Formation mechanism of CFRP pipe concave drilling defects

Due to the excellent performance of carbon fiber-reinforced plastic (CFRP), it is used more and more widely in the form of pipe and shaft parts. In order to reveal the formation mechanism of CFRP pipe concave drilling defects, the causes of hole entrance defects, exit defects, and exit sidewall defects were analyzed by combining theory with experiment, and the effects of different processing parameters on hole exit delamination defects were studied. Through theoretical analysis, it is found that the delamination at the front end of the chisel edge does not necessarily affect the final defects of the hole in CFRP pipe concave drilling. The experiment proves that the chisel edge can effectively drill through the outermost material and has no effect on the formation of the final hole damage. When the candle stick drill is used for drilling, there is almost no damage at the hole entry. After the outermost woven fiber cloth is drilled through, different degrees of damage occur at the intersection of longitudinal and transverse fibers.