Drilling tool
A drilling tool includes at least two chip flutes and a chisel edge with a thinned region. The thinned region merges continuously into the chip flutes in such a way that the thinned region forms the end of the respective chip flute in the region of the chisel edge.
1. A process for producing a drilling tool, the process comprising:
feeding a rotating grinding disk into a drill blank;
forming a chisel edge;
forming a curved major cutting edge which extends from the chisel edge in a radial direction of the drill blank;
forming a thinned region near an end of the drill blank, via moving the grinding disk in a radial direction of the drill blank, wherein the thinned region extends to the chisel edge and the curved major cutting edge; and
forming a chip flute which continuously adjoins the thinned region, via moving the grinding disk in a longitudinal direction of the drill blank;
wherein said forming of the thinned region comprises:
forming a portion of the chip flute, and an end of the chip flute, in the region of the chisel edge; and
forming the thinned region to merge continuously, without any discontinuities, without any kinks, and without any ridges, into a remainder of the chip flute.
2. The process of claim 1 , further comprising rotating the drill blank while performing at least one of:
said forming of a thinned region; or
said forming of a chip flute.
3. The process of claim 1 , further comprising performing an end grinding of the drill blank.
4. The process of claim 1 , further comprising forming a curved major cutting edge with the grinding disk.
5. The process of claim 1 , further comprising:
grinding a protective chamfer along a minor cutting edge via a follow-up motion of the grinding disk;
wherein said follow-up motion comprises using a set angle of a grinding disk, the set angle being less than a lead angle of the chip flute.
6. The process of claim 1 , wherein said forming of the thinned region and said forming of the chip flute are performed in a single-stage grinding process.
7. The process of claim 6 , wherein said forming of the thinned region is performed prior to said forming of the chip flute.
8. The process of claim 1 , comprising:
forming a major flank disposed on a side of the chisel edge;
wherein said forming of the thinned region results in the chip flute extending continuously, without any discontinuities, without any kinks, and without any ridges, to each of: the chisel edge, the major cutting edge, the major flank; and
wherein said forming of the thinned region and said forming of the chip flute are performed continuously with respect to one another.
9. The process of claim 8 , wherein said forming of the chip flute comprises forming the chip flute to be fully concave toward a central axis of the drilling tool, when viewed in transverse cross-section at one or more axial points along the chip flute.
10. The process of claim 7 , wherein the drilling tool comprises a core diameter that is reduced steadily, from a normal core diameter to a reduced core diameter at the chisel edge by the thinned region.
11. The process of claim 10 , wherein the normal core diameter does not increase between the thinned region and a region of run-out of the chip flutes.
12. The drilling tool of claim 10 , wherein the reduced core diameter corresponds to 0.01 to 0.2 times an outside diameter of the drilling tool.
13. The drilling tool of claim 1 , wherein the thinned region has a longitudinal extent in the longitudinal direction of the drill which corresponds to 0.1 to 1.5 times an outside diameter of the drilling tool.
14. The process of claim 1 , wherein:
said forming of the chip flute comprises forming a helical chip flute; and
said forming of the thinned region comprises forming a helical thinned region.
15. The process of claim 1 , wherein the chip flute extends to a first defining axial edge which, when viewed in transverse cross-section, is disposed adjacent an outer circumference of the drilling tool.
16. The process of claim 15 , comprising:
grinding a protective chamfer along a minor cutting edge via a follow-up motion of the grinding disk;
the protective chamfer extending helically in a generally axial direction at an outer circumference of the drilling tool;
wherein the defining axial edge of at least one of the chip flutes comprises an edge of the protective chamfer.
17. The drilling tool of claim 15 , wherein each of the chip flutes extends to a second defining axial edge which, when viewed in transverse cross-section, is disposed adjacent an outer circumference of the drilling tool.