Research On The NC System Design And The Simulation Of Aspheric Surface Fabrication Based On Tool Swing Feeding

Compared with spherical element, aspheric element has significant advantagesof reducing spherical aberration and coma, which causes aspheric components’application more widely. However, it is particularly important to do more researchon aspheric surface fabrication processing and its equipment due to the difficultiesin manufacturing and detecting of high surface quality aspheric optics and abroadembargo on aspheric surface fabrication processing and its equipment technologyagainst our country. Aspheric optics cutting machine based on tool swing feedingwhich eliminate the error of rail straightness, can reduce the difficulty of asphericoptics machining. In order to fabricate high precision aspheric optics,high-performance CNC system is needed and simulation of surface topography inaspheric optics fabrication for predicting machining accuracy and optimizing cuttingparameters is demanded.According to the method of aspheric optics fabrication based on tool swingfeeding, CNC system is designed and the simulation of surface topography inaspheric optics fabrication is performed.Firstly, related parameters for aspheric optics machining are calculated.Reappraisal of the calculation method for a best fitting spherical surface combiningasphericity with asphericity slope is investigated. Variable for aspherical generalequation is Cartesian coordinate of points. However, it is rotation angle of thebalance staff as variable when aspheric optics are fabricated based on tool swingfeeding. Thus, the relation between Cartesian coordinate and rotation angle of thebalance staff is established.Secondly, CNC system for aspheric optics fabrication is designed based onUMAC and IPC, in which IPC as a host computer completes non-real-time tasks andUMAC as a lower computer accomplishes real-time tasks. Meanwhile, man-machineinterface is designed using VC++6.0software and software modules are realized.Thirdly, dynamic model of linear motor is constructed and MATLAB/Simulinkmodel for linear motor servo system is built based on PID and Notch filters UMACprovide. The best PID parameters are obtained by debugging the Simulink model.And lastly, the surface topography in aspheric optics fabrication is simulated.The Simulink model for the surface topography in aspheric optics fabrication isestablished by evaluating cutting force and building the model of the balance staff’shydraulic servo system and micro-feeding system, and considering the influences ofspindle beating, elevation error and machine tool vibration. The machining processof a paraboloid mirror is simulated using the model as an example. The profile accuracy and the surface roughness are obtained by data processing.