CUTTING INSERT AND TOOL FOR MACHINING A WORKPIECE

Abstract

Cutting insert having a clamping section, a cutting head, and a cantilever arm, at a first end of which the cutting head is arranged and at a second end of which, opposite the first end, the clamping section is arranged, wherein the cantilever arm has a smaller cross-section than the clamping section, wherein the cutting head comprises at least one cutting edge and a rake face adjacent to the at least one cutting edge, an wherein the rake face comprises a relief-like surface having a chip-breaking geometry that causes chip deflection and thus chip breakage.

Claims

1. A cutting insert comprising: a clamping section having a teardrop-shaped or cylindrical cross-section; a cutting head; and a cantilever arm; wherein the cutting head is arranged at a first end of the cantilever arm and the clamping section is arranged at a second end of the cantilever arm opposite the first end, wherein the cantilever arm has a smaller cross-section than the clamping section, wherein the cutting head comprises at least one cutting edge and a rake face adjacent to the at least one cutting edge, and wherein the rake face comprises a relief-like surface having a chip-breaking geometry that is configured to cause chip deflection and chip breakage.

2. The cutting insert according to claim 1, wherein the chip-breaking geometry is a pressed geometry.

3. The cutting insert according to claim 1, wherein the chip-breaking geometry is a laser cut geometry.

4. The cutting insert according to claim 1, wherein the chip-breaking geometry comprises a raised structure.

5. The cutting insert according to claim 1, wherein the chip-breaking geometry comprises a recessed structure.

6. The cutting insert according to claim 1, wherein a first portion of the chip-breaking geometry comprises a raised structure and a second portion of the chip-breaking geometry comprises a recessed structure.

7. The cutting insert according to claim 1, wherein the at least one cutting edge comprises a first cutting edge and a second cutting edge, wherein the first cutting edge and the second cutting edge lie in a cutting plane, and wherein the chip-breaking geometry is raised and/or recessed relative to the cutting plane.

8. The cutting insert according to claim 1, wherein the chip-breaking geometry extends along an entire length of the at least one cutting edge.

9. The cutting insert according to claim 1, wherein the rake face and the chip-breaking geometry are mirror symmetrical.

10. The cutting insert according to claim 1, wherein the at least one cutting edge comprises a first cutting edge and a second cutting edge, wherein the first cutting edge and the second cutting edge lie in a cutting plane and are oriented at an angle 90° relative to each other.

11. The cutting insert according to claim 10, wherein the first cutting edge and the second cutting edge are connected to each other via an arcuate edge that lies in the cutting plane.

12. The cutting insert according to claim 1, wherein an upper surface of the clamping section is convexly curved and a lower surface of the clamping section comprises a first partial surface, a second partial surface, and a third partial surface, wherein the first partial surface is convexly curved and arranged opposite to the upper surface, wherein the second partial surface and the third partial surface lie opposite to one another, are each designed as planar surfaces, and run at an acute angle relative to one another, and wherein the second partial surface and the third partial surface are connected to one another via the first partial surface.

13. A tool for machining a workpiece, comprising: a cutting insert having a clamping section, a cutting head, and a cantilever arm, a tool holder having at a front end a cutting insert receptacle that is configured as a cup-shaped recess in the tool holder and configured to receive the clamping section of the cutting insert; and a fastening element that is configured to fasten the cutting insert in the cutting insert receptacle; wherein the cutting head is arranged at a first end of the cantilever arm and the clamping section is arranged at a second end of the cantilever arm opposite the first end, wherein the cantilever arm has a smaller cross-section than the clamping section, wherein the cutting head comprises at least one cutting edge and a rake face adjacent to the at least one cutting edge, and wherein the rake face comprises a relief-like surface having a chip-breaking geometry that is configured to cause chip deflection and chip breakage.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0045] FIG. 1 illustrates a perspective view of an embodiment of the tool;

[0046] FIG. 2 illustrates an exploded view of the embodiment of the tool shown in FIG. 1,

[0047] FIG. 3 illustrates a longitudinal section of the embodiment of the tool shown in FIG. 1;

[0048] FIG. 4 illustrates a cross-section of the embodiment of the tool shown in FIG. 1;

[0049] FIG. 5 illustrates a perspective view of a first embodiment of the cutting insert;

[0050] FIG. 6 illustrates a detailed view of the cutting insert shown in FIG. 5;

[0051] FIG. 7 illustrates a perspective view of a second embodiment of the cutting insert;

[0052] FIG. 8 illustrates a detailed view of the cutting insert shown in FIG. 7;

[0053] FIG. 9 illustrates a perspective view of a third embodiment of the cutting insert;

[0054] and

[0055] FIG. 10 illustrates a detailed view of the cutting insert shown in FIG. 9.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0056] FIGS. 1-4 show an embodiment of the tool in a perspective view, an exploded view, a longitudinal section view and a cross-sectional view. The tool is denoted therein in its entirety with the reference numeral 10. FIGS. 5-10 show three different embodiments of the cutting insert, which can be used in the tool. In each case, the cutting insert is denoted in its entirety with the reference numeral 12.

[0057] The tool 10 comprises a cutting insert 12 and a tool holder 14. The cutting insert 12 can be fastened to or in the tool holder 14 by means of a fastening element 16.

[0058] The tool holder 14 extends substantially along a holder longitudinal axis 18 and comprises a cutting insert receptacle 22 at a front face end 20. The cutting insert receptacle 22 is introduced into the tool holder 14 in the form of a cup-shaped recess. This cup-shaped recess forms a kind of blind hole in the tool holder 14.

[0059] The term “cup-shaped recess” is used herein to clarify that the recess forming the cutting insert receptacle 22 is a cavity in the tool holder 14, which has a closed peripheral wall that is circumferential with respect to the holder longitudinal axis 18 and is open toward the front end face 20 of the tool holder 14. In other words, the cup-shaped recess is formed in the tool holder 14 and is surrounded by the tool holder 14 all around the holder longitudinal axis 18. However, the term “cup-shaped recess” is not intended to be limited to any particular cross-sectional shape. The cross-section of this recess may also have a complex shape. The cup-shaped recess serving as a cutting insert receptacle 22 has a base or inner stop inside the tool holder 14. However, this base or inner stop does not need to be a closed wall. As will be explained further below, for example, one or more bores in the interior of the tool holder 14 can adjoin the cup-shaped recess or the cutting insert receptacle 22.

[0060] As can be seen in particular from the longitudinal sectional view and cross-sectional view shown in FIGS. 3 and 4, the cutting insert 12 is in the assembled state of the tool at least partially inserted into the cutting insert holder 22 and is fixed to the tool holder 14 by the fastening element 16. The fastening element 16 is configured as a screw in the present case. The screw 16 comprises an external thread which engages in an internal thread 26 arranged in the tool holder 14. The internal thread 26 runs along a thread axis 28 that preferably runs orthogonally to the holder longitudinal axis 18.

[0061] In the assembled state, the screw 16 presses the tool 10 preferably from above onto the cutting insert 12, whereby the latter is pressed with its underside into the cutting insert receptacle 22. In the assembled state, the cutting insert 12 contacts the tool holder 14 only with its underside and is contacted on its upper side by the screw 16.

[0062] However, in principle it is also possible for the cutting insert 12 to be clamped in the tool holder 14 with the aid of a clamping element, such as this is known from DE 10 2015 104 057 A1.

[0063] The cutting insert 12 comprises a clamping section 30, a cutting head 32, and a cantilever arm 34. The cantilever arm 34 connects the cutting head 32 to the clamping section 30. The cutting head 32 is arranged at a first or front end of the cantilever arm 34. The clamping section 30 is arranged at the opposite second or rear end of the cantilever arm 34. The clamping section 30, cantilever arm 34 and cutting head 32 are preferably integrally connected to each other.

[0064] In the presently shown embodiment, the clamping section 30 has a substantially teardrop-shaped cross-section (see FIG. 4). The upper surface 36 of the clamping section 30 is convexly curved. The lower surface 38 of the clamping section 30 opposite the upper surface 36 is divided into three partial surfaces 40, 42, 44. The first partial surface 40 is opposite the upper surface 36 and is also convexly curved. The second and third partial surfaces 42, 44 are opposite to each another and are connected to each other by the first partial surface 40. The second and third partial surfaces 42, 44 are each configured as planar surfaces. In the assembled state of the tool 10, the clamping section 30 of the cutting insert 12 preferably does not abut the tool holder 14 with it entire lower surface 38.

[0065] The abutment with the tool holder 14 takes place via the two planar surfaces 42, 44, whereas the first partial surface 40 of the clamping section 30 has no direct contact with the tool holder 14. The two partial surfaces 42, 44, which are designed as planar surfaces, rest against corresponding abutment surfaces 46, 48, which are arranged in the interior of the cutting insert receptacle 22. Both the two partial surfaces 42, 44 and the two abutment surfaces 46, 48 each run at an acute angle relative to one another. The abutment surfaces 46, 48 are preferably also designed as planar surfaces. In principle, the partial surfaces 42, 44 can abut the tool holder 14 or the inner walls of the cup-shaped cutting insert receptacle 22 over the entire surface or only linearly, i.e. along a line or straight line.

[0066] As further shown in FIG. 4, a cutting insert coolant passage 50 extends through the interior of the cutting insert 12. The cutting insert coolant passage 50 is arranged off-center in the present embodiment. The coolant enters the cutting insert coolant passage 50 through a coolant main passage 52, which extends through the interior of the tool holder 14. The coolant exits the cutting insert coolant passage 50 from a coolant outlet opening 54, which is arranged at a front side of the clamping section 30. The cutting insert coolant passage 50 as well as the coolant outlet opening 54 are thereby aligned in such a way that the resulting coolant jet is preferably directed in the direction of the cutting head 32.

[0067] The three embodiments of the cutting insert 12 shown in FIGS. 5-10 differ essentially in the respective shape of the cutting head 32. More specifically, the three embodiments differ in the shape and form of the rake face.

[0068] All three embodiments shown in FIGS. 5-10 have in common that the cutting head 32 comprises at least one cutting edge 56. In each of the three embodiments shown here, the cutting head 32 also comprises a second cutting edge 58. In principle, however, the cutting head 32 may comprise only one cutting edge without departing from the spirit and scope of the present disclosure.

[0069] A chip surface 60 is adjacent to the at least one cutting edge 56, 58 of the cutting head. All three embodiments shown here also have in common that the rake face 60 comprises a relief-like surface with a chip-breaking geometry 62, which causes chip deflection and thus chip breaking. However, the shape of the relief-like surface or the shape of the chip-breaking geometry 62, respectively, differs from one embodiment to another.

[0070] In the first embodiment shown in FIGS. 5 and 6, the chip-breaking geometry 62 is configured as a recessed structure 64 that is introduced into the rake face 60. Here, the recess 64 forming the chip-breaking geometry 62 is recessed or offset downward relative to a cutting plane in which the two cutting edges 56, 58 lie.

[0071] In the second embodiment shown in FIGS. 7 and 8, the chip-breaking geometry 62 is configured as a raised structure 66 that projects upward from the rake face 60. Thus, the chip-breaking geometry 62 is formed here by a raised structure 66. In this case, the raised structure 66 is not directly adjacent to the cutting edges 56, 58. However, as in the first embodiment shown in FIGS. 5 and 6, the chip-breaking geometry 62 also in this case preferably runs along the entire length of each of the two cutting edges 56, 58.

[0072] The embodiment shown in FIGS. 9 and 10 is a kind of combination of the first two embodiments. Here, the chip-breaking geometry 62 comprises both a recess 64, which is offset downward relative to the cutting plane, and an elevation 66, which projects upward relative to the cutting plane. The recess 64 is immediately adjacent to the two cutting edges 56, 58. It is arranged between the cutting edges 56, 58 and the elevation 66.

[0073] The chip-breaking geometry 62 of all three embodiments is preferably produced by pressing. Preferably, the entire cutting head 32 is produced in a single pressing operation, and only smaller sections, such as the two cutting edges 56, 58, are subsequently machined by grinding.

[0074] Alternatively, it is possible to produce the chip-breaking geometry 62 by means of laser machining of the cutting head 32. Such a laser machining, however, only allows the chip-breaking geometry 62 to be produced as a recessed structure 64, such as that shown in FIGS. 5 and 6.

[0075] According to all three embodiments, the rake face 60 is preferably mirror-symmetrical with respect to a plane of symmetry which is the same distance from each of the first and second cutting edges 56, 58. The first and the second cutting edges 56, 58 preferably lie in a common cutting plane, as already mentioned. They preferably run at an angle 90° relative to each other. The first and second cutting edges 56, 58 are preferably connected to each other via an arcuate edge 68. This arcuate edge forms the tip of the cutting head 32. The arcuate edge 68 is preferably also arranged in the cutting plane in which the first and second cutting edges 56, 58 lie.

[0076] It should be noted, however, that in other embodiments not shown here, the rake face 60 can in principle also be configured asymmetrically. This can make sense in particular because, depending on whether the tool is used in a pressing or a drawing cut, different chip thicknesses result, which may require different geometries.

[0077] Finally, it shall be noted that the cutting edges 56, 58 do not necessarily have to be designed as straight cutting edges. In principle, the cutting edges 56, 58 can also be designed as arcuate cutting edges. The shapes of the cutting head shown here serve merely as examples of a variety of possible shapes of the cutting head 32. Just like the cutting edges 56, 58, the shape of the rake face 60 can also vary as desired. The chipbreaking geometry 62, which is preferably designed as a free-form surface, can also vary in shape. However, it is basically designed as a depression and/or elevation so that the rake face 60 has a relief-like surface. The shape of the clamping section 30 likewise does not necessarily have to correspond to the shape shown here. The clamping section 30 can in principle also comprise a cylindrical cross-section.

[0078] It is to be understood that the foregoing is a description of one or more preferred exemplary embodiments of the invention. The invention is not limited to the particular embodiment(s) disclosed herein, but rather is defined solely by the claims below. Furthermore, the statements contained in the foregoing description relate to particular embodiments and are not to be construed as limitations on the scope of the invention or on the definition of terms used in the claims, except where a term or phrase is expressly defined above. Various other embodiments and various changes and modifications to the disclosed embodiment(s) will become apparent to those skilled in the art. All such other embodiments, changes, and modifications are intended to come within the scope of the appended claims.

[0079] As used in this specification and claims, the terms “for example,” “e.g.,” “for instance,” “such as,” and “like,” and the verbs “comprising,” “having,” “including,” and their other verb forms, when used in conjunction with a listing of one or more components or other items, are each to be construed as open-ended, meaning that the listing is not to be considered as excluding other, additional components or items. Other terms are to be construed using their broadest reasonable meaning unless they are used in a context that requires a different interpretation.