Thread milling tool and cutting element thereof

Abstract

The invention relates to an indexable cutting element (1, 30, 60) for a thread milling tool, comprising a first main surface (2) and a second main surface (3) arranged opposite one another and facing in opposite directions, and a peripheral surface (4) connecting said first and second main surfaces, the peripheral surface comprising an even number of at least four peripheral 5 sub-surfaces (5, 5 ', 6, 6', 7, 7 '), the peripheral sub-surfaces are arranged in pairs on opposite sides of the cutting element and face in opposite directions. For each pair of peripheral sub-surfaces, one sub-surface comprises one or more threaded cutting teeth (9) having a rake face (15) facing a first direction (S1) and the opposite sub-surface comprises a non-cutting surface (18, 19, 31, 32) and / or one or more threaded cutting teeth (9) having a rake face (15) facing a second direction 10 (S2), where the second direction (S2) is opposite the first direction (S1).

Description

Technical Field

[0001] The present invention relates to metal cutting, and in particular to a tool for milling threads in a metal workpiece. Background Art

[0002] Various methods for machining threads in a metal workpiece are known. One such method is thread milling, in which a thread is produced by a circular oblique cutting movement of a rotating thread milling tool, i.e., by using a helical interpolation tool path, in which during one revolution along the workpiece surface, the tool moves a distance corresponding to the pitch along the axis of rotation.

[0003] Some thread milling tools include replaceable cutting elements or inserts, typically made of cemented carbide. WO2005080037 discloses a slot milling cutter in which a single cutting insert is mounted in a slot located at the front of the tool. The cutting insert has two sets of radially opposed cutting teeth which are arranged to engage the workpiece during cutting. The cutting insert has serrations which cooperate with the serrations in the slot for stabilizing the positioning of the cutting insert in the radial direction of the thread milling cutter.

[0004] As with any other cutting element, the thread milling cutting element is subject to wear during the cutting process and will eventually wear out and need to be replaced. For efficiency and economic reasons, it may be desirable to use the cutting element for as long as possible.

[0005] Therefore, there is a need to increase the tool life of the cutting element for a thread milling tool. Summary of the Invention

[0006] It is an object of the present invention to mitigate the disadvantages of the prior art and to provide a cutting element for a thread milling tool of the above type which can be used for a long time before having to be replaced.

[0007] Accordingly, in a first aspect, the present invention relates to a cutting element for a thread milling tool, the cutting element comprising a first major surface and a second major surface which are arranged opposite to each other and face in opposite directions, and a peripheral surface connecting the first major surface and the second major surface. The peripheral surface comprises an even number of peripheral sub-surfaces which are arranged in pairs on opposite sides of the cutting element and face in opposite directions. For each pair of peripheral sub-surfaces, one sub-surface comprises one or more thread cutting teeth having a rake face facing a first direction, and the opposite sub-surface comprises a non-cutting surface and / or one or more thread cutting teeth having a rake face facing a second direction, wherein the second direction is opposite to the first direction. The number of peripheral sub-surfaces is at least four.

[0008] Thus, the cutting element is indexable, i.e., it can be mounted in the slots of the thread milling cutter body in at least two different orientations such that different pairs of peripheral sub-surfaces are operative depending on which orientation the cutting element is mounted in. As a result, the tool life of the cutting element is extended. Indexable cutting elements are currently known for many different types of cutting tools, but are not used for thread milling cutters of the type described herein.

[0009] It may be preferred that both sub-surfaces of each pair of peripheral sub-surfaces include one or more thread cutting teeth, as this will provide high productivity. However, it is also conceivable that only one of the sub-surfaces in each pair of peripheral sub-surfaces includes one or more thread cutting teeth and the opposite sub-surface includes only a non-cutting surface, such as a flat surface, which is arranged such that when the cutting element is mounted in the slot of the thread milling cutter body, the flat surface does not extend beyond the periphery of the cutter body, or at least does not extend so far as to interfere with the thread cutting process.

[0010] The first major surface and the second major surface may be flat surfaces or substantially flat surfaces extending in planes parallel to each other. A central neutral plane lies between the planes in which the first major surface and the second major surface extend and may extend parallel to these planes. The central axis of the cutting element extends perpendicular to the central neutral plane from the first major surface to the second major surface.

[0011] The cutting element may include a through-hole extending along the central axis of the cutting element from the first major surface to the second major surface. Such a through-hole can be used when, for example, fixing the cutting element in the slot of the thread milling cutter body by using screws or other fastening elements.

[0012] Each thread cutting tooth may include a rake face and a flank face (or clearance face), and a cutting edge formed at the intersection between the rake face and the flank face.

[0013] The rake face of the thread cutting tooth may extend in a respective plane corresponding to or parallel to the plane in which the first major surface and the second major surface extend. In other words, a first direction and a second direction opposite to each other may be perpendicular to such a plane.

[0014] In other embodiments, the rake face does not lie in a plane parallel to the plane in which the first major surface and the second major surface extend, but may be inclined relative to such a plane, for example in order to obtain an optimum rake angle. In addition, each rake face does not necessarily have to be a flat surface, but may have a partially curved shape and include additional geometric features, such as chip grooves, to improve operation, such as smoother cutting, improved chip breaking, etc.

[0015] Furthermore, it is conceivable that the rake face of the tooth may also be slightly inclined circumferentially along the peripheral sub-surface towards the central plane, thereby creating a small helix angle for smoother cutting.

[0016] The first and second directions opposite to each other should be understood as being opposite at least when observed in a side view of the cutting element, along a direction parallel to the direction in which the respective opposing peripheral sub-surfaces extend, towards the peripheral surface.

[0017] The second direction opposite to the first direction corresponds to an arrangement in which the surface normals at corresponding points on the respective rake faces of the thread-cutting teeth on the opposing peripheral sub-surfaces, points located in the central plane or on different sides of the central plane, will point towards or away from the central plane on their different sides.

[0018] The cutting element may have a positive basic shape. It is also conceivable that the cutting element is negative. The cutting element may be made of a wear-resistant material such as cemented carbide.

[0019] Each pair of peripheral sub-surfaces is arranged on opposite sides of the cutting element and faces opposite directions. The opposite directions used when referring to the directions in which the peripheral sub-surfaces face should be understood as being opposite to each other at least when observed in a plan view of the first or second main surface.

[0020] In view of the fact that the peripheral sub-surface includes one or more thread-cutting teeth, as used herein, the direction in which such a peripheral sub-surface faces should be understood as the direction in which the surface would face in the absence of such teeth, or the direction in which such thread-cutting teeth project. When observed in a plan view of the first or second main surface, this direction will be a radial direction relative to the central axis of the cutting element, a direction outward from the peripheral sub-surface and perpendicular to the direction along which the thread-cutting teeth are arranged in rows on the peripheral sub-surface.

[0021] For some embodiments, the surface normals of any two radially opposite points (i.e., points on opposite sides with respect to both the central axis and the central plane of the cutting element) on the respective sub-surfaces of a pair of peripheral sub-surfaces will be parallel, but will extend in opposite directions away from each other, i.e., the angle between such surface normals will be 180°.

[0022] The peripheral sub-surfaces can be adjacent to each other one after another along the peripheral surface in a circumferential direction completely surrounding the central axis of the cutting element. For example, there are no other intermediate sections of the peripheral surface located between the peripheral sub-surfaces. Thus, the peripheral surface can be formed entirely by the peripheral sub-surfaces, but it is also conceivable that the peripheral surface can include additional sections that are not considered to be part of any peripheral sub-surface according to the present disclosure. For example, the peripheral surface can include portions that face a direction different from any peripheral sub-surface.

[0023] According to some embodiments, the cutting element has six peripheral sub-surfaces. Preferably, the peripheral sub-surfaces are symmetrically arranged around the peripheral surface of the cutting element. A cutting element having six peripheral sub-surfaces not only provides increased tool life because it can be indexed up to three times, but also has a design that makes it particularly easy to provide a suitable contact surface that is arranged to abut against a corresponding support surface in a slot of a thread milling cutter body, which can help to stabilize the cutting element relative to the thread milling cutter body. However, it is also conceivable that the cutting element can have fewer (such as four) or more (such as eight or ten) peripheral sub-surfaces, and suitable contact surfaces can also be applied to such cutting elements.

[0024] According to some embodiments, each peripheral sub-surface includes one or more non-cutting surfaces and one or more thread cutting teeth. The non-cutting surfaces can be located on either one or both sides of the central neutral plane. Preferably, each peripheral sub-surface has the same number of thread cutting teeth. According to some embodiments, each peripheral sub-surface includes two or more thread cutting teeth arranged in rows along the peripheral sub-surface. It may be beneficial to have as many cutting teeth as possible. However, depending on the size of the cutting element and the type of thread being machined (e.g., pitch and size), the number of cutting teeth that can be applied to the peripheral sub-surface can be limited. According to some embodiments, each peripheral sub-surface has three thread cutting teeth.

[0025] If there is more than one cutting tooth on each peripheral sub-surface, a certain degree of redundancy is obtained, such that the cutting element does not rely on all cutting teeth not being damaged. For example, even if one tooth in a row of teeth on a peripheral sub-surface is worn or damaged in some way, the cutting element does not necessarily need to be indexed or replaced immediately because the remaining undamaged teeth in the row will ensure that the correct thread profile is machined in the workpiece. Thus, if there are two or more thread cutting teeth arranged in rows on each peripheral sub-surface, the tool life can be increased.

[0026] According to some embodiments, when observed in a plan view of the first major surface or the second major surface, the angle by which the directions in which two adjacent peripheral sub-surfaces face along the peripheral surface differ is equal to 360° divided by the total number of peripheral sub-surfaces. Accordingly, the peripheral sub-surfaces will be arranged symmetrically about the central axis of the cutting element, thereby forming a cutting element which has a substantially regular polygon shape in a plan view of the first major surface or the second major surface, the regular polygon having a plurality of sides corresponding to the number of peripheral sub-surfaces. Accordingly, the cutting element will be able to be easily mounted in a slot of a thread milling tool body in different orientations.

[0027] According to some embodiments, the cutting element includes six peripheral sub-surfaces, and the respective rake faces of the teeth in adjacent peripheral sub-surfaces face in different directions. The different directions may be exactly opposite, which would be the case if the respective rake faces extend in planes parallel to each other. On the other hand, if the rake faces are arranged in a non-parallel manner, the directions in which the respective rake faces face may not be exactly opposite. In any case, when located on different sides of the central plane of the cutting element, two respective rake faces will face the central plane or face away from the central plane.

[0028] Such a configuration may be preferred for a cutting element having six peripheral sub-surfaces, but such a configuration may also be applied to a cutting element having a greater number (such as ten) of peripheral sub-surfaces. Accordingly, indexing of the cutting element can be performed by rotating the cutting element about its central axis by an angle corresponding to 2∙360 / n relative to the thread milling tool body, where n is the number of peripheral sub-surfaces. In other words, for a cutting element having six peripheral sub-surfaces arranged symmetrically about the central axis of the cutting element, indexing is performed by rotating the cutting element about its central axis by an angle of 120°.

[0029] According to some embodiments, the rake face of each thread cutting tooth includes a chip gullet. A chip gullet that results in an increased (more positive) rake angle can improve chip formation control and may be beneficial when machining certain workpiece materials. For example, such a chip gullet can result in reduced cutting forces and lower temperatures, thereby providing improved surface integrity of the machined workpiece.

[0030] According to some embodiments, the cutting element is a single piece. Such a single piece can be a piece made entirely of cemented carbide, which is directly pressed and sintered into its final shape, or it can be composed of multiple parts that are non-removably connected to each other during sintering, or by brazing or any other suitable means for connecting the parts into a single piece. For example, such a cutting element can be formed by two identical parts connected to each other, where each identical part has at least four peripheral sub-surfaces, each peripheral sub-surface having a non-cutting surface or one or more thread-cutting teeth, and where the identical parts are connected in such a way that each of the resulting at least four peripheral sub-surfaces includes a non-cutting surface (from one of the multiple identical parts) and one or more thread-cutting teeth (from another of the multiple identical parts). Instead of being formed as a single piece, it is also conceivable that the cutting element is formed by two such identical parts that, when installed together in a slot of a thread milling cutter body, do not attach to each other but are fixed in the configuration described above.

[0031] Thus, according to some embodiments, the cutting element includes two separate parts arranged in a detachable manner with respect to each other. In addition to a simplified manufacturing process, such a cutting element can also provide other benefits. For example, a non-fixed interface between the multiple parts that allows for slight movement between the multiple parts can have a beneficial damping effect during machining, such as reducing vibration and thereby improving the machining result.

[0032] According to some embodiments, the cutting element includes at least two contact surfaces that face different directions and are arranged to abut corresponding support surfaces in a slot of the cutter body for preventing the cutting element from shifting relative to the cutter body when the cutting element is installed in the slot.

[0033] Preferably, the contact surfaces are arranged such that when the cutting element is installed in a slot of a thread milling cutter body, each contact surface abuts a corresponding support surface located in the slot, and each contact surface extends in a direction inclined with respect to the central axis of the thread milling cutter body. Thus, in the case where two such inclined contact surfaces face different directions and abut corresponding support surfaces in a slot of a thread milling cutter body, stable fixation of the cutting element with respect to the cutter body is obtained.

[0034] According to some embodiments, the contact surface is formed by a non-cutting surface included in the peripheral sub-surface. Thus, a convenient design for stabilizing the cutting element within the slot of the thread milling cutter body is obtained, where, in addition to the peripheral sub-surface, no additional contact surfaces arranged to face in other directions are required. Nevertheless, according to alternative embodiments, additional contact surfaces that are not part of any peripheral sub-surface may be formed in the peripheral surface.

[0035] For example, for a cutting element having only four peripheral sub-surfaces, i.e., a cutting element that is square or substantially square when viewed in a plan view of the first main surface or the second main surface, since when the cutting element is mounted in the slot of the thread milling cutter body, no peripheral sub-surface will extend in an inclined direction with respect to the central axis of the thread milling cutter body, it may not be suitable to use any non-cutting surface on the peripheral sub-surface as a contact surface. In such a case, dedicated contact surfaces may be formed in the peripheral surface that are not part of the peripheral sub-surface according to the present disclosure and do not face in the same direction as any peripheral sub-surface.

[0036] On the other hand, given that the cutting element has six peripheral sub-surfaces, when the cutting element is mounted in the slot of the thread milling cutter body, the non-cutting surfaces on two adjacent peripheral sub-surfaces may be suitable for use as contact surfaces.

[0037] According to some embodiments, each peripheral sub-surface includes two non-cutting surfaces that form separate contact surfaces. For example, each peripheral sub-surface may include: one or more teeth arranged in rows along the peripheral sub-surface in a circumferential direction with respect to the central axis of the cutting element; and a non-cutting surface arranged adjacent to the first main surface (i.e., between the first main surface and the row of thread cutting teeth); and another non-cutting surface arranged adjacent to the second main surface (i.e., between the second main surface and the row of thread cutting teeth). When the cutting element is mounted within the slot of the thread milling cutter body, one or both of these non-cutting surfaces may be used as contact surfaces. Thus, if these two non-cutting surfaces are used as contact surfaces, when the cutting element is mounted in the slot of the thread milling cutter body, a total of four contact surfaces will abut the corresponding support surfaces in the slot of the thread milling cutter body.

[0038] According to some embodiments, at least one of the contact surfaces in each peripheral sub-surface has a length different from at least one of the contact surfaces in any adjacent peripheral sub-surface along the peripheral surface. Thus, if the slots in the thread milling cutter for mounting the cutting elements include corresponding support surfaces with different lengths, the cutting element can be mounted in the slot only in a limited number of positions, thereby preventing the cutting element from being incorrectly mounted in the slot.

[0039] According to another aspect, the present invention relates to a thread milling cutter including a cutter body having a front end, a rear end, and a central axis extending from the front end to the rear end, in which a slot is formed. The thread milling cutter includes a cutting element according to any of the embodiments described herein, the cutting element being arranged in the slot such that the teeth in two peripheral sub-surfaces of a pair of peripheral sub-surfaces included in a pair of opposite peripheral sub-surfaces are in an operating position for milling a thread in a workpiece, while the teeth included in the other peripheral sub-surfaces are in a non-operating position.

[0040] Thus, when the cutting element is mounted in the slot of the thread milling cutter body in a specific orientation, only the teeth of a single pair of peripheral sub-surfaces are operable. Thus, for example, a cutting element having two pairs of peripheral sub-surfaces (i.e., four peripheral sub-surfaces) can be used in two different orientations (capable of two indexings), while a cutting element having three pairs of peripheral sub-surfaces (i.e., six peripheral sub-surfaces) can be used in three different orientations (capable of three indexings).

[0041] The teeth arranged in the non-operating position do not interfere with the thread milling process. The exact arrangement to ensure this will depend, for example, on the number of peripheral sub-surfaces (i.e., the angle between adjacent peripheral sub-surfaces) and the length of each peripheral sub-surface relative to the number of thread cutting teeth and the size of each thread cutting tooth (i.e., the type of thread to be machined).

[0042] The cutter body can be made of a material different from that of the cutting element, such as steel. The rear end of the cutter body can be adapted to be directly or indirectly clamped to a machine tool interface of a machine tool (e.g., a computer numerical control (CNC) machine tool).

[0043] The cutting element can be arranged in the slot in the cutter body such that the central axis of the cutting element is perpendicular or substantially perpendicular to the central axis of the cutter body.

[0044] Each threading cutting tooth disposed at the operating position projects in a direction perpendicular or substantially perpendicular to the central axis of the threading milling cutter. In other words, each of the two peripheral sub-surfaces including the threading cutting teeth at the operating position faces a direction perpendicular or substantially perpendicular to the central axis of the threading milling cutter. By rotating such a threading milling cutter about its central axis while applying a circular oblique cutting motion of the cutter, threads can be milled in a workpiece, such as internal threads in a hole of the workpiece.

[0045] According to some embodiments, the threading milling cutter body further includes a first support surface and a second support surface, the first support surface and the second support surface being disposed in the slot and respectively adjacent to a first contact surface and a second contact surface on the cutting element, wherein each of the first contact surface and the second contact surface and the first support surface and the second support surface faces a direction inclined with respect to the central axis of the threading milling cutter.

[0046] Thus, the cutting element is stably received within the slot of the threading milling cutter body, thereby preventing any displacement of the cutting element within the slot. To fix the cutting element in place, screws or clamps or some other fastening element can be used.

[0047] Other possible features and advantages of the solution will become apparent from the following detailed description. Description of the Drawings

[0048] The solution will now be described in more detail by way of exemplary embodiments and with reference to the drawings, in which:

[0049] Figure 1 is a perspective view of a cutting element according to a first embodiment of the present invention.

[0050] Figure 2 is Figure 1 a plan view of a first major surface of the cutting element shown.

[0051] Figure 3 is Figure 1-2 a side view of the cutting element shown in Figure 2 as viewed from the right side in

[0052] Figure 4 towards the peripheral surface of the cutting element.

[0053] Figure 5 shows a Figure 4 threading milling cutter body shown in Figures 1-3 and a

[0054] Figure 6 Is a perspective view of a cutting element according to the second embodiment.

[0055] Figures 7-9 Is the same as Figures 1-3 The corresponding view in, but shows a cutting element according to the third embodiment.

[0056] All the figures are schematic, not necessarily drawn to scale, and generally show only the parts necessary to illustrate the corresponding embodiments, while other parts may be omitted or only suggested. Unless otherwise specified, similar reference numerals refer to similar parts in different figures. Detailed Description

[0057] Figures 1-3 Shows a cutting element 1 according to the first embodiment. The cutting element 1 includes a first major surface 2, a second major surface 3, and a peripheral surface 4. The peripheral surface 4 includes six peripheral sub - surfaces 5, 5', 6, 6', 7, 7', which are arranged in pairs on opposite sides of the cutting element 1 and face in opposite directions when viewed in a plan view of the first major surface, as Figure 2 Shown. The cutting element further includes a through - hole 8 that extends from the first major surface 2 to the second major surface 3 along the central axis C of the cutting element.

[0058] Each peripheral sub - surface 5, 5', 6, 6', 7, 7' includes three thread - cutting teeth 9. Each tooth 9 includes a rake face 15, a flank face 16, and a cutting edge 17 formed at the intersection between the rake face 15 and the flank face 16.

[0059] For each pair of peripheral sub - surfaces 5, 5', 6, 6', 7, 7', the teeth 9 of one sub - surface 5, 6, 7 have a rake face 15 facing a first direction S1 (as Figure 3 Shown), while the teeth 9 of the other sub - surface 5', 6', 7' have a rake face 15 facing a second direction S2 opposite to the first direction S1.

[0060] Figure 4 Shows a tool body 10 including a slot 11 in which the cutting element 1 can be arranged, and Figure 5 Shows a thread - milling cutter including the tool body 10 and the cutting element 1. The tool body 10 has a front end 12, a rear end 13, and a tool - body central axis L. The cutting element 1 is fixed within the slot 11 by a screw 25 that extends through a hole 26 in the tool body on one side of the slot, further through the through - hole 8 in the cutting element, and engages a threaded hole 27 on the other side of the slot.

[0061] The cutting element 1 is mounted in a slot 11 of the tool body 10 such that two sub - surfaces of a pair of peripheral sub - surfaces 5, 5' face in a direction perpendicular to the central axis L of the tool body, as Figure 5 shown. These two peripheral sub - surfaces 5, 5' are in an operating position, i.e., when the thread - milling tool is used and rotated about the central axis L of the tool body in the rotational direction R, its cutting teeth 9 will cut threads in the workpiece. The cutting teeth 9 of the other peripheral sub - surfaces 6, 6', 7, 7' (including the cutting teeth 9 of the peripheral sub - surfaces 6', 7 that partially extend out of the slot in the forward direction) are in a non - operating position and will not interfere with the cutting process.

[0062] Each peripheral sub - surface 5, 5', 6, 6', 7, 7' of the cutting element includes two non - cutting surfaces 18, 19 having different lengths, as Figure 3 best shown in Figure 4 shown. These non - cutting surfaces are flat and serve as contact surfaces that are arranged to abut corresponding support surfaces 21, 22 in the slot 11 of the tool body 10. When the cutting element is mounted in the slot, four contact surfaces 18, 19 on two adjacent peripheral sub - surfaces 6, 7' in the non - operating position abut the corresponding support surfaces 21, 22 in the slot.

[0063] Since the contact surfaces 18, 19 and the corresponding support surfaces 21, 22 have different lengths, the cutting element cannot be incorrectly mounted in the slot. In other words, the cutting element can only be mounted for machining in the Figure 5 shown rotational direction R. Thus, when the operating thread - cutting teeth in the active peripheral sub - surfaces 5, 5' are worn and the cutting element needs to be indexed (i.e., new thread - cutting teeth are to be placed in the operating position), the cutting element 1 must be removed from the slot 11, then rotated through an angle of 120° about its central axis C, and then reinstalled in the slot 11.

[0064] Figure 6 A cutting element 30 according to a second embodiment is shown. The cutting element also includes six peripheral sub - surfaces, where three of the peripheral sub - surfaces each include three thread - cutting teeth 9, while each of the intermediate peripheral sub - surfaces includes only a flat non - cutting surface 31 but no cutting teeth. Such a cutting element 30 will still be able to be indexed three times. However, when compared with the reference Figures 1-5When compared to the described embodiments, a thread milling cutter using such a cutting element 30 will have a reduced productivity because for each revolution of the thread milling cutter, only one set of cutting teeth 9 will engage the workpiece. Each flat non-cutting surface 31 serves as a contact surface that is arranged to abut a corresponding support surface in a slot of the tool body when the cutting element 30 is installed in the slot of the tool body, in a manner similar to that described above with reference to the first embodiment. Each peripheral sub-surface including the thread cutting teeth 9 further includes a plurality of small non-cutting surfaces 32, which also serve as contact surfaces that are arranged to abut a support surface in the thread milling cutter body.

[0065] Figures 7-9 A cutting element 60 according to a third embodiment is shown. As Figure 7 and Figure 9 best shown, the cutting element includes two separate cutting element portions 30A, 30B, each cutting element portion being the same as the cutting element 30 shown in Figure 6 wherein when the cutting element portions 30A, 30B are installed in a slot of the tool body, they are fixed relative to each other. By combining the cutting element portions 30A, 30B into the cutting element 60, each peripheral sub-surface will include three thread cutting teeth 9 and three small non-cutting contact surfaces 32 (from the peripheral sub-surface of one of the portions 30A, 30B) and a large flat non-cutting contact surface 31 (from the peripheral sub-surface of the other of the portions 30A, 30B). In this embodiment, the central neutral plane P of the cutting element 60 corresponds to the interface between the cutting element portion 30A and the cutting element portion 30B. The combination of the two portions 30A, 30B results in a cutting element that is similar to the cutting element according to the first embodiment described with reference to Figures 1-5 wherein when the cutting element is installed in a thread milling cutter body, two sets of cutting teeth 9 will be in an operating position. For other embodiments, when viewed in a plan view of the first main surface, the peripheral sub-surfaces are arranged in pairs on opposite sides of the cutting element 60 and face in opposite directions, as Figure 8 best shown. As Figure 7 shown, the rake face 15 of each tooth 9 includes a chip gullet, resulting in an increased positive rake angle. The chip gullet can provide improved chip formation control and reduce the cutting force and temperature during machining.

[0066] Although the above description contains many specificities, these should not be construed as limiting the scope of the concepts described herein, but rather as merely providing illustrations of some exemplary embodiments of the concepts described. It should be understood that the scope of the currently described concepts fully encompasses other embodiments that may become apparent to those skilled in the art, and thus the scope of the currently described concepts is not limited.

Claims

1. A cutting element (1, 30, 60) for a thread milling cutter, comprising: - a first major surface (2) and a second major surface (3), the first major surface (2) and the second major surface (3) being arranged opposite to each other and facing in opposite directions, and - a peripheral surface (4) connecting the first major surface and the second major surface, the peripheral surface comprising an even number of peripheral sub - surfaces (5, 5', 6, 6', 7, 7'), the peripheral sub - surfaces being arranged in pairs on opposite sides of the cutting element and facing in opposite directions, wherein, for each pair of peripheral sub - surfaces, one sub - surface comprises one or more thread - cutting teeth (9) having a rake face (15) facing a first direction (S1), and the opposite sub - surface comprises a non - cutting surface (18, 19, 31, 32) and / or one or more thread - cutting teeth (9) having a rake face (15) facing a second direction (S2), wherein the second direction (S2) is opposite to the first direction (S1), characterized in that the number of the peripheral sub - surfaces is at least four.

2. The cutting element according to claim 1, wherein, the number of the peripheral sub - surfaces is six.

3. The cutting element according to any one of the preceding claims, wherein, each of the peripheral sub - surfaces comprises one or more non - cutting surfaces and one or more thread - cutting teeth.

4. The cutting element according to any one of the preceding claims, wherein, each of the peripheral sub - surfaces comprises two or more thread - cutting teeth, the two or more thread - cutting teeth being arranged in rows along the peripheral sub - surface.

5. The cutting element according to any one of the preceding claims, wherein, when observed in a plan view of the first major surface or the second major surface, the angle by which the directions faced by two adjacent peripheral sub - surfaces along the peripheral surface differ is equal to 360° divided by the total number of peripheral sub - surfaces.

6. The cutting element according to any one of the preceding claims, wherein, each rake face comprises a chip gullet.

7. The cutting element according to any one of the preceding claims, wherein, the cutting element is a single piece.

8. The cutting element according to claims 1 - 6, wherein, the cutting element comprises two separate parts (30A, 30B) arranged in a detachable manner with respect to each other.

9. The cutting element according to any one of the preceding claims, comprising at least two contact surfaces facing different directions and arranged to abut corresponding support surfaces (21, 22) in a slot (11) of a tool body (10) to prevent displacement of the cutting element relative to the tool body when the cutting element is mounted in the slot.

10. The cutting element according to claims 9 and 3, wherein, the contact surfaces are formed by the non - cutting surfaces included in the peripheral sub - surfaces.

11. The cutting element according to claim 10, wherein, Each peripheral sub-surface includes two non-cutting surfaces that form separate contact surfaces.

12. The cutting element according to any one of claims 10-11, wherein, for each peripheral sub-surface, at least one of the contact surfaces has a length different from that of at least one of the contact surfaces on any adjacent peripheral sub-surface along the peripheral surface.

13. A thread milling cutter, comprising a cutter body (10) having a front end (12), a rear end (13), and a central axis (L) extending from the front end to the rear end, and a slot (11) formed in the front end (12), wherein, the thread milling cutter includes a cutting element (1, 30, 60) according to any one of claims 1 to 12, and the cutting element (1, 30, 60) is arranged in the slot (11) such that the teeth (9) in two peripheral sub-surfaces of a pair of peripheral sub-surfaces included in the pair of opposite peripheral sub-surfaces are arranged in an operating position for milling a thread in a workpiece, while the teeth included in the other peripheral sub-surfaces are arranged in a non-operating position.

14. The thread milling cutter according to claim 13 and including a cutting element according to any one of claims 9-12, further comprising a first support surface (21) and a second support surface (22), the first support surface (21) and the second support surface (22) respectively adjoining a first contact surface and a second contact surface of the at least two contact surfaces, wherein each of the first contact surface and the second contact surface and the first support surface and the second support surface faces a direction inclined with respect to the central axis (L) of the thread milling cutter.

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