Back-Bending in the Primary Flow of Chip.

Abstract

The primary flow in a chip may sometimes bend backward in the center of thickness a little toward rake face. This phenomenon occurs always when gaseous oxygen is blown against the cutting edge from the beginning of cutting carbon steel with the speed range in which built-up edge occurs. For this reason, it is that a wedge-type built up edge with a sharp nose edge formed by the effect of oxide film occurs, the chip cut by the sharp built-up edge with a large rake angle impinges violently against the rake face of the tool and it is sheared again. The mechanism of the back-bending of primary flow can be explained by considering shear planes having the angle of φ2, φ21 and φ22 in addition to the ordinary shear angle φ1.