Patent ID: 11883887
Assignee: MK-TOOLS-SERVICE GMBH
Field: Machine tools (Mechanical engineering)
Classification: CPC B | IPC B

Claim 28:
29. Drill, comprising:
a base body extending substantially longitudinally in a direction axial to a drill axis, said base body comprising a drilling portion,
a radially inward core region in relation to the drill axis and a radially outer region provided in the base body in the drilling portion,
the drilling portion comprising a plurality of spiral-shaped recesses in the outer region,
a plurality of wall parts, each of the plurality of wall parts arranged between two respective spiral-shaped recesses, and
at least four central cutting edge portions, each of the at least four central cutting edge portions extends radially inwardly, in relation to the drill axis, up to a front tip,
wherein:
each of the at least four central cutting edge portions is of a cutting configuration;
in at least one of the central cutting edge portions a central rake face of the base body extends at a central rake angle up to the central cutting edge portion and a central flank of the base body extends at a central clearance angle up to the central cutting edge portion;
the central rake angle is measured between the central rake face and a geometric radial reference face, which extends in parallel to the drill axis;
the central rake angle is at least −5° and/or is at most 20°, wherein negative values of the central rake angle correspond to an undercut of the central cutting edge portion; and
the central clearance angle is measured between the central flank and a geometric reference plane extending perpendicularly to the drill axis, and wherein the central clearance angle is at least 3° and/or at most 25°.