Research On Drilling Carbon Fiber Reinforced Plastic With Double Point Angle Drill

Carbon Fiber Reinforced Plastic(CFRP) exhibits a high specific strength, low interlaminar stress and high specific modulus, it is a typical lightweight and durability material of high performance composites in a new generation of aerospace applications. In the drilling process, the unreasonable selection of cutting parameters and tool geometry will cause defects such as burr, tear and damages on hole wall.Traditional drill has been unable to meet the requirement of high precision and high efficiency machining. Optimizing tool geometry and selecting reasonable cutting parameters have important significance to the improvement of hole quality.A series of tests has been carried out to investigate the drilling axial force, hole quality and the distribution law of drilling axial force and hole damage along cutting edge when drilling CFRP-T700. The major work of this thesis includes the following aspects:(1) A normal twist drill and three double point angle drills were used to drilling CFRP. The influence law of the cutting parameters to drilling axial force has been studied. The experiment analyzed the different of drilling axial force between the normal twist drill and the double point angle drills when drilling CFRP. The empirical model of drilling axial force of the four type of drill has been established by binary linear regression method. The results show that, from the perspective of reducing axial force, the double point angle drill, which ratio of the second main cutting edge and the first main cutting edge is 1, is more suitable for drilling CFRP.(2) Damage theory analysis of hole entry and exit when drilling CFRP with the normal twist drill and the double point angle drills has been carried out. The influence of with or without plate on hole exit quality has been analyzed. The change regularity of the four drill in tear at hole entry and exit with different cutting parameters has been studied. The hole wall quality and the hole entry and exit quality of the normal twist drill compared with that of the double point angle drills.The results show that the use of plate can improve the quality of hole exit significantly, and the double point angle drill can be more efficient to get a better hole entry and exit quality.(3) Phases experiments have been carried out with the normal twist drill and the double point angle drills to reveal the distribution law of drilling axial force and hole damage along cutting edge. The results show that the double point angle drill is more easy to realize without tear and burr-free, and is more suitable for CFRP hole machining.