超精密多轴飞刀铣削金刚石刀具磨损在线测量和预测的理论及应用研究

Ultra-precision raster milling (UPRM) is an enabling technology for directly manufacturing non-rotational symmetric freeform surfaces with nanometric surface roughness. The fabrication of freeform optics is difficult and time-consuming because of the complexity of the profiles and the stringent requirement of quality. The wear of the cutting tool is significant as a tiny degradation of the tool will lead to poor surface roughness and form accuracy. Therefore, to improve the component quality and the productivity, it is a critical issue to develop an accurate and pragmatic methodology on in-progress tool wear monitoring and compensation in UPRM. .In this project, a new auto-regressive method of the 3D reconstruction surface of tool wear will be established to support the on-position-image measurement in UPRM, and on establishing the relationship between tool wear and surface integrity. Streaming images will be collected by CCD camera and the digital image will be processed to reconstruct the 3D topographic surface. The dynamic characteristics of the ultra-precision raster milling process will be monitored by a dynamometer and force transducer and analyzed by a data-dependent system (DDS) and a fast Fourier transformation (FFT) algorithm to on-line monitor the cutting tool wear. A 3D finite element (FE) model will be built based on a mechanical and thermal model to predict tool wear taking place at the tool-tip interface. The simulation results will be verified with experiments conducted under various machining conditions...This study will not only lead to a better understanding of the micro-cutting process, but also serve as a sensitive tool to monitor the tool wear. The research findings will lead to a better understanding of the UPRM process and provide optimum cutting strategies to reduce tool wear which in turn will enable a better control of the surface integrity of UPRM surfaces in the production of freeform optical components.

本项目使用交叉学科的方法对超精密飞刀铣削金刚石刀具切削有色金属的刀具磨损机理、测量方法及预报模型进行系统的研究。提出了一种可应用于超精密飞刀铣削金刚石刀具磨损在线检测方法，基于飞刀铣削的动态特性，使用力传感器对刀具磨损实现了间接的在线监测。开发了一套光学系统用于支持超精密飞刀铣削中金刚石刀具磨损在位测量，使用自回归的方法重建刀具磨损位置的三维形貌。提出通过有限元的方法对超精密飞刀铣削进行数值仿真，研究不同切削条件下刀具磨损机理、预测刀具寿命，建立切削策略、刀具磨损和表面完整性之间的关系，降低刀具磨损和提高加工质量的目的。通过该项目的研究，有望获得一种全新的超精密多轴铣削金刚石刀具磨损在线在位测量方法，有助于促进微切削机理的理论研究的突破，并为自由曲面光学元件应用市场提供可靠、低花费且高效的加工技术，同时也有利于实现金刚石刀具在超精密加工技术中的的广泛应用，具有重要的理论和现实意义。

超精密飞刀铣削是一种新型的超精密多轴联动铣削技术，可以直接加工出具有亚微米级尺寸精度和纳米级表面粗糙度的复杂微结构表面和自由曲面。然而，超精密飞刀铣削中出现的刀具磨损将直接影响被加工表面的质量，为此需要对超精密飞刀铣削中的刀具磨损进行在线监测。本项目在理论与实验研究了超精密飞刀铣削切削机理的基础上，深入研究超精密飞刀铣削切削力特征及其在刀具磨损在线监测中的应用，发现了切削力频谱与刀具磨损之间的对应关系；深入研究了基于切屑形貌的超精密飞刀铣削刀具磨损的在线表征方法，发现了刀具磨损特征与切屑形貌特征之间的对应关系；深入研究了超精密飞刀铣削加工表面质量的影响因素，发现了刀具振动、主轴振动、材料滑移等对加工表面质量的影响规律；深入研究了基于超精密飞刀伺服控制的多尺度表面微结构加工方法，发现了多尺度加工方法在微结构成形过程中的作用。本项目的研究提出了一系列实用可靠的超精密飞刀铣削刀具磨损监测方法，为扩展超精密飞刀铣削在工业中的应用提供了理论与实验基础。项目资助发表论文24篇，SCI收录19篇；培养博士后2名，博士生3人，硕士生4名；出版专著1本，待出版1本。