液氮冷却对碳纤维复合材料钻削表面完整性的影响

目的 研究液氮冷却与钻削工艺对碳纤维复合材料钻削质量的影响。方法 采用YG10X硬质合金钻头开展碳纤维平纹织物/环氧树脂层压复合材料（T300）的液氮低温钻削与常温干式钻削的对比试验研究。分析液氮低温作用下不同钻削参数时的声发射信号有效电压值（Root-Mean-Square of Acoustic Emission Signals，AE-RMS），并结合孔的加工质量与声发射信号进行有效的识别。结果 与常温干式钻削相比，液氮低温钻削的AE-RMS在钻削阶段平均值增大，且信号相对平稳，在钻出阶段末尾处减小，且无明显突变，孔出口分层因子和出口毛刺减小。在vf=30 mm/min时，孔出口分层因子降低了9.2%，孔壁表面质量提高。结论 与常温干式钻削相比，液氮低温钻削在钻削阶段中，AE-RMS增大，但其波动幅度减小，孔出口毛刺、撕裂等缺陷减少。通过SEM观察，液氮低温钻削下的纤维断口明显减少，树脂涂覆表面整洁平滑，横向纤维与树脂界面有较好的结合性，没有大面积纤维树脂剥离，孔壁表面质量提高。

Effects of Liquid Nitrogen Cooling on Drilling Surface Integrity of Carbon Fiber Reinforced Plastics

This paper aims to discuss the effects of liquid nitrogen cooling and drilling parameters on the driving quality of carbon fiber composites. Liquid nitrogen cryogenic and room temperature dry drilling experiments were carried out for carbon fiber reinforced composites T300 with YG10X cemented carbide drill. Root-Mean-Square of Acoustic Emission Signals (AE-RMS) of different drilling parameters was analyzed, and the corresponding signals of the hole processing quality were identified effectively. Compared with dry drilling at room temperature, the average value of AE-RMS under liquid nitrogen cryogenic drilling increased clearly with less fluctuation in the drilling phase; meanwhile it decreased and had no obvious variation at the end of the drilling phase. Furthermore, the hole outlet delamination factor as well as burr decreased. When vf=30mm/min, the hole outlet delamination factor was reduced by 9.2%, and the hole wall surface quality was improved. Compared with dry drilling at normal temperature, liquid nitrogen low temperature drilling has the following characteristics: AE-RMS increases during the drilling phase, but its fluctuation amplitude decreases. Defects such as burrs and tears at the hole exit are reduced. The SEM observation shows that the fracture of the fiber under low temperature drilling of liquid nitrogen is significantly reduced, the surface of the resin coating is neat and smooth, and the interface between the transverse fiber and the resin has less peeling and the surface quality of the hole wall is improved.