Turning tool and cutting insert thereof
By designing a negative-shaped turning insert, the back tool surface is shortened to 75% of the maximum thickness and a transition area is set at the cutting edge, which solves the problems of insufficient clearance and high friction risks in internal turning operations, achieving more efficient machining and longer tool life.
Patent Information
- Application Number
- CN202380086338.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2022-12-22
- Filing Date
- 2023-11-29
- Publication Date
- 2025-07-11
AI Technical Summary
Existing turning tools have problems with unfavorable cutting conditions in internal turning operations, especially when small hole processing, the surface clearance between the cutting insert and the workpiece is insufficient and the friction risk is high.
A cutting insert is designed with a negative basic shape, with a length of extension of the backplane surface less than 75% of the maximum thickness of the cutting insert, and a transition area is provided between the cutting edge and the backplane surface to increase the gap while maintaining the strength of the cutting insert.
Without damaging the strength of the cutting insert, the gap with the workpiece surface is increased, the risk of friction is reduced, and the processing efficiency and tool life is improved.
Smart Images
Figure CN120303075A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present invention relates to metal cutting and, in particular, to turning operations in which a turning tool is used to machine a rotating workpiece. BACKGROUND OF THE INVENTION
[0002] In the field of metal cutting, a turning tool can be used to machine the surface of a rotating workpiece, such as the inner surface of a hole in the workpiece. This is known as internal turning or boring. In such machining operations, the tool can extend along a central axis parallel to the axis of rotation of the workpiece.
[0003] Turning tools generally include a cutting insert made of a wear-resistant material, such as cemented carbide, which is arranged to engage the workpiece surface. For external turning operations, cutting inserts with a negative basic shape are generally used, i.e., cutting inserts without an inherent clearance angle. Negative cutting inserts have the advantage of high cutting edge strength and are suitable for heavy cutting conditions. However, for internal turning operations, positive cutting inserts, i.e., cutting inserts with an inherent clearance angle, are generally used to ensure clearance relative to the workpiece surface.
[0004] EP3456442 discloses a turning tool for internal turning, which turning tool has a cutting insert with a negative basic shape. The required clearance is achieved by the proper placement and orientation of the cutting insert within the tool body. However, if the cutting insert is tilted too much, this may result in less favorable cutting conditions (e.g., with regard to chip breaking).
[0005] Accordingly, there is a need for an improved turning tool for internal turning operations. SUMMARY OF THE INVENTION
[0006] An object of the present invention is to mitigate the drawbacks of the prior art and to provide: an improved cutting insert with good accessibility and high strength; and a turning tool for internal turning operations for use with such a cutting insert.
[0007] Accordingly, in a first aspect, the present invention relates to a cutting insert for a turning tool, wherein the cutting insert comprises a first side and a second side which are arranged opposite to each other and face in opposite directions, the first side and the second side extending substantially in respective first and second planes which are parallel to each other, wherein the first side comprises a first rake face. A central axis extends from the first side to the second side in a direction perpendicular to the first and second planes. The cutting insert further comprises an outer peripheral surface connecting the first side and the second side, wherein the outer peripheral surface comprises a first flank face extending parallel to or substantially parallel to the central axis. A first cutting edge is arranged at the intersection between the first flank face and the first rake face, wherein the cutting edge comprises a first nose cutting edge. The cutting insert has a maximum thickness measured from the first side to the second side in a direction parallel to the central axis. The first flank face adjacent to the first nose cutting edge has an extension length in a direction parallel to the central axis which is less than 75% of the maximum thickness of the cutting insert.
[0008] Accordingly, an increased clearance to the machined surface in internal turning operations is obtained without compromising the strength of the cutting insert.
[0009] The first flank face is parallel to the central axis of the cutting insert, which means that the cutting insert has a negative basic shape. For increased stability, it is preferable that the turning tool for internal turning and the cutting insert arranged on the turning tool are as large as allowed by the diameter of the hole to be machined. The inventors have found that even if the length of the flank face (i.e., the part of the outer peripheral surface closest to the inner wall of the hole to be machined) is reduced, the strength of the cutting insert provided in part by the thickness of the cutting insert can be maintained to a sufficient extent. Thereby, an increased clearance to the machined surface is obtained. This is particularly useful when machining small holes where the available space in the hole very much limits the size of the turning tool and the cutting insert.
[0010] Accordingly, with the design according to the present invention, a relatively thick cutting insert with a negative basic shape can be used for internal turning, wherein the risk of friction between the flank face and the machined surface is reduced.
[0011] Even though some cutting inserts according to the prior art may have a surface which is slightly axially raised relative to the trailing edge of the cutting edge and / or the flank face, this raise is smaller than that proposed in the present invention and is not used to increase the clearance, but is mainly an effect of the production process and / or facilitates a firm mounting of the cutting insert in the insert seat.
[0012] The first flank adjacent to the first cutting edge of the tip can have an extension length in a direction parallel to the central axis that varies slightly along the cutting edge of the tip, i.e., the cutting edge of the tip can be curved in a side view. However, according to the present disclosure, at all positions along the cutting edge of the tip, and in particular at the position where the extension length of the cutting edge of the tip is maximum, the extension length of the first flank is less than 75% of the maximum thickness of the cutting insert.
[0013] The term "turning tool" should be understood as a cutting tool for machining a rotating workpiece. In the context of machining the inner surface of a hole in a rotating workpiece, such a tool is sometimes also referred to as a boring bar. The central axis of such a turning tool is parallel to, but usually not coaxial with, the axis of rotation of the workpiece, and the turning tool can be radially moved within the hole to engage the surface of the workpiece. Thereby, it is possible to machine a varying internal profile of the hole by changing the radial displacement between the turning tool and the axis of rotation of the workpiece.
[0014] As used herein, the term "cutting edge" should be understood as a combination of cutting edge segments that together form a complete cutting edge, and may include multiple cutting edge segments, such as a tip cutting edge, a main cutting edge, and an auxiliary cutting edge. Thus, according to the present disclosure, each cutting edge of the cutting insert can include not only the tip cutting edge, but also the main cutting edge and possibly also the auxiliary cutting edge, where the main cutting edge can extend from one end of the tip cutting edge, and the auxiliary cutting edge can extend from the other end of the tip cutting edge. Thus, the cutting insert according to the present invention can include a first cutting edge that includes a first main cutting edge, a first auxiliary cutting edge, and a first tip cutting edge.
[0015] Each cutting edge of such a main cutting edge and auxiliary cutting edge can be straight in a plan view of the first side or the second side. The tip cutting edge can be convexly curved in a plan view, i.e., preferably arcuate. In such a view, the tip cutting edge can be formed by, for example, a single radius connecting the main cutting edge to the auxiliary cutting edge, or the tip cutting edge can include multiple curved segments having different radii.
[0016] The first side and the second side extend generally in respective first and second planes that are parallel to each other. This means that at least a substantial portion of the first side and the second side extends in such planes. At least some portions of the first side and the second side can be flat surfaces, at least some of which extend in the respective first and second planes, but the first side and the second side can also include various geometric structures, which include, for example, recesses or protrusions for changing the cutting geometry and improving chip breaking, and can also include regions having flat or curved surfaces that are inclined or perpendicular to the first and second planes with respect to the first and second planes.
[0017] The central axis of the cutting insert extends from a first side to a second side, extends through the geometric center of the cutting insert, and extends perpendicular to a first plane and a second plane, with the corresponding first side and second side extending generally in the first plane and the second plane. The cutting insert may include a through-hole that opens in the first side and the second side, and the through-hole can be used to fasten the cutting insert within a blade seat of a tool body using a fastening element such as a screw. The through-hole may extend along the central axis of the cutting insert and may be circular in a cross-section perpendicular to the central axis.
[0018] The cutting insert according to the present invention is primarily intended and adapted for longitudinal turning, i.e., where the feed direction is parallel to the rotational axis of the workpiece. In longitudinal turning, the main cutting edge can be arranged to serve as a front cutting edge, while the nose cutting edge is arranged to produce a cylindrical or surface concentric with the rotational axis of the metal workpiece.
[0019] According to some embodiments, a first flank face adjacent to a first nose cutting edge has an extension length in a direction parallel to the central axis that is greater than 30% of the maximum thickness of the cutting insert and may be, for example, between 40% and 70% of the maximum thickness of the cutting insert.
[0020] By making the extension length of the flank face at least 30% of the maximum thickness and, for example, between 40% and 70%, an optimal compromise can be achieved between the resulting clearance and the strength of the cutting insert.
[0021] According to some embodiments, the maximum thickness of the cutting insert is between 3 mm and 6 mm, and the extension length of the flank face is between 1 mm and 4.5 mm. As an example, for a cutting insert with a maximum thickness of 3 mm, the flank face may have an extension length between 1 mm and 2.25 mm (e.g., approximately 2 mm), and for a cutting insert with a maximum thickness of 6 mm, the flank face may have an extension length between 2 mm and 4.5 mm (e.g., approximately 4 mm).
[0022] The second side of the cutting insert may include a contact surface that is arranged to abut against a support surface in a blade seat of a turning tool. Such a contact surface may be formed at least in part by a flat surface portion of the second side that extends in a second plane, and the flat surface portion may be located in a region of the second side that surrounds the central axis of the cutting insert, for example adjacent to an opening of a through-hole that extends through the cutting insert along the central axis. The second side may include a transition region that extends from such a contact surface to the first flank face. The transition region may include an inclined surface portion that is inclined relative to the central axis. In other words, preferably, the transition between the shortened flank face and the contact surface of the cutting insert is not simply formed by one or more 90° steps (i.e., where one portion extends from the flank face parallel to the second plane and another portion extends towards the contact surface parallel to the central axis), but includes at least some portion that is inclined relative to the second plane and the central axis. This may be preferred for the production of the cutting insert, and such a transition from the flank face to the contact surface will also be less brittle and substantially maintain the strength of the cutting insert.
[0023] According to some embodiments, the distance that the transition region extends from the intersection between the first flank face and the transition region and in the direction of a radial line towards the central axis of the cutting insert is at least 10% of the total distance from that point to the central axis along that radial line. Thereby, the transition region provides a significant recess in the flank face, thus ensuring sufficient clearance to the machined surface. The extension of the transition region may be greatest at the intersection between the transition region and the first flank face adjacent to the first tip cutting edge. As an example, the transition region may extend a distance of at least 0.5 mm in the direction of a radial line towards the central axis of the cutting insert from the intersection located between the first flank face and the transition region.
[0024] The first cutting edge may include a first major cutting edge that is connected to the first tip cutting edge and extends from the first tip cutting edge along the intersection between the first flank face and the first rake face. According to some embodiments, the distance from such a first major cutting edge to the second side decreases away from the first tip cutting edge. Thus, according to such embodiments, in a side view of the cutting insert, the major cutting edge does not extend parallel to the first side and the second side, but is inclined away from the tip cutting edge. In other embodiments, at least a portion of the first major cutting edge may extend parallel to the first side and the second side.
[0025] A cutting insert may include a plurality of flank faces, rake faces, and corresponding cutting edges formed at intersections therebetween. In other words, the cutting insert may be indexable such that different cutting edges may be positioned at operative positions for machining a workpiece, depending on the orientation of mounting the cutting insert in a pocket of a turning tool body. The flank faces of all the cutting edges will extend parallel to each other and parallel or substantially parallel to the central axis.
[0026] Thus, according to some embodiments, the outer peripheral surface includes a second flank face, and the first side or the second side includes a second rake face, wherein a second cutting edge is disposed at an intersection between the second flank face and the second rake face, the second cutting edge includes a second tip cutting edge, and wherein the second flank face adjacent to the second tip cutting edge has an extension length in a direction parallel to the central axis that is less than 75% of the maximum thickness of the cutting insert.
[0027] Thus, both the first flank face and the second flank face of such an indexable cutting insert have an extension length in a direction parallel to the central axis that is less than 75% of the maximum thickness of the cutting insert.
[0028] Thus, according to some embodiments, the outer peripheral surface includes a first flank face and a second flank face, while the first side includes a first rake face and the second side includes a second rake face, wherein a first cutting edge including a first tip cutting edge is disposed at an intersection between the first flank face and the first rake face, and a second cutting edge including a second tip cutting edge is disposed at an intersection between the second flank face and the second rake face, and wherein each of the first flank face and the second flank face adjacent to the first tip cutting edge and the second tip cutting edge respectively has an extension length in a direction parallel to the central axis of the cutting insert that is less than 75% of the maximum thickness of the cutting insert. The first flank face and the second flank face may be disposed on opposite sides or substantially opposite sides of the outer peripheral surface.
[0029] According to other embodiments, the second side may include a first opposing rake face opposite to the first rake face, wherein a first opposing cutting edge is disposed at an intersection between the first opposing rake face and the first flank face. Preferably, the first opposing cutting edge has a design similar to that of the first cutting edge and thus includes a first opposing tip cutting edge. Thus, the cutting insert may be double-sided, i.e., wherein the cutting edges are disposed at opposite ends of the first flank face such that the cutting insert can be indexed simply by inverting the cutting insert within the pocket. The first flank face serves as the flank face for both the first cutting edge and the first opposing cutting edge. Thus, the first flank face adjacent to the first opposing tip cutting edge has an extension length in a direction parallel to the central axis that is less than 75% of the maximum thickness of the cutting insert.
[0030] For such an embodiment, at least a portion of the transition region at the second side is formed by the first opposing rake face.
[0031] The cutting insert may further have a second flank face, a second rake face disposed at the first side, and a second opposing rake face disposed at the second side, such that the cutting insert has: a first cutting edge and a second cutting edge disposed at respective intersections between the first side and the first and second flank faces; and a first opposing cutting edge and a second opposing cutting edge disposed at respective intersections between the second side and the first and second flank faces. In other words, the cutting insert may be indexable four times.
[0032] According to some embodiments, the cutting insert has a rhombic or substantially rhombic basic shape in a plan view of the first side or the second side. However, the cutting insert may also have other shapes suitable for turning.
[0033] According to another aspect, the present invention relates to a turning tool, the turning tool comprising a tool body, the tool body including a blade seat, and a cutting insert according to any of the embodiments described herein is mounted in the blade seat.
[0034] The turning tool may be arranged for machining a metal workpiece and may include a front end and a rear end, the cutting insert being mounted at the front end, and the rear end being adapted to be directly or indirectly clamped to a machine interface of a machine tool (such as a computerized numerical control (CNC) lathe). Description of the Drawings
[0035] The solution will now be described in more detail by means of exemplary embodiments and with reference to the drawings, in which:
[0036] Figure 1 is a perspective view of a cutting insert according to a first embodiment.
[0037] Figure 2 is a top view of a cutting insert according to a first embodiment.
[0038] Figures 3 to 5 is as seen from Figure 2 a side view of a cutting insert according to a first embodiment as seen in the direction III-V indicated therein.
[0039] Figure 6 shows a turning tool according to an embodiment of the present invention during an internal turning operation on a workpiece, wherein the turning tool includes Figures 1 to 5 the cutting insert shown therein.
[0040] Figure 7 is Figure 6 a view of the turning tool and the workpiece in section VII-VII indicated therein.
[0041] Figure 8 is Figure 7 An enlarged view of a part of the turning tool and the workpiece shown in
[0042] Figure 9 A perspective view of a cutting insert according to the second embodiment.
[0043] Figure 10 A top view of a cutting insert according to the second embodiment.
[0044] Figure 11 A side view of a cutting insert according to the second embodiment.
[0045] Figure 12 A perspective view of a cutting insert according to the third embodiment.
[0046] Figure 13 A top view of a cutting insert according to the third embodiment.
[0047] Figure 14 A side view of a cutting insert according to the third embodiment.
[0048] All the drawings are schematic, not necessarily drawn to scale, and generally show only the components necessary to illustrate the corresponding embodiments, while other components may be omitted or merely suggested. Unless otherwise specified, the same reference numerals in different figures refer to the same components. Detailed Description of the Invention
[0049] Referring to Figures 1 to 5 , the cutting insert 1 according to an embodiment of the present invention will now be described.
[0050] The cutting insert 1 has: a first side 2; a second side 3; and an outer peripheral surface 4 connecting the first side 2 and the second side 3. The first side 2 and the second side 3 face in opposite directions and extend substantially in respective first plane P1 and second plane P2 (shown in Figure 5 ) that are parallel to each other. A central axis L (also shown in Figure 5 ) extends from the first side 2 to the second side 3 and is perpendicular to the parallel planes P1, P2. The central axis L passes through the geometric center GC of the cutting insert. A through hole 13 extends along the central axis L.
[0051] The outer peripheral surface 4 includes a first flank face 7 and a second flank face 8. The first side 2 includes a first rake face 11, and the second side 3 includes a second rake face 12. At the junction between the first flank face 7 and the first rake face 11, a first cutting edge 5 is formed. At the junction between the second flank face 8 and the second rake face 12, a second cutting edge 6 is formed.
[0052] The first cutting edge 5 includes a first tip cutting edge 51, a first major cutting edge 52, and a first auxiliary cutting edge 53. Accordingly, the first flank 7 further includes a first tip flank 71, a first major flank 72, and a first auxiliary flank 73 (shown in Figure 4 ).
[0053] Correspondingly, the second cutting edge 6 includes a second tip cutting edge 61, a second major cutting edge 62, and a second auxiliary cutting edge 63, and the second flank 8 includes a second tip flank 81, a second major flank 82, and a second auxiliary flank 83 (shown in Figure 3 ).
[0054] The flanks 7 and 8 are parallel to the central axis L.
[0055] As best seen in Figure 5 , the first side 2 includes: a first flat contact surface 34 extending in a first plane P1; and a first transition region 35 extending from the second flank 8 to the first contact surface 34. Most of the surface of the first transition region 35 is arranged obliquely with respect to the central axis L, and thus extends in an inclined manner with respect to the central axis L and the first plane P1. The second side 3 includes: a second flat contact surface 36 extending in a second plane P2; and a second transition region 37 extending from the first flank 7 to the second contact surface 36. The second transition region 37 is arranged in a manner corresponding to that of the first transition region 35.
[0056] Each of the tip cutting edges of the first tip cutting edge 51 and the second tip cutting edge 61 is convexly curved in a plan view, as best seen in Figure 2 , while the first major cutting edge 52 and the first auxiliary cutting edge 53, and the second major cutting edge 62 and the second auxiliary cutting edge 63 are straight in such a view. Accordingly, the first major flank 72 and the first auxiliary flank 73, and the second major flank 82 and the second auxiliary flank 83 are flat surfaces, while the tip flanks 71, 81 are convex surfaces connecting the corresponding major flanks and auxiliary flanks, and each convex surface is formed by a single radius. In a side view, the first major cutting edge 52 and the first auxiliary cutting edge 53, and the second major cutting edge 62 and the second auxiliary cutting edge 63 are respectively inclined away from the first tip cutting edge 51 and the second tip cutting edge 61.
[0057] Accordingly, as seen in Figures 3 to 5 , the distance from the first major cutting edge 52 to the second side 3 decreases away from the first tip cutting edge 51, and the distance from the second major cutting edge 62 to the first side 2 decreases away from the second tip cutting edge 61. Correspondingly, the distance from the first auxiliary cutting edge 53 to the second side 3 decreases away from the first tip cutting edge 51, and the distance from the second auxiliary cutting edge 63 to the first side 2 decreases away from the second tip cutting edge 61.
[0058] The first major flank 72 and the second major flank 82 are adjacent to each other and are located on the same flat sub-surface of the outer peripheral surface 4, as best seen in Figure 5 this.
[0059] As best seen in Figure 5 this, each of the first flank 7 and the second flank 8 adjacent to the corresponding first tip cutting edge 51 and second tip cutting edge 61 has an extension length h in a direction parallel to the central axis L that is much smaller than the total thickness t of the cutting insert. In this first embodiment, the extension length h is approximately 70% of the total thickness t. The flanks 7, 8 have a maximum flank extension length in a direction parallel to the central axis L at the points along the tip cutting edges 51, 61. Thus, in this embodiment, the maximum extension length of each of the first flank 7 and the second flank 8 in a direction parallel to the central axis L is approximately 70% of the total thickness t of the cutting insert 1.
[0060] Figures 6 to 8 A turning tool 10 including a tool body 20 according to an embodiment of the present invention is shown. The turning tool 10 participates in an internal turning operation for machining a workpiece 31 along a feed direction F, where the workpiece 31 rotates in a rotational direction R about a spindle axis W. The tool body 20 has a front end 21, a rear end 22, and a tool body central axis C that longitudinally extends through the tool body from the front end 21 to the rear end 22. Although not shown in Figure 6 this, the workpiece 31 and the turning tool 10 are arranged in a machine tool, such as a computerized numerical control (CNC) lathe.
[0061] The tool body outer peripheral surface 23 connects the front end 21 and the rear end 22. A groove 26 for evacuating chips is formed in the tool body outer peripheral surface 23. The tool body 20 further includes a first blade seat and a second blade seat formed at the junction between the front end 21 and the tool body outer peripheral surface 23. The first blade seat and the second blade seat are located on opposite sides with respect to the tool body central axis C.
[0062] Threaded holes are located in each blade seat. According to Figures 1 to 5The cutting insert 1 is mounted in the first insert seat using a screw that extends through the through-hole 13 in the cutting insert 1 and into the threaded hole in the first insert seat. The second cutting insert 30 is likewise mounted in the second insert seat. The second cutting insert 30 is different from the first cutting insert 1 and is used in different machining operations. For example, the turning tool 10 can be controlled such that when machining in the forward direction (e.g., into a hole in the workpiece), the second cutting insert 30 first engages the surface of the rotating workpiece 31, and then the turning tool 10 can be controlled such that when machining in the backward direction (e.g., out of the hole), the first cutting insert 1 engages the workpiece 31.
[0063] As Figures 7 to 8 seen, when machining the inner surface 32 of the hole in the workpiece 31, the cutting insert 1 is engaged. For an efficient machining process, it is important that the clearance between the flank face 7 and the machined surface 32 is sufficient. In the illustrated embodiment, sufficient clearance is obtained by having a shortened flank face 7 as described previously with reference to Figure 5 ... As Figure 8 shown by the dashed line in..., a flank face 7 with a greater extension length would interfere with the machined surface 32, resulting in friction between the workpiece and the cutting insert, which would adversely affect the tool life and the quality of the machined surface.
[0064] Since most of the cutting insert 1 still has a thickness corresponding to the maximum thickness t of the cutting insert, the shortened flank face 7 does not significantly affect the strength of the cutting insert 1.
[0065] Figures 9 to 11 is a schematic view of a cutting insert 40 according to a second embodiment. The cutting insert 40 differs from the cutting insert 1 in the first embodiment in that: the cutting insert 40 has a different shape in a top view, namely a generally diamond shape, as Figure 10 best seen in...; and the second rake face 12 is arranged on the first side 2, i.e., such that the first cutting edge 5 and the second cutting edge 6 are respectively formed at the intersections between the first side 2 and the first flank face 7 and the second flank face 8. For the first embodiment, the second side 3 of the cutting insert includes: a flat contact surface 36; and transition regions 37 that extend between the contact surface 36 and the respective first flank face 7 and second flank face 8. In this second embodiment, each of the first flank face 7 and the second flank face 8 adjacent to the respective nose cutting edges of the first cutting edge 5 and the second cutting edge 6 has a maximum extension length h in a direction parallel to the central axis L that is approximately 60% of the total thickness t of the cutting insert 40.
[0066] Figures 12 to 14Schematic view of a cutting insert 90 according to the third embodiment. The cutting insert 90 differs from the cutting insert 40 in the second embodiment in that: the cutting insert 90 is double-sided, that is, the cutting insert 90 includes: a first opposing rake face 91 and a second opposing rake face 92 disposed on the second side 3; and corresponding first opposing cutting edges 93 and second opposing cutting edges 94 formed at the intersections between the first flank 7 and the second flank 8 and the first opposing rake face 91 and the second opposing rake face 92, respectively. In such an embodiment, the first transition region 35 on the first side 2 extending between the first contact surface 34 and the first flank 7 and the second flank 8 is at least partially formed by the first rake face 11 and the second rake face 12, while the second transition region 37 on the second side 3 extending between the second contact surface 36 and the first flank 7 and the second flank 8 is at least partially formed by the first opposing rake face 91 and the second opposing rake face 92. In this third embodiment, the maximum extension length h in the direction parallel to the central axis L of each of the first flank 7 and the second flank 8 adjacent to the respective tip cutting edges of the first cutting edge 5 and the second cutting edge 6 is approximately 50% of the total thickness t of the cutting insert 90.
[0067] Although the foregoing description contains many specificities, these should not be construed as limiting the scope of the concepts described herein, but merely as exemplifications of some exemplary embodiments of the concepts described. It should be understood that the scope of the presently described concepts fully encompasses other embodiments that may be obvious to those skilled in the art, and the scope of the presently described concepts is therefore not limited.
Claims
1. A cutting insert (1, 40, 90) for a turning tool, the cutting insert comprising: - A first side (2) and a second side (3) arranged opposite to each other and facing in opposite directions, the first side and the second side extending substantially in respective first and second planes (P1, P2) parallel to each other, wherein the first side includes a first rake face (11); - A central axis (L) extending from the first side (2) to the second side (3) in a direction perpendicular to the first plane (P1) and the second plane (P2); - An outer peripheral surface (4) connecting the first side (2) and the second side (3), wherein the outer peripheral surface (4) includes a first flank face (7) extending parallel to or substantially parallel to the central axis (L); and - A first cutting edge (5) arranged at the intersection between the first flank face (7) and the first rake face (11), wherein the first cutting edge includes a first nose cutting edge (51); wherein the cutting insert has a maximum thickness (t) measured from the first side (2) to the second side (3) in a direction parallel to the central axis (L), characterized in that the first flank face (7) adjacent to the first nose cutting edge (51) has an extension length (h) in a direction parallel to the central axis (L) that is less than 75% of the maximum thickness (t) of the cutting insert.
2. The cutting insert according to claim 1, wherein the first flank face adjacent to the first nose cutting edge has an extension length (h) in a direction parallel to the central axis that is greater than 30% of the maximum thickness (t) of the cutting insert.
3. The cutting insert according to any one of the preceding claims, wherein the first flank face adjacent to the first nose cutting edge has an extension length (h) in a direction parallel to the central axis between 40% and 70% of the maximum thickness (t) of the cutting insert.
4. The cutting insert according to any one of the preceding claims, wherein the second side includes a contact surface (36) arranged to abut against a support surface in a blade seat of a turning tool.
5. The cutting insert according to claim 4, wherein the second side includes a transition region (37) extending from the contact surface (36) to the first flank face (7).
6. The cutting insert according to claim 5, wherein the transition region (37) includes an inclined surface portion inclined with respect to the central axis (L).
7. The cutting insert according to any one of claims 5 and 6, wherein Starting from the intersection between the first flank face (7) and the transition region (37) and in the direction of a radial line towards the central axis (L), the transition region (37) extends a distance that is at least 10% of the total distance from the point to the central axis (L) along the radial line.
8. The cutting insert according to any one of the preceding claims, wherein the first cutting edge (5) comprises a first major cutting edge (52) which is connected to the first nose cutting edge (51), and the first major cutting edge (52) extends from the first nose cutting edge (51) along the intersection between the first flank face (7) and the first rake face (11).
9. The cutting insert according to claim 8, wherein the distance from the first major cutting edge (52) to the second side (3) decreases away from the first nose cutting edge (51).
10. The cutting insert according to any one of the preceding claims, wherein the outer peripheral surface comprises a second flank face (8), and the first side (2) or the second side (3) comprises a second rake face (12), and wherein a second cutting edge (6) is arranged at the intersection between the second flank face (8) and the second rake face (12), wherein the second cutting edge (6) comprises a second nose cutting edge (61), and the second flank face (8) adjacent to the second nose cutting edge (61) has an extension length (h) in a direction parallel to the central axis (L) which is less than 75% of the maximum thickness (t) of the cutting insert.
11. The cutting insert (90) according to any one of the preceding claims, wherein the second side (3) comprises a first opposing rake face (91) opposite to the first rake face (11), and wherein a first opposing cutting edge (93) is arranged at the intersection between the first opposing rake face (91) and the first flank face (7).
12. The cutting insert (40, 90) according to any one of the preceding claims, wherein the cutting insert has a rhombic or substantially rhombic basic shape in a plan view of the first side or the second side.
13. A turning tool (10) comprising a tool body (20), the tool body (20) comprising a blade seat, and the cutting insert (1, 40, 90) according to any one of claims 1 to 12 being mounted in the blade seat.