颗粒增强铝基复合材料高功率激光-铣削协同加工关键技术研究

Particle reinforced aluminium matrix composites have been widely used in aerospace and other fields in recent years, but the existing processing technology has become a key step that restricts its application. In order to solve the problems including severe tool wear, low efficiency following traditional milling and thermal damage in laser cutting of thin-walled aluminium matrix composites, high-power laser-milling cooperative machining process is proposed to cut aluminium matrix composites in this project, which combines the advantages of high material removal rate with laser cutting and low level of damage with milling process. Based on the mathematical mapping between residual stress distribution and the key process parameters, it can optimize the distribution of residual compressive stress in the machined surface layer, and achieve high-efficiency and low-damage processing of thin-walled aluminum matrix composites. The temperature field and thermal stress distribution of high-power laser cutting aluminium matrix composites are studied, and the width of heat affected layer is accurately predicted to achieve continuous milling with minimum cutting depth. The evolution mechanism of coupled stress field under the effect of initial thermal stress fields and the regulation mechanism of residual compressive stress in subsurface layer are explained, and the theory and technology of high-efficiency and low-damage processing of aluminium matrix composites are formed. The research results are of great significance to promote the further application of aluminum matrix composites.

颗粒增强铝基复合材料近年来在航空航天等领域广泛应用，但现有加工技术已成为制约其推广应用的关键环节。为解决目前铝基复合材料薄壁件铣削加工中刀具磨损严重、加工效率低和激光加工中热损伤等问题，本项目提出铝基复合材料高功率激光-铣削协同加工的方法，创新性地结合高功率激光高效率去除和铣削低损伤加工的优势，并基于残余应力分布特征量与关键工艺要素间的数学映射关系优化加工表面层残余压应力分布，实现铝基复合材料薄壁件的高效低损伤加工。研究高功率激光切割铝基复合材料温度场和热应力分布规律，并准确预测变质层宽度，实现最小切削量的连续铣削加工；阐明多热力场叠加作用下耦合应力场的分布演变机理和加工表面层残余压应力调控机理，形成铝基复合材料高效低损伤加工理论和技术。研究成果对促进铝基复合材料的进一步应用具有重要意义。

为解决目前铝基复合材料切削加工中刀具磨损严重、加工效率低和激光加工中热损伤等问题，本项目提出了铝基复合材料高功率激光-铣削协同加工的方法。首先表征了不同厚度和不同体积分数的SiCp/Al复合材料光纤激光切割后的切缝特征与表面形貌，并阐明了不同切缝形貌的形成机理。研究了激光工艺参数对已加工表面形貌及宏、微观缺陷的影响规律，建立了激光切割过程中材料流动路径和已加工表面形貌形成的理论模型，阐明了表面形貌特征与典型缺陷的形成机理。利用统计学分析法研究了激光工艺参数对切缝几何形状的影响规律，发现切割速度、激光功率和辅助气体压力是影响切缝宽度的显著因素。根据铝合金基体和碳化硅颗粒的热物性参数和热传导公式，建立了激光切割复合材料三维有限元模型，仿真分析了激光工艺参数对温度场和残余应力分布的影响规律，并与实验测量结果进行了对比验证。在激光快速切割复合材料后，采用有限元方法建立了铝基复合材料铣削仿真模型，实现了对颗粒失效模式、表面缺陷成形以及残余应力分布的准确预测。建立了SiCp/Al复合材料两相切削有限元模型，研究了切削路径、颗粒失效模式与表面缺陷之间的关联关系。利用铣削加工实验和有限元模型研究了工艺参数对切削力、表面质量和残余应力的影响规律。建立了SiCp/Al复合材料等效均质三维铣削加工有限元模型，对铣削温度和残余应力分布演变进行仿真分析，并结合铣削实验研究了工艺参数对铣削温度和表面缺陷类型的影响。创新性地提出了SiCp/Al复合材料高功率激光-铣削协同加工工艺，通过实验分析了协同加工工艺的优势，揭示了工艺参数对加工表面质量及残余应力的影响规律。发现激光切割的表面质量较差，存在烧伤、浮渣、条纹和裂纹等热损伤缺陷，而激光-数控铣削协同加工方法不但拥有激光加工效率高的优点，而且弥补了激光加工表面质量差的缺点，通过热应力和机械应力耦合叠加实现了加工表面残余应力的优异分布。