MILLING TOOL

Abstract

A milling tool includes a tool body having a front and a rear end between which an envelope surface extends. At least one insert seat having an outer border delimiting the insert seat from the front end and the envelope surface is provided. At least one double-sided cutting insert having an upper side, a lower side, an upper cutting edge and a lower cutting edge is radially mounted in the insert seat with the lower side abutting a bottom contact surface to provide an active upper cutting edge. In a direction of rotation of the tool body, at least a part of the lower cutting edge neighboring the outer border and located behind the active upper cutting edge, does not protrude by more than 0.5 mm from the outer border, and a distance between the part of the lower cutting edge and the outer border is smaller than 0.5 mm.

Claims

1. A milling tool comprising: a tool body having a central rotation axis around which the tool body is rotatable in a direction of rotation, the tool body including a front end and a rear end between which an envelope surface extends, at least one insert seat formed in a transition between the front end and the envelope surface, wherein said at least one insert seat includes a bottom contact surface and an outer border delimiting the insert seat from the front end and the envelope surface of the tool body; and at least one indexable double-sided cutting insert having an upper side and a lower side connected by a side surface extending around a periphery of the cutting insert, an upper cutting edge being formed in a transition between the side surface and the upper side and a lower cutting edge being formed in a transition between the side surface and the lower side, wherein each cutting insert is securely and detachably radially mounted in a respective insert seat of the tool body with the lower side abutting the bottom contact surface, so that the upper cutting edge has an active chip-removing upper cutting edge, the milling tool being configured so that at least a part of the lower cutting edge neighbouring said outer border, said part being located behind the active chip-removing upper cutting edge in the direction of rotation, does not protrude by more than 0.5 mm with respect to the outer border, and so that a distance between said part of the lower cutting edge and said outer border is smaller than 0.5 mm in the direction of rotation of the tool body.

2. The milling tool according to claim 1, wherein said part of the lower cutting edge does not protrude by more than 0.4 mm with respect to the outer border of the insert seat.

3. The milling tool according to claim 1, wherein said part of the lower cutting edge protrudes outside of said outer border.

4. The milling tool according to claim 1, wherein said outer border protrudes outside of said part of the lower cutting edge.

5. The milling tool according to claim 4, wherein said outer border protrudes outside of said part of the lower cutting edge by a maximum of 0.5 mm.

6. The milling tool according to claim 5, wherein said outer border protrudes outside of said part of the lower cutting edge by a maximum of 0.4 mm.

7. The milling tool according to claim 1, wherein the distance between said part of the lower cutting edge and said outer border is smaller than 0.4 mm in the direction of rotation.

8. The milling tool according to claim 1, wherein the at least one indexable cutting insert includes at least two primary cutting edge portions arranged around each of the upper side and the lower side, respectively.

9. The milling tool according to claim 8, wherein said part of the lower cutting edge includes at least one primary cutting edge portion.

10. The milling tool according to claim 9, wherein said part of the lower cutting edge includes at least one secondary cutting edge portion.

11. The milling tool according to claim 8, wherein said part of the lower cutting edge includes at least one corner radius cutting edge portion.

12. The milling tool according to claim 1, wherein said part of the lower cutting edge includes at least all portions of the lower cutting edge which are neighbouring the envelope surface of the tool body.

13. The milling tool according to claim 12, wherein said part of the lower cutting edge includes all portions of the lower cutting edge which are neighbouring the outer border of the insert seat.

14. The milling tool according to claim 1, wherein each of the upper side and the lower side are at least partly recessed with respect to the upper and the lower cutting edges, respectively.

15. (canceled)

16. The milling tool according to claim 1, wherein said part of the lower cutting edge does not protrude by more than 0.3 mm with respect to the outer border of the insert seat.

17. The milling tool according to claim 1, wherein said part of the lower cutting edge does not protrude by more than 0.2 mm with respect to the outer border of the insert seat.

18. The milling tool according to claim 5, wherein said outer border protrudes outside of said part of the lower cutting edge by a maximum of 0.3 mm.

19. The milling tool according to claim 5, wherein said outer border protrudes outside of said part of the lower cutting edge by a maximum of 0.2 mm.

20. The milling tool according to claim 1, wherein the distance between said part of the lower cutting edge and said outer border is smaller than 0.3 mm in the direction of rotation.

21. The milling tool according to claim 1, wherein the distance between said part of the lower cutting edge and said outer border is smaller than 0.25 mm in the direction of rotation.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The invention will in the following be described by means of example with reference to the appended drawings, in which:

[0029] FIG. 1 shows a perspective view of a milling tool according to the invention,

[0030] FIG. 2 shows a top view of the tool in FIG. 1,

[0031] FIG. 3 shows a partial exploded view of the tool in FIG. 1,

[0032] FIG. 4 shows a partial perspective view of the tool in FIG. 1,

[0033] FIG. 5 shows a partial side view of the tool in FIG. 1,

[0034] FIG. 6 shows a cross section taken along the line VI-VI in FIG. 5,

[0035] FIG. 7 shows a partial side view of the tool in FIG. 1,

[0036] FIG. 8 shows a cross section taken along the line VIII-VIII in FIG. 7, and

[0037] FIG. 9 shows a partial front view of the tool in FIG. 1.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0038] A milling tool 1 and details of this milling tool 1 according to an embodiment of the invention are shown in FIGS. 1-9. The milling tool 1 is configured for shoulder milling and comprises a tool body 100 and a plurality of cutting inserts 200 mounted in the tool body by means of screws 300. The tool body 100 has a central rotation axis C around which the tool body is rotatable in a direction of rotation R. Between a front end 101 and a rear end 102 of the tool body 100, an envelope surface 103 extends. Six insert seats 104 are in the shown embodiment formed in a transition between the front end 101 and the envelope surface 103. Each insert seat 104 comprises a bottom contact surface 105 and has an outer border 106 delimiting the insert seat 104 from the front end 101 and the envelope surface 103 of the tool body 100. In front of each insert seat 104 in the direction of rotation R, a chip pocket 107 is provided. In the rear end 102 of the tool body, a coupling interface in the form of an arbour coupling 108, configured to engage with a spindle of a machine via an adaptor (not shown), is provided.

[0039] In each insert seat 104, a trigonal shaped double-sided cutting insert 200 is mounted. Each cutting insert 200 has an upper side 201 and a lower side 202 connected by a side surface 203 extending around a periphery of the cutting insert 200. The cutting insert 200 is in the shown embodiment indexable with three index positions per side, i.e. a total of six index positions.

[0040] Around the upper side 201, an upper cutting edge 204 including three cutting edges 204a, 204b, 204c is thus formed in a transition between the side surface 203 and the upper side 201. A lower cutting edge 214 comprising three cutting edges 214a, 214b, 214c is correspondingly formed in a transition between the side surface 103 and the lower side 102. Each of the upper side 201 and the lower side 202 are recessed with respect to the upper and the lower cutting edges 204, 214. The cutting insert 200 is radially mounted in the insert seat 104 with its lower side 202 abutting the bottom contact surface 105 of the insert seat 104. The upper cutting edge 204a in this case becomes an active chip-removing cutting edge, while the remaining cutting edges are inactive in a milling operation. The upper side thereby forms a rake surface.

[0041] Since the upper side 201 and the lower side 202 are identical, and since each of the cutting edges 204a, 204b, 204c, 214a, 214b, 214c are in turn identical, only the active chip-removing cutting edge 204a will be described in detail.

[0042] The active cutting edge 204a comprises four cutting edge portions 205a, 206a, 207a, 208a, including a primary cutting edge portion 205a configured to generate a side wall in the workpiece (not shown) during a milling operation, a corner radius cutting edge portion 206a, a first secondary cutting edge portion 207a in the form of a surface generating cutting edge portion or wiper cutting edge portion, and a second secondary cutting edge portion 208a, which is here mostly inactive in the milling operation, yet may become active as a ramping cutting edge portion.

[0043] When the cutting insert 200 is mounted in the insert seat 104, a segment of the lower cutting edge 214, including most of the cutting edge 214b and the cutting edge 214c, is hidden within the tool body 100. A small clearance is provided around the hidden segment of the lower cutting edge 214, such that there is no contact between the hidden segment of the lower cutting edge 214 and the tool body 100. Another segment of the lower cutting edge 214 neighbours the outer border 106 of the insert seat 104. This segment of the lower cutting edge 214 is located behind the active chip-removing upper cutting edge 204a, and thus includes a lower primary cutting edge portion 215a, a lower corner radius cutting edge portion 216a, a lower first secondary cutting edge portion 217a, and a lower second secondary cutting edge portion 218a, of which all are inactive. As can be seen from FIGS. 3 and 4, the lower primary cutting edge portion 215a is located directly behind the upper second secondary cutting edge portion 208a in the direction of rotation, i.e. neighbouring the front side 101 of the tool body 100. The lower second secondary cutting edge portion 218a is located behind the active upper primary cutting edge portion 205a, neighbouring the envelope surface 103 of the tool body 100.

[0044] The segment of the lower cutting edge 214 that neighbours the outer border 106 of the insert seat 104 includes a part, in the shown embodiment equalling the entire segment neighbouring the outer border 106, which is located such that it does not protrude by more than 0.5 mm with respect to the outer border 106. In the shown embodiment, said part of the lower cutting edge 214 is approximately level with the outer border 106. In other words, none of the lower cutting edge 214 and the outer border 106 protrudes outside of the other one by a substantial amount. The transition between the tool body 100, both along the front side 101 and the envelope surface 103, and the side surface 203 of the cutting insert 200, is smooth. This can be seen in detail in FIG. 5-9.

[0045] Moreover, a distance d provided between said part of the lower cutting edge 214 and the outer border 106 of the insert seat 104 is smaller than 0.5 mm in the direction of rotation R of the tool body 100 along the entire segment of the lower cutting edge 214 neighbouring the outer border 106. FIG. 6 shows the distance d between the inactive lower primary cutting edge portion 215a and the outer border 106, and FIG. 8 shows the distance d between the inactive lower second secondary cutting edge portion 218a and the outer border 106. The distance d between said part of the lower cutting edge 214 and the outer border 106 is approximately constant along the lower cutting edge 214a. The distance d is chosen such that it is smaller than the thickness of a chip produced in a milling operation, so that such a chip cannot enter in between the cutting insert 200 and the tool body 100 and get stuck, thereby potentially causing harm to the workpiece and to the cutting insert 200 during continued milling. Since furthermore the part of the lower cutting edge 214 is level with the outer border 106, chips cannot destroy the segment of the inactive lower cutting edge 214a which is exposed, and the entire lower cutting edge 214 is thereby protected during milling.

[0046] The segment of the lower cutting edge neighbouring the outer border of the insert seat may include different numbers of cutting edge portions depending on the design of the cutting insert. For example, in a cutting insert having a large number of primary cutting edge portions, more than one inactive lower primary cutting edge portion may be included in that segment. The part of the lower cutting edge which is protected as discussed above may include all of those cutting edge portions or only some of them.

[0047] 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 example, the tool body may comprise several insert seats, of which not all of the insert seats need to be provided in a transition between the front end and the envelope surface. If the tool body is intended for a deep shoulder milling tool, also known as a long edge milling tool, it is possible to have insert seats provided around a periphery of the tool body, in an area between the front end and the rear end. Of course, the shape of the cutting inserts may be varied as well as the number of cutting inserts. For example, the cutting inserts may be circular, octagonal, hexagonal, triangular, trigonal, heptagonal, square, etc. Instead of screws, other fastening members can be used for mounting the cutting inserts in the tool body, such as e.g. clamping members.