| 题名 | 环抛过程中热积聚效应及其对面形控制的影响 |
| 作者 | 洪美娟 |
| 学位类别 | 硕士 |
| 答辩日期 | 2016 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 徐学科 |
| 关键词 | 环形抛光 热积聚 面形 |
| 其他题名 | Influence of Heat Accumulation on Surface Figure Controlling during Continuous Polishing |
| 中文摘要 | 本文围绕大口径超精密光学元件在环形抛光加工过程中遇到的难题，开展了环形抛光中热积聚效应影响的研究，并实现了热积聚效应的有效抑制。 环形抛光技术以其良好的全频谱均匀去除能力、收敛速度快、加工精度高和生产成本低等特点，成为大口径光学元件加工的首选方式。但是环形抛光技术目前依旧存在着诸多不足，如加工周期加工质量的可控性程度不高，对操作者的经验依赖性强等，其根本原因是人们对环形抛光的规律认识不够，尤其是一些工艺参数的影响。在这些影响因素中，热积聚效应是极为重要的一个，热积聚效应体现在系统的温度分布及变化情况。大口径光学元件、抛光胶盘等对热积聚效应非常敏感。加工过程中温差引起的工件形变通常远远超过所要求的工件面形；环境温湿度的变化影响着热积聚效应导致抛光胶盘温度变化从而产生不同程度的蠕变变形，间接影响工件面形；检测时需长时间恒温，影响加工效率；不同材质的工件在相同的工艺条件下因热积聚效应的不同，所得面形不同，给加工带来很大不便。因此，本论文围绕着环抛过程中的热积聚效应，开展了相应的工作，主要如下： 介绍了环抛过程中的热积聚效应，包括热积聚效应的形成及实验探测。分析了环抛过程中导致热积聚效应形成所涉及的热学现象，讨论了抛光过程中热量的产生原因与散失机制及相关影响因素，为抑制热积聚效应提供了理论指导。对? 260 mm × 26 mm Nd:glass工件温度分布情况进行了测量，获得了工件的加工面径向温差及上下表面温差，证实了热积聚效应的存在。 研究了热积聚效应对环抛中面形控制的影响。首先，对热积聚效应的影响进行理论分析。使用有限元分析软件ANSYS对? 260 mm × 26 mm同等大小不同材质的工件在同等上下表面温差和径向温差下的形变进行了仿真。结果表明，钕玻璃热形变比K9和ULE要大，即使温差只有0.1℃，所引起的热形变已远远超过加工精度要求。然后，将三块? 260 mm × 26 mm同等大小不同材质的工件置于同一工件环中，在相同的加工条件下进行抛光对比实验，探究不同材质工件受热积聚效应影响的差异以及同一工件受热积聚效应影响的变化情况。结果发现：钕玻璃受热积聚效应影响最大，抛光过程中面形波动最为激烈；加工过程中，工件受的热积聚效应并不是一成不变的，而是随着各影响因素的变化而出现一定程度的波动。 研究了抑制热积聚效应的方法。运用循环注液并配合加深加宽沟槽的方法，工件的上下表面温差及加工面径向温差得到一定程度的降低；并且加工过程中工件面形线性收敛，面形也更加规则。运用抛光胶盘改性的方法，在胶盘中掺杂石墨，胶盘的热导率提高，及时导走了环抛过程中产生的热量，并且降低了工件与胶盘间的摩擦系数，减少了产热量，对抑制热积聚效应起到一定程度的作用。 |
| 英文摘要 | This thesis focuses on problems encountered in continuous polishing of large aperture ultra-precision optical elements, carried out research in the influence of heat accumulation, and effectively inhibitted heat accumulation effect. Having the advantages in full-spatial-frequency homogeneous removement, a high speed of convergence, a high precision of process and low production costs make continuous polishing the first choice for large aperture optical elements manufacturing. However, there are still many problems in continuous polishing,such as low controllability of processing cycle and processing quality, strong dependence of the operator's experience.The primary cause is people's lacking understanding of the law to continuous polishing, especially the effect of some processing parameters. In all these processing parameters, heat accumulation effect is a significant one.Heat accumulation effect is reflected in the system of temperature distribution and changes. The large aperture optical elements and pads are very sensitive to heat accumulation effect. The thermal deformation caused by temperature difference is far surpass processing precision required; pads have different degrees of creep deformation on account of variety of environment temperature and humidity which affect heat accumulation, indirectly effects the workpieces surface figure; it takes a long time to achieve constant temperature which affects the processing efficiency; different material of workpieces gain different surface figures in the same process conditions,owing to different extent heat accumulation effect, which brings great inconvenience in processing. Therefore, this thesis carried out the corresponding work about the heat accumulation effect in continuous polishing,mainly as follows: Introduced the heat accumulation effect in continuous polishing process, including the formation and experimental detection. Analyzed the thermal phenomena involved in the continuous polishing process,discussed generation and dissipation of the heat during polishing process and the effect factors on these thermal phenomena,, which give rise to heat accumulation effect, provided a theoretical guidance to the inhibition of heat accumulation effect.Measured the temperature difference of ? 260 mm × 26 mm Nd:glass, obtained the temperature difference along the polishing surface and temperature difference between top and bottom surface, proved the heat accumulation effect to be existing.The results showed that workpieces of different aperture own different temperature difference, the larger the aperture, the bigger the temperature difference. Studied the influence of heat accumulation on surface figure controlling.First, simulations were made about the deformation of ? 260 mm × 26 mm different material workpieces under variational temperature difference. The result shows that,with same temperature difference, Nd:glass deforms more severely than K9 and ULE. Even though the temperature difference is as tiny as 0.1°C, the deformations are far surpass processing precision required.Then, to explore the diverse influence of heat accumulation on workpieces of different material and the fluctuation of heat accumulation, three ? 260 mm × 26 mm workpieces were polished in one ring at the same time.It was found that:Nd:glass suffers the most from heat accumulation,owns the most intense surface figure fluctuation.And, the heat accumulation effect are not constant, it changes with the influencing factors. Researched on methods to restrain heat accumulation. By circulation slurry injection with deepen and widen the groove, both the temperature difference between the upper and lower surface of the workpiece and the temperature difference along the radial direction of the polishing interface are reduced to some extent; the surface figures are linearly convergent and more inerratic. By the method of doping graphite in pads,the thermal conductivity of pads increased, conducted the heat timely, to a certain degree of inhibition of heat accumulation effect. |
| 语种 | 中文 |
| 内容类型 | 学位论文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/16976]  |
| 专题 | 上海光学精密机械研究所_学位论文 |
| 推荐引用方式 GB/T 7714 | 洪美娟. 环抛过程中热积聚效应及其对面形控制的影响[D]. 中国科学院上海光学精密机械研究所. 2016. |
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