Research On The Technology Of Compliant Digitalized Precision Polishing For Aspheric Surfaces

Aspheric parts of high precision and low roughness are widely used in the military field, the aeronautics and astronautics field and some high-tech fields. Existing aspheric precision machining technology and equipments can not effectively satisfy this kind of technical needs, thereby related research work is a hot issue in the modern precision manufacturing. Therefore, it has been the imperative development trends to exploit new aspheric parts processing methods with high precision and develop the relevant ultra-precision machining equipments, breaking through the limit of the existing technology according to the existing technical level.By developing an aspheric ultra-precision machining device based on force / position hybrid servo control and its numerical control system, this thesis aims at realizing the low cost and high efficiency of aspheric surface machining and meeting the needs of accuracy and surface roughness. The fine characters of Magnetorheological Fluids (MRF) devices are analyzed and verified in this thesis, such as the rapid response, continuous controllable damping and good stability. The decoupling problem of force and position hybrid control in polishing process can not be easily solved, so the overall plan of the hybrid control utilizing the CNC system and MRF device is put forward. A new compliant polishing tool system for aspheric surfaces with the platform of a general CNC lathe is developed, which is based on the controllable damping characteristic of the MRF. Also the adaptive tool, non-adaptive tool, bladder polishing tool are developed respectively in this thesis. According to the function of workpiece shape, the mathematical model of the tool path is established. And then using the automatic programming software Mastercam, the normative NC code is generated after the movement plan of the tool path. Then the controlling of polishing tool's position and posture is implemented by the code. Similarly, the closed-loop control system of the normal polishing force is implemented by the programs in software Labview. From the standpoint of experiments, the polishing effects of three different polishing tools, planes of workpieces and materials of workpieces are researched in this thesis. Experiments results show that, the efficient technology and equipment of compliant polishing for aspheric surfaces, integrated with CAD/CAM technology make a great practical sense on the mass production and popularization of aspheric parts.