Patent ID: 9636756
Date: 2017-05-02
CPC Classifications: B23B,Y10T

Claim:
1. A multi-lip drilling tool with internal cooling ducts and point grinding with point thinning, in which a main cutting edge transitions into a central cutting edge section in the area of the drill core, wherein a cooling duct guided to the drill hit is formed in each drill web, and the cooling duct has the following characteristics as viewed in the cross section of the drill: a) It has the cross sectional form of an unsymmetrical kidney, wherein b) the largest circle (KE) essentially inscribed in the cooling duct cross section overlaps with the center of the drill webs and bounds the contour of the cooling duct cross section via a central angle (WZKE) in a range of between 80 and 90° in a radially external region (KEZW) facing away from the rotational direction; c) radially externally and in the cutting direction, the boundary curve (KEZW) defined by the inscribed circle (KE) is adjoined essentially in the circumferential direction by a cross sectional contour section (BQ d) the smaller radius of curvature (R e) radially internally and outside the inscribed largest circle (KE), the concave curve (KK) is once again adjoined by a convex duct bulging section (AKA) with a radius of curvature (R f) the curvature of the cross sectional boundary continuously increases from the bulging section (AKA) to the region KEZW.