基于位错动力学理论的金刚石微径铣刀裂纹损伤及其抑制基础研究

Diamond micro-diameter cutter is the key element to influence the development of micro-machining technology and the failure of tool can affect its cutting performance greatly. This project will build the discrete dislocation dynamics model for diamond crystal and investigate the relationship between the crystal mechanics properties and evolvement mechanisms of dislocation, clarifying the evolvement rule of diamond dislocation. With the couple frame of discrete dislocation dynamics and crystal plasticity, the research can present the interaction between diamond dislocation evolvement and micro-crack, clarifying the development mechanism of diamond dislocation. According to the couple correlation dynamic multiscale simulation of micro-milling, this research will analyze the dynamic extension mechanisms of crack in diamond micro-diameter cutter and investigate the inner relation between micro-crack and failure of diamond micro-tool, putting forward the suppression strategy based on the correlation analysis of ‘dislocation-crack-damage’ for the crack damage in diamond tool. Moreover, this project will develop experimental validation platform for single crystal diamond and chemical vapor deposition (CVD) diamond micro-diameter cutters and explore the failure reason of diamond micro-tool according to the experiments for tool fabrication and mciro-milling. The failure evaluation system for the diamond micro-diameter cutter can be constructed and the cutting techniques aiming to improve the stability of micro-cutting can be gained. This project can underpin the theoretical and technical foundation for the stability of micro-cutting and the cutting performance improvement of diamond tool.

金刚石微径铣刀是影响微细加工技术发展的关键器件，而刀具的失效对其切削性能产生重要的影响。本项目将建立金刚石晶体离散位错动力学理论模型，研究晶体力学特性与位错演变间的深层次关系，揭示金刚石位错的演变规律；结合离散位错与晶体塑性耦合框架，阐明金刚石位错演变与微裂纹的交互作用规律，揭示金刚石微裂纹的演化机理；根据微细铣削跨尺度的关联耦合动态仿真结果，分析微细铣削加工条件下金刚石微径铣刀裂纹的动态扩展机制，研究裂纹损伤与金刚石微刀具失效之间的内在关系，提出基于“位错-裂纹-损伤”关联分析的裂纹损伤抑制策略；搭建单晶和化学气相沉积（CVD）薄膜金刚石微刀具的实验验证平台，通过金刚石微刀具制备实验和微细铣削加工实验，探究金刚石微刀具的失效根源，建立金刚石微径铣刀的失效评价体系，获得金刚石微刀具稳定切削的优化条件。本项目将为提高微细加工的稳定性、实现金刚石刀具切削性能的跃升奠定理论和技术基础。

金刚石刀具的损伤和失效是制约其性能的重要因素。本项目以位错理论为基础，以抑制损伤失效、提升切削性能为目标，开展了相关研究。项目建立了金刚石晶体离散位错动力学理论模型，开发了2.5D离散位错动力学-有限元耦合仿真软件，分析了金刚石裂纹的损伤现象及应力场分布情况，揭示了金刚石晶体纳米压痕与刻划过程中位错的演变规律；建立了CVD金刚石膜纳米压痕与刻划的仿真模型，研究了压痕和刻划对晶体内位错的影响，探讨了晶粒尺寸等因素对位错演变的影响。项目提出了离散位错动力学与物理基材料塑性模型联合计算方法，揭示了微切削过程中工件的晶粒细化机理，定量地求解出物理基材料塑性模型中与位错演变相关的内禀常数。项目完成了金刚石微刀具化学气相沉积装置的工程设计和分析，为建立金刚石刀具制备平台奠定了基础。项目建立了微细铣削仿真模型，分析了微细铣削加工条件下金刚石微径铣刀裂纹的动态扩展机制，研究了裂纹损伤与金刚石微刀具失效之间的内在关系，为切削中刀具裂纹和损伤的抑制提供条件。项目完成了系列微细切削加工实验，对刀具的切削性能进行了优化，拟合获得了最优切削参数。本项目创造性地将位错动力学相关建模仿真手段引入到微细切削领域，经过4年的研究，取得了丰富的成果。项目在国内外期刊上发表学术论文24篇，其中SCI论文19篇、EI论文21篇。申请国家发明专利5项，已获得授权发明专利4项，获得软件著作权4项。部分研究成果获得省部级二等奖2项，三等奖1项。该项目的完成对优化金刚石刀具的切削条件，提升刀具的切削性能，指导具体的加工实践具有重要的意义。