Drill with a centering drill insert, and a method of using a drill with a centering drill insert, and the insert therefor

摘要

An insert includes a body portion and at least one cutting edge disposed on the periphery thereof. The cutting edge includes an inner lip and an outer lip disposed at an angle with respect to one another. A line extending along the inner lip intersects with a line extending along the outer lip at the vertex of the angle. The angular cutting edge further includes a protuberance disposed between, and connecting the inner and outer lips and projecting outwardly away from the body portion beyond the vertex of the angle defined by the intersection of the lines extending from the inner and outer lips. The protuberance having an inner lip connected to the inner lip of the cutting edge and an outer lip connected to the outer lip of the cutting edge to form smooth curvilinear transitions between the lips of the protuberance and the lips of the cutting edge.