End mill

Abstract

To provide an end mill which, in particular, enables reliable quality in the case of face milling and in boring operations.SOLUTION: Provided on an end side of a cutting region are at least one first point thinning of a core between (first) two mutually adjacent cutting edges, and at least one second point thinning between two (other, or second) mutually adjacent cutting edges. The first point thinning is to have a (point thinning) angle of 30° to 45°, and the second point thinning is to have a (point thinning) angle of 35° to 50°. Moreover, the first point thinning is to have a (point thinning) opening angle of 30° to 50°, and the second point thinning is to have a (point thinning) opening angle of 40° to 60° (the opening angle always being the angle between flanks of the point thinning in top view onto the end side of the end mill).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The invention relates to an end mill for subtractive machining of metallic materials, in particular steel and titanium, according to the preamble of claim 1. [Background technology]

[0002] An end mill having a fastening part and a cutting zone is known from US Pat. No. 5,399,633. The cutting zone is formed by a rotationally symmetric core, in this case by four cutting edges arranged helically around the core and integrally connected to the core.

[0003] The four cutting edges have in each case one circumferential primary cutting edge and one secondary cutting edge on the free end side of the cutting area, as a result of which it is realized that in the case of face milling with secondary cutting edges, a good surface quality is achieved.

[0004] However, this type of end mill has the disadvantage that it is not suitable for drilling operations with a feed direction substantially along the rotation axis of the end mill and therefore for subtractive machining using end-side proximal secondary cutting edges, since there are no cutting edges located in the area close to the center.

[0005] Even in the case of tools in which at least a portion of the cutting edge extends substantially to the axis of rotation of the end mill, the drilling operation is difficult since the necessary chip removal cannot be reliably guaranteed.

[0006] Furthermore, in order to enable a drilling operation or even subtractive machining on the entire end side, the end mill of the '159 patent provides a point thinning of the core between the respective mutually adjacent cutting edges on its end side.

[0007] In the end mill of (Patent Document 1), the point thinnings are dimensioned at 30° to 40° (between the second and third cutting edges and between the fourth and first cutting edges) and 20° to 40° (between the first and second cutting edges and between the third and fourth cutting edges).

[0008] The '610 patent provides or sizes its point thinning angle as referenced relative to the axis of rotation of the end mill.

[0009] For example, when measured with respect to the end mill's proximal normal plane relative to the end mill's axis of rotation, the end mill of (Patent Document 1) provides point thinnings of 50°-60° (between the second and third cutting edges and between the fourth and first cutting edges) and 50°-70° (between the first and second cutting edges and between the third and fourth cutting edges), respectively. This means that the point thinning angles whose magnitudes are provided herein are the angles enclosed between (1) the connecting line / straight line of the deepest point of the point thinning, i.e., the point furthest axially from the end mill and connected to the piercing point of the end mill's axis of rotation that passes through the end mill's proximal normal plane, and (2) the end mill's proximal normal plane.

[0010] Thus, the end mill of the '661 patent provides a very steeply extending point thinning, which indeed improves the drilling action, but it sacrifices tooth thickness and tooth stability and therefore the rigidity and quality of the end mill in the case of face milling. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] German Patent Application Publication No. 102015116623A1 Summary of the Invention [Problem to be solved by the invention]

[0012] The object of the present invention is to improve end mills known from the prior art and to further improve them with a view to enabling reliable quality, in particular in the case of face milling and in drilling operations. [Means for solving the problem]

[0013] This object is achieved by an end mill having the features of the independent claims.

[0014] Advantageous developments of the invention are the subject of the dependent claims and the following description.

[0015] Any terms used, such as top, bottom, front, back, left or right, unless expressly defined otherwise, shall be understood according to ordinary understanding and with respect to the drawings of this application. Terms used, such as radial and axial, unless expressly defined otherwise, shall be understood with respect to the center or axis of symmetry of the components described herein and with respect to the drawings of this application.

[0016] The term "substantially," as it is used, can be understood (as understood by the Supreme Court) to mean "to a realistic yet significant extent." Thus, deviations from the precision thus implied by the term can occur unintentionally (i.e., without any functional basis) due to manufacturing or assembly tolerances, etc.

[0017] Preferably, the end mill made from solid carbide provides the fastening and the cutting zone, which is formed by a core and at least two, in particular four (or even a larger number, for example six or eight) cutting edges arranged around the core and extending helically around the rotation axis of the end mill, each of said cutting edges having in each case one circumferential primary cutting edge and one secondary cutting edge at the end of the cutting zone, i.e. one end-side proximal secondary cutting edge.

[0018] At the end side of the cutting region, there is provided at least one first point thinning of the core between two (first) adjacent cutting edges and at least one second point thinning between two (other or second) adjacent cutting edges.

[0019] The end mill is further distinguished in that the first point thinning is designed geometrically differently from the second point thinning or differs in geometric terms from the second point thinning, or in other words, simply put, the end mill implements at least two geometrically different point thinnings.

[0020] Furthermore, the first point thinning has a (point thinning) angle of 30° to 45°, particularly 32° to 38°, especially about 35°, and the second point thinning has a (point thinning) angle of 35° to 50°, particularly 39° to 46°, especially about 42.5° (always with respect to a normal plane (e.g. proximal to the end side) to the rotation axis of the end mill).

[0021] Here, in an end mill, the point thinning angle is measured or stated, for example, with respect to the end-side proximal normal plane relative to the rotation axis of the end mill, which means that the point thinning angle measured here is the angle enclosed between (1) the connecting line / straight line of the deepest point of the point thinning, i.e., the point furthest axially from the end side, connected to the piercing point of the rotation axis of the end mill that passes through the end-side proximal normal plane of the end mill, and (2) the end-side proximal normal plane.

[0022] Furthermore, the first point thinning has an opening angle of 30° to 50°, in particular 35° to 45°, especially about 40°, and the second point thinning has an opening angle of 40° to 60°, in particular 41° to 50°, especially about 42.5° (the opening angle is always the angle between the flanks of the point thinnings in a top view on the end side of the end mill).

[0023] Here, the point thinning opening angle is measured as the angle between the flanks of the point thinning in the top view of the end mill's end side, in other words, the flanks of the point thinning in the top view of the end mill's end side converge to an angle that appears in its perspective view, specifically here the point thinning opening angle (the tip of the angle may also be optionally rounded).

[0024] Here, point thinning can include any design embodiment whereby the material of the core and potentially also the cutting edges in the end side areas of the cutting edge region is reduced in a limited localized area in the circumferential direction between the cutting edges.

[0025] Core is understood to mean the rotationally symmetric core area of ​​the end mill in the cutting area. The cutting edges are arranged centrally about this core and are formed integrally with it. The base of each chip removal groove formed circumferentially between the cutting edges is delimited by the core.

[0026] In a preferred embodiment, the point thinning can be formed as a gap in the region on the end side of the cutting area, which approaches the rotation axis of the end mill in the direction from the fastening part to the end side of the cutting area. This type of gap can be particularly easily realized, for example, by grinding.

[0027] End mills are based on the knowledge or concept that as the point thinning angle increases, the end mill's ability to perform drilling operations is enhanced or improved, and therefore the point thinning angle is made larger or steeper. However, as the point thinning increases or the point thinning angle becomes larger / steeper, the tooth thickness decreases, which compromises or potentially compromises the strength and rigidity of the end mill and, in the case of face milling, its quality.

[0028] Proceeding from this knowledge, the end mill according to the invention now seeks to find a compromise between these competing requirements, namely chip removal and stability of or in a drilling operation and in the case of face milling.

[0029] Surprisingly, it is now demonstrated that when a larger first point thinning angle is implemented that facilitates the drilling operation but potentially worsens the face milling, the potentially "compromising aspect" can be "compensated" by a simultaneously implemented smaller second point thinning angle, thereby meeting or potentially meeting the competing requirements.

[0030] However, as has also been demonstrated, the two different "competing" point thinnings should not or should not, on the one hand, be in the range of extreme limits (e.g., less than 20° or more than 70°) and, on the other hand, be too far away or deviate too far from each other, since in both such "extres" (both absolute and relative) the effects of the competition can no longer be stabilized or compensated for.

[0031] The same is true for the (point-thinning) opening angle provided by the end mill. Here too, a large (point-thinning) opening angle creates enough space for chip removal and / or has a positive effect on the drilling action, but removes material from the teeth, which also reduces stiffness. Here too, the first and second (point-thinning) opening angles can similarly achieve a compromise between competing effects or compensate for the compromise as has surprisingly been demonstrated.

[0032] This means that the end mill according to the invention achieves the feat of "reconciling" or compensating for the opposing effects in the middle range of point thinnings due to its "balanced distribution" of point thinnings, i.e. on the one hand a first smaller point thinning and on the other hand a second larger point thinning not too far away (in terms of value) from the first point thinning, and thus achieving a positive compromise between (or sufficient rigidity for) a good drilling action and face milling.

[0033] Moreover, such end mills according to the present invention are easy to manufacture due to their "balanced distribution of point thinning" and are cost effective to manufacture.

[0034] In particular, in order to implement balance and compensation, it may be provided that the first point thinning has a (point thinning) angle of 32° to 38°, in particular about 35°, and the second point thinning has a (point thinning) angle of 39° to 46°, in particular about 42.5°.

[0035] The same is equally true for the preferred point thinning opening angles, which may be implemented such that the first point thinning has an opening angle of 35° to 45°, in particular approximately 40°, and the second point thinning has an opening angle of 41° to 50°, in particular approximately 42.5°.

[0036] It also appears to be particularly advantageous when multiple first and second point thinnings are implemented, the first and second point thinnings alternating with each other in the circumferential direction on the end side of the end mill.

[0037] It also appears to be advantageous when the end proximal secondary cutting edge of the first cutting edge of the first tooth is longer than the end proximal secondary cutting edge of the second cutting edge of the second tooth, and the first point thinning congruently forms a tip pocket of the first cutting edge or first tooth, and the second point thinning congruently forms a tip pocket of the second cutting edge or second tooth.

[0038] Similarly, a plurality of first teeth or first cutting edges having longer end side proximal secondary cutting edges and chip pockets due to first point thinnings and a plurality of second teeth or second cutting edges having shorter end side proximal secondary cutting edges and chip pockets due to second point thinnings may be provided, with the longer end side proximal secondary cutting edges via their respective first point thinnings and the shorter end side proximal secondary cutting edges via their respective second point thinnings alternating with each other in the circumferential direction of the cutting portion at the end side of the end mill.

[0039] It also proves to be advantageous when the first and second point thinnings proceeding from the end side end at substantially the same axial height of the cutting zone.

[0040] According to a preferred design embodiment, it may be provided that the cutting region comprises a total of four cutting edges, the first and third cutting edges and the second and fourth cutting edges being located substantially opposite each other or approximately radially opposite each other, and a first point thinning is provided between the first and second cutting edges and between the third and fourth cutting edges, and a second point thinning is provided between the second and third cutting edges and between the fourth cutting edge and the first cutting edge.

[0041] Furthermore, it also proves to be advantageous when the cutting edges are distributed non-uniformly in the circumferential direction of the cutting zone, which can be established, for example, in particular with respect to a predefinable axial height relative to the end face of the end mill (corresponding to a height of 0 mm) or a height of about 0.5×D (D=diameter of the cutting zone) axially below the end face of the end mill.

[0042] Here, in particular, i.e. in the mentioned uneven distribution, it can also be provided that in the circumferential direction of the cutting zone and at a predefinable axial height of the cutting zone, the angles between the first and the second cutting edge and between the third and the fourth cutting edge are in each case more than 90°, in particular about 97.5°, and / or the angles between the second and the third cutting edge and between the fourth cutting edge and the first cutting edge are in each case less than 90°, in particular about 82.5°, and in particular that the predefinable axial height is the end face of the end mill (corresponding to a height of 0 mm) or is axially below the end face of the end mill by about 0.5 x D (D = diameter of the cutting zone).

[0043] It may also be provided that the circumferential primary cutting edges of the cutting edges have different helix angles, in particular that the circumferential primary cutting edges of the cutting edges in the circumferential direction of the cutting area have a first helix angle alternating with a second helix angle, the second helix angle being different from the first helix angle.

[0044] It may also be advantageous to implement a particular geometry for the cutting edge.

[0045] In this way it can be provided that the cutting edges on the secondary cutting edges, in particular the end face of each cutting edge, have a clearance angle of 5° to 7°, in particular about 6°, relative to a plane perpendicular to the axis of rotation of the end mill.

[0046] It may also be provided that the secondary cutting edges, and in particular the chip pocket proximal (end) face of each secondary cutting edge, have a rake angle of 2° to 4°, in particular about 3°, relative to a plane parallel to the axis of rotation of the end mill.

[0047] It may further be provided that the end proximal secondary cutting edge and the circumferential primary cutting edge of the cutting edge transition into one another via a corner chamfer, in particular having a corner chamfer angle of about 45°.

[0048] It also proves advantageous if the core of the end mill is of cylindrical design.

[0049] In a preferred design embodiment, it can further be provided that at least the cutting area is coated, in particular having a coating with a layer thickness of 0.0010 mm to 0.006 mm, in particular 0.0015 mm to 0.005 mm, in particular 0.0018 mm to 0.004 mm.

[0050] It also proves advantageous if the end mill is made from solid carbide.

[0051] The above given description of the advantageous design of the present invention includes a large number of features which, in some cases combined, are reproduced in the individual dependent claims. However, these features may conveniently be considered individually and may be combined into suitable further combinations.

[0052] Although some terms may be used in the singular or in combination with numerals in the specification and / or claims in each case, the scope of the present invention is not intended to be limited to the singular form or respective numerals of these terms. Furthermore, the terms "a" or "an" should not be understood as numerals, but rather as indefinite articles.

[0053] The above-mentioned characteristics, features and advantages of the present invention and the manner in which they are achieved will become more apparent and more clearly understood with the following description of exemplary embodiments of the invention, which are illustrated in more detail in conjunction with drawings / figures (wherein the same components and functions have the same designations in the drawings / figures).

[0054] The exemplary embodiments are used to explain the present invention and do not limit the present invention to the combination of features included with respect to the functional features set forth therein. Moreover, for this reason, preferred features of each exemplary embodiment are explicitly considered separately, taken from one exemplary embodiment, introduced into another exemplary embodiment to complement the other exemplary embodiment, and can be combined with any one of the claims. [Brief description of the drawings]

[0055] [Figure 1] 1 illustrates a side view of a solid carbide end mill having a cutting region and a fastener according to one embodiment of the present invention. [Diagram 2] FIG. 2 shows a front view of the free end side of the solid carbide end mill of FIG. 1. [Diagram 3] FIG. 2 shows an image of the free end side of the solid carbide end mill of FIG. [Figure 4-1] (Point Thinning Long Tooth) An image of a side view of a solid carbide end mill with point thinning on the long tooth in FIG. [Figure 4-2] (Point Thinning Long Tooth) An image of a side view of a solid carbide end mill with point thinning on the short tooth in Figure 1 is shown. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0056] - (Solid Carbide) End Mills (Figs. 1 and 4) Figures 1 and 2 show (schematically) an end mill 1 (made of solid carbide) in various views and details. Here, Figure 1 shows the solid carbide end mill 1 in a side view. Figure 2 shows the solid carbide end mill 1 in a front view of its (free) end side 12. Figures 3-4 show images from different perspectives (end side, side) of the solid carbide end mill 1 in each case.

[0057] The solid carbide end mill 1 has a fastening part 2 and a cutting area 3 which in this case has four teeth 4, 5, 6 and 7 or four cutting edges 4, 5, 6 and 7.

[0058] The fastening part 2 has a cylindrical shape and is designed to be received in a chuck of a machine for machining a workpiece, such as for example a CNC milling centre (not shown).

[0059] In this case, the cutting area 3 formed by the core 8 which is of cylindrical design and the cutting edges 4 , 5 , 6 and 7 or teeth 4 , 5 , 6 and 7 arranged around the core 8 adjoins the fastening part 2 .

[0060] Here, the cutting edges / teeth 4, 5, 6 and 7 extend helically about the axis of rotation 9 of the solid carbide end mill 1 and are integrally formed with a (cylindrical) core 8.

[0061] Each cutting edge 4, 5, 6 and 7 has in each case one circumferential primary cutting edge 10 and a (proximal to the end side) secondary cutting edge 11 on the end side 12 of the cutting area 3, said cutting edges being designed to interact in a subtractive manner with the workpiece (not shown) to be machined during rotation of the solid carbide end mill 1 about the rotation axis 9.

[0062] For improved clarity, the reference numbers for the primary cutting edge 10 and the secondary cutting edge 11 are not fully included for all cutting edges 4, 5, 6 and 7 in the illustrations in the figures. However, each cutting edge 4, 5, 6 and 7 has a (circumferential) primary cutting edge 10 and an (end-proximal) secondary cutting edge 11.

[0063] 2, the end proximal secondary cutting edges 11 of cutting edges 4 and 6 herein are longer than the end proximal secondary cutting edges 11 of cutting edges 5 and 7. For this reason, hereinafter there will also be reference to "long teeth" 4 and 6 in the case of "long" cutting edges 4 and 6, and "short teeth" 5 and 7 in the case of "short" cutting edges 5 and 7.

[0064] The end-side proximal secondary cutting edge 11 and the circumferential primary cutting edge 10 of all cutting edges 4, 5, 6 and 7 merge into one another as a corner chamfer 18, which in each case has in particular a corner chamfer angle α of approximately 45°.

[0065] Furthermore, in the region of the end side 12 of the cutting region 3, in this case, four point thinnings 13-1, 13-2, 13-3 and 13-4 of the core 8 are provided, which correspond to the number of the four cutting edges 4, 5, 6 and 7, and each of them jointly forms a chip removal space 16-1, 16-2, 16-3 and 16-4 of each cutting edge 4, 5, 6 and 7, respectively (point thinning 13-1 of cutting edge 4, point thinning 13-2 of cutting edge 5, point thinning 13-3 of cutting edge 6 and point thinning 13-4 of cutting edge 7).

[0066] As a result of these point thinnings 13-1, 13-2, 13-3 and 13-4, the core 8 in the circumferential direction 17 of the solid carbide end mill 1 is reduced in cross section between the cutting edges 4, 5, 6 and 7 in a locally limited manner.

[0067] The point thinnings 13-1, 13-2, 13-3 and 13-4 are produced, for example by grinding, in the region of the end side 12 of the cutting zone 3 in the chip removal grooves 14-1, 14-2, 14-3 and 14-4 between the respective cutting edges 4, 5, 6 and 7 in each case and are formed as gaps approaching the rotation axis 9 of the solid carbide end mill 1 in the direction from the fastening portion 2 to the end side 12 of the cutting zone 3 (point thinning 13-1 for chip removal groove 14-1, point thinning 13-2 for chip removal groove 14-2, point thinning 13-3 for chip removal groove 14-3 and point thinning 13-4 for chip removal groove 14-4).

[0068] In this specification, the point thinnings 13-1, 13-2, 13-3, 13-4 are selected in such a way that the first point thinning 13-1 and the third point thinning 13-3 are (geometrically) identical to each other and (geometrically) different from the second point thinning 13-2 and the fourth point thinning 13-4 (similarly, the second point thinning 13-2 and the fourth point thinning 13-4 are (geometrically) identical to each other).

[0069] Further, the first point thinning 13-1 and the third point thinning 13-3 should each have a (point thinning) angle 20 of 30° to 45°, here about 35° (see FIG. 4-1), and the second point thinning 13-2 and the fourth point thinning 13-4 should each have a (point thinning) angle 21 of 35° to 50°, here about 42.5° (see FIG. 4-2) (always with respect to a normal plane (e.g., proximal to the end side) to the axis of rotation of the end mill).

[0070] Furthermore, the first point thinning 13-1 and the third point thinning 13-3 must each have a (point thinning) opening angle 22 of 30° to 50°, here about 40°, and the second point thinning 13-2 and the fourth point thinning 13-4 must each have a (point thinning) opening angle 23 of 40° to 60°, here about 42.5° (the opening angle is always the angle between the flanks of the point thinnings in a top view on the end side of the end mill) (see FIG. 3).

[0071] When visualized in the top view of the end side 12 shown in FIG. 3, the flanks 26 of the point thinnings 13-1 / 13-3 and 13-2 / 13-4 converge to angles 22 and 23 appearing in a perspective view of 40° and 42.5°, respectively, and the extremities in the direction of the rotation axis 9 are in each case rounded (rounding 27), with, by way of example, radii corresponding to 0.075 to 0.125 times the cutting zone diameter 28 (for point thinnings 13-1 and 13-3) and 0.1 to 0.3 times the cutting zone diameter 28 (for point thinnings 13-2 and 13-4), respectively.

[0072] In simplified and visualized terms, this means that the first point thinning 13-1 and the third point thinning 13-3 on the longer end-side proximal secondary cutting edge 11 are respectively (geometrically) identical, and likewise the second point thinning 13-2 and the fourth point thinning 13-4 on the shorter end-side proximal secondary cutting edge 11 are respectively (geometrically) identical, with the second point thinning 13-2 and the fourth point thinning 13-4 "extending steeper and at a larger (point thinning) opening angle" than the first point thinning 13-1 and the third point thinning 13-3, respectively. In this way, the two different point thinnings 13-1 and 13-3 and 13-2 and 13-4 alternate with each other in the circumferential direction 17 on the end side 12 of the end mill, respectively.

[0073] Furthermore, the solid carbide end mill 1 provides that all point thinnings 13-1, 13-2, 13-3 and 13-4 proceeding on the end side (12) terminate at substantially the same axial height (19) of the cutting zone 3 to ensure uniform discharge of chips into the respective chip removal grooves 14-1, 14-2, 14-3 and 14-4, respectively.

[0074] As particularly highlighted in FIG. 1 , the chip removal grooves 14-1, 14-2, 14-3 and 14-4 in this specification are respectively arranged between two adjacent (in the circumferential direction 17) cutting edges 4 and 5, or 5 and 6, or 6 and 7, or 7 and 4 of the teeth 4, 5, 6 and 7 in each case, and serve, in conjunction with the point thinnings 13-1, 13-2, 13-3 and 13-4, to discharge the chips generated by the primary cutting edges 10 and secondary cutting edges 11 of the cutting edges 4, 5, 6 and 7.

[0075] This means that the chip removal grooves 14 and the point thinnings 13 in each case jointly form chip removal spaces 16 at the cutting edges / teeth 4, 5, 6 and 7.

[0076] As a result of the point thinning 13-1, 13-2, 13-3 and 13-4, the cross-sections of the chip removal grooves 14-1, 14-2, 14-3 and 14-4 become larger in the region of the end side 12 of the cutting zone 3, and as a result of that chip from the central proximal region of the secondary cutting edge 11 (proximal to the end side) can be particularly suitably moved away (see the introduction relating to the present invention regarding the balancing properties of the drilling operation and point thinning).

[0077] All cutting edges / teeth 4, 5, 6 and 7 have in each case a clearance angle 24 of 5° to 7°, in particular 6°, which means that the angle between the end face 15 of each secondary cutting edge 11 and the (normal) plane perpendicular to the rotation axis 9 is respectively 5° to 7° or in particular 6°.

[0078] Similarly, all cutting edges / teeth 4, 5, 6 and 7 have in each case an (end) rake angle 25 of 2° to 4°, in particular here about 3°, which means that the chip pocket proximal (end) face of (i.e. here each) secondary cutting edge 11 presents a rake angle 25 of 2° to 4°, in particular about 3°, with respect to a plane parallel to the rotation axis 9 of the end mill.

[0079] As can also be derived from FIG. 2, which is highlighted by the drawn auxiliary lines, the cutting edges 4, 5, 6 and 7, and the secondary cutting edge 11 are arranged in a non-uniform distribution in the circumferential direction 17 of the solid carbide end mill 1 in conjunction with the primary cutting edge 10, thereby promoting stability of the cutting edges 4, 5, 6 and 7 and reducing vibration.

[0080] As stated, this unevenness relates to a normal plane (relative to the rotation axis 9), which is approximately 0.5×D below the axial direction 19 (in the direction of the rotation axis 9) of the end side 12 (D=diameter of the cutting area 3 of the solid carbide end mill 1).

[0081] Thus, the first cutting edge 4 and the third cutting edge 6, as well as the second cutting edge 5 and the fourth cutting edge 7, are located substantially opposite each other or approximately radially opposite each other on the end side 12, but the angle between the first cutting edge 4 and the adjacent fourth cutting edge 7 (in the clockwise direction) and the angle between the third cutting edge 6 and the adjacent second cutting edge 5 (in the clockwise direction) are designed in each case to be less than 90° (first angular pitch 29), particularly preferably about 82.5°. This means that the angle between the fourth cutting edge 7 and the adjacent third cutting edge 6 (in the clockwise direction) and the angle between the second cutting edge 5 and the adjacent first cutting edge 4 (in the clockwise direction) are greater than 90°, preferably about 97.5° (second angular pitch 30).

[0082] Because the helix angle of cutting edges 4 and 6, here approximately 36.5° (first helix angle 31), is different from the helix angle of cutting edges 5 and 7, here approximately 38° (second helix angle 32), this results in an unequal pitch of cutting edges 4, 5, 6 and 7 in almost all axial direction 19 normal planes to the rotation axis 9 of the solid carbide end mill 1 in the axial extent 19 region of point thinnings 13-1, 13-2, 13-3 and 13-4 (this unequal pitch of cutting edges 4, 5, 6 and 7 in cutting region 3 varies along the rotation axis 9).

[0083] This unequal pitch of the cutting edges 4, 5, 6 and 7, due to its advantageous stabilization, is particularly important in the region of the end side 12 of the cutting zone 3, since the reduction in the cross section of the core 8 of the solid carbide end mill 1 as a result of the point thinnings 13-1, 13-2, 13-3 and 13-4 is most pronounced here in order to form and separate two long secondary cutting edges 11 that reach substantially up to the axis of rotation 9 and to enable the ejection of chips from the secondary cutting edges 11 in the axial direction 19 close to the axis of rotation 9.

[0084] This is particularly important in drilling operations because, for holes in solid material without pilot holes, material must be subtractively removed over the entire cross section of the cutting area 3 .

[0085] Furthermore, it is provided that in the solid carbide end mill 1 at least the cutting area 3 is coated, in particular having a coating 33 with a coating thickness of 0.0010 mm to 0.006 mm, in particular 0.0015 mm to 0.005 mm, in particular 0.0018 mm to 0.004 mm.

[0086] Although the invention has been illustrated and described by means of preferred exemplary embodiments, the invention is not limited to the disclosed examples and other variations can be derived therefrom without departing from the scope of protection of the invention. [Explanation of symbols]

[0087] List of References 1 Solid Carbide End Mill 2 Fastening Part 3 Cutting area 4 First cutting edge / First (long) tooth 5 Second cutting edge / Second (short) tooth 6 3rd cutting edge / 3rd (long) tooth 7 4th cutting edge / 4th (short) tooth 8 (cylindrical) core 9 Rotation Axis 10 (Circumference) Primary cutting edge 11 (proximal end) secondary cutting edge 12 Solid carbide end mill or cutting area end side 13 or 13-1, 13-2, 13-3, 13-4 Point Thinning 14 or 14-1, 14-2, 14-3, 14-4 Chip removal groove 15 End face 16 or 16-1, 16-2, 16-3, 16-4 Chip removal space 17 Circumferential direction 18 Corner chamfering 19 Axial direction, “axis” 20 (point thinning) angles of the first and third point thinnings 13-1 and 13-3, respectively 21 (point thinning) angles of the second and fourth point thinnings 13-2 and 13-4, respectively 22 (point thinning) opening angles of the first and third point thinnings 13-1 and 13-3, respectively 23 (point thinning) opening angles of the second and fourth point thinnings 13-2 and 13-4, respectively 24 Clearance angle 25 (front) rake angle 26 Flank 27 Rounding 28 Cutting area diameter 29 First Angular Pitch 30 Second angular pitch 31 First twist angle 32 Second twist angle 33 Coating α Corner chamfer angle

Claims

1. 1. An end mill having a fastening part and a cutting area, the cutting area being formed by a core and at least two cutting edges arranged around the core and extending in a spiral around the axis of rotation of the end mill, each of the cutting edges having in each case one circumferential primary cutting edge and one secondary cutting edge at the end side of the cutting area, the end side of the cutting area being provided with at least one first point thinning of the core between two adjacent cutting edges and at least one second point thinning between two adjacent cutting edges, the first point thinning being designed differently from the second point thinning, the first point thinning having a (point thinning) angle of 30° to 45° and the second point thinning having a (point thinning) angle of 35° to 50°, the first point thinning having an opening angle of 30° to 50° and the second point thinning having an opening angle of 40° to 60°.

2. 2. The end mill according to claim 1, characterized in that the first point thinning has a (point thinning) angle of 32° to 38°, in particular about 35°, and the second point thinning has a (point thinning) angle of 39° to 46°, in particular about 42.5°.

3. 3. The end mill according to claim 1 or 2, characterized in that the first point thinning has an opening angle of 35° to 45°, in particular about 40°, and the second point thinning has an opening angle of 41° to 50°, in particular about 42.5°.

4. The end mill of any one of claims 1 to 3, characterized by a plurality of the first point thinnings and the second point thinnings, the first point thinnings and the second point thinnings alternating with each other in a circumferential direction on the end side of the end mill.

5. The end mill of any one of claims 1 to 4, characterized in that the end-side proximal secondary cutting edge of a first cutting edge of a first tooth is longer than the end-side proximal secondary cutting edge of a second cutting edge of a second tooth, the first point thinning congruently forms a chip pocket of the first cutting edge or the first tooth, and the second point thinning congruently forms a chip pocket of the second cutting edge or the second tooth.

6. 6. The end mill of claim 5, characterized by a plurality of first teeth or first cutting edges having the longer end side proximal secondary cutting edges and the chip pockets due to the first point thinnings, and a plurality of second teeth or second cutting edges having the shorter end side proximal secondary cutting edges and the chip pockets due to the second point thinnings, wherein the longer end side proximal secondary cutting edges via their respective first point thinnings and the shorter end side proximal secondary cutting edges via their respective second point thinnings alternate with each other in the circumferential direction of the cutting portion on the end side of the end mill.

7. The end mill according to any one of claims 1 to 6, characterized in that the first point thinning and the second point thinning proceeding from the end side end at substantially the same axial height of the cutting area.

8. The end mill according to any one of claims 1 to 7, characterized in that the cutting region includes a total of four cutting edges, the first cutting edge and the third cutting edge, and the second cutting edge and the fourth cutting edge are located substantially opposite each other or approximately radially opposite each other, the first point thinning is provided between the first cutting edge and the second cutting edge and between the third cutting edge and the fourth cutting edge, and the second point thinning is provided between the second cutting edge and the third cutting edge and between the fourth cutting edge and the first cutting edge.

9. An end mill according to any one of the preceding claims, characterized in that the cutting edges are distributed non-uniformly in the circumferential direction of the cutting area.

10. 10. The end mill according to claim 1, characterized in that in the circumferential direction of the cutting area and at a predefinable axial height of the cutting area, the angles between the first and second cutting edges and between the third and fourth cutting edges are in each case more than 90°, in particular about 97.5°, and / or the angles between the second and third cutting edges and between the fourth and first cutting edges are in each case less than 90°, in particular about 82.5°, in particular the predefinable axial height is the end face of the end mill (corresponding to a height of 0 mm) or is approximately 0.5 x D (D = diameter of the cutting area) axially below the end face of the end mill.

11. 11. An end mill according to claim 1, characterized in that the circumferential primary cutting edges of the cutting edges have different helix angles, in particular the circumferential primary cutting edges of the cutting edges in the circumferential direction of the cutting zone have a first helix angle alternating with a second helix angle, the second helix angle being different from the first helix angle.

12. An end mill according to any one of claims 1 to 11, characterized in that the cutting edges on the secondary cutting edges, in particular the end faces of each cutting edge, have a clearance angle of 5° to 7°, in particular about 6°, relative to a plane perpendicular to the rotation axis of the end mill.

13. An end mill according to any one of claims 1 to 12, characterized in that the secondary cutting edges, in particular the chip pocket proximal (end) faces of each secondary cutting edge, have a rake angle of 2° to 4°, in particular about 3°, relative to a plane parallel to the rotation axis of the end mill.

14. The end mill according to any one of claims 1 to 13, characterized in that the end-side proximal secondary cutting edge and the circumferential primary cutting edge of the cutting edge transition into each other via a corner chamfer, in particular with a corner chamfer angle of 45°.

15. An end mill according to any one of the preceding claims, characterized in that the core is of cylindrical design.

16. 16. An end mill according to claim 1, characterized in that at least the cutting area is coated, in particular having a coating with a layer thickness of 0.0010 mm to 0.006 mm, in particular 0.0015 mm to 0.005 mm, especially 0.0018 mm to 0.004 mm.

17. An end mill according to any one of the preceding claims, characterized in that it is a solid carbide end mill.

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