Turning tool kit, and cutting inserts for said turning tool kit

Abstract

The present invention relates to a turning tool kit (100) for turning operations, the kit comprising a tool body (1), at least a first cutting insert (6), and a second cutting insert (6'), each of which is selectively configurable on a seat (5) of the tool body. The first and second cutting inserts (6, 6') each comprise at least two cutting edges (10, 10'), each cutting edge having a nose cutting edge (101, 101') that separates and connects a front cutting edge (102, 102') and a rear cutting edge (103, 103'). The forward cutting edges (102) of at least two cutting edges (10) on the first cutting insert (6) each form a first acute angle (A) with respect to each rear cutting edge (103), while the forward cutting edges (102') of at least two cutting edges (10') on the second cutting insert (6') each form a second acute angle (B) with respect to each rear cutting edge (103'), where the second acute angle (B) is greater than the first acute angle (A). The forward cutting edges (102') of at least two cutting edges (10') on the second cutting insert (6') each transition to an auxiliary non-cutting edge (104') that forms the same angle as, or substantially the same angle as, the first acute angle (A) with respect to each rear cutting edge (103'). The present invention also relates to a cutting insert (6',6'') for use in such a turning tool kit.

Description

Technical Field

[0001] The present invention relates to metal cutting, and more particularly to a turning tool and a cutting insert for the turning tool.

Background Art

[0002] In the field of metal cutting, a turning tool can be used to machine the surface of a rotating workpiece (e.g., the inner surface of a hole in a workpiece). This is called 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] A turning tool typically includes a cutting insert made of a wear-resistant material (e.g., carbide), and the cutting insert is arranged to engage the workpiece surface.

[0004] To manufacture a part, multiple machining operations may be required, and different tools may be used for different operations. A turning tool is typically designed to hold a single cutting insert with a specific geometry adapted to a particular machining operation.

[0005] European Patent No. 3456442 (EP3456442) discloses a turning tool having two different cutting inserts (one roughing cutting insert and one finishing cutting insert) attached to the front end of a tool body. This allows different turning operations to be performed with the same turning tool without the need for tool change.

[0006] However, current turning tools are still not very versatile in performing multiple different turning operations optimally, for example, with respect to the profile of the machined surface.

[0007] Therefore, there is a need for a highly versatile turning tool that can be used in a greater variety of situations and applications.

[0008] Summary of the Invention The object of the present invention is to provide a turning tool kit usable in a number of different turning operations, and cutting inserts for said turning tool kit, so as to mitigate the drawbacks of the prior art and reduce the number of tool changes required when manufacturing parts.

[0009] Therefore, according to the first aspect, the present invention relates to a turning tool kit for turning operations, the turning tool kit comprising a tool body, the tool body having a front end, a rear end, a central axis extending from the front end to the rear end, and a seat for housing a cutting insert. The turning tool kit further comprises at least a first cutting insert and a second cutting insert, each of which is selectively configurable in the seat, the first cutting insert and the second cutting insert each having a first side and a second side facing each other in opposite directions, a peripheral surface connecting the first side and the second side, and at least two cutting edges, each cutting edge located at the intersection between the first side and the peripheral surface, and having a nose cutting edge that separates and connects the front cutting edge and the rear cutting edge. The front cutting edge of each of the at least two cutting edges on the first cutting insert forms a first acute angle with respect to each rear cutting edge when viewed in the plane of the first side of the first cutting insert. The forward cutting edge of each of the at least two cutting edges on the second cutting insert forms a second acute angle with respect to each rear cutting edge, when viewed in the plane of the first side of the second cutting insert, where the second acute angle is greater than the first acute angle. The forward cutting edge of each of the at least two cutting edges on the second cutting insert transitions into an auxiliary non-cutting edge that forms the same angle as, or substantially the same angle as, the first acute angle with respect to each rear cutting edge, when viewed in the plane of the first side of the second cutting insert.

[0010] This allows for the selective use of cutting inserts optimized for different situations on the same tool body, thereby reducing the number of tool changes required when manufacturing parts.

[0011] For longitudinal turning operations, cutting inserts with a front cutting edge and a rear cutting edge can cut in both the forward and backward feed directions, i.e., in a direction parallel to the axis of rotation of the workpiece (which in the case of internal turning operations is usually also parallel to the central axis of the turning tool body). For example, in internal turning operations, such a turning tool may be used in a forward machining operation where the turning tool moves into the hole. In such a forward machining operation, the front cutting edge functions as the primary cutting edge (at least when the cutting depth is large), and the nose cutting edge generates the surface.

[0012] When machining in the forward direction, it may be advantageous to use different forward cutting angles depending on the machining operation being performed. The forward cutting angle should be understood as the angle formed by the forward cutting edge with respect to the feed direction during longitudinal turning, i.e., with respect to the axis of rotation of the workpiece.

[0013] Each of the first and second cutting inserts is provided with at least two cutting edges, so that when the cutting insert is mounted in one of the available indexing positions in the seat, at least one of the two cutting edges is indexable, i.e., at least one of the two cutting edges is positioned in an active position for machining the workpiece. When the first cutting insert is mounted in the seat, the peripheral surface adjacent to the front cutting edge that is not in the active position functions as a contact surface that abuts against the support surface of the seat. The inventors have found that by designing the second cutting insert in accordance with this disclosure, a similar contact surface is provided on the second cutting insert as well. Thus, the second cutting insert fits into the seat due to the front cutting edge transitioning into an auxiliary non-cutting edge that extends in the same way as the front cutting edge of the first cutting insert. In fact, when one of the cutting edges of the first cutting insert is positioned in the seat in the active position, the active forward cutting edge of the first cutting insert extends in the first plane, and when one of the cutting edges of the second cutting insert is positioned in the seat in the active position, the auxiliary non-cutting edge adjacent to the active forward cutting edge of the second cutting insert extends in the same first plane. Therefore, when the second cutting insert is mounted in the seat, the peripheral surface adjacent to the auxiliary non-cutting edge adjacent to the forward cutting edge that is not in the active position functions as a contact surface that abuts against the corresponding support surface in the seat.

[0014] The nose cutting edge of the first cutting insert may have a similar shape to the nose cutting edge of the second cutting insert. However, the geometric shapes of the nose cutting edges of the first and second cutting inserts may also be significantly different without affecting the ease of mounting the cutting insert to the seat, thereby further increasing the potential versatility of the turning tool kit. Thus, according to the turning tool kit of the present invention, the same turning tool body can be used to machine multiple different types of surfaces and profiles.

[0015] A "turning tool" should be understood as a cutting tool used to machine a rotating workpiece. Such tools are sometimes called boring bars when used to machine the inner surface of a hole in a rotating workpiece. The central axis of such internal turning tools is usually parallel to the axis of rotation of the workpiece, but not coaxial with it.

[0016] As used herein, the term "cutting edge" should be understood, unless otherwise specified, as a combination of cutting edge segments that together form a complete cutting edge, and in this case, at least a nose cutting edge, a front cutting edge, and a rear cutting edge.

[0017] While the front and rear cutting edges may be linear in a plan view of the first side of the cutting insert, the nose cutting edge may be convexly curved in such a plan view, for example, in an arc shape. Thus, in this view, the nose cutting edge may be formed by a single radius connecting the front cutting edge to the secondary cutting edge. Alternatively, the nose cutting edge may include multiple curved segments of different radii, and, if applicable, linear or substantially linear segments, such as those for forming so-called wiper cutting edges.

[0018] As used herein in relation to cutting edges, the acute angle formed by the front cutting edge with respect to the rear cutting edge should be understood as the acute angle at which the extension of the front cutting edge intersects the corresponding extension of the rear cutting edge; that is, as viewed in a plan view of the first side of the cutting insert, as the angle at which a virtual line continuing from the front cutting edge and along the same direction as the front cutting edge intersects a virtual line continuing from the rear cutting edge and along the same direction as the rear cutting edge.

[0019] In this context, the first acute angle and the second acute angle, which is "substantially the same," should be understood as the same angle within reasonable manufacturing tolerances of the cutting inserts, and at least close enough to be effective, i.e., the angle at which each cutting insert can be positioned on the seat of the tool body.

[0020] According to some embodiments, when one of the cutting edges of a first cutting insert is positioned in the seat in the active position, the active forward cutting edge of the first cutting insert forms an obtuse first forward cutting angle, and when one of the cutting edges of a second cutting insert is positioned in the seat in the active position, the active forward cutting edge of the second cutting insert forms an obtuse second forward cutting angle, where the second forward cutting angle is smaller than the first forward cutting angle. According to some embodiments, the first forward cutting angle is at least 2° greater than the second forward cutting angle, up to 15° greater, and between 8° and 12°, for example, 10° greater.

[0021] For example, the first front cutting angle could be between 95° and 115°, and the second front cutting angle could be between 90° and 100°.

[0022] A second cutting insert may be used in forward machining operations where a large cutting depth is desired. The second forward cutting angle is preferably relatively close to 90°, for example, between 90° and 95°. Using a relatively large forward cutting angle in combination with a large cutting depth can result in an undesirable chip formation process (where the formed chip takes on a "sawtooth" shape around its outer circumference, potentially leading to damage to the cutting edge). Therefore, for many materials, a second forward cutting angle of up to 95° (but not exceeding this) may be appropriate. However, for some materials, a slightly larger second forward cutting angle (up to 100° in some cases) may be usable.

[0023] The first cutting insert, with its relatively large forward cutting angle, is not very suitable for use in forward machining operations with large cutting depths due to the aforementioned problems. Instead, it can be used in applications requiring a large forward cutting angle, with a small cutting depth, for example, for profiles that cannot be machined in other ways.

[0024] According to some embodiments, the maximum distance between the nose cutting edges of any two cutting edges among at least two cutting edges on a first cutting insert is different from the maximum distance between the nose cutting edges of any two cutting edges among at least two cutting edges on a second cutting insert.

[0025] A turning tool kit may comprise two or more different cutting inserts having different forward cutting angles and / or different nose cutting edge shapes. Thus, according to some embodiments, a turning tool kit comprises a third cutting insert similar to a second cutting insert, the third cutting insert having first and second sides positioned opposite each other and facing each other in opposite directions, a peripheral surface connecting the first and second sides, and at least two cutting edges, each cutting edge including a nose cutting edge positioned at the intersection of the first side and the peripheral surface, separating and connecting the front and rear cutting edges. The forward cutting edge of each of the at least two cutting edges on the third cutting insert forms a third acute angle with respect to each rear cutting edge when viewed in a plan view of the first side of the third cutting insert, where the third acute angle is greater than the first acute angle, and the forward cutting edge of each of the at least two cutting edges on the third cutting insert transitions to an auxiliary non-cutting edge that forms the same angle as, or substantially the same angle as, the first acute angle with respect to each rear cutting edge when viewed in a plan view of the first side of the third cutting insert.

[0026] The third acute angle may be different from, but may be the same as, the second acute angle. The shape of the nose cutting edge of the third cutting insert may differ from the geometric shape of the nose cutting edge of the first cutting insert and / or the shape of the nose cutting edge of the second cutting insert.

[0027] According to a second aspect, the present invention relates to a cutting insert for a turning tool kit according to any of the embodiments described herein, where the cutting insert has a first side and a second side that are disposed on opposite sides and face each other in opposite directions, a peripheral surface connecting the first side and the second side, and at least two cutting edges, each cutting edge being disposed at an intersection of the first side and the peripheral surface and including a nose cutting edge that separates and connects a front cutting edge and a rear cutting edge. For each of the at least two cutting edges, the front cutting edge transitions to an auxiliary non-cutting edge. When the cutting insert is viewed in a plan view of the first side, the auxiliary non-cutting edge forms a first acute angle with respect to the rear cutting edge, and the front cutting edge forms a second acute angle with respect to the rear cutting edge, where the second acute angle is greater than the first acute angle.

[0028] Such a cutting insert corresponds to the second cutting insert of the turning tool kit defined above, whereby it has the compatibility necessary to be attachable to a seat of a turning tool body originally designed for a cutting insert having a cutting edge with an angle between the rear cutting edge and the front cutting edge corresponding to the first acute angle.

[0029] According to some embodiments, the second acute angle is at least 2° and up to 15° greater than the first acute angle, for example, between 8° and 12°, for example, 10° greater.

[0030] According to some embodiments, the first acute angle is between 30° and 70°. For example, the first acute angle is between 35° and 45°, for example, 40°.

[0031] According to some embodiments, the second acute angle is between 32° and 85°. For example, the second acute angle is between 45° and 55°, for example, 50°.

[0032] The cutting insert may have two cutting edges, thereby allowing it to be indexed twice. In another embodiment, the cutting insert may have three cutting edges, thereby allowing it to be indexed three times.

[0033] According to some embodiments, the length of the front cutting edge of the cutting insert is no more than 15% of the maximum distance between any two of the two cutting edges. The relatively short front cutting edge provides a sufficiently large contact surface on the peripheral surface of the cutting insert, allowing the cutting insert to be firmly mounted to the seat. For example, the length of the front cutting edge of the cutting insert may be between 5 and 10% of the maximum distance between any two of the two cutting edges.

[0034] In some embodiments, the leading cutting edge of a cutting insert transitions to an auxiliary non-cutting edge via a radiused transition. Such a radiused transition may be formed by a single radius. In other embodiments, the transition may be sharp.

[0035] If the transition is rounded, that is, if there is a non-zero extension in the plan view of the first side of the cutting insert, the length of the forward cutting edge should be understood as the distance from the point on the cutting edge where the nose cutting edge ends to the point where such a transition begins.

[0036] The cutting insert may be made of a wear-resistant material, such as cemented carbide.

[0037] The present solution will now be described in more detail with reference to exemplary embodiments and the attached drawings. [Brief explanation of the drawing]

[0038] [Figure 1] A turning tool kit according to one embodiment is shown, including a tool body and three different cutting inserts. [Figure 2] a represents the tool body on which the first cutting insert is located. b represents the tool body on which the second cutting insert is located. c represents the tool body on which the third cutting insert is located. [Figure 3] Figure a is a plan view of the first side of the first cutting insert. Figure b is a side view of the first cutting insert as seen from direction IIIb shown in Figure 3a. [Figure 4] Figure a is a plan view of the first side of the second cutting insert. Figure b is a side view of the second cutting insert as seen from the IVb direction shown in Figure 4a. [Figure 5] Figure a is a plan view of the first side of the third cutting insert. Figure b is a side view of the third cutting insert as seen from the Vb direction shown in Figure 5a. [Figure 6] This shows the seat portion of the tool body. [Figure 7] The following diagram schematically shows the arrangement of three different cutting inserts when mounted on the seat of the tool body.

[0039] All drawings are schematic and not necessarily to scale. In general, they show only the parts necessary to illustrate each embodiment, with other parts omitted or merely suggested. Unless otherwise specified, similar reference numerals refer to similar components in different drawings. [Modes for carrying out the invention]

[0040] Figure 1 shows a turning tool kit 100 comprising a turning tool body 1, having a first cutting insert 6, a second cutting insert 6', and a third cutting insert 6'', each cutting insert designed to fit into a seat 5 of the tool body 1. In the illustrated embodiment, an additional cutting insert 4 is also positioned on the tool body. The additional cutting insert 4 is a roughing insert intended for use in an initial machining operation before machining the surface with any of the first, second, or third cutting inserts 6, 6', 6''.

[0041] The tool body 1 has a front end 2 and a rear end 3. The central axis C (shown in Figures 2a-2c) extends longitudinally through the tool body 1 from the front end 2 to the rear end 3.

[0042] As shown in Figure 2a, when the first cutting insert is mounted on the seat 5 of the tool body 1, it has a forward cutting edge 102 that forms an obtuse forward cutting angle α with respect to the feed direction F when machining in the forward direction during longitudinal turning. The feed direction F is parallel to the axis of rotation of the workpiece (and in the illustrated embodiment, it is also parallel to the central axis C of the tool body). When the machining operation is an internal diameter turning operation, the feed direction F corresponds to the direction into the machined hole.

[0043] The forward cutting angle α of the first cutting insert 6 is considerably larger than 90°, in this case approximately 102°. Such a forward cutting angle may be necessary in certain applications, for example, when machining a specific profile inside a hole. However, a drawback of such a relatively large cutting angle is that it can lead to an undesirable chip formation process, where the formed chip takes on a "sawtooth" shape around its outer circumference, potentially leading to damage to the cutting edge. To avoid this problem, it is preferable to use a cutting depth that does not exceed two-thirds of the nose edge when performing forward cutting operations with such cutting inserts.

[0044] Therefore, for other applications, such as machining tight profiles, it may be better to use a forward cutting angle close to 90°, which increases the cutting depth and improves productivity. In this case, the forward cutting edge can participate in the cutting without the aforementioned problems. A forward cutting angle of up to 95° may be appropriate for many materials. For some materials, a slightly larger forward cutting angle (up to 100° in some cases) may be usable.

[0045] Therefore, as shown in Figures 2b-2c, a second cutting insert 6' (resulting in a forward cutting angle β) or a third cutting insert 6'' (resulting in a forward cutting angle γ) can be mounted on the seat 5 to enable greater cutting depth when machining in the feed direction F (i.e., forward direction). In the illustrated embodiment, the forward cutting angle β of the second cutting insert 6' is the same as the forward cutting angle γ of the third cutting insert 6'' (in this case, approximately 92°). Therefore, in the illustrated embodiment, the difference between the second cutting insert 6' and the third cutting insert 6'' lies not in the forward cutting angle, but in the geometry of each nose edge, which will be described in more detail later. However, according to other embodiments, the turning tool kit may include multiple cutting inserts, each with a different forward cutting angle.

[0046] Figures 3a and 3b show the first cutting insert 6 in more detail. The first cutting insert 6 has a first side 7, a second side 8, and a peripheral surface 9, and includes three cutting surfaces 10 formed at the intersection of the first side 7 and the peripheral surface 9. Thus, a portion of the first side 7 located adjacent to the cutting edge 10 corresponds to the rake face of each cutting edge 10, and a portion of the peripheral surface 9 located adjacent to the cutting edge 10 corresponds to the relief face of each cutting edge 10. Each cutting edge 10 includes a front cutting edge 102, as well as a nose cutting edge 101 and a rear cutting edge 103. As shown in Figure 3a, in the plan view of the first side 7 of the cutting insert 6, the front cutting edge 102 forms an acute angle A with respect to the rear cutting edge 103, or more precisely, an extension of the front cutting edge 102 (i.e., a virtual line continuing from the front cutting edge 102 and along the same direction as the front cutting edge 102) intersects with the corresponding extension of the rear cutting edge 103 at an acute angle A, which in the illustrated embodiment is approximately 40°. Since the cutting insert 6 is indexable, i.e., has more than one cutting edge 10, the geometry of the cutting edges 10 (including the acute angle A) will affect the design of the seat 5. This is because the seat 5 must securely accommodate and support the cutting insert 6 along at least a portion of the peripheral surface 9. In other words, the required position and extensions of the support surface in the seat 5 (which are positioned to abut a portion of the peripheral surface 9 of the cutting insert 6) will depend on the extensions of the cutting edges 10 of the cutting insert, particularly the acute angle A.

[0047] Figures 4a and 4b show the second cutting insert 6' in more detail. Similar to the first cutting insert 6', the second cutting insert 6' has a first side 7', a second side 8', and a peripheral surface 9', and includes three cutting edges 10' formed at the intersection of the first side 7' and the peripheral surface 9'. Each cutting edge 10' includes a front cutting edge 102', a nose cutting edge 101', and a rear cutting edge 103'. As shown in Figure 4a, in a plan view of the first side 7' of the second cutting insert 6', the front cutting edge 102' forms an acute angle B with respect to the rear cutting edge 103', and this angle is approximately 50° in the illustrated embodiment.

[0048] In contrast to the first cutting insert 6, the front cutting edge 102' of the second cutting insert 6 has a relatively short extension and transitions to an auxiliary non-cutting edge 104' via a rounded transition section 105'. The auxiliary non-cutting edge 104' forms an angle A with respect to the rear cutting edge 103'. As a result, even though the extension of the front cutting edge 102' of the second cutting insert 6' differs from that of the front cutting edge 102 of the first cutting insert 6, it becomes possible to position the second cutting insert 6' on the seat 5. This will be further explained below with reference to Figures 6 and 7.

[0049] Figures 5a and 5b show the third cutting insert (6'') in more detail. Similar to the first cutting insert 6 and the second cutting insert 6', the third cutting insert 6'' has a first side 7'', a second side 8'', and a peripheral surface 9'', and comprises three cutting edges 10'' formed at the intersection of the first side 7'' and the peripheral surface 9''. Each cutting edge 10'' comprises a front cutting edge 102'', a nose cutting edge 101'', and a rear cutting edge 103''. As shown in Figure 5a, in a plan view of the first side 7'' of the third cutting insert 6'', the front cutting edge 102'' forms an acute angle C with respect to the rear cutting edge 103'', and this angle is approximately 50° in the illustrated embodiment.

[0050] Similar to the second cutting insert 6', the front cutting edge 102'' of the third cutting insert 6'' transitions to an auxiliary non-cutting edge 104' via a relatively short, rounded transition section 105''. The auxiliary non-cutting edge 104'' forms an angle A with respect to the rear cutting edge 103''. This allows the third cutting insert 6'' to also be positioned on the seat 5.

[0051] In the illustrated embodiment, the acute angle C for the third cutting insert 6'' is the same as the acute angle B for the second cutting insert 6'. The main difference between the third cutting insert 6'' and the second cutting insert 6' lies in the design of their respective nose cutting edges 101', 101''. The nose cutting edge 101'' of the third cutting insert 6'' is a wiper design and therefore includes multiple sections with different curvatures, whereas the nose cutting edge 101' of the second cutting insert 6' is formed by a single radius, similar to the nose cutting edge 101 of the first cutting insert 6. Thus, the second and third cutting inserts 6', 6'' have the same forward cutting angle when mounted on the seat 5, and the choice of which cutting insert to use is rather based on what geometric shape of the nose cutting edge is preferred. The nose cutting edge 101'' of the third cutting insert 6'', which has a wiper geometric shape, may be suitable for efficiently machining high-quality surfaces and may be preferred when machining internal surfaces without changing the profile, for example, in the case of cylindrical holes, but it cannot be used in many other cases where precision profiles are being machined. Instead, in such situations, either the second cutting insert 6'' or the first cutting insert 6'' can be used.

[0052] The seat 5 (shown in detail in Figure 6) comprises first, second, and third side support surfaces 121, 122, and 123 arranged to abut against the first, second, and third side contact surfaces 131, 132, and 133, respectively, the contact surfaces located on the peripheral surfaces 9, 9', and 9'' of each cutting insert 6, 6', and 6''. The seat 5 further comprises a bottom support surface 16 arranged to abut against at least a portion of the second surfaces 8, 8', and 8'' of each cutting insert 6, 6', and 6'' when the cutting insert is mounted on the seat 5. The bottom support surface 16 includes a screw hole 14.

[0053] Figure 7 schematically shows the positions of the first, second, and third cutting inserts 6, 6', and 6'' when mounted on the seat 5. However, this is for illustrative purposes only, and it should be noted that the three different cutting inserts 6, 6', and 6'' cannot be mounted on the seat 5 simultaneously. The contour of the first cutting insert 6 is shown with a solid line, the contour of the second cutting insert 6' is shown with a dotted line, and the contour of the third cutting insert 6'' is shown with a dashed line. For clarity, the first faces 7, 7', and 7'' of each cutting insert are shown without geometric details in Figures 1-5 (including chip breakers, etc.). As can be seen in Figure 7, the peripheral surfaces 9, 9', 9'' of the cutting inserts 6, 6', 6'' are provided with corresponding first, second, and third contact surfaces 131, 132, 133, respectively, which are positioned to abut against the associated first, second, and third support surfaces 121, 122, 123 in the seat 5. This ensures that any of the three cutting inserts 6, 6', 6'' attached to the seat 5 will be securely housed in the seat once it is installed. The cutting inserts can be fixed to the seat using a fixing element 15 (for example, a screw extending through a central hole in the cutting insert into a threaded hole 14 in the seat 5).

[0054] When the first cutting insert 6 is positioned on the seat 5, its active forward cutting edge (the cutting edge that extends radially outward from the tool body) extends toward the first plane P. When the second cutting insert 6' or the third cutting insert 6'' is positioned on the seat 5, the auxiliary non-cutting edges adjacent to its active forward cutting edge each extend toward the same first plane P.

[0055] As shown in Figure 7, the first contact surface 131 and the third contact surface 133 of the second and third cutting inserts 6', 6'' are located on peripheral surfaces 9', 9'' below the auxiliary non-cutting edges 104', 104'' adjacent to the two inactive forward cutting edges 102', 102''. To ensure that the contact surfaces 131, 133 of the second and third cutting inserts 6', 6'' are large enough to provide good support, it is desirable that each forward cutting edge 102', 102'' is not too long. Therefore, the length t' (see Figure 4a) of each forward cutting edge 102' of the second cutting insert 6' is preferably relatively short with respect to the maximum distance d' between the two nose cutting edges 101' of the second cutting insert 6', for example, less than 15% of the maximum distance d'.

[0056] In response to this, the length t'' (see Figure 5a) of each front cutting edge 102'' of the third cutting insert 6'' is preferably relatively short with respect to the maximum distance d'' between the two nose cutting edges of the third cutting insert 6'', for example, less than 15% of the maximum distance d''.

[0057] In the embodiments shown in Figures 4a and 5a, the lengths t', t'' are only about 6-8% of the respective maximum distances d', d''. Typically, such lengths are sufficient and will cover most of the relevant cutting depths.

[0058] For each of the second cutting insert 6' and the third cutting insert 6'', the front cutting edges 102',102'' transition to auxiliary non-cutting edges 104',104'' via rounded transition sections 105',105''. The length of the front cutting edge 102',102'' is measured from the cutting edge point where the nose cutting edge 101',101'' ends to the point where the transition section 105',105'' begins.

[0059] In the turning tool kit according to the illustrated embodiment, the maximum distances d',d'' between the nose cutting edges 101',101'' of the second and third cutting inserts 6',6'' are smaller than the maximum distance d between the nose cutting edges 101 of the first cutting insert. As a result, the active nose cutting edges 101,101',101'' of the first, second, and third cutting inserts 6,6',6'' are located at different radial distances from the central axis C of the tool body 1 when mounted on the seat 5 (see Figure 7). However, such differences are easily taken into account in the machine control when machining the workpiece.

[0060] Although the above description includes several specific embodiments, these should be interpreted as not limiting the scope of the concept described herein, but merely presenting some exemplary embodiments of the concept described. It should be appreciated that the scope of the concept described herein fully encompasses other embodiments that may be apparent to those skilled in the art, and therefore the scope of the concept described herein is not limited.

Claims

1. Tool body (1), At least a first cutting insert (6) and a second cutting insert (6'), A turning tool kit (100) for turning work, comprising, the tool body (1) ・Front end (2), ・Rear end (3), - A central axis (C) extending from the front end (2) to the rear end (3), and - Seat portion (5) for housing the cutting insert, It has, The first and second cutting inserts can be selectively positioned on the seat portion (5), and the first cutting insert and the second cutting insert (6, 6') are respectively - The first side (7, 7') and the second side (8, 8') are positioned on opposite sides of each other and facing each other in opposite directions. - Peripheral surfaces (9, 9') connecting the first side and the second side, - At least two cutting edges (10, 10'), Each cutting edge is positioned at the intersection between the first side (7, 7') and the peripheral surface (9, 9'), and has a nose cutting edge (101, 101') that separates and connects the front cutting edge (102, 102') and the rear cutting edge (103, 103'). The front cutting edge (102) of each of the at least two cutting edges (10) on the first cutting insert (6) forms a first acute angle (A) with respect to each rear cutting edge (103) when viewed in the plane of the first side (7) of the first cutting insert (6), and the front cutting edge (102') of each of the at least two cutting edges (10') on the second cutting insert (6') forms a first acute angle (A) with respect to each rear cutting edge (103') when viewed in the plane of the first side (7') of the second cutting insert (6'). A turning tool kit, wherein a second acute angle (B) is formed with respect to the first acute angle (A), the second acute angle (B) being greater than the first acute angle (A), and the forward cutting edge (102') of each of the at least two cutting edges (10') on the second cutting insert (6') transitions to an auxiliary non-cutting edge (104') that, when viewed in the plane of the first side (7') of the second cutting insert (6'), forms the same angle as, or substantially the same angle as, the first acute angle (A) with respect to each rear cutting edge (103').

2. When a first cutting insert (6) is positioned on the seat (5) and one of the cutting edges (10) of the first cutting insert is in the active position, the active forward cutting edge (102) of the first cutting insert (6) forms an obtuse first forward cutting angle (α). When a second cutting insert (6') is positioned on the seat (5) and one of the cutting edges (10') of the second cutting insert is in the active position, the active forward cutting edge (102') of the second cutting insert (6') forms an obtuse second forward cutting angle (β). The turning tool kit according to claim 1, wherein the second front cutting angle (β) is smaller than the first front cutting angle (α).

3. The turning tool kit according to claim 2, wherein the first front cutting angle (α) is at least 2° and up to 15° greater than the second front cutting angle (β).

4. The turning tool kit according to claim 2 or 3, wherein the first front cutting angle (α) is between 95° and 115°, and the second front cutting angle (β) is between 90° and 100°.

5. When a first cutting insert (6) is positioned on the seat (5) and one of the cutting edges (10) of the first cutting insert is in the active position, the active forward cutting edge of the first cutting insert (6) extends toward the first plane (P). When a second cutting insert (6') is positioned on the seat (5) and one of the cutting edges (10') of the second cutting insert is in the active position, an auxiliary non-cutting edge adjacent to the active forward cutting edge of the second cutting insert (6') extends to the first plane (P). A turning tool kit according to any one of claims 1 to 4.

6. A turning tool kit according to any one of claims 1 to 5, wherein the maximum distance (d) between each nose cutting edge (101) of any two cutting edges (10) on the first cutting insert (6) is different from the maximum distance (d') between each nose cutting edge (101') of any two cutting edges (10') on the second cutting insert (6').

7. A cutting insert (6', 6'') for use in a turning tool kit according to any one of claims 1 to 6, wherein the cutting insert (6', 6'') - The first side (7, 7') and the second side (8, 8') are positioned on opposite sides of each other and facing each other in opposite directions. - Peripheral surfaces (9, 9') connecting the first side and the second side, - At least two cutting edges (10, 10'), Each cutting edge is positioned at the intersection between the first side (7', 7'') and the peripheral surface (9', 9''), and has a nose cutting edge (101', 102'') that separates and connects the front cutting edge (102', 102'') and the rear cutting edge (103', 103''), and for each of at least two cutting edges (10', 10''), the front cutting edge (102', 102'') transitions into an auxiliary non-cutting edge (104', 104''), A cutting insert (10', 10'') viewed from a plane on its first side (7', 7''), wherein an auxiliary non-cutting edge (104', 104'') forms a first acute angle (A) with respect to the rear cutting edge (103', 103''), and the front cutting edge (102', 102'') forms a second acute angle (B, C) with respect to the rear cutting edge (103', 103''), the second acute angle (B, C) being greater than the first acute angle (A).

8. The cutting insert according to claim 7, wherein the second acute angle (B, C) is at least 2° and up to 15° greater than the first acute angle (A).

9. The cutting insert according to claim 7 or 8, wherein the first acute angle (A) is between 30° and 70°.

10. A cutting insert according to any one of claims 7 to 9, wherein the second acute angle (B, C) is between 32° and 85°.

11. A cutting insert according to any one of claims 7 to 10, wherein the length (t) of the front cutting edge is up to 15% of the maximum distance (d) between any two nose cutting edges of at least two cutting edges.

12. A cutting insert according to any one of claims 7 to 11, wherein the front cutting edge (102', 102'') transitions to an auxiliary non-cutting edge (104', 105'') via a rounded transition section (105', 105'').

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