US 7,201,542 B2Granted

Solid drill bit for machine tools

AssigneeKomet Praezisionswerkzeuge Robert Breuning GmbH

InventorsAndree Fritsch, Hans Haidinger, Alexander Krause, Jacek Kruszynski, Helmut Morlok, Frank Roeser, Henry Schuett, Miltiadis Theodorou

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Abstract

A solid drill bit for machine tools. has a bit body and two movable inserts located a radial distance apart in insert seats of the bit body. The inserts have a rectangular or quadratic contour, project axially over the bit body with their major cutting edges and overlap in their working area. The outer movable insert projects radially beyond the periphery of the bit body with its outer cutting edge corner and with the adjoining minor cutting edge. Starting from the cutting edge corner, the minor cutting edge is inclined in the direction of the bit body at a setting angle of less than 3.2 °. The minor cutting edge has a guiding edge that is slidingly supported against the wall of the bore over at least part of its length due to a radially outwardly oriented thrust force.

Claims19

Dependent claims

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 (αa) 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.

A solid drill bit for machine tools comprising:

a bit body having a cutting end, the bit body including:
first and second chip conveying channels extending to the cutting end;
a first recess opening in an area of the first chip conveying channel adjacent the cutting end;
and
a second recess opening in an area of the second chip conveying channel adjacent the cutting end;
a radially innermost movable insert that is rectangular or square in contour and that is mounted in the first recess, the innermost movable insert having a front facing major cutting edge projecting axially beyond the cutting end of the bit body, the major cutting edge of the innermost movable insert having a pre-cutting spacing (d) from the major cutting edge of the outermost movable insert that is smaller than a corner radius of the major cutting edge;
and
a radially outermost movable insert that is rectangular or square in contour and mounted in the second recess, the outermost movable insert being mounted radially from the innermost movable insert, wherein a working area of the outermost movable insert overlaps a working area of the innermost movable insert, the outermost movable insert comprising:
a front facing major cutting edge projecting axially beyond the cutting end of the bit body;
a minor cutting edge that is perpendicular to the major cutting edge and that projects radially outwardly beyond the periphery of the bit body, the minor cutting edge including:
a guiding edge comprising at least one of a land of a flank and a curvature of the minor cutting edge;
and
a separate actual cutting edge that is shifted radially inwardly with respect to the guiding edge;
and
an outer rounded cutting edge corner joining the major cutting edge and the minor cutting edge, the minor cutting edge being inclined starting out from the cutting edge corner in its longitudinal extent at a defined setting angle that is 1.2° to 3.2° in a longitudinal direction of the bit body,
wherein a face angle (αa) of the major cutting edge of the innermost movable insert is greater than a face angle (αa) of the major cutting edge of the outermost movable insert, and
wherein the guiding edge rests slidingly during a 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 so that the actual cutting edge of the minor cutting edge remains free from wear, whereby after movement of the outermost insert so that the actual cutting edge functions as the major cutting edge, the actual cutting edge is free from wear before a drilling operation begins.

14 more elements

Dependencies are inferred from the claim text.