Metal cutting inserts for drilling tools and drilling tools

Abstract

A metal cutting drill insert (100, 400) for a drilling tool comprises: opposing top surfaces (101, 401) and bottom surfaces (102, 402), an axis of symmetry of the cutting drill insert extending between the top and bottom surfaces, and a peripheral side surface (103, 403) extending between the top and bottom surfaces, wherein the top surface (101, 401) comprises a rake face (104, 404) and the side surface (103, 403) comprises a clearance face (105, 405). The metal cutting drill insert further comprises at least one stepped cutting edge (106, 406) configured to cut continuous chips along the at least one stepped cutting edge, wherein the at least one stepped cutting edge is formed at the intersection of a rake face (104, 404) of the top surface (101, 401) and an adjacent clearance face (105, 405) of the side surface (103, 403), wherein in a top view facing the top surface of the metal cutting insert, the at least one stepped cutting edge comprises a first part edge (108, 508) and a second part edge (109, 509). A step formed by a transition edge (107, 507) between two partial edges (109, 509); characterized in that, in a top view of the top surface (101, 401) facing the metal cutting insert (100, 400), the step extends a first distance h1 in a radial direction relative to the axis of symmetry; and in a side view of the peripheral side surface (103, 503) facing the metal cutting insert (100, 400), the step extends a second distance h2 in a direction from the bottom surface toward the top surface, wherein 0.8·h1≤h2≤1.2·h1.

Description

Technical Field

[0001] The present invention relates to a metal cutting insert for a drilling tool, and more particularly to a metal cutting insert having a stepped cutting edge.

[0002] The invention also relates to a drilling tool. Background Art

[0003] Drilling is an important operation in modern subtractive manufacturing, especially drilling holes in metals proves to be a demanding operation.

[0004] In metal drilling, drills with replaceable metal cutting inserts are often used, especially in CNC operations. Modern drills of the aforementioned type typically include a center insert for drilling the central area of ​​the drilled hole, and a peripheral insert for removing material in the peripheral area of ​​the drilled hole. Due to the different cutting geometries, the center insert and the peripheral insert typically adopt different geometries. The latest geometry of the center insert adopts a stepped edge with a smooth transition from the first part edge to the second part edge. The smooth transition is typically referred to as a transition edge or transition zone. It is advantageous to cut continuous chips of a predetermined length from the drilled material. Chip control is critical in modern CNC metal drilling, especially chip removal has a great influence on the surface finish of the drilled hole, and also affects the drill speed.

[0005] The use of stepped edge inserts is problematic because the cut chips moving from the stepped cutting edge to the release side of the insert experience elevated temperatures in the transition region. Such elevated temperatures may have an adverse effect on the life of the insert, particularly the life of the transition edge.

[0006] Therefore, there is a need for improvements in metal cutting inserts to reduce the temperature in the transition zone.

[0007] It is therefore an object of the present invention to provide an improved metal cutting insert which reduces the temperature in the transition region. Summary of the invention

[0008] According to the invention, the above object is achieved by a metal cutting insert having the features defined in claim 1 .

[0009] The inventors have recognized that the elevated temperature in the transition region of the stepped edge is caused by compression of the chips in the transition region. The inventors have recognized that this elevated temperature can be reduced by incorporating steps of the stepped edge in a side view of the metal cutting insert in addition to the conventional steps seen in a top view of the insert.

[0010] The metal cutting insert according to the present invention comprises: opposite top and bottom surfaces, between which the axis of symmetry of the cutting drill insert extends, and between which the peripheral side surface extends. The top surface comprises a rake face, and the side surface comprises a clearance face; at least one stepped cutting edge is configured to cut continuous chips along the at least one stepped cutting edge, wherein the at least one stepped cutting edge is formed at the intersection of the rake face of the top surface and the adjacent clearance face of the side surface, wherein in a top view facing the top surface of the metal cutting insert, the at least one stepped cutting edge comprises a step formed by a transition edge between a first part edge and a second part edge; characterized in that in a top view facing the top surface of the metal cutting insert, the step extends a first distance h1 in a radial direction relative to the axis of symmetry; and in a side view facing the peripheral side surface of the metal cutting insert, the step extends a second distance h2 in a direction from the bottom surface toward the top surface, wherein 0.8·h2≤h1≤1.2·h2. The step seen in the top view is consistent with the step seen in the side view of the metal cutting insert.

[0011] According to one embodiment, the second distance h2 is 0.9·h1≤h2≤1.1·h1. In this way, the temperature rise in the transition region is reduced.

[0012] According to one embodiment, the second distance h2 is 0.95·h1≤h2≤1.05·h1. In this way, the temperature rise in the transition region is further reduced.

[0013] According to one embodiment, the first distance hi is substantially equal to the second distance h2. In this way, the temperature increase in the transition region is reduced in a preferred manner.

[0014] According to one embodiment, the stepped cutting edge comprises a corner edge connected to a first part edge, and wherein the corner edge is connected to a second part edge of another stepped cutting edge of the insert.

[0015] According to one embodiment, the corner part edge provides a continuous edge from the first part edge of the stepped cutting edge to the second part edge of the further stepped cutting edge. In this way, the corner edge allows forming a continuous edge around the entire metal cutting insert.

[0016] According to one embodiment, the transition edge has a curved edge, wherein the curved edge has the same shape in the top view and in the side view. In this way, minimal compression forces act on the chips, thereby reducing the temperature in the transition area.

[0017] According to one embodiment, the blade comprises a through hole extending between the top and bottom surfaces of the blade, the through hole being aligned along said axis of symmetry and extending through the opposing top and bottom surfaces.

[0018] According to one embodiment, a plurality of stepped cutting edges are symmetrically arranged around the symmetry axis. According to one embodiment, when moving along the stepped cutting edges in a counterclockwise direction around the metal cutting drill insert, the transition edge provides a step in a positive radial direction relative to the symmetry axis in a top view. Thus, when the metal cutting insert is mounted in a drill tool, the second part edge is always the outermost edge of the first part edge and the second part edge in a radial direction.

[0019] The present invention also relates to a metal cutting drill tool comprising an elongated drill body having a boring shaft and a mounting shank. The metal cutting drill tool further comprises at least one drill insert according to the embodiments described herein, the drill insert being mounted on the end of the boring shaft.

[0020] Other advantages of the present invention will become apparent from the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Embodiments of the present invention will now be described in detail with reference to the accompanying drawings, in which:

[0022] Figure 1 is a perspective view of a metal cutting insert according to an embodiment of the present invention,

[0023] Figure 2 yes Figure 1 A top view of a metal cutting insert is shown,

[0024] Figure 3 yes Figure 1 and Figure 2 A side view of a metal cutting insert is shown,

[0025] Figure 4 is a perspective view of a metal cutting insert according to another embodiment of the present invention,

[0026] Figure 5 yes Figure 4 A top view of a metal cutting insert is shown.

[0027] Figure 6 yes Figure 4 and Figure 5 A side view of a metal cutting insert is shown,

[0028] FIG. 7 is a side view of a drilling tool according to an embodiment of the present invention, and

[0029] FIG. 8 is an end view of the drilling tool shown in FIG. 7 . DETAILED DESCRIPTION

[0030] Reference now Figure 1-Figure 3 , Figure 1-Figure 31 and 2. A first embodiment of the present invention is shown. In these figures, a metal cutting drill insert for a drilling tool is disclosed, generally indicated at 100, and Figure 4 400. The metal cutting drill insert 100 includes a top surface 101, 401 and a bottom surface 102, 402 relative to each other, wherein the axis of symmetry of the cutting drill insert extends between the top surface and the bottom surface, and a peripheral side surface 103, 403 extends between the top surface and the bottom surface. The top surface 101, 401 includes a rake face 104, 404, and the side surface 103, 403 includes a clearance face 105, 405. The metal cutting drill insert further includes at least one stepped cutting edge 106, 406, which is configured to cut continuous chips along the at least one stepped cutting edge. The at least one stepped cutting edge is formed at the intersection of the rake face 104, 404 of the top surface 101, 401 and the adjacent clearance face 105, 405 of the side surface 103, 403. In a top view facing the top surface of the metal cutting insert, the at least one stepped cutting edge comprises a step formed by a transition edge 107 , 507 between the first part edge 108 , 508 and the second part edge 109 , 509 .

[0031] Metal cutting drill inserts are characterized by Figure 2 In a top view facing the top surface 101, 401 of the metal cutting insert 100, 400, the step extends a first distance h1 in a radial direction relative to the axis of symmetry. Figure 3 In a side view facing the peripheral side surface 103, 503 of the metal cutting insert 100, 400, the step extends a second distance h2 in the direction from the bottom surface toward the top surface, wherein 0.8·h1≤h2≤1.2·h1. By having the step in both the top view and the side view, compression of the chips is avoided and the temperature is thereby significantly reduced.

[0032] The step seen in the top view corresponds to the step seen in the side view of the metal cutting insert.

[0033] In another embodiment, the second distance h2 is 0.9·h1≤h2≤1.1·h1.

[0034] In yet another embodiment, the second distance h2 is 0.95·h1≤h2≤1.05·h1.

[0035] In a preferred embodiment, the first distance hi is substantially equal to the second distance h2. In theory, this will be the optimum step height for optimum temperature reduction associated with chip evacuation on the transition edge. This will provide continuous chips to be formed and reduced transition edge wear.

[0036] Reference now Figure 4-Figure 6 , Figure 4-Figure 6 A second embodiment of a metal cutting drill insert is shown, generally indicated at 400. The second embodiment of the metal cutting drill insert is similar to that described above with reference to FIG. Figure 1-Figure 3 The difference from the first embodiment described is that the second embodiment includes a stepped cutting edge 406, which includes a corner edge (510) connected to a first partial edge 508, and wherein the corner edge 510 is connected to a second partial edge (509') of another stepped cutting edge (406') of the blade 500.

[0037] The corner edge 510 allows a continuous stepped cutting edge to be formed around the insert 500. The corner part edge provides a continuous edge from a first part edge of a stepped cutting edge to said second part edge of another stepped cutting edge.

[0038] Reference now Figure 5 and Figure 6 .exist Figure 5 In the figure, a metal cutting insert according to a second embodiment is disclosed in a top view and in Figure 6 In FIG. 5 , the same blade is disclosed in a side view. The transition edge 507 has a curved edge, wherein the curved edge is Figure 5 In the top view and Figure 6 The side view has the same shape.

[0039] The metal cutting drill insert 500 includes a through hole 511 extending between the top surface 401 and the bottom surface 402 of the insert, the through hole being aligned along the axis of symmetry 411 and extending through the opposing top surface 401 and the bottom surface 402 .

[0040] exist Figure 5 In the embodiment, a plurality of stepped cutting edges 406, 406' are symmetrically arranged around the symmetry axis.

[0041] also, Figure 5 It is disclosed that the transition edge 507 provides a step in a positive radial direction relative to the axis of symmetry in a top view when moving along the stepped cutting edge 406, 406' in a counterclockwise direction around the metal cutting drill insert.

[0042] In Fig. 7, a metal cutting drill tool according to one embodiment is disclosed, generally indicated at 700. The drill tool 700 comprises an elongated drill body 701 having a boring shaft 702 centered about a longitudinal axis 704 and a mounting shank 703. The drill tool 700 further comprises at least one drill insert 100, 100', 400, 400' according to any one of the preceding claims, mounted at the end of the boring shaft 702.

[0043] The boring spindle also exhibits a drill flute 705, 705' associated with each insert for effective chip evacuation and chip control.

[0044] In FIG. 8 , a view facing the end of the boring shaft with the blade is disclosed, wherein the drill 700 is configured to rotate in a counterclockwise direction around a longitudinal axis 704 , as indicated by R in the figure.

Claims

1. A metal cutting drill bit blade (100, 400) for a drilling tool, comprising: Opposing top surfaces (101, 401) and bottom surfaces (102, 402), an axis of symmetry of the metal cutting drill insert extending between the top surface (101, 401) and the bottom surface (102, 402), and a peripheral side surface (103, 403) extending between the top surface and the bottom surface, wherein the top surface (101, 401) includes a rake face (104, 404) and the side surface (103, 403) includes a clearance face (105, 405); at least one stepped cutting edge (106, 406) configured to cut a continuous chip along the at least one stepped cutting edge, wherein the at least one stepped cutting edge is formed at the intersection of a rake face (104, 404) of the top surface (101, 401) and an adjacent clearance face (105, 405) of the side surface (103, 403), wherein in a top view facing the top surface of the metal cutting drill insert, the at least one stepped cutting edge includes a step formed by a transition edge between a first part edge (108, 508) and a second part edge (109, 509); Characterized in that, in a top view facing the top surface (101, 401) of the metal cutting drill insert (100, 400), the step extends a first distance h1 in a radial direction relative to the symmetry axis; and In a side view facing the peripheral side surface (103, 503) of the metal cutting drill insert (100, 400), the step extends a second distance h2 in a direction from the bottom surface toward the top surface, wherein 0.8·h1≤h2≤1.2·h1.

2. The metal cutting drill insert (100, 400) according to claim 1, characterized in that: The second distance h2 is 0.9·h1≤h2≤1.1·h1.

3. The metal cutting drill insert (100, 400) according to claim 1, characterized in that: The second distance h2 is 0.95·h1≤h2≤1.05·h1.

4. The metal cutting drill insert (100, 400) according to claim 1, characterized in that: The first distance h1 is equal to the second distance h2.

5. The metal cutting drill insert (100, 400) according to any one of claims 1 to 4, characterized in that: The stepped cutting edge includes a corner edge (510) connected to the first part edge, and wherein the corner edge is connected to a second part edge of another stepped cutting edge of the metal cutting drill insert.

6. The metal cutting drill insert (100, 400) according to claim 5, characterized in that: The corner edge provides a continuous edge from the first part edge of the stepped cutting edge to the second part edge of the further stepped cutting edge.

7. The metal cutting drill insert (100, 400) according to any one of claims 1 to 4, characterized in that: The transition edge has a curved edge, wherein the curved edge has the same shape in the top view and the side view.

8. The metal cutting drill insert (100, 400) according to any one of claims 1 to 4, characterized in that: The metal cutting drill insert includes a through hole extending between the top surface (101) and the bottom surface (102) of the metal cutting drill insert, the through hole being aligned along the axis of symmetry and extending through the opposing top and bottom surfaces.

9. The metal cutting drill insert (100, 400) according to any one of claims 1 to 4, characterized in that: A plurality of stepped cutting edges (106) are symmetrically arranged around the symmetry axis.

10. The metal cutting drill insert (100, 400) according to any one of claims 1 to 4, characterized in that: When moving along the stepped cutting edge in a counterclockwise direction around the metal cutting drill insert, the transition edge provides a step in a positive radial direction relative to the axis of symmetry in a top view.

11. A metal cutting drill (700), comprising: an elongated drill body (701) having a boring shaft (702) and a mounting shank (703); and Characterized in that the metal cutting drill tool (700) further comprises at least one metal cutting drill blade (100, 100') according to any one of the preceding claims, and the metal cutting drill blade (100, 100') is mounted on the end of the boring shaft (702).

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