Kozo Kishi1 and Hiroshi Eda1
1Department of Mechanical Engineering, Faculty of Engineering, Utsunomiya University, Utsunomiya
The plastic flow of a machined surface layer is produced through a shearing zone which involves a built-up edge. Therefore, the plastic flows of the built-up edge and the machined surface layer were observed by an optical microscope and an electron microscope for 0.25%, 0.45%C steels. The present study has been carried out by an analytical method for describing the relation between built-up edge and the burr or rotational slip in the machined surface layer. Emphasis is placed on the metallurgical behaviour of the work material in the extreme conditions of strain and disintergration in the built-up edge as it is an important factor in the machined surface layer. Changes of structural features in different types of the built-up edge and in the burr or rotational slip are discussed. The results are summarized as follows. The burr and the rotational slip are a disintergrated fragments of the built-up edge. In the range of cutting speed 0 ∼ 20 m/min, the nose type built-up edge seems to become a rotational slip. Also, in the range of cutting speed 20 ∼ 40 m/min, the trapezoid type built-up edge tends to become a burr. But the burr and the rotational slip almost disappears in the plate type built-up edge beyond the cutting speed 40 m/min.
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