Wear mechanism of double point angle drill bit in drilling CFRP composites

In order to investigate the wear mechanism and variational law at the different cutting edges of the cutting tool used for machining carbon fiber reinforced plastics (CFRP), based on the typical tungsten carbide double point angle drill, the wear mechanism and law of influence on the hole-exit delamination at the chisel edge and influence on the final drilling quality at the secondary cutting edge were analyzed, respectively. By reducing wear measurement interval of the drill bit, and introducing the values of cutting edge rounding and flank wear width, the wear recession of the chisel edge and the secondary cutting edge in the drilling were characterized. By means of the microscope measurement of the cutting edge and the calculation of cutting edge rounding, it is found that chipping is dominant at the chisel edge and secondary cutting edge is reground and re-sharpened after flank wear. The wear law of this type of double point angle drill was also obtained, and the effects of wearing capacity on thrust force and drilling torque were analyzed based on the tool wear results. The results show that thrust force caused by the chisel edge has weak correlation with the cutting edge rounding of chisel edge, and the drilling torque corresponds well with the flank wear of the secondary cutting edge.