基于激光与管电极电解同步复合（Laser-STEM）的低损伤大深度小孔加工技术基础研究

Low damage and large depth small holes are increasingly needed in various fields, such as aerospace and precision machinery. The high-efficiency high-quality fabrication of low damage and high aspect ratio small holes has become a research focus, home and abroad. To address the issues of machining depth, efficiency and surface quality in the large-depth small hole drilling process, this project proposed the synchronized laser and shaped tube electrochemical hybrid machining (Laser-STEM) to process low damage and large depth small holes. Laser-STEM could be applied to fabricate large depth and low damage small holes in high efficiency, combining the advantages of laser beam machining, electrochemical etching and the coupling effects. In the laser-STEM process, laser beam could be transmitted to the machining area via the internal total reflection induced by a solid boundary constraint, and the machining products could be flown away from the machining gap by internal electrolyte flushing and rotary tube electrode in high efficiency, thus the laser and electrochemical hybrid machining could occur in large depth, with the feeding of the tube electrode into the workpiece. This project will in depth explore the controllable coupling mechanism of laser and electrochemical fields based on the solid boundary constrained layer induced internal total reflection, study the materials removal mechanisms of laser and electrochemical hybrid machining method in which multi-fields are coupled in the deep machining zone, and develop a dynamical mathematical model of the varying machining gap during the Laser-STEM process. Moreover, this project will also focus on the key technologies such as the establishment of liquid cored tube electrode and the design of the laser-tube electrode coupling system, the monitoring of the hybrid machining status, and the process characteristics of the laser-STEM process. Thus, this project will process deep small precision holes, with high surface quality and high machining efficiency, extending the current process limits.

低损伤大深度小孔在航空航天、精密机械等领域需求日益迫切，其高效高质制造技术已成为国内外研究热点。为满足深小孔加工对加工深度、表面质量和加工效率等的综合要求，本项目提出基于激光与管电极电解同步复合的低损伤大深度小孔加工技术，综合利用激光加工、电解加工及其耦合效应，实现大深度精密小孔的高效加工。通过固体边界全光导约束效应将激光能量场同步传导至加工区域，结合管电极的大深度进给，采用内孔高速冲液和电极旋转促进产物排出，实现大深度加工区域的激光与电化学能量场的持续耦合介入和材料高效去除。本项目重点研究基于固体边界全光导约束的激光与电化学能量场耦合机制，揭示激光与管电极电解同步复合低损伤大深度加工机理，建立加工间隙演化数学模型，突破液核光纤管电极制备、激光-管电极耦合装置设计、加工状态特征参数提取与分析、过程控制、工艺参数匹配等关键技术，拓展低损伤大深度小孔高效制造的工艺极限。

针对难加工材料低损伤大深度小孔的高效精密加工难题，本项目提出基于液核光纤的激光与管电极电解复合加工技术（Laser-STEM），通过工具电极内孔中光束全反射效应高效传导激光，利用介入激光高效去除端面中心材料，同时利用管电极电解加工提高加工表面质量和加工精度，实现大深径比微小孔的高质高效加工。本项目建立了激光与管电极电解同步复合加工试验平台，制备出折射率阶跃变化的液核光纤工具电极，搭建了加工状态在线监测与控制系统；阐明了电解液中激光全光反射传导的物理机制，得出激光全反射耦合条件，揭示了液核光纤工具电极传导激光的能量损耗（吸收和散射效应）机制及激光功率密度分布规律，实现激光能量的高效传导（＞80%）；提出“收缩式”液核光纤工具电极，实现激光与电化学能量场的协同耦合控制，减小了端面材料残余高度；通过加工轮廓检测，结合多物理场耦合仿真和理论分析，揭示了同步介入激光对提升管电极电解加工效率的影响机理，阐明了加工间隙的分布规律和演化过程，探索了电解液类型（钝化性/非钝化性电解液）对激光电解复合加工机理的影响规律；试验研究了镍基高温合金、钛合金等激光与管电极电解复合加工工艺规律，开展了深小孔、微流道、深窄槽、型腔等典型结构加工试验研究。研究结果表明，相较于单一电解加工，激光与管电极电解复合加工的材料去除速率可提高118%，加工精度提高67.2%。实现了深度109mm、直径0.9mm、无再铸层、无微裂纹、无热影响小孔的高效精密加工，工具电极的最高进给速率达6.1mm/min。本项目共计发表学术论文15篇，其中SCI收录6篇，EI收录5篇；会议论文6篇；获授权发明专利7项，其中美国发明专利1项；培养研究生5名，其中毕业1名。