【作者】 王慧军；

【导师】 张飞虎；

【作者基本信息】 哈尔滨工业大学 ， 机械制造及其自动化， 2007， 博士

【摘要】 光学技术的飞速发展对光学系统提出了许多新要求,促使光学系统中越来越多的采用非球面镜。非球面镜能够矫正多种像差,改善仪器成像质量,简化系统结构,在军事、航空航天、电子工业等领域的应用越来越广泛。现有的光学加工方法大多受到加工条件的限制而不能应用于具有小曲率半径的凹非球曲面光学元件的加工,因此具有小曲率半径的凹非球曲面光学元件的超精密加工是目前光学加工所面临的难题。开发新型的适用于小曲率半径非球面及自由曲面光学元件的超精密加工方法对光学加工业有着重要的意义。本文提出的超声波磁流变复合抛光技术是针对小曲率半径的凹非球曲面和自由曲面光学元件进行超精密抛光加工而提出的新方法,在国内外属于首创。本文对超声波磁流变复合抛光的关键技术进行了研究,具体的研究内容包括:第一,综述了国内外非球面光学抛光技术的研究现状,尤其是磁流变抛光技术的发展,为研究超声波磁流变复合抛光技术提供借鉴。第二,对超声波磁流变复合抛光方法的原理及抛光作用机制进行了研究。在超声波磁流变复合抛光中,首先在磁场作用下形成磁流变抛光工具头,施加超声作用后,超声对磁场无影响,超声能够增强抛光的机械作用和化学作用,从而提高了抛光效率,改善了抛光去除特性。经实验验证,超声波磁流变复合抛光的表面质量略低于普通磁流变抛光,但是其材料去除率是磁流变抛光的3.1倍,超声与磁场共同作用实现了材料的抛光去除。第三,在超声波磁流变复合抛光原理及作用机制研究基础上,参考Preston方程,通过分析工件所受的超声压力、磁场压力和流体动压力,分别建立了工件静止、转动和抛光工具头倾斜时超声波磁流变复合抛光材料去除数学模型,并通过实验验证了模型的正确性,为计算机控制抛光时,面形误差的修正奠定了理论基础。第四,在超声波磁流变复合抛光理论分析基础上,自行研制了超声波磁流变复合抛光实验装置。研究了磁场的分布形式对抛光加工的影响,研制了旋转超声发生装置和磁流变液循环装及粘度控制系统,为后续的超声波磁流变复合抛光工艺实验等研究奠定了基础。第五,在自行研制的超声波磁流变复合抛光实验装置上,通过大量的工艺实验,初步研究了超声波磁流变复合抛光主要工艺参数,包括磁感应强度、超声振幅、工件与抛光工具头之间的间隙、抛光工具头转速和工件转速等对材料去除率与表面粗糙度的影响,得出了超声波磁流变复合抛光光学玻璃取得较好效果的工艺参数组合范围,为超声波磁流变复合抛光技术的推广应用奠定了基础。更多还原

【Abstract】 With the rapid development of modern optical technology, more and more aspheric lens have been applied for many new requirements of the optical systems presented. Aspheric lens can adjust many kinds of aberrations, improve the image quality of the instruments and simplify the structure of the system. Aspheric lens have been widely applied in many fields, such as military, aeronautics and aviation, electronics and so on. Most existing technologies for optical fabrication can not be applied in the machining of concave aspheres with small radius for the restriction of their machining conditions. The ultraprecision machining technology for concave aspheric elements with small radius is the great puzzle facing with optical fabrication. Therefore, it is urgent for the optical fabrication field to explore new ultraprecision machining technology suitable for aspheres with small radius and freeform surfaces.Ultrasonic-magnetorheological compound finishing (UMC finishing), which is first presented by the dissertation in both domestics and overseas, is a new kind of polishing technology for the ultraprecision machining of concave aspheres with small radius and freeform surfaces. The key technologies of UMC finishing are studied in the dissertation. The main aspects of the study are including:First, the general status of optical polishing technology for aspheres, especially magnetorheological finishing (MRF) in both domestic and overseas is reviewed. The review could be used as references for the study of UMC finishing technology.Second, the principle and the mechanism of UMC finishing method are studied. The magnetorheological polishing head is formed by the magnetic field, and the ultrasonic acts on it in UMC finishing. The magnetic field is not affected by the ultrasonic. The ultrasonic in UMC finishing can increase both the mechanical action and the chemical action in polishing, therefore, not only the polishing efficiency is increased, but also the material removal characteristic is reformed. The experimental results show that the material removal efficiency in UMC finishing is 3.1 times higher than that of in MRF, although the surface quality in UMC finishing is a little less than that of in MRF. The experiment also testifies that the material is removed by the coaction of the ultrasonic and the magnetic field in the process of UMC finishing.Third, the mathematical material removal models in UMC finishing when the workpiece is stationary, the workpiece is rotatory and the polishing head is oblique are established respectively. The mathematical models are established based on the study of the principle and the mechanism of UMC finishing. The mathematical models are got by the analysis of the ultrasonic stress, the magnetic stress and the hydrokinetic stress on the workpiece in the polishing zone according to the Preston empirical equation. The validity of the models is examined by the experimental results. The model established will be the theoeretical basis for the surface shape figuring in computer-controlled UMC finishing.Fourth, the experimental set-up of UMC finishing is developed independently based on the theoretical analysis of UMC finishing. The effect of the distribution forms of the magnetic field on the polishing results are studied in UMC finishing. The rotary ultrasonic equipment and the circulating and the viscosity-controlling system for magnetorheological fluid are developed. The experimental set-up of UMC finishing is the basis for further processing experiments.Fifth, many processing experiments are carried out on the experimental set-up of UMC finishing. The effects on both the material removal rate and the surface roughness in UMC finishing by the main processing parameters, such as the magnetic flux density, the ultrasonic vibration amplitude, the gap between the polishing head and the workpiece, the rotational speed of polishing head and the rotational speed of the workpiece are studied preliminarily. The processing parameters combination is achieved to get better polishing result in UMC finishing optical glass. The study will be the basis for the further application of UMC finishing technology.更多还原