Patent ID: 6655479
Filing Date: 2003-12-02
Classification: B23B

Abstract:
A helical drill bit for drilling in rock comprising an axially extending shank (2) with a chuck insert end (3) at one end and a drilling head (4) at the other end, said shank having at least one axially extending helical discharge groove (7), said groove (7) having a base (8) spaced radially inward from an outer circumferential surface of said shank with a groove reinforcement extending radially outwardly from the groove base (8), and the position and/or geometric form of said groove reinforcement (9) varying in the axial direction of said discharge groove (7), said shank having a helical land forming the outer circumferential surface of said shank, said groove reinforcement (9) has the location thereof in said groove (7) defined by a rib lead angle (&bgr;) differing slightly from a lead angle &agr; of said helical land.