关键词: 聚四氟乙烯(PTFE), 成屑形成机理, 切屑毛边, 剪切面理论, 断裂理论, 分形理论

Abstract: In order to study the chip formation mechanism of PTFE materials in cutting processes, single factor orthogonal cutting experiments and quasi-static mechanics experiments were designed. Firstly, cutting speed and cutting thickness were taken as variables, the continuous chip and chip edge forming mechanism of PTFE materials were proposed based on the shear plane theory and fracture theory. Secondly, by analyzing the height and spacing of the edges, the influences of cutting parameters on the edge morphology were explored. Finally, the fractal theory was used to analyze the cutting force stability, revealing the relationship among the number of burrs, frequency and cutting force stability. The results show that the PTFE continuous chips are generated because the true compressive strain of the materials does not exceed the fracture yield strain in the cutting processes. The burrs are produced because of the nucleation and propagation of cracks at the lamellar structure of the chip edges. In addition, cutting parameters will affect the generation of burrs, when the cutting speed is as 100 mm/min and the cutting thickness is as 0.3 mm, the number of chip edges is the least, the frequency is the smallest and the cutting force is the most stable. The research results may provide reference for the edge suppression and surface processing quality optimization of PTFE materials in cutting processes. 

Key words: polytetrafluoroethylene(PTFE), mechanism of chip formation, chip edge, shear plane theory, fracture theory, fractal theory