Axial Deviation of a Hole in Deep Drilling : Influence of Tool Geometry (Comparison of Single and Multi-Edged Tools)

Abstract

The influence of tool geometry on hole deviation is investigated using four types of deep hole drilling tools, i.e., the normal type of gun drill, the standard type of BTA tool, the two-edged gun drill and a multi-edged BTA tool. Two types of workpiece are used, to make their influence clear : One of them has an asymmetric wall hardness of bonded plate is lower than that of the other. As a result, it is found experimentally and theoretically that the balancing of the cutting forces on the tool head contributed to a decrease of hole deviation. However, the existence of some unbalanced force is more effective for giving an accurate hole size than the complete balancing condition of the forces, because the latter condition gives oversized hole.