초록
In end milling process, which is characterized by the use of a rotating tool, the undeformed chip thickness varies periodically with phase change of the tool. Although many efforts have concentrated on the study of end milling process, the analysis of shear and chip-tool friction behaviors has not been reported. Recently, a model has been proposed to simulate the shear and friction characteristics of an up-end milling process in terms of the equivalent oblique cutting. In the current study, the varying undeformed chip thickness and the cutting forces in a down-end milling process are replaced with the equivalent ones of oblique cutting. Then it is possible to simulate the shear and the chip-tool friction characteristics of a down-end milling process. The proposed model has been verified through two sets of cutting tests i.e., down-end milling and the equivalent oblique cutting tests. The experimental results show that the proposed model is suitable to analyze the shear and chip-tool frictional characteristics of down-end milling process. The specific cutting energy decreases with increase in equivalent undeformed chip thickness in a down-end milling process.