Indexable insert drill

Abstract

An indexable insert drill is disclosed that avoids formation of a breakout slug and therefore is particularly suited for drilling a laminate workpiece or stacked workpieces. The tool includes a cylindrical body provided with opposed flutes. A radially inner indexable carbide insert is releasably secured in the back wall of one flute at the leading end of the body and a radially outer insert is similarly secured in the back wall of the opposed flute. The inserts present an active cutting edge generally disposed in a transverse plane containing the axis of the tool and in axially leading relation relative to the tool body, and together are adapted to cut a hole of given diameter with the active cutting edges providing for overlap therebetween. The active cutting edges of the respective inserts have an axially leading point adjacent to their inner extremity disposed in a common plane generally normal to the tool axis and extend obliquely therefrom at a trailing angle relative to that common plane with the active cutting edge of the inner insert having a lesser trailing angle than the active cutting edge of the outer insert. The location and orientation of the inserts in the tool body providing for their respective active cutting edges to cut paths that intercept each other such that each insert will cut a pair of radially spaced chip segments as the tool progresses relative to a workpiece.