CFRP管面钻削缺陷形成机制

Formation mechanism of drilling defects on CFRP pipe surface

碳纤维增强复合材料(CFRP)传动轴因性能优越广泛应用于汽车、航空航天、船舶、冷却塔风机等轻量化领域,但其钻削过程中容易出现毛刺、分层等缺陷。为了揭示CFRP管面钻削缺陷形成机制,选择双锋角钻头和三尖二刃钻对CFRP管面钻孔,利用分步钻削盲孔和通孔的方法,分析了损伤部位的受力情况,揭示了入口撕裂、出口毛刺和分层产生原因。根据实验结果,发现双锋角钻头钻孔时入口撕裂损伤较大,损伤位置在钻头与管面接触最低点,且主要是那部分水平缠绕CFRP管的纤维,原因是水平缠绕的纤维屈曲变形最大,对切削力更加敏感。双锋角钻头和三尖二刃钻的横刃对孔最终出口分层没有影响,主切削刃的切削行为决定孔最终出口分层。相同钻头钻孔时,轴向力不是唯一影响分层因子的因素,还需考虑切削热。相比双锋角钻头,三尖二刃钻因锋利的外缘尖角能有效划断纤维,使出口分层较小。

Carbon fiber reinforced polymer(CFRP)drive shaft is widely used in lightweight fields such as automobile,aerospace,ship and cooling tower fan because of its excellent performance,but it is prone to burr,delamination and other defects in the drilling process.In order to reveal the formation mechanism of defects in CFRP pipe surface drilling,double point angle drills and candle stick drills were selected to drill CFRP pipe surface.Using the method of drilling blind holes and through holes by some steps,the force of the damaged part was analyzed to study the causes of hole entry tear,hole exit burr and delamination.According to the experimental results,it is found that the hole entry tear of the double point angle drill is large.The tear damage is located at the lowest point of the contact between the drill bit and the pipe surface,and it is mainly the fibers that are horizontally wound around the CFRP pipe.The reason is that the horizontally wound fibers have the largest buckling deformation and are more sensitive to the cutting force.The chisel edge of double point angle drill and candle stick drill had no effect on the final delamination of the hole,and the cutting action of the main cutting edge determined the hole final exit delamination.For using the same drill,the axial force is not the only factor affecting the delamination factor,and the cutting heat should also be considered.Compared with the double point angle drill,the candle stick drill can effectively cut the fiber due to the sharp outer corner edge,making smaller hole exit delamination.