Researchs On The Thrust Force And Holes Quality In Drilling CFRP

Carbon fiber reinforced plastics (CFRP) are characterized by superior strength-to-weight, specific modulus, stiffness-to-weight ratios, and they possess a large number of advantages, such as low thermal expansion coefficient, high fatigue strength and anticorrosion, etc. They have been used widely in airplanes, spaceships, national defense, industry and sport equipment, etc. Drilling of CFRP is a conventional technology in the process of installing fasteners on the CFRP components, but it's hard to guarantee the quality of hole drilling on CFRP, CFRP is a kind of typical difficult-to-machine material because of its characteristics such as high strength, high hardness, and anisotropy.According to the difficulty of machining CFRP, the basic and experimental researches about thrust force and holes quality on drilling CFRP have been carried out in this thesis. The main works have been done as follows:(1) The YG6X solid carbide twist drill and two kind brazed diamond core drills have been used in the CFRP drilling experiment. This thesis has analyzed the drilling processes when the twist drill and core drill were been used, and the effects of process parameters on thrust force have been studied. At the same time, the thrust forces and wear pattern of the solid carbide twist drill and brazed diamond core drill have been compared, and then the brazed diamond core drill has been considered to be a favorable drill on drilling CFRP.(2) The thesis has discussed the reasons why the spallings of hole's entrance and exit generated when the YG6X solid carbide twist drill and brazed diamond core drills have been used. The effects of process parameters on the qualities of hole's entrance and exit have been studied. At the same time, the qualities of holes'entrance and exit of the twist drill and core drill have been compared, and then discovered that we can obtain the high quality holes efficiently when used the brazed diamond core drill.(3) The AuCl3 solution approach has been used to detect the holes'delamination, and the thesis has analyzed the reasons of why the delamination generated when used the twist drill and core drill. The characteristics of the delamination of the holes which drilled by the two kind drills, and then the methods about how to reduce the delamination have been put forward.(4) The morphologies of holes'wall have been observed, and the effects of the angular separation between fiber direction and cutting direction on the roughness of the holes'wall, and then the characteristics of morphologies of holes'wall generated by the two kind drills have been compared. Experiment results have discovered that the angular separation was varied periodically, and because of the variety, the roughnesses of the holes'wall were different.