Patent ID: 6030155
Filing Date: 2000-02-29
Classification: B23B,B23P,Y10T

Abstract:
A drill tool for machine tools comprising a drill body having at least two chip transport grooves which are delimited at their flanks by helical ribs,and comprising a cutting head which is disposed at a front face side of the drill body,the cutting head having at least two segment portions which are radially outwardly delimited by partially cylindrical circumferential surfaces and which are separated from each other by chip spaces which end in the adjacent chip transport grooves in a direction of chip flow and which are aligned essentially parallel to a tool axis,and at least two cutting inserts which are each disposed in a cutting insert recess of the segment portions in a region of respective essentially axially parallel radial chip breaker faces and the cutting inserts each having at least one active cutting edge which protrudes axially over the cutting head,wherein the chip breaker faces each end in a helical flank of the adjacent chip transport groove at a transition point in the direction of chip flow,wherein a first transition face is located at at least one of the transition points, which transition face recedes step-like from a first limiting edge of the chip breaker face while broadening a cross section of the chip space and which ends in a flank of the adjacent chip transport groove,wherein the chip spaces each have a chip guide face disposed at the adjacent segment portion, which is positioned opposite the respective chip breaker face at the side of the cutting insert and which, in a cross section through the chip space, includes an angle of 0.degree. to 110.degree. with the chip breaker face,the chip guide face having a second transition face at at least one of the transition points, the second transition face receding step-like in the chip flow direction from a second limiting edge of the chip guide face while broadening the cross section of the chip space and ending in a second flank of the adjacent chip transport groove,the second limiting edge extending into the region between the active cutting edge and the middle of the adjacent cutting insert, so that the cross sectional surface of the chip space continually increases from the tip of the cutting head to the chip transport groove,wherein the drill body has a drill shank at its end opposite the cutting head, said shank free of ribs and having a central coolant supply duct,wherein second and third coolant ducts are located in the ribs of the drill body, said second and third coolant ducts are helically curved with the same curvature as the ribs and extend from the cutting head over the entire length of the ribs with a constant slant angle (.beta.) with respect to the tool axis, and end in the central supply duct in the region of the ribless drill shank,and wherein the helix pitch of the chip transport grooves and the width of the chip transport grooves increase continuously or step-like in the chip flow direction.