| Blisk is a new structure form in aircraft engine.The hub and blade are designedto be an integral structure, which simplifies the structure, reduces the weight,enhances the reliability and improves the aerodynamic efficiency. At the same time,the blisk blade surface is designed by the theory of aerodynamic theory, the thrust toweight ratio of the engine is greatly improved which is the key in designing aircraftengine. But it is critical for the form, accuracy and surface roughness. Nowadays, themanual polishing of the blisk is widely used in China,which has the disadvantage oflow processing efficiency, hard work intensity and hard to ensure the accuracy of thesurface precision of the blade.The manufacturing technology of blisk is difficult, generally involves five-axisCNC machine for processing. As the blade is easy-deformed under pressure, theefficiency of fabricating a blisk is time consuming and the accuracy of five-axiscontrol is difficult to ensure. In this paper, in order to improve blisk processing quality,the position control of the feed axis and the grinding and polishing force control areinvestigated in depth.The hardware of the control system for blisk polishing and grinding machine toolis analyzed. Based on the force/position decoupled control strategy，the hardware ofthe position control system and the grinding and polishing force control system isselected and analyzed. The position control is controlled by CNC system and ACservo system, the grinding and polishing force is provided by a pneumatic force servo.The flow of the grinding and polishing process is planned in detail, the software of thegrinding and polishing force control is developed.The position control system is modeled and simulated. Especially, permanentmagnet synchronous motor and machine driven system have been modeled separately.The current loop, velocity loop and position loop of the AC servo system are designedin detail. Both the simulation model of single-axis position control system and double-axis cooperation control system are established. According to the simulationresults, the step response time of the system is not only short and non-overshoot, butalso with good performance of trajectory tracking and anti-jamming capability. Themechanical system and control system were united by ADAMS and MATLAB, whichrealizes the mechatronics system united simulation, offering a foundation fordesigning and debugging the physical prototype. The method in this paper provides anew way for analysis of AC servo position control system performance.A linearized mathematical model of the pneumatic system for the grinding andpolishing force control has been built and the system stability is analyzed. Theinfluence of cylinder friction is studied and a simplified mathematical model offriction is built. A disturbance observer is designed which effectively restrains theadverse effects of friction on the force control system. The PID control theory andfuzzy control theory are introduced and designed. The simulation analysis which isbased on DOB is carried out according to different input signal. Although thestructure of PID control is simple, it is lack of self-adjustment capability. Fuzzy PIDcontrol has good robustness and adaptability, which is an effective solution to theissues of pneumatic control system, such as strongly nonlinear, time-varying, etc. Aprototype of the grinding and polishing force control system is built byReal-TimeWorkshop in MATLAB. Force control experiment of PID control and fuzzyPID control is conducted on the grinding and polishing machine. The experimentalresults show that the performance of fuzzy PID control is better than that of PIDcontrol. |
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