively control the polishing pressure,which verified the feasibility of the proposed trajectory pressure loading control scheme.Through the research of this thesis,a method of real-time control of polishing pressure using NC program instructions in open CNC system was explored,which provided reference and guidance for further research.