大长径比CVD金刚石微铣刀的激光诱导辅助精密刃磨机理与方法研究

Micro structures with high deep-width rate, such as slow wave microstructure with the groove width of 30 micrometers and the groove height of 120 micrometers etc., are widely used in aerospace, medical fields and so on. Micro CVD diamond end mill with large slenderness ratio is the necessary tool to manufacture micro structures with high deep-width rate. Low grinding efficiency and stiffness are the main reasons restricting high quality and efficient manufacturing of micro CVD diamond end mill with large slenderness ratio. In this project, a new method of precision sharpening assisted by laser-induced graphitization for micro CVD diamond end mill with large slenderness ratio is proposed to improve the processing efficiency and reduce the grinding force. The formation mechanism of reactive layer under laser irradiation of micro CVD diamond end mill, as well as the grinding mechanism of the transition layer will be investigated in detail. Meanwhile, the mechanism of precision grinding assisted by laser-induced graphitization for CVD diamond is analyzed by means of simulation, theoretical analysis and machining experiments. The transition layer components and interface roughness of CVD diamond after laser irradiation are regulated to reduce the grinding force and its fluctuation range, so as to achieve high quality and efficient removal of CVD diamond. In view of the weak rigidity in the grinding of micro CVD diamond end mill with large slenderness ratio, the study for the design of tool blank, design of self-adaption bracket, fabricating process and sharpening technology is carried out to increase the rigidity of micro mill in the process of precision grinding. The theoretical basis and key technology to manufacture micro CVD diamond end mill with large slenderness ratio will be formed. The expected results of this project include: figure out the mechanism of precision grinding assisted by laser-induced graphitization for CVD diamond; extract out the hybrid fabrication theory and method for micro CVD diamond end mill with large slenderness ratio; design and fabricate 5 micro mills with the diameter ≤500 micrometers, aspect ratio ≥ 3; apply for 2 invention patents; publish 4~6 SCI/EI indexed paper; attend 3 academic conferences; assist in training 2 to 3 graduate students. The research on this project is of great significance to the precision machining of the micro structures with high deep-width rate.

在国防、航空航天及医疗等领域的尖端装备中，高深宽比微结构件，如槽宽和槽高分别为30微米和120微米的慢波微结构，壁厚和高度分别为3微米和30微米的微流道等应用广泛，此类微结构件（特征尺寸≤500微米，深宽比≥3）的高使役性能要求其尺寸精度达到微米级，且表面粗糙度Ra值达到纳米级，这些都是对现有诸多微加工技术能力的极限挑战。目前大长径比CVD金刚石微铣刀是铣削高深宽比微结构的必备工具。针对大长径比CVD金刚石微铣刀高硬度和低刚性导致的难加工问题，本项目提出激光诱导石墨化辅助精密刃磨新方法。拟重点研究激光诱导CVD金刚石表面改性层形成机理和CVD金刚石石墨化后过渡层的磨削机理等关键科学问题；同时，通过建模仿真、理论分析和加工实验等手段，解析CVD金刚石激光诱导石墨化辅助精密磨削机理，调控CVD金刚石激光诱导石墨化后过渡层组分及分界面平整度来降低磨削力及其波动范围，实现CVD金刚石的高质高效去除；其次，针对大长径比微铣刀的弱刚性特点，进行微铣刀的毛坯设计、自适应托架设计、制备工序和刃磨工艺研究来增加其刃磨过程中的刚度；最终形成大长径比CVD金刚石微铣刀的高质高效制备理论基础和关键技术。项目的预期成果包括：探明CVD金刚石激光诱导石墨化辅助精密磨削机理；形成大长径比CVD金刚石微铣刀的复合制备理论和方法；设计制备出5把直径≤500微米，深宽比≥3的大长径比微铣刀；申请发明专利2项；发表SCI/EI源刊等学术论文4~6篇；参加学术会议3人次；协助培养研究生2~3名。本项目研究有望解决大长径比金刚石微铣刀制备难的问题，为实现高深宽比微结构的高精密低成本制造奠定基础，对微切削技术的发展和国防民用等领域装备小型化有重要的科学意义与实用价值。

大长径比化学气相沉积（Chemical Vapor Deposition，CVD）金刚石微铣刀是铣削高深宽比微结构的必备工具。针对大长径比CVD金刚石微铣刀高硬度和低刚性导致的难加工问题，本项目开展了CVD金刚石激光诱导石墨化及过渡层控制机制、CVD金刚石石墨化后的过渡层磨削机理、CVD金刚石微铣刀的制备及应用基础等方面研究工作。主要研究成果如下：.（1）基于高斯脉冲纳秒红外激光束，分析并验证了CVD金刚石在红外激光作用下的石墨化现象；探索了激光参数对CVD金刚石的点/线刻蚀影响规律，获取了点/线刻蚀的激光能量密度阈值；解析了激光参数对去除深度、过渡层表面粗糙度等的影响规律，阐明了激光诱导金刚石石墨化机理，优化了激光参数，为后续过渡层表面精密磨削提供参考。.（2）研究了砂轮粒度、磨削参数等对过渡层磨削表面粗糙度、形貌、切削刃钝圆半径等的影响规律，优化了砂轮粒度和磨削参数；并基于以上研究结果，揭示了过渡层磨削去除及亚微米级刀刃钝圆半径创成机理，反向优化了激光参数；通过有限元仿真与试验相结合的方法阐明了CVD金刚石微细铣刀的极限锋利度及其限制条件。 .（3）提出了激光诱导石墨化辅助精密刃磨大长径比CVD金刚石微铣刀新方法，高效制备出了长径比≥3且直径≤200μm的金刚石微铣刀，其刀刃钝圆半径可达200nm（为已有报道中最锋利的金刚石微铣刀），可获得粗糙度Sa小于20nm、几乎无毛刺钛合金微槽，其切削性能明显由于商用硬质合金刀具，对我国高深宽比微结构件的精密加工具有十分重要的意义。.本项目实施以来，以第一或通讯作者在IJMTM（IF=10.331/2021，中科院1区）、《机械工程学报》等杂志上发表论文17篇，其中SCI检索论文14篇（8篇中科院1区，TOP），EI检索论文3篇，单篇最高Google学术引用110余次；以第一发明人授权国家发明专利5项，受理国家发明专利3项；参加学术会议14人次，做口头报告交流6人次；入选中国科协“青年人才托举工程”计划、江苏省高层次人才创新创业计划等，获中国刀协切削先进技术研究分会青年新秀奖、第九届高速与复合加工国际会议一等奖（唯一最高奖）等；指导（含协助指导）博士、硕士研究生10名，获国家留学基金委奖学金（CSC）3人次、研究生国家奖学金3人次。