Rotatable cutting bit insert

摘要

A multi-portion carbide cutting insert which affixes to the forward end of a rotatable cutting bit. The cutting insert has an axially forward tip portion and a flange portion with at least four mediate portions between the tip portion and the flange portion. The first mediate portion has an included angle less than that of the second mediate portion. The second mediate portion has an included angle greater than that of the third mediate portion. The fourth mediate portion has the largest included angle.