AN INDEXABLE INSERT DRILL AND A CENTRE INSERT THEREFOR

摘要

An indexable insert drill and a center insert therefor are provided to improve strength in the most sensitive area of the center insert in the two portions that are situated in the cross-plane while surrounding a screw hole. A center insert for an indexable insert drills comprises an upper part(32) and a lower part between which a through hole extends. The center insert has an elongate basic shape that is mirror-symmetrical in relation to an imaginary longitudinal central plane(P) with which a center axis(C3) of the hole coincides. The center insert has longitudinal side contact surfaces(36) parallel to each other and end support surfaces(37,38) formed adjacent to chip-removing cutting edges(35) at two opposite short ends.