大口径SiC反射镜磨削用金属基圆弧砂轮的在线修整技术

发布时间：2018-06-14 07:07

本文选题：大口径SiC反射镜 + 金属基圆弧砂轮　；参考：《哈尔滨工业大学》2016年硕士论文

【摘要】：目前随着空间技术的迅速发展,对空间反射镜有大口径、高精度的需求,如导弹预警、天文或空间望远镜、深空探测器、卫星等装置的反射镜需要更高的成像质量,使得大口径、高精度的反射镜的制造技术格外重要。SiC作为新一代反射镜材料,具有优越的物理与机械性能,但是SiC具有较高的硬脆特性,难于加工,采用圆弧砂轮的轨迹包络磨削加工对SiC反射镜的加工具有优势。目前采用金属基金刚石圆弧砂轮的精密磨削加工是大口径SiC反射镜的一种重要加工方式。但是由于SiC较高的硬脆特性以及加工大口径尺寸的需求,金刚石圆弧砂轮在磨削过程中的损耗量较大。同时圆弧砂轮截面的圆弧廓形易磨损破坏,严重影响SiC反射镜面形精度。所以,圆弧砂轮的在线修整技术十分关键。因此,本文针对大口径SiC反射镜磨削用金属基金刚石圆弧砂轮的在线修整技术进行了研究。提出基于双轴回转展成运动的圆弧包络任意球体的电火花修整砂轮的方法。并研制了大口径SiC反射镜磨削用金属基圆弧砂轮的在线修整装置,实现了金属基圆弧砂轮的电火花在线修整。解决了圆弧砂轮在线修整的难题,提高了大口径SiC反射镜的加工质量和效率,为空间光学先进制造技术提供支持。首先,本文分析了圆弧砂轮的优点以及采用圆弧砂轮的轨迹包络磨削法的原理,得出其具有砂轮利用率高、寿命长的优点。提出基于双轴回转展成运动的圆弧包络任意球体的电火花修整砂轮的方法,通过建立三维空间数学模型,分析、推导得到砂轮修整的原理公式。分析了圆弧砂轮的圆弧廓形的结构形式、修整电极旋转轴线和砂轮旋转轴线夹角的规律,确定了砂轮的结构形式和圆弧砂轮的修整角度。其次,对圆弧砂轮的圆弧半径的选择进行了分析和确定。然后分别计算、设计了锥形砂轮、杯形修整电极、电火花修整装置和在线电解修锐装置,研制出大口径SiC反射镜磨削用金属基金刚石圆弧砂轮的在线修整装置。研究了在线修整装置应用过程中,砂轮的蚀除规律和圆弧砂轮的圆弧半径变化规律;并对磨削过程中圆弧砂轮需要修整的情况进行了预测计算。最后,对电火花修整圆弧砂轮的表面形貌进行实验研究,获得了电火花放电参数对砂轮表面形貌的影响规律。通过研制的大口径SiC反射镜磨削用金属基圆弧砂轮在线修整装置进行加工实验,对圆弧砂轮的修整效果进行了验证,结果表明,采用基于双轴回转展成运动的圆弧包络球体的电火花修整方法可较好实现金属基圆弧砂轮的在线修整。
[Abstract]:At present, with the rapid development of space technology, there is a need for large aperture and high precision space mirrors, such as missile warning, astronomical or space telescopes, deep space detectors, satellites and other devices that require higher imaging quality. It makes the manufacture technology of large aperture and high precision mirror especially important. Sic, as a new generation mirror material, has superior physical and mechanical properties, but sic has higher hardness and brittleness, so it is difficult to process. The arc grinding wheel with track envelope grinding has advantages in sic mirror machining. At present, precision grinding of metal based diamond circular arc grinding wheel is an important machining method for large diameter sic mirror. However, due to the high hardness and brittleness of sic and the requirement of machining large caliber size, the loss of diamond arc grinding wheel in grinding process is larger. At the same time, the arc profile of the arc grinding wheel section is easy to wear and destroy, which seriously affects the precision of sic reflective mirror. Therefore, the online dressing technology of arc grinding wheel is very important. Therefore, the on-line dressing technology of metal-based diamond arc grinding wheel for large diameter sic mirror grinding is studied in this paper. This paper presents a method of dressing grinding wheel with electric spark of free sphere with arc envelope based on the motion of rotation and expansion of two axes. The on-line dressing device of metal based circular arc grinding wheel for large diameter sic mirror grinding is developed, and the EDM on-line dressing of metal base circular arc grinding wheel is realized. The problem of on-line dressing of circular arc grinding wheel is solved, the machining quality and efficiency of large-aperture sic mirror are improved, and the advanced manufacturing technology of space optics is supported. Firstly, the advantages of arc grinding wheel and the principle of track envelope grinding of circular arc wheel are analyzed in this paper, and the advantages of high utilization ratio and long life of grinding wheel are obtained. This paper presents a method of dressing grinding wheel with electric spark of circular arc envelope free ball based on the motion of double axis rotation. The principle formula of grinding wheel dressing is derived by establishing and analyzing the mathematical model of three dimensional space. The structure form of arc profile of arc grinding wheel and the law of angle between dressing electrode rotation axis line and grinding wheel rotation axis line are analyzed. The structure form of grinding wheel and the dressing angle of circular arc grinding wheel are determined. Secondly, the selection of arc radius of arc grinding wheel is analyzed and determined. Then, the conical grinding wheel, cup dressing electrode, electric spark dressing device and on-line electrolytic dressing device are designed, and the on-line dressing device for metal based diamond circular arc grinding wheel for large diameter sic mirror grinding is developed. The erosion law of grinding wheel and the variation law of arc radius of arc grinding wheel are studied in the course of application of on-line dressing device, and the prediction calculation is carried out on the condition that the grinding wheel needs dressing in the grinding process. Finally, the effect of discharge parameters on the surface morphology of circular arc grinding wheel was studied experimentally. The machining experiment was carried out by the on-line dressing device of metal base circular arc grinding wheel for large diameter sic mirror grinding, and the effect of circular arc grinding wheel was verified. The results show that, The on-line dressing of metal based circular arc grinding wheel can be better achieved by adopting the EDM dressing method of circular arc envelope sphere based on biaxial rotation motion.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：V46

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