碳纤维复合材料(Carbon fiber reinforced plastic, CFRP)/钛合金叠层的钻孔机理不同于单层材料钻孔,钛合金切屑在排出孔外过程中会对CFRP孔质量造成损伤。为了探究CFRP在叠层钻孔时的质量特性,设计正交试验分析了钛合金切屑和切削参数对CFRP层钻孔质量的影响。观察了轴向切削力和力矩的变化以及钛合金切屑形态,分析CFRP层孔径超差和入口撕裂的机理。结果表明：大进给量条件下,高温、高硬度的钛合金切屑会对CFRP产生严重的侵蚀,是导致CFRP孔径超差的主要原因,并会增大入口撕裂程度;CFRP入口撕裂主要产生在切削速度和纤维方向夹角θ=45 °的位置,低切削速度不利于切削CFRP,会加大入口撕裂程度。因此,应使用小进给量钻削钛合金层,使用大切削速度钻削CFRP层;在保证钻头强度的前提下,推荐使用具有较大容屑空间的钻头。
The mechanism in drilling carbon fiber reinforced plastic (CFRP) and titanium stack materials differs from that in drilling single material. Titanium chips evacuation through the hole deteriorates the CFRP hole quality. To investigate the quality characteristics of CFRP-layer in drilling of CFRP/Ti stacks, orthogonal experiments are designed for analyzing the effects of both titanium chips and cutting parameters on drilling performance of CFRP-layer. The thrust force, torque and titanium chip morphology are firstly observed. Then the mechanism of hole diameter out of tolerance and entrance spalling is studied. The results show that, with higher feed rate, titanium chips with high temperature and high hardness cause catastrophic erosion of the CFRP-layer, resulting in hole diameter out of tolerance, and increase of entrance spalling. The entrance spalling occurs when the cutting direction and the fibers create a 45 ° angle. Low cutting speed is not suitable for CFRP-layer machining, which worsens the entrance spalling. Therefore, low feed rate and high cutting speed are recommended for drilling of titanium and CFRP layers respectively. Under the premise of enough strength, the drill with larger chip flute is recommended.
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