Tangential cutting insert, cutting tool with a tangential cutting insert, and method for producing a tangential cutting insert

Abstract

A tangential cutting insert for a turning tool is described, which comprises a first tangential cutting insert side and a second tangential cutting insert side, wherein one of the tangential cutting insert sides is assigned more than two cutting edges, and the cutting edges are arranged in a star shape about a tangential cutting insert center axis. The tangential cutting insert is produced completely from cubic crystalline boron nitride, polycrystalline cubic boron nitride, polycrystalline diamond, or ceramic. In addition, a cutting tool with such a tangential cutting insert is presented. A method for producing a tangential cutting insert is also explained.

Claims

1. An indexable tangential cutting insert for a turning tool, with a first tangential cutting insert side and a second tangential cutting insert side, wherein one of the tangential cutting insert sides is assigned more than two cutting edges, and the cutting edges are arranged in a star shape about a tangential cutting insert center axis, characterized in that the indexable tangential cutting insert is produced completely from cubic crystalline boron nitride, polycrystalline cubic boron nitride, polycrystalline diamond, or ceramic, and the cutting edges are cutting corners and are respectively arranged along an extension of the tangential cutting insert in the direction of the tangential cutting insert center axis substantially on the edge of the tangential cutting insert, and the cutting corners can be alternately arranged on opposite edges of the indexable tangential cutting insert when viewed in a peripheral direction of the indexable tangential cutting insert.

2. The indexable tangential cutting insert according to claim 1, characterized in that the indexable tangential cutting insert comprises 3 to 32 cutting edges.

3. The indexable tangential cutting insert according to claim 1, characterized in that the indexable tangential cutting insert has a fastening opening, wherein a fastening opening center axis corresponds to the indexable tangential cutting insert center axis.

4. The indexable tangential cutting insert according to claim 1, characterized in that cutting edges are assigned to both tangential cutting insert sides.

5. The indexable tangential cutting insert according to claim 1, characterized in that the cutting edges run substantially parallel to the tangential cutting insert center axis.

6. The indexable tangential cutting insert according to claim 1, characterized in that the cutting edges are cutting corners and are respectively arranged along an extension of the indexable tangential cutting insert in the direction of the tangential cutting insert center axis substantially centrally on the indexable tangential cutting insert.

7. The indexable tangential cutting insert according to claim 6, characterized in that the cutting corners each have an edge angle () of substantially 90.

8. The indexable tangential cutting insert according to claim 1, characterized in that the cutting corners each have an edge angle () of less than 90.

9. The indexable tangential cutting insert according to claim 1, characterized in that the indexable tangential cutting insert has a circular basic shape in a plan view along the center axis of a fastening opening.

10. The indexable tangential cutting insert according to claim 1, characterized in that the indexable tangential cutting insert has a rectangular basic shape in a plan view along the center axis of a fastening opening.

11. The indexable tangential cutting insert according to claim 1, characterized in that the indexable tangential cutting insert comprises 6 to 20 cutting edges.

12. A cutting tool with an indexable tangential cutting insert according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention is explained below with reference to various embodiments which are shown in the accompanying drawings. In the figures:

(2) FIG. 1 shows a cutting tool according to the invention with a tangential cutting insert according to the invention which was produced by means of a method according to the invention according to a first embodiment in a perspective illustration,

(3) FIG. 2 shows the tangential cutting insert according to the invention from FIG. 1 in a perspective illustration,

(4) FIG. 3 shows the tangential cutting insert according to the invention from FIGS. 1 and 2 in a side view,

(5) FIG. 4 shows the tangential cutting insert according to the invention from FIGS. 1 to 3 in a plan view,

(6) FIG. 5 shows a cutting tool according to the invention with a tangential cutting insert according to the invention which was produced by means of a method according to the invention according to a second embodiment in a perspective illustration,

(7) FIG. 6 shows the cutting tool according to the invention with the tangential cutting insert according to the invention from FIG. 5 in a side view,

(8) FIG. 7 shows the cutting tool according to the invention with the tangential cutting insert according to the invention from FIGS. 5 and 6 in a plan view,

(9) FIG. 8 shows a cutting tool according to the invention with a tangential cutting insert according to the invention which was produced by means of a method according to the invention according to a third embodiment in a perspective illustration,

(10) FIG. 9 shows the tangential cutting insert according to the invention from FIG. 8 in a perspective illustration,

(11) FIG. 10 shows the tangential cutting insert according to the invention from FIGS. 8 and 9 in a side view,

(12) FIG. 11 shows the tangential cutting insert according to the invention from FIGS. 8 to 10 in a plan view,

(13) FIG. 12 shows a cutting tool according to the invention with a tangential cutting insert according to the invention which was produced by means of a method according to the invention according to a fourth embodiment in a perspective illustration,

(14) FIG. 13 shows a ring of cubic crystalline boron nitride from which a tangential cutting insert according to the invention can be produced by means of a method according to the invention,

(15) FIG. 14 shows an alternative contour for the ring from FIG. 13,

(16) FIG. 15 shows another alternative contour for the ring from FIG. 13,

(17) FIG. 16 shows a cutting insert according to another embodiment in a plan view,

(18) FIG. 17 shows cutting insert from FIG. 16 in a side view, and

(19) FIG. 18 shows the cutting insert from FIGS. 16 and 17 in a perspective view.

DETAILED DESCRIPTION

(20) FIGS. 1 to 4 show a cutting tool 10, which is a turning tool in the portrayed embodiment, with a tangential cutting insert 12.

(21) The latter has a first tangential cutting insert side 12a and a second tangential cutting insert side 12b and comprises eight cutting edges 14a, 14b, 14c, 14d, 14e, 14f, 14g, 14h that are arranged in a star shape about a tangential cutting insert center axis 16.

(22) All eight cutting edges 14a to 14h are assigned to the first tangential cutting insert side 12a.

(23) Moreover, the tangential cutting insert 12 is star-shaped and has a fastening opening 18, wherein a fastening opening center axis corresponds to the tangential cutting insert center axis 16.

(24) The tangential cutting insert 12 is connected via a screw 20 arranged in the fastening opening 18 to a tool main body 22 of the cutting tool 10.

(25) In the present embodiment, the cutting edges 14a to 14h are designed as so-called cutting corners.

(26) They are respectively arranged along an extension of the tangential cutting insert 12 in the direction of the tangential cutting insert center axis 16 substantially on the edge of the tangential cutting insert 12.

(27) In other words, the cutting edges 14a to 14h respectively lie in the region of a transition from an axial boundary surface of the tangential cutting insert 12 to a peripheral boundary surface. They are thus provided on an axial edge of the tangential cutting insert 12 (see in particular FIGS. 2 and 4).

(28) An edge angle is substantially 90 (see FIG. 4).

(29) The cutting edges 14a-14h designed as cutting corners can moreover be rounded with a radius R.

(30) Since the cutting edges 14a to 14h are only provided on an axial edge of the tangential cutting insert 12, i.e., are assigned exclusively to the first tangential cutting insert side 12a, the tangential cutting insert can be called a one-sided cutting insert.

(31) The tangential cutting insert can in particular be used for turning an inner perimeter or turning an outer perimeter.

(32) In one variant of the first embodiment, cutting edges 24a to 24h that are designed as cutting edges are provided instead of the cutting edges 14a to 14h that are designed as cutting corners.

(33) The cutting edges 24a to 24h respectively run substantially parallelly to the tangential cutting insert center axis 16.

(34) Such a tangential cutting insert 12 is particularly suitable for turning grooves.

(35) In another variant (not shown), the tangential cutting insert 12 according to the first embodiment is designed as a two-sided cutting insert. This means that in addition to the cutting edges 14a to 14h assigned to the first tangential cutting insert side 12a, another eight cutting edges are provided, which are assigned to the second tangential cutting insert side. These cutting edges are also designed as cutting corners with an edge angle of substantially 90.

(36) This tangential cutting insert 12 can also be used for turning an inner perimeter or turning an outer perimeter.

(37) In all of the variants, the tangential cutting insert 12 is produced entirely from cubic crystalline boron nitride. Alternatively, it can also be produced from polycrystalline cubic boron nitride, polycrystalline diamond, or ceramic.

(38) FIGS. 5 to 7 show a second embodiment of the tangential cutting insert 12. This tangential cutting insert is designed as a one-sided cutting insert with eight cutting edges 14a to 14h designed as cutting corners.

(39) In contrast to the first embodiment, the edge angle of the cutting edges 14a to 14h is however less than 90.

(40) In the portrayed exemplary embodiment, the edge angle is substantially 80.

(41) In the embodiments in FIGS. 1 to 7, the edge radius is only shown on one side. It is in principle also possible to also provide the edge radius on the other side of the cutting edges. An indexable insert is then obtained, which must however be used in a right and a left holder depending on which side is to be used.

(42) FIGS. 8 to 11 show a third embodiment of the tangential cutting insert 12. Only the differences from the previous embodiments will be addressed.

(43) The tangential cutting insert 12 is now designed as a two-sided cutting insert. Viewed along the tangential cutting insert center axis 16, cutting edges are therefore provided on both sides of the tangential cutting insert 12.

(44) In the portrayed embodiment, the cutting edges 14a to 14h are assigned to the first tangential cutting insert side 12a and the cutting edges 14i to 14p are assigned to the second tangential cutting insert side 12b.

(45) The cutting edges 14a to 14p are respectively arranged substantially on the edge of the tangential cutting insert 12.

(46) If the tangential cutting insert 12 is viewed in the peripheral direction, the cutting edges 14a to 14p are alternatingly provided on opposite edges of the tangential cutting insert 12.

(47) The height h of a cutting edge that projects in a radial direction beyond the peripheral surface of the cutting insert, i.e., the width of the cutting face, has a magnitude of around 0.2 to 1 mm.

(48) The cutting edges 14a to 14p in the third embodiment are designed as cutting corners. They have an edge angle of less than 90 which, in the portrayed embodiment, is substantially 80.

(49) The cutting corners can be rounded (not shown).

(50) Overall, the tangential cutting insert 12 according to the third embodiment therefore has 16 cutting edges 14a to 14p.

(51) The tangential cutting insert 12 according to the second and third embodiment is particularly suitable for producing shoulders.

(52) Since the cutting corners on the side 12a are slightly offset from the cutting corners on the side 12b in the peripheral direction, this results in a clearing that ensures a spacing of the inactive cutting corners from the workpiece surface. This can be seen in FIG. 11; the radius r.sub.2 is larger than the radius r.sub.1.

(53) Assuming that cutting occurs with the cutting corner on side 12a that can be seen furthest to the right, the two right cutting corners on side 12b lie at a distance (viewed in the illustration of FIG. 11) from the center axis that is smaller than the distance at which the active cutting corner is located from the center axis. This is because the cutting corners on side 12b lie before and behind the projection plane, whereas the active cutting corner lies in the projection plane.

(54) FIG. 12 shows a fourth embodiment of the tangential cutting insert 12. Again, only the differences from the previous embodiments will be addressed.

(55) The tangential cutting insert 12 now has eight cutting edges 14a to 14h designed as cutting corners, which are respectively arranged along the extension of the tangential cutting insert 12 in the direction of the tangential cutting insert center axis 16 substantially centrally on the tangential cutting insert 12.

(56) The cutting edges 14a to 14h have an edge angle of substantially 90.

(57) This tangential cutting insert 12 is particularly well-suited for turning grooves or for turning threads.

(58) The tangential cutting inserts 12 according to all of the embodiments can be produced as follows.

(59) First, a disk or a ring 26 of cubic crystalline boron nitride, polycrystalline cubic boron nitride, polycrystalline diamond, or ceramic is provided (see FIG. 13).

(60) Alternatively, a disk or ring with a non-round outer contour that is better adapted to the future contour of the cutting insert can also be produced. For example, a square ring (see FIG. 14) or even a hexagonal ring (see FIG. 15) can be used.

(61) The disk or ring 26 can be produced by means of a pressing method.

(62) The ring 26 only differs from the disk by the presence of a central opening that can be used as fastening opening 18. If a disk is used, the fastening opening 18 must be produced separately.

(63) Then, the tangential cutting insert 12 is manufactured from the disk or the ring 26 by grinding, in particular peripheral grinding, or by a laser machining method.

(64) The above-described manufacturing of the tangential cutting insert 12 can be preceded by a rough machining step that, for example, comprises a laser machining method or a spark erosion method. The above-described manufacturing can then be called a fine machining step.

(65) FIGS. 16 to 18 show another embodiment of the cutting insert 12. For the features and designs known from the preceding embodiments, the same reference symbols are used, and reference is made in this respect to the explanations above.

(66) The basic difference between the cutting insert 12 according to FIGS. 16 to 18 and the preceding embodiments is that it has a substantially rectangular basic shape in a plan view. With this basic shape, the same advantages are achievable as with a substantially circular basic shape. Very many cutting edges that can be used individually for machining a workpiece by further adjusting the cutting insert can be provided on a blank. In contrast to a cutting insert with a round basic shape that is further adjusted in the peripheral direction about the center axis of the fastening opening in order to use the next cutting edge after a cutting edge, the cutting insert according to FIGS. 16 to 18 is further adjusted in a translatory manner, i.e., along the longitudinal axis of the main body (in a vertical direction in FIG. 16).