TOOL BODY AND A MILLING TOOL

Abstract

A tool body for a milling tool includes a front end and a rear end between which a center axis and a peripheral envelope surface extend. The tool body is arranged to be rotated in a direction of rotation around the center axis. At least one insert seat is configured to support a cutting insert. A chip pocket is provided in front of the insert seat in the direction of rotation, delimited by a wall surface. A surface pattern including a plurality of first grooves and second grooves is formed on at least a portion of the wall surface. The second grooves intersect the first grooves and each groove of the first grooves and/or each groove of the second grooves has a concave groove profile.

Claims

1. A tool body for a milling tool, the tool body comprising: a front end and a rear end between which a centre axis and a peripheral envelope surface extend, the tool body being configured to be rotated in a direction of rotation around the centre axis; at least one insert seat formed in a transition between the front end and the peripheral envelope surface, wherein the insert seat is configured to support a cutting insert adapted arranged to be mounted therein; a chip pocket provided in front of the insert seat in the direction of rotation, wherein the chip pocket is delimited by a wall surface; and a surface pattern including a plurality of first grooves and second grooves formed on at least a portion of the wall surface (9), wherein the second grooves intersect the first grooves and wherein each groove of the first grooves and/or each groove of the second grooves has a concave groove profile.

2. The tool body according to claim 1, wherein, for each first groove and/or each second groove, as seen in a sectional view orthogonal to a length extension of the groove, the concave groove profile extends between a first end point and a second end point, wherein a first tangent to the concave groove profile at the first end point and a second tangent to the concave groove profile at the second end point intersect below the concave groove profile, wherein an angle δ formed by the first tangent and the second tangent is such that 90°≤δ≤175°.

3. The tool body according to claim 1, wherein the first grooves are arranged such that two neighbouring first grooves are immediately adjacent to each other.

4. The tool body according to claim 1, wherein the concave groove profile is arc shaped.

5. The tool body according to claim 4, wherein a radius of curvature or an approximated radius of curvature of the arc shaped concave groove profile is within the range of 1-6 mm.

6. The tool body according to claim 4, wherein a radius of curvature of the concave groove profile of the first grooves is equal to a radius of curvature of the concave groove profile of the second grooves.

7. The tool body according to claim 1, wherein the wall surface includes a front wall surface facing the insert seat, wherein the surface pattern covers at least a part of the front wall surface.

8. The tool body according to claim 1, wherein the surface pattern includes a plurality of protrusions formed between the first and second grooves, each protrusion being delimited by two neighbouring first grooves and two neighbouring second grooves.

9. The tool body according to claim 8, wherein each protrusion forms a ridge extending along the first grooves.

10. The tool body according to claim 8, wherein each protrusion, as seen in a sectional view orthogonal to a length extension of the first or the second grooves, has a rounded top.

11. The tool body according to claim 1, wherein the first grooves are spaced by a first distance of 0.5-3 mm and/or the second grooves are spaced by a second distance of 0.5-3 mm.

12. The tool body according to claim 1, wherein the first grooves are parallel to each other and/or the second grooves are parallel to each other on at least a portion of the wall surface.

13. The tool body according to claim 1, wherein, on a planar or essentially planar wall surface portion, the second grooves extend at an angle with respect to the first grooves, wherein the angle is within the range of 30-90°.

14. The tool body according to claim 1, wherein a maximum depth of the first grooves and/or the second grooves is within the range of 0.03-0.20 mm.

15. A milling tool comprising: a tool body according to claim 1; and at least one cutting insert mounted in the at least one insert seat.

16. A method for manufacturing a tool body according to claim 1, the method comprising: providing a tool body blank; removing material from the tool body blank by a first tool to create a space forming the chip pocket; machining the insert seat; creating the first grooves in the wall surface with a first ball-nose milling cutter; creating the second grooves in the wall surface with a second ball-nose milling cutter, such that the second grooves intersect the first grooves to create a surface pattern, the second ball-nose milling cutter being the same type of milling cutter as the first ball-nose milling cutter; and optionally, polishing and/or applying any other final treatment for deburring and/or rounding off sharp scallops between the grooves.

17. The tool body according to claim 1, wherein the wall surface includes a front wall surface facing the insert seat, wherein the surface pattern covers a major part of the front wall surface.

18. The tool body according to claim 1, wherein the wall surface includes a front wall surface facing the insert seat, wherein the surface pattern covers the entire front wall surface.

19. The tool body according to claim 1, wherein the wall surface includes a front wall surface facing the insert seat, wherein the surface pattern covers a major part of the wall surface.

20. The tool body according to claim 1, wherein the wall surface includes a front wall surface facing the insert seat, wherein the surface pattern covers the entire wall surface.

21. The tool body according to claim 1, wherein the first grooves are parallel to each other and/or the second grooves are parallel to each other on at least a portion of the front wall surface.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Embodiments of the invention will in the following be described by means of example with reference to the appended drawings, in which:

[0038] FIG. 1 is a perspective view schematically showing a milling tool according to an embodiment of the invention,

[0039] FIG. 2 is a perspective view schematically showing a part of a surface pattern of a tool body according to an embodiment of the invention,

[0040] FIG. 3 is a top view showing the surface pattern in FIG. 2,

[0041] FIG. 4 is a perspective view showing a partially created surface pattern as in FIG. 2,

[0042] FIG. 5 is a sectional view along the line V-V in FIG. 3,

[0043] FIG. 6 is a photography showing a tool body according to another embodiment of the invention, and

[0044] FIG. 7 is a scanned image of a wall surface of the tool body in FIG. 6.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0045] A milling tool 1 comprising a tool body 2 according to an embodiment of the invention is schematically shown in FIG. 1 and a tool body 2 according to another embodiment is shown in FIG. 6. In both embodiments, the tool body 2 comprises a front end 3 and a rear end 4 between which a centre axis C and a peripheral envelope surface 5 extend. The tool body 2 is configured to be rotated in a direction of rotation R around the centre axis C.

[0046] A plurality of insert seats 6 are formed in a transition between the front end 3 and the peripheral envelope surface 5. Each insert seat 6 is configured to support a cutting insert 7 adapted to be mounted therein. A chip pocket 8 is provided in front of each insert seat 6 in the direction of rotation R, wherein the chip pocket 8 is delimited by a wall surface 9, including a front wall surface 10 facing the insert seat 6 in the direction of rotation R. The cutting insert 7 is adapted to be fastened in the insert seat 6 using a fastening member 11, here in the form of a screw. When seen along the centre axis C and toward the front end 3, the chip pocket 8 of the milling tool 1 in FIG. 1 is substantially U-shaped. However, the chip pocket may be much more open and have other shapes.

[0047] The wall surface 9 is curved and covered by a surface pattern, preferably formed by ball nose milling followed by polishing. The surface pattern is shown in greater detail in FIGS. 2-5, in which the surface pattern is shown on a flat surface.

[0048] The surface pattern is formed by a plurality of first grooves 12, 12a-e, extending in parallel on at least a portion of the front wall surface 10, or essentially in parallel since the wall surface 9 is curved, with a first length extension L.sub.1, and a plurality of second grooves 13, 13a-e extending in parallel or essentially in parallel with a second length extension L.sub.2 on at least a portion of the front wall surface 10. For example, each two neighbouring first grooves 12, e.g. the grooves 12a, 12b, or second grooves 13, e.g. the groves 13a, 13b, may extend essentially in parallel, while first grooves 12 located on opposite ends of the wall surface 9 may have non-parallel extensions due to the curved wall surface 9. The second grooves 13 intersect the first grooves 12 and extend at an angle α with respect to the first grooves 12. In the shown embodiment, α=37°. Each groove of the first grooves 12 and of the second grooves 13 has a concave groove profile 17. In other words, in a sectional view orthogonal to the first length extension L.sub.1 of one of the first grooves 12, a surface of the first groove 12 may be described as a concave curve. In the shown embodiment, the first and second grooves 12, 13 have identically shaped concave groove profiles 17, wherein the concave groove profile 17 may be described by a circular arc with a radius of curvature R.sub.1 (first groove 12)=R.sub.2 (second groove 13)=1.5 mm.

[0049] The first grooves 12 are arranged so that two neighbouring first grooves 12a, 12b are immediately adjacent to each other. This can be clearly seen in FIG. 4, showing a surface pattern which is only partly created, including three first grooves 12a, 12b, 12c and three intersecting second grooves 13a, 13b, 13c. While the neighbouring first grooves 12a, 12b are immediately adjacent, neighbouring second grooves 13b, 13c are separated by a ridge 18 having a flat top surface, extending along the second grooves 13b, 13c. The first grooves 12 are equispaced by a first distance d.sub.1=1.1 mm (see FIG. 3) and have a depth h.sub.1=0.11 mm (see FIG. 5). The second grooves 13 are equispaced by a second distance d.sub.2=1.8 mm (see FIG. 3) and have a depth h.sub.2=0.10 mm (not shown), i.e. slightly smaller than the first grooves 12. The depths h.sub.1 and h.sub.2 may vary within the surface pattern.

[0050] Delimited by two neighbouring first grooves 12 and two neighbouring second grooves 13, protrusions 14, 14a-c are formed. For example, as shown in FIG. 3, the protrusion 14b is delimited by the first grooves 12b, 12c and the second grooves 13b, 13c. As seen in a sectional view orthogonal to to the first length extension L.sub.1 of one of the first grooves 12 (see FIG. 5), each protrusion 14 is convexly rounded with a relatively small radius of curvature, in the shown embodiment 0.08 mm, in comparison with the radius of curvature R.sub.1 of 1.5 mm of the concave groove profile. Each protrusion 14 forms a ridge having a flat top surface and extending in the first length direction L.sub.1. The ridge is broken on each side by the second grooves 13 and has in the shown embodiment a length in the first length direction L.sub.1 of approximately 0.5 mm.

[0051] The milling tool 1 is provided with a system of internal coolant channels. At least one coolant channel has at least one outlet 20 in the chip pocket 8. The system of internal coolant channels can be of any known kind.

[0052] As seen in the sectional view in FIG. 5, orthogonal to the length extension L.sub.1 of one of the first grooves 12d, the concave groove profile 17 extends between a first end point 15 and a second end point 16. A first tangent z.sub.1 to the concave groove profile at the first end point 15 and a second tangent z.sub.2 to the concave groove profile at the second end point 16 intersect below the concave groove profile 17. An angle δ formed by the first tangent z.sub.1 and the second tangent z.sub.2 is such that 90°≤δ≤175°, preferably 110°≤δ≤170°. In the shown embodiment, δ=136°. A corresponding angle may be defined also for the second grooves 13 (not shown).

[0053] For the first grooves 12, the angle δ may be defined as:

[00001]$\delta =2\arccos \frac{\sqrt{2R_1{h}_{1C}-h_{1C}^2}}{R_1}$

[0054] wherein h.sub.1c is the depth of the concave profile and is equal to h.sub.1 before polishing. After polishing, h.sub.1c is smaller than h.sub.1 as the height of the convexly rounded portion is not included.

[0055] A scanned image of a portion of the wall surface 9 of the tool body 2 shown in FIG. 6 is shown in FIG. 7.

[0056] The tool body 2 may be manufactured by means of a method comprising the following steps: [0057] providing a tool body blank, [0058] removing material from the tool body blank by a first tool to create a space forming the chip pocket 8, [0059] machining the insert seat 6, [0060] machining the first grooves 12, 12a-e in the wall surface 9 of the chip pocket 8 with a first ball-nose milling cutter, [0061] machining the second grooves 13, 13a-e in the wall surface 9 of the chip pocket 8 with a second ball-nose milling cutter, such that the second grooves 13, 13a-e intersect the first grooves 12, 12a-e to create a surface pattern, the second ball-nose milling cutter being preferably the same milling cutter as the first ball-nose milling cutter, [0062] preferably, but not necessarily, polishing and/or applying any other final treatment for deburring and/or rounding off sharp scallops between the grooves 12, 12a-e, 13, 13a-e.

[0063] The step of machining the insert seat 6 may be done either before or after the steps of machining the grooves.

[0064] During machining of a workpiece using the milling tool 1 shown in FIG. 1, chips are removed from the workpiece by a cutting edge of the cutting insert 7 and hit the front wall surface 10 of the chip pocket 8 during evacuation from the working area. Thanks to the surface pattern, the contact area between the chips and the front wall surface 10 is reduced. The friction arising when the chips travel upward along the front wall surface 10 is consequently also reduced and a smooth chip evacuation is achieved, minimising the risk of chip jamming.

[0065] The invention is of course not limited to the embodiments disclosed, but may be varied and modified within the scope of the following claims. For instance, the shape of the cutting inserts may be varied as well as the number of insert seats in the tool body. The surface pattern may be formed only on a part of the wall surface, such as only on the front wall surface or on a portion of the front wall surface.