Key Technologies Of Tool Post Applied To Large Ellipticity Surface High-speed Turning

Piston has a key influence on engine performance.It becomes deformed due to lateral pressure,high temperature and high load working in heavy-duty engine.So piston surface is designed as a shape of large ellipticity and combined line,high frequency and precision requirements increase the difficulty of piston surface machining,which also improve control system requirements for high real-time and quick response capability.It is widely to use the all-digital CNC based on PC,and the control of high-frequency linear servo system has been a key technology in CNC control system.Therefore,in this paper,machining trajectory and control technologies are optimized,main research contents are as follows:(1)Piston profile characteristics and mathematical model were analyzed.For the piston which cylindrical cross section is combined line,existing design technique had defects.So three kinds of reconstruction and implementation ways were put forward,and which were verified in theory by MATLAB.(2)For improving system rapidly response capability and avoiding influence on machining precision by system delayed feedback,based on feedforward theory,acceleration feedforward was added into current loop,and it was verified in Simulink.(3)A fuzzy self-adapted PID controller was designed,which was combination of PID control and intelligent control;It achieved position and velocity loop parameter self-tuning.And it was compared with traditional PID control.(4)And the hardware configuration and control strategy of high-frequency linear servo system applied for large-ellipticity surface turning were introduced.Compared with other CNC research technology at home and abroad,the research and development advantages of using EtherCAT technology in TwinCAT were pointed out.By experiment without load,the assumption was verified that acceleration feedforward in current loop is beneficial to improve system rapidly response capability;by experiment with load,reconstruction and implementation ways mentioned above were possible to decrease impact and improve accuracy.