Soichi Ibaraki, Kyoto University

In a finishing process of die and mold by using a ball end mill, a contour parallel tool path is usually used under a constant depth of cut (typically about 0.1 mm) and a constant feedrate. In such a process, the cutting force acting on a tool is usually less than 20 N. However, it significantly varies depending on the machining geometry, which causes the variation of tool deflection, and then deteriorates the machining accuracy. To address this issue, we propose a tool path design scheme to control the depth of cut in an intermediate-finishing process, such that the cutting force in a finishing process is regulated constant in a finishing process and thus the machining accuracy is improved. To this goal, in this paper we experimentally investigate the following:
1) the relationship between the angular location of the cutting point on a tool and the cutting force, and
2) the relationship between the depth of cut and the cutting force.
The relationship between the depth of cut and the engagement angle can be computed from a CAD model. A mathematical prediction model of the cutting force can be identified based on these relationships.

Key Words: finishing process, ball end mill, cutting force, machining accuracy, cutting point, engagement angle