Study On Key Technology Of Inclined Magnetorheological Polishing For Micro Aspherical Surface

In recent years, with the wide applications of high-performance asphericoptical parts in the field of aerospace, optical telecommunication, weaponry andso on, the demanding for micro aspheric optical components have increasedacutely. Also, market put forward higher and higher requirements for theirmanufacturing accuracy. Ultra precision turning and grinding are generally used toprocess the small aspheric surface, but there are some machining marks andsurface defects left by turning and grinding. Therefore, in order to improve thesurface quality of the parts, the subsequent ultra precision polishing is likely to benot only required, but essential. However, the traditional polishing methods arehard to process micro aspheric parts due to their small machining space and highsurface quality requirements. Aimed at the problems above, magneticrheologicalpolishing (MRP) was introduced to process the small aspheric parts, and aninclined axis magneticrheological polishing method is proposed, which combinedwith the traditional ultra-precision turning and grinding to realize high efficiencyand precision.This thesis’s outline is as follows:1. Characteristics and application of small aspheric surface are analyzed, thepresent machining technologies of small aspheric surface including ultra precisionturning, grinding, polishing technology are summarized, and aimed at problemsexist in present ultra precision polishing of small aspheric surface, thecorresponding solution measures are proposed.2． The micro aspheric surface inclined axis magneticrheological polishing isdeveloped, in which polishing principle is analyzed, and its polishing pathcontrolling mathematical model is established. The geometric interferenceproblem including curvature interference and cutter bar interference are discussed,the corresponding interference mathematic model is established, the removalmechanism in the processing of inclined magneticrheological polishing is studied,and affecting parameters such as fluid dynamic pressure, magnetization pressureare analyzed, at last, its removal mathematical model is established, whichprovides the theoretical foundation for practical application of inclined axismagneticrheological polishing. 3. The micro aspheric surface inclined axis magneticrheological polishingdevice, especially suitable polishing head are developed, the internal excitationmagnetic field is analyzed by the finite element simulation method, the magnitudeof the magnetic field in the processing region and machining removal rate aretested, which provide feasible processing device for the realization of microaspheric inclined axis magneticrheological polishing.4. The basic composition and classification of magnetic polishing fluid arediscussed, this paper discusses three kinds of magnetic polishing fluid such asmagnetic fluid (MF), magnetorheological fluid (MRF), magnetic compound fluid(MCF) and their basic properties of stable performance, chain performance,viscosity performance and polishing performance. The high performancecompound magnetic fluid is developed, the polishing performance of magneticliquid based on nano diamond and micron ceria composite abrasive particle isanalyzed by experiments, which provide good performance of polishing fluid forthe realization of micro aspherical inclined axis magneticrheological polishing.5. The ultra precision turning, grinding and inclined axis magneticrheologicalpolishing are organic combined. The machining equipment and process of ultraprecision turning-inclined axis magneticrheological polishing and ultra-precisiongrinding-inclined axis magneticrheological polishing are developed for the smalltungsten carbide and stainless steel aspheric surface.