Study On The Drilling Technology Of CFRP

Carbon fiber reinforced plastics(CFRP) are characterized by superior strength-to-weight and stiffness-to-weigh ratios, high fatigue strength and good heat resistance. They have been used widely in airplanes, spaceships, automobiles and sport equipment, etc.The thesis presents an intensive study on drilling of CFRP, especially the high speed and high quality drilling technology. A horizontal and a vertical high speed drilling machines were developed specially for the purpose of high speed drilling of CFRP. It was demonstrated that the two machines were ideal equipment for composite drilling and they could also be used for small hole high speed drilling on other materials.Based on the principle of orthogonal cutting of CFRP, this thesis discussed the deformation of chips, and the microstructure of machined surface, etc. Cutting forces were studied using the orthogonal cutting model, and some satisfactory mathematical relationships were obtained.The thesis studied the cutting forces of CFRP during high speed drilling, discussed the effects of cutting parameters on drilling forces, and established the empirical equations concerning drilling force and the drill speed, feed rate, diameter of drill, etc.The microstructure on the hole surface of CFRP is a very important characteristic of the quality of hole drilling. By using a scanning electron microscope, the author carried out a detailed observation of the microstructure of the hole surface, and obtained many SEM micrographs of microstructure of hole surface, and reached many valuable conclusions.Spalling and fuzzing are defects of CFRP hole at exit. The thesis summarized their typical feature. The formation process of the defects consists of two phases of chisel edge action and major edge action. The relations between the size of spalling and drilling parameters were discussed.Delamination is another main defect of CFRP drilling. However, there is little study on delamination between layers which can be located qualitatively. This thesis presented two methods of detection for delamination between layers, i.e. the scanning acoustic microscope (SAM) method and AuCl3 solution approach. A 3-D...