Abstract
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.
Claims
1-13. (canceled)
14. A process for producing a drilling tool, the process comprising: feeding a rotating grinding disk into a drill blank; forming a thinned region near the end of the drill blank, via moving the grinding disk in a radial direction of the drill blank; and forming a chip flute which continuously adjoins the thinned region, via moving the grinding disk in a longitudinal direction of the drill blank.
15. The process of claim 14, 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.
16. The process of claim 14, further comprising performing an end grinding of the drill blank.
17. The process of claim 14, further comprising forming a curved major cutting edge with the grinding disk.
18. The process of claim 14, 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.
19. The process of claim 14, wherein said forming of the thinned region and said forming of the chip flute are performed in a single-stage grinding process.
20. The process of claim 19, wherein said forming of the thinned region is performed prior to said forming of the chip flute.
21. The process of claim 14, wherein: the drilling tool comprises a chisel edge; the thinned region comprises a portion of the chip flute and forms an end of the chip flute in the region of the chisel edge; and the thinned region merges continuously, without any discontinuities, without any kinks, and without any ridges, into a remainder of the chip flute.
22. The process of claim 21, wherein: the drilling tool comprises: a major cutting edge; and a major flank disposed on a side of the chisel edge; and the chip flute extends continuously, without any discontinuities, without any kinks, and without any ridges, to each of: the chisel edge, the major cutting edge, the major flank.
23. The process of claim 22, wherein the chip flute is 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.
24. The process of claim 21, 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.
25. The process of claim 24, wherein the normal core diameter does not decrease between the thinned region and a region of run-out of the chip flutes.
26. The drilling tool of claim 24, wherein the reduced core diameter corresponds to 0.01 to 0.2 times an outside diameter of the drilling tool.
27. The drilling tool of claim 14, 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.
28. The process of claim 14, 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.
29. The process of claim 14, 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.
30. The process of claim 29, 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.
31. The drilling tool of claim 29, 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.
Description
DESCRIPTION OF THE FIGURES
[0020] FIG. 1 shows an illustration of the point of a drilling tool according to the invention, with the left-hand half of FIG. 1 showing a plan view of the drill point in a longitudinal direction of the drilling tool and the right-hand half showing a corresponding side view of the drill point;
[0021] FIG. 2 shows a conventional drilling tool point without thinning in accordance with the prior art;
[0022] FIG. 3 shows a conventional drill point with thinning in accordance with the prior art, with the left-hand half of FIG. 3 showing the plan view of the drill point with conventional thinning in a longitudinal direction of the drilling tool and the right-hand half showing the side view of this drill point;
[0023] FIG. 4 shows the side view of the profile of the core diameter of a drilling tool in accordance with the prior art,
[0024] FIG. 5 shows the side view of the core profile of a drilling tool according to the invention;
[0025] FIG. 6 shows the side view of the core profile of a drilling tool with a constant bevel;
[0026] FIGS. 7 to 11 show the core profile of the drilling tool illustrated in FIG. 5 in section at various positions spaced apart in a longitudinal direction of the drilling tool;
[0027] FIG. 12 shows the position of the grinding disk of a grinding tool at the beginning of the grinding process according to the invention as it grinds a curved major cutting edge onto a drilling tool, in a plan view of the drill point on the left-hand side and in side view on the right-hand side;
[0028] FIG. 12 shows the views from FIG. 12 with the position of the grinding disk at the end of the thinned region of the curved major cutting edge of the drilling tool;
[0029] FIG. 14 shows the illustrations according to FIG. 12 but for grinding a thinned region on a tool with a straight major cutting edge, and
[0030] FIG. 15 Shows the grinding disk from FIG. 14 at the end of the thinning operation.
DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENT
[0031] The drilling tool illustrated in FIG. 1 has the two major cutting edges 1a and 1b with a protective chamfer 12, and the chisel edge 8, which connects the major cutting edges 1a, 1b and has the thinned region 2. The continuous transition from the thinned region 2 into the corresponding chip flute 3a can be seen in the right-hand half of FIG. 1. From the left-hand part of FIG. 1 it can be seen that, corresponding to the two major cutting edges 1a, 1b, two chip flutes 3a and 3b are also formed on the drilling tool according to the invention. Here, the term continuous transition should be understood to mean that the (chip flute) wall region which directly adjoins the end of the drill (end face), in particular the chisel edge, and extends in an axial direction has a smooth surface without ridges and kinks. Adjoining the major cutting edges 1a and 1b there are respective major flanks 4a and 4b. These end at a step 20 or ridge, which forms the transition to the chip flute 3a, 3b. The direction of rotation 5 of the drilling tool is furthermore indicated by a corresponding arrow in FIG. 1. The longitudinal direction 6 of the drilling tool and the radial direction 7 are also shown in FIG. 1.
[0032] FIG. 2 likewise shows a plan view of the drilling point of a drilling tool, said plan view corresponding to the left-hand view in FIG. 1, although this is according to the prior art. This prior art drilling tool too has two major cutting edges 1a, 1b, two corresponding major flanks 4a, 4b and two chip flutes 3a, 3b. However, there is no thinned region here. On this prior art tool, the chisel edge 8 connecting the two major cutting edges 1a and 1b obviously has a very much greater width in radial direction 7 than the chisel edge 8 with the thinned region 2 on the subject matter of the invention illustrated in FIG. 1.
[0033] Finally, FIG. 3 shows the drill point of a drilling tool with conventional thinning in accordance with the prior art. This known tool too has two major cutting edges 1a, 1b, two chip flutes 3a, 3b and two major flanks 4a, 4b. Also visible, at the transition from the major cutting edges 1a, 1b to the chisel edge 8, are the two ground ridges 9 in the region of the major cutting edges 1a, 1b, which are formed by the repeated application of the grinding disk to the region of the cutting edges during the production of the thinned region 2 on the conventional tool illustrated in FIG. 3.
[0034] FIG. 4 shows the profile of the core diameter geometry in side view. In contrast to the profile of the core diameter geometry according to the prior art, which is shown in FIG. 4, the embodiment according to the invention, which is illustrated in FIG. 5, has a thinned region 2 with a twist corresponding to the helical shape of the chip flute 3a, 3b. This thinned region 2 has a longitudinal extent L in a longitudinal direction 6 of the drilling tool. The magnitude of this longitudinal extent corresponds to 0.1 to 1.5 times the outside circumference diameter D1 of the drilling tool. The central diameter d of the thinned region corresponds to 0.01 times to 0.2 times the outside circumference diameter D1. The actual core diameter D of the drilling tool corresponds to 0.1 to 0.6 times the outside circumference diameter D1.
[0035] Finally, FIG. 6 shows a core profile with a constant bevel. Here, the longitudinal extent L of the thinned region 2 corresponds to no more than 1.0 times the outside circumference diameter D1. The major cutting edges 1a, 1b of this embodiment can be reground.
[0036] FIG. 7 to FIG. 11 show various sections through the drilling tool illustrated in FIG. 5 along the longitudinal direction 6 at different longitudinal distances LA. The figures are computer-generated illustrations in which the peripheral boundary edge is indicated only by the circular profile of the outside circumference diameter D1. FIG. 7 shows the view of the drill point at a longitudinal distance LA=90, and is therefore equivalent to an end view. FIG. 8 shows the cross section of the drilling tool illustrated in FIG. 7 sectioned at the point which corresponds to the longitudinal distance LA from the drill point in the longitudinal direction 6 of the drilling tool corresponding to 0.11 times the outside circumference diameter D1. The central circle depicted indicates the periphery of the drilling tool at the level of this longitudinal distance LA. FIG. 9 shows the same drilling tool sectioned at the point of the longitudinal distance LA from the point of the drilling tool corresponding to 0.2 times the outside circumference diameter D1. FIG. 10 shows the profile at a longitudinal distance LA amounting to half the value of the outside circumference diameter D1 from the drilling point. Finally, FIG. 11 shows through the drilling tool at a longitudinal distance LA corresponding to 1.5 times the outside circumference diameter D1.
[0037] From a comparison of FIGS. 7 to 9, on the one hand, the increase in the core diameter d is very clearly visible. On the other hand, the helical profile of the chip flute wall and hence also of the thinned region can also be seen. The profile of the chip flute wall in the section plane is represented by the thick black lines.
[0038] Finally, FIG. 12 to FIG. 15 show by way of example the progress of the process according to the invention for producing the drilling tool according to the invention. At the beginning of the production process, the rotating grinding disk 10 feeds into the drill blank 11 from the drill point. Initially, the grinding disk 10 performs a grinding movement in a radial direction 7 of the drill blank 11 in order to grind the thinned region in the region of the major cutting edge. For continuous grinding of the chip flutes 3a, 3b, the grinding disk 10 then moves along the drill blank 11 in the longitudinal direction 6 of the drilling tool. For this purpose, the drill blank 11 is moved along the circumference of the grinding disk in this embodiment, or changes its angular position relative to the grinding disk. In the first example, shown in FIGS. 12 and 13, from the angular position of the grinding disk A=36.918 to the angular position A=20.632. The angular position of the drill blank 11 therefore varies, i.e. the tilt of the center line thereof relative to the radial of the grinding disk 10 varies (when considered in the plane of the drawing). In the second. embodiment, which is shown in FIGS. 14 and 15, the center line is in alignment with the radial of the grinding disk 10 at the beginning of the process, in contrast to the preceding example.
[0039] Ifin the illustrative embodimenta helical chip flute 3a, 3b is to be ground, the drill blank 11 rotates in the direction of rotation 5 during the grinding movement. of the grinding disk 10.
[0040] During the grinding of a curved major cutting edge 1a, 1b, as shown in FIG. 12 and FIG. 13, the point of disk engagement changes, beginning from the drill tip to a length in the longitudinal direction of the drilling tool which corresponds to 3 times the outside circumference diameter D1. The change in the point of disk engagement changes in a range of from 0 to 120, based on the central longitudinal axis of the drilling tool 11, relative to the center of the grinding disk 10.
[0041] FIG. 14 and FIG. 15, in contrast, show the case of production of a straight major cutting edge 1a and 1b.
