Research On Magnetorheologicalfluid Circulating System And Design Of Megnetic Circuit Of Ultrasonic Assisted Magnetorheological Finishing

With the rapid development of modern optics and its corresponding science and techniques, the application of optical facilities become more and more abroad, especially the aspheric optical facilities, so it is exigent to develop a new ultra-precision process method which is suitable for hard-brittle material in aspheric process. Magnetorheological Dressing (MRF) is a new developed ultra-precision process abroad for optical aspheric surface which can fine finish optical facilities efficiently, it integrate electromagnetic, hydrodynamic and chemistry in optical facilities process. Ultrasonic assisted MRF is a flexible polishing process in which the polishing spot can be controlled, and there is no subsurface destroyed layer on polished surface, so it is satisfy the demands of optical facilities which are used in aviation, aerospace and national defense. The application prospects of MRF are wider.The circulating system for MR fluid is the very important component in the Ultrasonic assisted MRF equipment, so it has great significance to develop a steady circulating system. Several problems are resolved in this paper:Firstly, the control system for viscosity of the MR fluid is developed. The variation of current in the armature of mixed electromotor is monitored real time to calculate the variation of the viscosity of the MR fluid. The experiment shows that this system can steadily hold the viscosity characteristic and it is beneficial in MRF process.Secondly, the space distribution for magnetic field of electromagnet is analyzed theoretically, the design of magnetic circuit for MR dressing is optimized with the software of the finite element analysis and the suitable magnetic circuit of the magnetic plug for this experiment equipment is developed.Lastly, this system is applied in the ultrasonic assisted MRF machine tool, and several experiment are finished. The experiment result shows that this system can obtain steady MR fluid circulating, and the dressed piece has a good dressing quality.