抄録
In this paper, changes of cutting mechanism in the plasma hot machining of 18% Mn steel are analyzed by means of a two-dimensional cutting simulator incorporated with the flow stress characteristics measured. Firstly, the outline of the simulator is presented, and then the material properties and simulation models used in the analysis are described. Experimental observations, such as the decreases in cutting forces and shear angle, the increases in chip curl radius and chip contact length in the hot machining are successfully simulated. These changing phenomena can closely be related to the changes of strain rate, strain, temperature and flow stress distributions within the primary deformation zone. Especially, the drop of flow stress at the free-surface sides of workpiece and chip by the heating is a main cause of the changing mechanism. Under an ideal heating condition, in which the heat penetrates up to the undeformed chip thickness, the temperatures on the rake face and finished surface are almost independent of the heating. Relating this fact to a wear equation proposed elesewhere, less cratering in the hot machining can analytically be predicted, which is due to the decrease in normal stress on the rake face.
