激光诱导可控氧化辅助微细铣削高硬材料基础研究

The poor rigidity of micro milling tools and the high cutting force are the main reasons for the low manufacturing efficiency, surface integrity and processing controllability in micro milling of high hardness materials. In this project, a new method of laser-induced controllable oxidation assisted micro milling is proposed based on a new idea that controllable micro-zone oxidation can reduce cutting force. A controllable oxidation reaction would take place in the cutting zone and loose oxides which are easy-to-cut could be synthesized. The cutting force would be decreased and mass removal rate would be achieved. Subsequently micro milling would be applied to the subsurface materials and micro structures with high quality would be manufactured. The micro-zone oxidation mechanisms of workpiece materials under both laser irradiation and oxidizer, as well as the micro milling mechanisms of subsurface materials, will be investigated in detail. The forming mechanisms of loose oxidation will be studied. A control strategy of loose oxidation will be proposed, and then the oxidation behavior would be adjusted subjectively. An optimization model of the process in micro milling subsurface materials will be established. A method for manufacturing micro structures with both high accuracy and high quality will be proposed. The tool failure mechanisms (wear and fracture) and its suppression method will be studied. The results of this project will provide both theoretical and technical supports for high precision micro machining of high hardness materials.

高硬材料微细铣削过程的高比切削力和微铣刀的弱刚性是导致微结构加工效率低、表面完整性差和工艺可控性低等问题的主要原因，本项目创新可控微区氧化降低切削载荷新思路，提出激光诱导可控氧化辅助微细铣削新方法。使待加工区域材料发生快速可控氧化，生成易于被去除的疏松氧化物，有效降低切削载荷，实现大余量去除；随后对亚表层材料进行精密微细铣削，达到微结构的高效、高质量加工目标。项目重点研究在激光和氧化剂耦合作用下的材料微区氧化机制，以及多场耦合作用下亚表层材料的特殊微细铣削机理等关键科学问题；在此基础上，探讨疏松氧化物的生成机理，提出基于疏松氧化物的氧化调控策略，实现材料氧化行为的主观调控；建立亚表层材料微细铣削工艺优化模型，提出高硬材料微结构高精度控形、控性工艺方案；研究刀具失效机理与刀具失效(磨损和破损)抑制方法。本项目的研究结果将为高硬材料微结构的高效精密加工提供理论和技术支撑。

高硬材料微结构在航空航天、生物医疗和汽车电子等领域有着广泛应用，微细铣削是实现高硬材料微结构高效精密加工和工业批量化生产的重要方法。但是，微铣刀的弱刚性和微细铣削高比切削力导致高硬材料微结构微细铣削加工效率低、表面完整性差和工艺可控性低等问题。本项目创新可控微区氧化降低切削载荷新思路，提出了激光诱导可控氧化辅助微细铣削新工艺。研究了硬质合金和TiB2基陶瓷材料氧化反应的热/动力学规律，揭示了激光热诱导下材料的微观组织演变和性能突变机理，阐明了激光诱导材料氧化机理。建立了激光辐照下工件温度场分布模型，探明了激光参数对温度场分布的影响规律。开展了激光诱导材料氧化试验，制定了基于疏松氧化物的激光诱导氧化调控策略。探明了氧化层和亚表层组分、微观结构和尺寸特征，为微细铣削试验和激光氧化辅助微细铣削工艺综合优化奠定了基础。明确了亚表层材料的组织、性能和厚度变化规律，为微细铣削参数的制定奠定了基础。揭示了亚表层微细铣削表面创成机理，探明了铣削用量对亚表层铣削力、刀具失效形式和表面完整性的影响规律，构建了基于表面完整性的微细铣削工艺优化模型。揭示了微细铣刀的失效形式和失效机理，提出了刀具失效抑制方法，实现了亚表层材料的精密去除。搭建了激光诱导可控氧化辅助微细铣削试验平台，设计了高深宽比微槽结构，确定了微结构加工精度和表面质量评价方法。形成了高深宽比微槽的激光诱导可控氧化辅助微细铣削工艺方案，在硬质合金和TiB2基陶瓷材料上加工了深宽比分别为5和2的微槽。开展了新工艺和常规微细铣削对比试验，新工艺的加工精度和质量均优于常规工艺，且加工效率和刀具寿命得到大幅度提高。本项目解决了高硬材料微细铣削中微细刀的弱刚性和高比切削力之间的矛盾难题，实现了硬质合金和TiB2基陶瓷材料等高硬材料微结构的高效高质量加工，项目研究成果具有重要的理论意义和工程应用价值，有利于促进微细加工技术的发展。