Carbon Fiber Composite Drilling Axial Force And The Experimental Research On The Tool Wear

Carbon fiber reinforced composites (CFRP) as an advanced composite material are widely used as structural and functional materials. CFRP was belonged to the typical difficult-to-machine material in the process. Its characteristics such as laminated structure and anisotropy make it easy to produce delamination, tear, and the surface accuracy is difficult to ensure. High hardness, high strength and low thermal conductivity of CFRP easily lead to tool wear and failure, affect the processing quality, efficiency, and high processing costs.According to the difficulty of machining CFRP, the basic experimental studies on thrust force, holes quality and tool wear have been carried out on drilling CFRP in this thesis. The main works and achievements have been done as followed:(1) Studying the binary cutting mechanism and the drilling process of CFRP, and analyzed the causes of the holes defects. The results showed that the deformations of chips were affected by fiber orientation, and the thrust force has a direct relationship to delamination, tear, burr and other drilling defects.(2) Researching the influence of the bit materials, drilling parameters on the thrust force by orthogonal tests. The test results showed that the effects of the coating materials on the thrust force was the largest, and then were spindle speed and feed rate. The thrust force of the import kind of diamond coating (S-DLC) bit was far less than that of the YG6X bit, TiAlN coating, TiCN coating bit, and the surface of the hole wall was more smooth, and less tear, burr which appeared on the import and export side. The single factor tests of PCD and S-DLC bit were showed that both of the two kinds of bit could high the quality of processing CFRP.(3) Researching the relationship between the thrust force and tear factor on different materials bit by three groups contrast tests, Results showed that tear factor increased with thrust force in a linear relationship, and PCD and S-DLC bit could greatly reduce the drilling thrust force and tear defects.(4) Analyzing tool wear mechanism, and researched the tool failure forms and mechanism during drilling CFRP by SEM. The results showed that the failure forms of the bit were mainly flank wear on the main cutting edge, chipping, chip adhesion and coating flaking. The thrust force increased linearly with VB value. In contrast, PCD and S-DLC bit had brtter abrasion resistance and cutting stability. (5) Observing hole wall surface morphology by SEM, and found that resin coated surface and fiber fracture surface were the mainly surface morphology, and fiber fracture surface included five kinds. There was no fiber fracture surface on the bore wall and the surface was smooth, which were produced by PCD and S-DLC bits.