【摘要】 碳纤维增强树脂基复合材料(CFRP)构件在航空航天领域的连接装配需大量使用沉头孔。为解决传统机械CFRP钻孔易导致分层、毛刺及刀具磨损等问题，研究采用飞秒激光结合五轴振镜系统实现CFRP沉头孔高质量低损伤加工的新方法，并系统分析工艺参数对孔质量的影响规律。通过对T800S/环氧树脂CFRP层合板开展单因素实验，着重研究了激光平均功率(17.5～25 W)、重复频率(50～300 kHz)、扫描速度(200～400 mm/s)、入射角(1°～9°)等工艺参数对沉头孔锥度、热影响区(HAZ)和底部形貌的影响。结果表明，较低平均功率(17.5～20 W)有利于控制HAZ并改善底面质量；扫描速度250～300 mm/s可实现高效烧蚀与良好表面质量的平衡；入射角从1°增加到9°时，锥度得到有效修正，HAZ从106μm增大至177μm。重复频率为50 kHz时，制孔深达1.85 mm且锥度较小，300 kHz时孔深降至0.6 mm且热积累加剧。研究证实飞秒激光五轴振镜加工方法是制备高质量CFRP沉头孔的有效手段，综合优化参数组合可获得较高的孔质量，为航空航天CFRP构件精密加工提供了重要工艺依据。更多还原

【Abstract】 Objective Carbon fiber reinforced plastic(CFRP) composites have garnered increasing interest from the aviation and aerospace industries due to their exceptional material properties, including a high strength-to-weight ratio, excellent corrosion resistance, and superior fatigue resistance. In the aerospace field, a large number of countersunk holes are required for the joining and assembly of CFRP components. However, due to the characteristics of CFRP, such as low interlayer bonding strength and high material hardness, quality issues like delamination defects and burrs are prone to occur during mechanical machining. The five-axis galvanometer system offers key advantages for machining complex structures by dynamically adjusting the laser beam’s incident angle. When drilling variable cross-section features such as the sidewalls of counterbored holes, precise control of the beam incident angle ensures that the laser focus always falls on the machining area. This significantly improves the machining quality and dimensional accuracy of the sidewalls, effectively reducing energy loss and thermal damage caused by defocusing. Therefore, this paper proposes a novel method for machining counterbored holes in CFRP using a five-axis galvanometer femtosecond laser system and conducts systematic experimental research on the process.Methods This paper adopts a systematic research method based on the single-factor controlled experiment, and conducts countersunk hole machining on T800S/epoxy resin CFRP laminates by virtue of a self-built domestic femtosecond laser five-axis galvanometer hybrid drilling platform. The key parameters such as laser average power(17.5-25 W), repetition frequency(50-300 kHz), scanning speed(200-400 mm/s), laser incident angle(1°-9°) are adjusted independently in sequence, so as to systematically investigate the influence rules of each parameter on the size of heat-affected zone(HAZ), hole taper and bottom surface morphology of the countersunk holes. With the analytical method combining microscopic observation and quantitative measurement, the mapping relationship between each process parameter and machining quality is clearly revealed, which thus provides a reliable process basis for high-quality and low-damage femtosecond laser machining of CFRP countersunk holes.Results and Disscussions Through systematic experimental research on femtosecond laser five-axis galvanometer machining of countersunk holes in CFRP laminates. Low average power(17.5-20 W) combined with medium scanning speed(250-300 mm/s) helps reduce the HAZ and achieve favorable hole bottom quality.Increasing the laser incident angle to a certain range(e.g., 9°) can significantly improve the perpendicularity of the hole wall and reduce the taper, while an excessively large angle(e.g., increasing to 5°) will lead to a marked expansion of the HAZ. A relatively low repetition frequency(50 kHz) is conducive to achieving greater hole depth and better taper, whereas high frequency(300 kHz) will intensify heat accumulation. The helical scanning strategy integrating five-axis galvanometer with turntable rotation can effectively homogenize energy distribution and facilitate chip removal, thereby suppressing fiber pull-out and resin residue.Conclusions Laser average power, scanning speed, incidence angle, repetition rate, and scanning strategy are all critical factors affecting the quality of countersunk holes processed in CFRP using femtosecond lasers: Lower power(17.5-20 W) reduces the heat-affected zone and ensures a flat hole bottom surface, while higher power(>22.5 W) increases hole taper; A scanning speed of 250-300 mm/s effectively balances material removal efficiency and thermal accumulation control; an incidence angle of 9° significantly reduces hole taper, while larger angles exacerbate thermal damage; A 50 kHz repetition rate achieves maximum processing depth and optimal taper. Higher frequencies increase heat accumulation, reduce processing depth, and expand the heataffected zone. The helical scanning strategy, combining a five-axis galvo scanner with turntable rotation, evenly distributes energy and improves chip evacuation. This effectively suppresses defects such as fiber pull-out, resin residue, and recast layers, enhancing the morphological integrity and dimensional consistency of countersunk holes.The research shows that the combination of femtosecond laser and five-axis galvanometer system enables high-quality and low-damage machining of CFRP countersunk holes, and comprehensive optimization of process parameters can significantly improve hole shape accuracy and integrity while ensuring machining efficiency.更多还原