Patent ID: 7201542
Filing Date: 2007-04-10
Classification: B23B,Y10S,Y10T

Abstract:
1. A solid drill bit for machine tools with a bit body and at least two movable inserts, rectangular or square in contour, each arranged at a radial distance from one another and in a recess in the bit body in the area of a chip-conveying channel, project with their front facing end major cutting edges axially beyond the bit body, and radially overlap one another in their working area, wherein the radially outermost movable insert projects radially beyond the periphery of the bit body with its outer rounded cutting edge corner and with its following minor cutting edge, which is perpendicular to the respective major cutting edge, and wherein the respective minor cutting edge is inclined starting out from the cutting edge corner in its longitudinal extent at a defined setting angle (α a ) of less than 3.2° in direction of the bit body, and wherein the minor cutting edge of the outermost movable insert comprises a guiding edge and an actual cutting edge which is shifted radially inwardly compared with the guiding edge so that the guiding edge rests slidingly during the drilling operation under the action of a radially outwardly directed thrust force at least over a part of its length against a wall of a created bore, and wherein the guiding edge is formed by at least one of a land of a flank and curvature of the minor cutting edge.