PERIPHERAL MILLING TOOL AND METHOD FOR ARRANGING CUTTING EDGES

Abstract

A circumferential milling tool (10) for cutting metal is described, which comprises a milling cutter body (14) that can be rotated about a tool axis (12) and has at least two cutting edge groups. The arrangement of the first cutting edge group results in a first average chip thickness for the cutting edges (16) of the first cutting edge group and a second average chip thickness for the cutting edges (18, 20, 22, 24, 26) of the second cutting edge group. The first average chip thickness and the second average chip thickness are substantially equal. A method for arranging cutting edges (16, 18, 20, 22, 24, 26) on a circumferential milling tool (10) that can be rotated about a tool axis (12) is presented as well.

Claims

1. A circumferential milling tool for cutting metal, comprising a milling cutter body that can be rotated about a tool axis, on which at least two cutting edge groups are arranged, wherein the cutting edges of a first cutting edge group are arranged on a circular path which has a first diameter (d.sub.1) and extends around the tool axis and the cutting edges of a second cutting edge group are arranged on a circular path which has a second diameter (d.sub.2) and extends around the tool axis, wherein the cutting edges of the first cutting edge group are arranged at a first setting angle (κ.sub.1) and the cutting edges of the first cutting edge group are assigned a first average chip thickness (h.sub.m1) for a predetermined first tooth feed (f.sub.z1) and a predetermined first cutting width (A.sub.e1) and the cutting edges of the second cutting edge group are arranged on the milling cutter body at a second setting angle (κ.sub.2) such that they are assigned a second tooth feed (f.sub.z2) and a second cutting width (A.sub.e2) which result from the predetermined first tooth feed (f.sub.z1) and the predetermined first cutting width (A.sub.e1) and which in turn result in a second average chip thickness (h.sub.m2) that is assigned to the cutting edges of the second cutting edge group, wherein the first average chip thickness (h.sub.m1) and the second average chip thickness (h.sub.m2) are substantially equal.

2. The circumferential milling tool according to claim 1, wherein cutting edges of a third cutting edge group are provided, which are arranged on a circular path which has a third diameter (d.sub.3) and extends around the tool axis, and which are arranged on the milling cutter body at a third setting angle (κ.sub.3) such that they are assigned a third tooth feed (f.sub.z3) and a third cutting width (A.sub.e3) which result from the predetermined first tooth feed (f.sub.z1) and the predetermined first cutting width (A.sub.e1) and which in turn result in a third average chip thickness (h.sub.m3) that is assigned to the cutting edges of the third cutting edge group, wherein the third average chip thickness (h.sub.m3) is substantially equal to the first average chip thickness (h.sub.m1) and/or the second average chip thickness (h.sub.m2).

3. The circumferential milling tool according to claim 1, wherein the cutting edges are cutting edges of cutting inserts, in particular indexable inserts, arranged on the milling cutter body.

4. The circumferential milling tool according to claim 1, wherein the first average chip thickness (h.sub.m1) and/or the second average chip thickness (h.sub.m2) and/or the third average chip thickness (h.sub.m3) differ by at most 10%.

5. The circumferential milling tool according to claim 1, wherein the circumferential milling tool is a side milling cutter, a slotting cutter, a profile cutter, an angular milling cutter or a face milling cutter.

6. The circumferential milling tool according to claim 1, wherein the cutting edges of the first cutting edge group and/or the second cutting edge group and/or the third cutting edge group are arc-shaped, in particular circular arc-shaped.

7. The circumferential milling tool according to claim 1, wherein the setting angle (κ) of the cutting edges of different cutting edge groups are different.

8. The circumferential milling tool according to claim 6, wherein the setting angle (κ) of the arc-shaped cutting edges of different cutting edge groups adjoin one another with or without overlapping.

9. The circumferential milling tool according to claim 1, wherein the different cutting edge groups comprise different numbers of cutting edges.

10. The circumferential milling tool according to claim 1, wherein the cutting edges of at least one cutting edge group are distributed evenly around the circumference.

11. A method for arranging cutting edges on a circumferential milling tool that can be rotated about a tool axis, comprising the following steps: a) arranging cutting edges of a first cutting edge group on a circular path which has a first diameter (d1) and extends around the tool axis and each with a first setting angle (κ.sub.1), so that, at a predetermined rotational speed of the circumferential milling tool and a predetermined feed rate of the circumferential milling tool, a first cutting width (A.sub.e1) and a first tooth feed (f.sub.z1) for the cutting edges of the first cutting edge group are set, which result in a first average chip thickness (h.sub.m1) that is assigned to the cutting edges of the first cutting edge group, a) arranging cutting edges of a second cutting edge group on a circular path which has a second diameter (d.sub.2) and extends around the tool axis and each with a second setting angle (κ.sub.2), and wherein the second diameter (d.sub.2) and/or the second setting angle (κ.sub.2) are selected such that, at the predetermined rotational speed of the circumferential milling tool and the predetermined feed rate of the circumferential milling tool, a second cutting width (A.sub.e2) and a second tooth feed (f.sub.z2) for the cutting edges of the second cutting edge group are set, which result in a second average chip thickness (h.sub.m2) that is assigned to the cutting edges of a second cutting edge group, and the second average chip thickness (h.sub.m2) and the first average chip thickness (h.sub.m1) are substantially equal.

12. The method according to claim 11, wherein the first average chip thickness (h.sub.m1) and the second average chip thickness (h.sub.m2) are selected such that they differ by at most 10%.

13. The method according to claim 11, wherein the different cutting edge groups comprise different numbers of cutting edges.

14. The method according to claim 11, wherein the cutting edges of at least one cutting edge group are distributed evenly around the circumference.

Description

[0036] The invention is explained below with the aid of different design examples, which are shown in the accompanying drawings. The drawings show:

[0037] FIG. 1 in a perspective view, a circumferential milling tool according to the invention in a first embodiment, the cutting edges of which are arranged using a method according to the invention,

[0038] FIG. 2 the circumferential milling tool of FIG. 1 in a plan view,

[0039] FIG. 3 the circumferential milling tool of FIG. 2 in a sectional view along the line III-III,

[0040] FIG. 4 a detail IV of the circumferential milling tool of FIG. 3, wherein a fir-tree groove produced by means of the circumferential milling tool is also shown schematically,

[0041] FIG. 5 a sketch that serves to explain FIG. 4 in more detail,

[0042] FIG. 6 a sketch that serves to explain FIG. 4 in more detail,

[0043] FIG. 7 in a plan view, a circumferential milling tool according to the invention in a second embodiment, the cutting edges of which are arranged using a method according to the invention,

[0044] FIG. 8 a broken sectional view along the line VIII-VIII of the circumferential milling tool of FIG. 7,

[0045] FIG. 9 a detail IX of the circumferential milling tool of FIG. 8,

[0046] FIG. 10 in a lateral view, a circumferential milling tool according to the invention in a third embodiment, the cutting edges of which are arranged using a method according to the invention, and

[0047] FIG. 11 an example of a workpiece contour produced by means of the circumferential milling tool of FIG. 10, whereby an associated starting contour is shown as well.

[0048] FIGS. 1 to 6 show a circumferential milling tool 10 that is configured as a side milling cutter. Said tool is intended to produce grooves, in particular so-called fir-tree grooves 11 (see FIG. 4).

[0049] The circumferential milling tool 10 comprises a milling cutter body 14 that can be rotated about a tool axis 12.

[0050] It comprises a total of six cutting edge groups, which are described below in particular with reference to FIG. 4. The cutting edges of all six cutting edge groups are formed by indexable inserts arranged on the milling cutter body 14.

[0051] A first cutting edge group comprises the cutting edges 16, each of which has a circular shape. The cutting edges 16 can be referred to as main cutting edges.

[0052] A second cutting edge group is formed by the cutting edges 18. They also have a circular shape. The cutting edges 18 can also be referred to as main cutting edges.

[0053] Both the cutting edges 16 of the first cutting edge group and the cutting edges 18 of the second cutting edge group are arranged on a circular path having the same diameters. However, the cutting edges 16 of the first cutting edge group are preferably offset along the tool axis relative to the cutting edges 18 of the second cutting edge group.

[0054] A third cutting edge group, that comprises the cutting edges 20, is provided as well. These are circular. The cutting edges 20 can be referred to as relief cutting edges, whereby they in particular relieve the load on the cutting edges 16.

[0055] Furthermore, a fourth cutting edge group, that comprises the cutting edges 22, is provided. These, too, are circular. The cutting edges 22 of the fourth cutting edge group can be referred to as relief cutting edges. They in particular relieve the load on the cutting edges 18.

[0056] Compared to the first and second cutting edge groups, the cutting edges 20, 22 of the third and fourth cutting edge groups are arranged on a somewhat smaller diameter. The diameters of the third and fourth cutting edge groups are the same.

[0057] The relative arrangement of the cutting edges 18 and the cutting edges 22 is shown in detail in FIGS. 5 and 6.

[0058] From this it can be seen that the effective setting angle κ of the cutting edges 18 ranges only from 90° to 30°. This directly influences an assigned average chip thickness.

[0059] As can be seen in FIG. 6, the setting angle κ of the cutting edges 22 starts at 45° and goes down to 0°.

[0060] The setting angles κ of the cutting edges 18 and 22 are therefore different and adjoin one another with overlapping. The overlapping range extends from 30° to 45°. The same applies to the cutting edges 16 in relation to the cutting edges 20.

[0061] In order to produce the upper contour of the fir-tree groove 11 shown in FIG. 4, a fifth cutting edge group with cutting edges 24 and a sixth cutting edge group with cutting edges 26 are provided as well. In the embodiment shown, the cutting edges 24 and 26 are provided by indexable inserts having a substantially rectangular shape.

[0062] The following table shows the average chip thicknesses achieved with the first to sixth cutting edge group h.sub.m. The calculation is carried out using the diameter d assigned to the respective cutting edge group, the number of teeth Z, the setting angle K, the cutting width A.sub.e and the tooth feed f.sub.z. The aforementioned formula is used

TABLE-US-00001 First Second Third Fourth Fifth Sixth cutting cutting cutting cutting cutting cutting edge edge edge edge edge edge group group group group group group d [mm] 200 200 188.2 188.2 159 159 Z [−] 6 6 4 4 2 2 K [°] 90 90 45 45 85 85 A.sub.e [mm] 6.1 6.1 5.0 5.0 0.5 0.5 f.sub.z [mm] 0.17 0.17 0.26 0.26 0.51 0.51 h.sub.m [mm] 0.030 0.030 0.029 0.029 0.028 0.028

[0063] The table further shows that the different cutting edge groups comprise different numbers of cutting edges 16, 18, 20, 22, 24, 26.

[0064] The individual cutting edges 16, 18, 20, 22, 24, 26 are distributed substantially evenly around the circumference of the milling cutter body 14 (see FIGS. 1 and 2).

[0065] In the circumferential milling tool 10 according to the first embodiment, an angular distance of 15° between adjacent cutting edges 16, 18, 20, 22, 24, 26 is always maintained, regardless of affiliation to one of the cutting edge groups. The altogether 24 cutting edges 16, 18, 20, 22, 24, 26 are thus evenly distributed around the circumference of the milling cutter body 14.

[0066] 36 cutting edge stations can alternatively be provided as well. With a total of 36 cutting edge stations, a so-called 9-part division can start at 0°, 10° and 20° respectively. Starting from a 0° position, nine cutting edge stations are thus distributed evenly around the circumference of the milling cutter body 14. The same procedure is used for the start position 10° and 20°. A so-called 3-part division starts at the positions at 30°, 70°, and 110°. Starting from these starting positions, three cutting edge stations are thus respectively distributed evenly around the circumference of the milling cutter body 14. With this arrangement of the cutting edge stations, adjacent cutting edges are always offset by 10°.

[0067] In another variant with 36 cutting edge stations, a 9-part division can start at 0° and at 20° respectively, and a 6-part division can start at 10°, 30° and 50° respectively.

[0068] In an additional alternative having 36 cutting edge stations, 6-part divisions can start at 0°, 20°, 30° and 50°, and 4-part divisions can start at 10°, 10° [sic] and 70° respectively.

[0069] If, alternatively, only 20 cutting edge stations are provided, 5-part divisions can start at 0° and 36° and 2-part divisions can start at 18°, 54°, 90°, 126° and 162° respectively.

[0070] The table also shows that the given average chip thicknesses h.sub.m of the individual cutting edge groups are substantially equal.

[0071] A further, second embodiment of the circumferential milling tool 10 is shown in FIGS. 7 to 9. This embodiment again differs from the two aforementioned embodiments only by the values given in the following table. Otherwise, we refer to the explanations above.

TABLE-US-00002 First Second Third Fourth Fifth Sixth cutting cutting cutting cutting cutting cutting edge edge edge edge edge edge group group group group group group d [mm] 200 200 197.8 197.8 153.3 153.3 Z [−] 6 6 4 4 2 2

[0072] A third embodiment is shown in FIGS. 10 and 11. Here the circumferential milling tool 10 is configured as a face milling cutter.

[0073] It comprises only three cutting edge groups. These are again formed by indexable inserts, whereby the cutting edges are designated with the reference signs 16, 18, 20 of the cutting edges of the first three cutting edge groups from the aforementioned design examples.

[0074] In contrast to the aforementioned embodiments, the diameters on which the cutting edges 16, 18, 20 belonging to the different cutting edge groups are arranged are now the same. The cutting edges 16, 18, 20 and the indexable inserts of the individual cutting edge groups carrying them are offset from one another only along the tool axis 12.

[0075] The exact characteristic values of the circumferential milling tool 10 according to the third embodiment are shown in the following table:

TABLE-US-00003 First Second Third cutting edge cutting cutting edge group edge group group d [mm] 63 63 63 Z [—] 12 6 4 K [°] 90 90 90 A.sub.e [mm] 50 8.7 4.0 f.sub.z [mm] 0.22 0.44 0.66 h.sub.m [mm] 0.159 0.160 0.165

[0076] It can be seen that the specified average chip thicknesses h.sub.m are substantially equal.

[0077] With a circumferential milling tool according to the third embodiment, casting radii 28 of a cast component 30, for example, which is only shown schematically, can be removed (see FIG. 11). In this way, a final contour 32 with a precisely extending corner edge 34 can be produced.

[0078] In all embodiments, the cutting edges are arranged on a circumferential milling tool 10 that can be rotated about a tool axis 12 with the aid of a method for arranging cutting edges 16, 18, 20, 22, 24, 26. The following procedure is used:

[0079] First, the cutting edges 16 of the first cutting edge group are arranged on a circular path, which has a first diameter d.sub.1 and extends around the tool axis 12. The cutting edges 16 are respectively positioned at a first setting angle κ.sub.1, so that, at a predetermined rotational speed and a predetermined feed rate of the circumferential milling tool 10, a first cutting width A.sub.e1 and a first tooth feed f.sub.z1 for the cutting edges 16 of the first cutting edge group are set. This results in a first average chip thickness h.sub.m1, which is assigned to the cutting edges 16 of the first cutting edge group.

[0080] A second cutting edge group is then arranged on a circular path, which has a second diameter d.sub.2 and extends around the tool axis 12. In the sense of the method described here, each cutting edge group that is additional to the first cutting edge group is referred to as a second cutting edge group.

[0081] As can be seen from the above design examples, the second diameter d.sub.2 can be the same as or different than the first diameter d.sub.1.

[0082] The cutting edges 18, 20, 22, 24, 26 belonging to the second cutting edge group are respectively arranged at a second setting angle κ.sub.2.

[0083] The second diameter d.sub.2 and/or the second setting angle κ.sub.2 are selected such that, at the predetermined rotational speed and the predetermined feed rate of the circumferential milling tool 10, a second cutting width A.sub.e2 and a second tooth feed f.sub.z2 for the cutting edges 18, 20, 22, 24, 26 of the second cutting edge group are set.

[0084] It is also possible to vary the number of cutting edges 16, 18, 20, 22, 24, 26 of a cutting edge group as an additional influencing variable.

[0085] This results in a second average chip thickness h.sub.m2 for the second cutting edge group, which is assigned to the cutting edges 18, 20, 22, 24, 26 of the second cutting edge group.

[0086] The second average chip thickness h.sub.m2 is set via the mentioned influencing factors in such a way that it is substantially equal to the first average chip thickness h.sub.m1.

[0087] As already discussed, this means that the first average chip thickness h.sub.m1 and the second average chip thickness h.sub.m2 differ from one another by at most 10%, preferably by at most 5%, further preferably by at most 2%.

[0088] The cutting edges 16, 18, 20, 22, 24, 26 of the individual cutting edge groups are preferably distributed evenly around the circumference.