超精密模辊机床几何误差建模及其补偿策略的研究

发布时间：2018-11-05 20:18

【摘要】：微结构表面是指具有特定的微小拓扑结构、形状尺寸只有几微米到几十微米、形状误差达到亚微米级、表面粗糙度达到纳米级、可以实现某种特定功能的表面结构,它在航天、能源、IT等领域都有广泛的应用。近几年随着大屏幕智能手机以及大尺寸液晶显示屏的普及,各类光学微结构膜片的应用日渐增加。而Roll-to-Roll压印技术凭借其加工效率高、良品率好、适合大批量生产等优点在众多加工方法中脱颖而出,是目前最有发展前景的大批量微结构加工技术。作为Roll-to-Roll压印技术的核心元件,辊筒模具表面微结构的加工质量将直接影响所压印膜片的好坏,因此对超精密辊筒模具加工机床具有非常高的要求。目前辊筒模具的超精密加工技术被国外垄断,其机床售价高达数千万元,而国内相关领域的研究才刚刚起步。目前国内自主研制的超精密模辊机床与国外存在一定的差距,究其原因还是在加工精度上存在一定问题。而几何误差作为影响机床加工精度的最主要误差源之一,会直接导致刀具的实际轨迹与理想轨迹出现偏差从而影响模具微结构表面的加工质量。鉴于此,本文基于实验室自主研制的国内首台大尺寸辊筒模具超精密加工机床,针对机床的几何误差开展研究,目的是为了减小机床几何误差对模具表面微结构的加工精度的影响从而压印出高质量的光学膜片。为此,本文主要包含以下几方面内容:首先,利用多体系统理论的低序体阵列将机床的机械结构转化为拓扑结构,然后利用齐次坐标变换的方式推导出机床的几何误差模型,得到机床在两个直线轴方向上的误差表达式,从而为后续的补偿提供前提基础。其次,利用激光干涉仪对几何误差模型中涉及到的各单项误差进行精确测量。考虑到实际加工过程中不同的微结构功能表面加工特点并不相同,本文分别提出了最优多项式拟合数控指令修正法以及NURBS拟合曲线插补补偿法对机床的几何误差进行补偿并进行了理论计算。最后为了说明两种补偿方法的可行性分别进行了环槽微结构阵列切削实验以及自由曲面加工检测实验,对补偿前后的加工结果进行检测对比。从最终的结果上看本文提出的补偿方法可以明显减小机床几何误差对加工精度的影响,使辊筒模具微结构表面的加工质量得到明显提升。
[Abstract]:A microstructural surface is a surface structure that has a specific micro topology, with shape sizes ranging from several microns to tens of microns, shape errors up to sub-micron levels, surface roughness at nanometer levels, which can achieve certain functions. Energy, IT and other fields have a wide range of applications. In recent years, with the popularization of large screen smart phone and large size liquid crystal display screen, the application of optical microstructural diaphragm is increasing day by day. Because of its high processing efficiency, good product rate and suitable for mass production, Roll-to-Roll imprint technology stands out among many processing methods, and is the most promising microstructural processing technology at present. As the core component of Roll-to-Roll imprint technology, the machining quality of the surface microstructure of the roller die will directly affect the quality of the embossed film, so the ultra-precision roller die machining machine has a very high requirement. At present, the ultra-precision machining technology of roller die is monopolized by foreign countries, and the price of machine tools is as high as tens of millions of yuan. At present, there is a certain gap between the developed ultra-precision die roller machine tool and foreign countries, and the reason is that there are still some problems in the machining precision. As one of the most important error sources which affect the machining accuracy of machine tools, geometric errors will directly lead to the deviation between the actual and ideal tracks of the tool, thus affecting the machining quality of the microstructural surface of the die. In view of this, this paper is based on the first ultra-precision machining machine tool for large-size roller die, which is developed independently by the laboratory, and studies the geometric error of the machine tool. In order to reduce the influence of geometric error on the machining accuracy of die surface, high quality optical film was imprinted. For this reason, this paper mainly includes the following aspects: firstly, the mechanical structure of the machine tool is transformed into topological structure by using the low sequence body array of the multi-body system theory, and then the geometric error model of the machine tool is derived by the homogeneous coordinate transformation. The error expression of the machine tool in the direction of two straight axes is obtained, which provides the premise for the subsequent compensation. Secondly, the laser interferometer is used to accurately measure the individual errors involved in the geometric error model. Considering that the characteristics of different microstructural functional surfaces are not the same during actual processing, In this paper, the optimal polynomial fitting NC instruction correction method and the NURBS fitting curve interpolation compensation method are proposed to compensate the geometric error of the machine tool, and the theoretical calculation is carried out. Finally, in order to illustrate the feasibility of the two compensation methods, the experiments of ring groove microarray cutting and free-form surface machining are carried out, and the machining results before and after compensation are compared. From the final results, the compensation method proposed in this paper can obviously reduce the influence of machine tool geometry error on machining accuracy, and improve the machining quality of the micro-structure surface of roller die.
【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】：2017
【分类号】：TG659

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