Metal Cutting Turning Tools

Abstract

A turning tool (1) comprising a connecting portion (3), the connecting portion (3) extending along a connecting axis (A2), the connecting axis (A2) defining a longitudinal axis of the turning tool (1), the turning tool (1) comprising a first cutting element (7) and a second cutting element (8), the first cutting element (7) comprising a first cutting blade (5), the second cutting element (8) comprising a second nose cutting blade (6) separating and connecting a second leading cutting blade (13) and a second trailing cutting blade (15), the first cutting element (7) comprising a first top surface (20), the second cutting element ( a turning tool (1), wherein the first cutting element (7) and the second cutting element (8) have a second top surface (21), the first and second cutting elements (7, 8) intersect with an imaginary circle or cylinder (C1) having its central axis (A3) parallel to or coincident with the connecting axis (A2), the first cutting element (7) is inclined with respect to the second cutting element (8) by an inclination angle (ω), said inclination angle (ω) being measured around the central axis (A3) of the imaginary circle (C1), and the first top surface (20) faces in a direction perpendicular or substantially perpendicular to the connecting axis (A2).

Description

[Technical Field]

[0001] The present invention is in the field of metal cutting, more particularly in the field of turning.

[0002] The present invention refers to a turning tool according to the preamble of claim 1. In other words, the present invention relates to a turning tool comprising a coupling part, the coupling part extending along a coupling axis, the coupling axis defining a longitudinal axis of the turning tool, the turning tool comprising a first cutting element and a second cutting element, the first cutting element comprising a first cutting edge, the second cutting element comprising a second nose cutting edge separating and connecting the second front cutting edge and the second rear cutting edge, the first cutting element comprising a first top surface, and the second cutting element comprising a second top surface. In a further aspect, the present invention relates to a machining method for a CNC lathe. [Background technology]

[0003] In metal cutting, turning is a common operation. CNC lathes are commonly used. Typically, complex shapes are machined from metal workpieces. To obtain complex shapes, it is common to use two or more turning tools, where the turning tools have different geometries or different orientations. For example, one turning tool may be suitable for machining in one direction, and a second turning tool may be suitable for machining in a different direction.

[0004] Conventionally, each turning tool is equipped with one turning insert. After turning using one turning insert, the first turning tool is typically indexed to a second turning tool. For example, a CNC lathe may include a turret, and indexing from one turning tool to the second turning tool is accomplished by rotating the turret through a predetermined angle. Indexing by rotating the turret can take time, depending on the CNC lathe, for example. The time when no cutting is occurring, such as when changing or indexing from one tool to another, can be referred to as downtime.

[0005] EP1317981A1 discloses a tool carrying a plurality of turning inserts, with which switching between different turning inserts can be achieved quickly by rotation of the turning tool about a connecting shaft.

[0006] The present inventors have discovered that there is a need for further improved turning tools. Summary of the Invention

[0007] It is an object of the present invention to provide a turning tool suitable for machining objects having complex shapes. A further object is to provide a turning tool that can be used with a wide range of CNC lathes. A still further object is to provide a turning tool that can be used for extended machining operations. A still further object is to provide a turning tool that can help reduce downtime.

[0008] At least one of the aforementioned objects is achieved by a turning tool as first defined, in which the first and second cutting elements intersect an imaginary circle or cylinder having a central axis parallel to or coincident with the connecting axis, the first cutting element is inclined at an inclination angle with respect to the second cutting element, the inclination angle being measured around the central axis of the imaginary circle, and the first top surface faces in a direction perpendicular or substantially perpendicular to the connecting axis.

[0009] With such a turning tool, a very rapid change or indexing from a first cutting element to a second element can be achieved by a linear movement of the turning tool.

[0010] The turning tool is for a CNC lathe, i.e., a computer or computerized numerically controlled lathe, i.e., any CNC machine suitable for turning, such as, for example, a turning lathe, a multitasking machine, a turn-mill machine, or a sliding-head machine. The turning tool is for machining a metal workpiece, such as a metal workpiece with an external surface that is a radially outer surface, where the radially outer surface faces away from an axis of rotation about which the metal workpiece can rotate. The turning tool is for turning said radially outer surface, i.e., external turning.

[0011] The turning tool includes a forward end and an opposite rearward end in the form of a linkage that is removably connectable to a CNC lathe, and more specifically to a machine interface of the CNC lathe, such as a machine spindle or tool revolver turret or tool post.

[0012] The connector may have a cross section in the shape of a square or rectangle. The connector may be conical or substantially conical, preferably according to ISO standard 26623-1 or the like.

[0013] The coupling portion extends along a coupling axis or central axis, which defines the longitudinal axis of the turning tool.

[0014] The turning tool comprises a first cutting element and a second cutting element. The first and second cutting elements are spaced apart. The first and second cutting elements are preferably cutting or turning inserts, i.e., replaceable elements made of a wear-resistant material, such as cemented carbide. Alternatively, the first and second cutting elements may be part of a single wear-resistant element, preferably made of a single piece of cemented carbide. The first cutting element comprises a first top surface. The first top surface comprises a rake face or rake surface.

[0015] The first cutting element comprises a first cutting blade. The first cutting blade may preferably be in the form of a nose cutting blade, i.e., a cutting blade that is convex in top view. The first cutting blade, or a portion of the first cutting blade, generates a machined surface. The first cutting element may be in the form of a circular cutting insert, i.e., an insert that is circular or substantially circular in top view. The radius of said circle is preferably 5 to 30 mm. Alternatively, the first cutting blade may be a nose cutting blade that is convex in top view, preferably in the form of a circular arc having a radius of curvature of 0.2 to 1.6 mm and disposed between or connecting the first leading, i.e., primary or main, cutting blade and the first trailing, i.e., auxiliary, cutting blade.

[0016] Alternatively, the first top surface may have a diamond, triangle, square, or polygonal shape in top view.

[0017] The first and second top surfaces may each be flat. Alternatively, one or both of said surfaces may be non-flat or non-planar. Preferably, said surfaces may comprise one or more chip breaking means in the form of one or more protrusions and / or depressions.

[0018] The direction in which the first top surface faces is the normal of the first top surface, i.e., the direction perpendicular to the first top surface. The direction is away from the first top surface, and, if the first cutting element is in the form of a cutting insert or turning insert having a first bottom surface, is away from the first bottom surface.

[0019] If the first top surface is non-planar, for purposes of defining the direction the first top surface faces, such first top surface may be defined as a plane parallel to or approximately a first mid-plane, said plane intersecting the first cutting edge or at least a portion of the first cutting edge. When the first cutting element is in the form of a cutting or turning insert having a first bottom surface, said first mid-plane is a plane midway between the first top surface and the first bottom surface.

[0020] Alternatively, the aforementioned first top surface may be defined as a plane that intersects all nose cutting edges that are bounded by or adjacent to the first top surface for purposes of defining the direction in which the first top surface faces.

[0021] Corresponding reasoning applies to the second top surface and the second cutting element.

[0022] The second cutting element includes a second nose cutting edge that separates and connects the second leading cutting edge and the second trailing cutting edge. The second cutting element includes a first top surface. The second top surface includes a rake face or rake surface. The second leading cutting edge is a leading cutting edge. The second trailing cutting edge is a trailing cutting edge.

[0023] The turning tool is preferably suitable for external turning of a cylindrical metal workpiece, such as longitudinal turning. The first and second cutting elements may alternatively be used for longitudinal turning of a metal workpiece that rotates in one direction about its axis of rotation.

[0024] The first and second cutting elements intersect with or are arranged along an imaginary circle or cylinder having a central axis parallel to or coincident with the connecting axis. Preferably, the central axis coincides with or substantially coincides with the connecting axis. Substantially coincident means less than 20 mm from the connecting axis. The first cutting element is inclined at an inclination angle relative to the second cutting element. The inclination angle is preferably at least 45°. More preferably, the inclination angle is 180° + / - 20°, and even more preferably 180° + / - 10°. When the inclination angle is 180°, the central axis of the imaginary circle or cylinder is located between the first cutting blade and the second nose cutting blade.

[0025] The turning tool is arranged for turning a rotatable metal workpiece about its axis of rotation, the axis of rotation being parallel to the central axis. The second nose cutting edge is the portion of the second cutting element closest to the central axis. The first cutting edge is the portion of the first cutting element closest to the central axis.

[0026] The first apex surface is inclined relative to the second apex surface by an angle equal to or within + / - 20° of the aforementioned inclination angle. If the first apex surface and the second apex surface both extend radially from the central axis of an imaginary circle, the aforementioned angle is equal to the inclination angle. Alternatively, the first cutting element and / or the second cutting element may be inclined positively or negatively by an angle of up to 10°. In another alternative, the first apex surface and / or the second apex surface may be arranged to form a positive or negative rake angle.

[0027] The first and second top surfaces face in the same direction along an imaginary circle, in other words, the first and second surfaces both face clockwise or counterclockwise.

[0028] The first top surface faces perpendicular or substantially perpendicular to the articulation axis, or within 15°. Stated differently, the first presumed direction of primary motion of the first cutting element according to ISO 3002-1:1982 is perpendicular or substantially perpendicular to the articulation axis, i.e., within 15°.

[0029] A first tool reference plane according to ISO 3002-1:1982 associated with a first cutting element may be parallel to or coincident with a second tool reference plane according to ISO 3002-1:1982 associated with a second cutting element. Coincide means that the first and second tool reference planes lie in a common plane. Preferably, the connecting axis extends in said common plane. Alternatively, the connecting axis extends in a plane parallel to said common plane. Alternatively, i.e., if said tool reference planes do not extend in a common plane, the first and second tool reference planes may be at an angle relative to each other, where said angle is equal to the angle between the first inferred direction of the primary motion of the first cutting element and the second inferred direction of the primary motion of the second cutting element. Preferably, the first and second tool reference planes intersect along a line that is coincident with or parallel to the rotation axis of the metal workpiece to be machined.

[0030] The direction in which the first top surface faces and the direction in which the second top surface faces may differ by 180° or substantially 180° when viewed in front view. In such a case, the first presumed direction of primary motion according to ISO 3002-1:1982 of the first cutting element is opposite to the second presumed direction of primary motion of the second cutting element. Preferably, the direction in which the first top surface faces and the direction in which the second top surface faces differ by at least 40°.

[0031] There is no part of the turning tool between the first cutting edge and the second nose cutting edge.

[0032] The turning tool includes an intermediate portion, the intermediate portion being located longitudinally between the connecting portion and the cutting element.

[0033] The first and second cutting elements preferably overlap in a longitudinal direction, where the longitudinal direction is defined by the connecting axis.

[0034] The first cutting edge and the second nose cutting edge are free ends. In other words, the cutting edges are positioned so that metal cutting operations can be performed.

[0035] According to one embodiment, the first cutting element comprises a first leading cutting edge and a first trailing cutting edge, the first cutting edge comprising a first nose cutting edge, the first nose cutting edge separating and connecting the first leading cutting edge and the first trailing cutting edge.

[0036] Such turning tools allow for the machining of more complex shapes, such as grooves. The first leading cutting edge, which is the primary or main cutting edge, and the first trailing cutting edge, which is the auxiliary cutting edge, are preferably straight or linear or substantially straight or substantially linear in top view. The first nose cutting edge is preferably arc-shaped and convex in top view, preferably with a radius of curvature of 0.2 to 1.6 mm.

[0037] The nose angle of the first cutting element, defined as the angle between the first leading cutting edge and the first trailing cutting edge, is preferably 160° or less, more preferably between 30° and 80°.

[0038] The first leading cutting edge is preferably positioned to form an acute first cutting angle when the turning tool is moved in a direction perpendicular to the connecting shaft and parallel to the rotation axis of the metal workpiece. The first cutting angle is preferably 3 to 45°, and more preferably 5 to 30°.

[0039] During the aforementioned movement of the turning tool, the first nose cutting edge and the first leading cutting edge are cutting, i.e., active.

[0040] No part of the turning tool is present along the straight line connecting the first and second nose cutting edges.

[0041] According to one embodiment, the second nose cutting edge is located in front of the first cutting edge measured along the connecting axis.

[0042] With such turning tools, more complex shapes can be machined. For example, a first rough cutting operation can be performed using one cutting element at a low entering angle in a longitudinal turn, and the remaining material can be removed by the other cutting element.

[0043] The distance from the rear end defined by the connecting portion to the second nose cutting edge is greater than the distance from the rear end to the first cutting edge, said distances being measured along a line parallel to the connecting axis. The difference in distances is preferably at least 1 mm, more preferably 2 to 30 mm.

[0044] According to one embodiment, the first nose angle, defined as the angle between the first leading cutting edge and the first trailing cutting edge, is an acute angle.

[0045] Such turning tools allow for machining of more complex shapes. More feed directions, such as out-facing, are possible with such turning tools. The first nose angle is conventionally measured in a top view. The aforementioned first nose angle is preferably 25 to 80°, more preferably 30 to 60°.

[0046] According to one embodiment, the turning tool comprises a forward-facing surface with at least two elements protruding in a forward direction from the forward-facing surface, a first of said protruding elements comprising a first cutting element and a second of said protruding elements comprising a second cutting element.

[0047] Preferably, the turning tool comprises an intermediate portion, said intermediate portion being located longitudinally between the connecting portion and the protruding element, said intermediate portion comprising a forward-facing surface, said forward-facing surface facing away from the connecting portion.

[0048] Each of said projecting elements is preferably connected to the intermediate part by one or more clamping means, said clamping means preferably comprising one or more screws or bolts each extending along an axis parallel to the connecting axis.

[0049] In other words, each of the projecting elements preferably comprises one or more threads, in which case said threads are in the form of a spiral around an axis along an axis parallel to the connecting axis.

[0050] The aforementioned protruding elements are preferably in the form of exchangeable cutting heads each having an insert seat, in which a cutting or turning insert is clamped or mounted within the aforementioned insert seat.

[0051] The intermediate portion preferably extends mainly in a direction perpendicular to the connecting axis.

[0052] The intermediate portion connects at least two forwardly projecting elements with the linkage portion, the forwardly projecting elements projecting away from the linkage portion and away from the forward-facing surface.

[0053] The forwardly projecting elements each have a longitudinal extension, i.e. an extension in a direction parallel to the connecting axis.

[0054] The first protruding element includes a first cutting element formed thereon, and the second protruding element includes a second cutting element.

[0055] According to one embodiment, the at least two forwardly projecting elements are spaced apart from the connecting shaft.

[0056] Preferably, the at least two forwardly projecting elements are spaced from the connecting axis by the same distance or substantially the same, ie + / - 10% distance.

[0057] According to one embodiment, the second nose angle, defined as the angle between the second leading cutting edge and the second trailing cutting edge, is an acute angle.

[0058] Such turning tools allow for machining of more complex shapes. More feed directions, such as outward, are possible with such turning tools. The first nose angle is conventionally measured in a top view. The aforementioned second nose angle is preferably 25 to 80°, more preferably 30 to 60°.

[0059] According to one embodiment, the first cutting element is in the form of a first turning insert and the second cutting element is in the form of a second turning insert, the first turning insert having a first top surface and an opposite first bottom surface, the second turning insert having a second top surface and an opposite second bottom surface, the first top surface having a first rake surface, and the second top surface having a second rake surface.

[0060] The first turning insert preferably includes a first leading cutting edge and a first trailing cutting edge.

[0061] The top surface comprises a rake surface and the bottom surface comprises a bearing or contact surface.

[0062] A first through hole for a first screw intersects the first top surface and the first bottom surface.

[0063] A second through hole for a second screw intersects the second top surface and the second bottom surface.

[0064] The first mid-plane extends substantially halfway between the first top surface and the first bottom surface, and the second mid-plane extends substantially halfway between the second top surface and the second bottom surface, preferably in parallel or substantially parallel planes.

[0065] According to one embodiment, the first cutting element is arranged such that the first leading cutting edge forms a first cutting angle of 3° to 45° when the turning tool is moved in a first direction parallel to the connecting axis, and the second cutting element is arranged such that the second leading cutting edge forms a second cutting angle of 3° to 45° when the turning tool is moved in a second direction opposite the first direction.

[0066] Such a turning tool can reduce wear. The first direction is preferably a forward direction. The second direction is parallel to the connecting shaft.

[0067] According to one embodiment, the first cutting element is positioned such that when turning in the first direction, the first trailing cutting edge forms a first clearance angle of between 93° and 135°.

[0068] With such a turning tool, the first cutting element can be used in more feed directions, for example outward, and more complex shapes can be machined with such a turning tool.

[0069] According to one embodiment, the second cutting element is positioned such that when turning in the second direction, the second trailing cutting edge forms a second clearance angle of between 93° and 135°.

[0070] With such a turning tool, the second cutting element can be used in more feed directions, for example outward. With such a turning tool, more complex shapes can be machined. The second direction is the backward direction.

[0071] According to one embodiment, the first and second cutting elements are positioned such that the second nose cutting edge is forward of the first cutting edge when cutting in the first direction.

[0072] With such turning tools, more complex shapes can be machined.

[0073] The first and second nose cutting edges are longitudinally spaced apart, where the connecting shaft defines a longitudinal axis.

[0074] Turning in a first direction in this context means moving the turning tool in a forward direction along the connecting shaft. The rear end of the turning tool is defined by the connecting part.

[0075] According to one embodiment, the first cutting element and the second cutting element are arranged so that they can be used to turn a metal workpiece that is rotatable in one direction about its rotation axis, said rotation axis being arranged perpendicular to and intersecting the connecting axis.

[0076] The first and second cutting elements may alternatively be used for machining, i.e., turning, without rotation of the turning tool.

[0077] According to one embodiment, the turning tool is arranged such that a cylindrical metal workpiece can be placed between the first and second cutting elements, the longitudinal axis of the metal workpiece being located between said cutting elements (7, 8).

[0078] The longitudinal axis is preferably perpendicular to the connecting axis. The cylindrical metal workpiece preferably has a diameter of 16 to 500 mm, more preferably 20 to 200 mm.

[0079] According to one embodiment, the link is square or rectangular in cross section or comprises a conical or substantially conical portion.

[0080] The aforementioned cross-sections are in a plane perpendicular to the connection axis. The connection preferably comprises a conical or substantially conical portion and a ring-shaped portion, such as a polygonal hollow tapered joining portion with a flange contact surface according to ISO 26623-1:2014 or a hollow tapered joining portion with a flange contact surface according to DIN 69893, ISO 12164-1 or ISO 12164-1F.

[0081] The connections are preferably arranged to allow quick changeover, in other words relatively fast manual or automatic clamping and removal. The connections are preferably arranged without threads. The connections are preferably arranged without or with less than three screw holes, bolt holes or locating pin holes.

[0082] The connector may have a cross-section in the shape of a square or rectangle, said cross-section being in a plane perpendicular to the connector axis. In such a case, the connector preferably has a length measured along the connector axis of 50 to 300 mm. When the connector has a square or square-shaped cross-section, the sides of the square preferably measure 20 mm, 25 mm, 25.4 mm, or 32 mm.

[0083] The coupling is arranged to be connected to, for example, a turret or a tool post or a tool holder.

[0084] Preferably, the coupling is a known coupling, so that the turning tool can be used on a known type of CNC lathe, i.e., the CNC lathe does not have to be specially made or modified to use the turning tool.

[0085] According to one embodiment, a turning method for a CNC lathe includes the steps of: providing a metal workpiece; providing the turning tool as described above; rotating the metal workpiece in one direction about its rotation axis; moving the turning tool in the first direction so that a first cutting blade cuts; moving the turning tool in one direction so that the first cutting blade is moved away from the metal workpiece and the second nose cutting blade is moved towards the metal workpiece; and moving the turning tool in a second direction so that the second front cutting blade cuts at a second entering angle of 5 to 45 degrees; The second direction is opposite or substantially opposite to the first direction.

[0086] The turning method is for a CNC lathe, i.e., a computer or computerized numerically controlled lathe, i.e., any CNC machine suitable for turning, such as, for example, a turning lathe, a multitasking machine, a turn-mill machine, or a sliding-head machine. A metal workpiece is provided. The metal workpiece has an outer surface, which is a radially outer surface. The radially outer surface faces away from the axis of rotation. The turning method is for turning the radially outer surface, i.e., external turning. The metal workpiece extends between a first end and a second end. The metal workpiece is clamped by a clamping means. The clamping means holds the metal workpiece and is at least partially controlled and driven by a motor or spindle.

[0087] The clamping means may be in the form of a collet chuck, face driver, or three-jaw chuck, and may also include a tailstock. The headstock end of the machine is preferably positioned at the first end of the metal workpiece. The second end of the metal workpiece opposite the first end of the workpiece may be the free end. Alternatively, the second end is in contact with the tailstock.

[0088] The method includes rotating the metal workpiece about its axis of rotation in one direction, which may be clockwise or counterclockwise, the axis of rotation being parallel to the central axis of an imaginary circle or cylinder.

[0089] The method includes moving the turning tool in a first direction, i.e., a first feed direction. The first direction may preferably be parallel to the axis of rotation and is also known as longitudinal turning. The aforementioned steps are included in a first pass, defined as between starting the cut and finishing the cut. The first pass is not necessarily a movement of the first cutting element along a straight line. When turning in the first direction, the first cutting edge is cutting. A finished cut surface is formed by the first cutting edge.

[0090] The first cutting element preferably comprises a first leading cutting edge and a first trailing cutting edge, wherein a first nose cutting edge separates and connects the first leading cutting edge and the first trailing cutting edge, and wherein the first leading cutting edge forms an acute first cutting angle when turning in the first direction.

[0091] After or during the completion of the cut, the turning tool is moved such that the first cutting blade is moved away from the metal workpiece and the second nose cutting blade is moved toward the metal workpiece, and during at least a portion of said movement, neither the first nor the second cutting element is cutting, i.e., no metal is cut by the first and second cutting elements during said movement.

[0092] The aforesaid movement of the turning tool is preferably a linear movement, i.e. the turning tool is moved in a straight line. The aforesaid movement of the turning tool is preferably in a direction perpendicular to the articulation axis and perpendicular to the rotation axis.

[0093] The method includes turning in a second direction. The second direction is opposite or substantially opposite to the first direction. For example, the first and second directions may be parallel to the axis of rotation but opposite directions. The aforementioned steps are included in a second pass, defined as between starting and finishing the cut. The second pass is not necessarily a movement of the first cutting element along a straight line. A finished cutting surface is formed by the second nose cutting edge. The second nose cutting edge and the second leading cutting edge are cut such that the second leading cutting edge cuts at a second entering angle of 5° to 45°, more preferably 5° to 30°.

[0094] The second cutting element is inactive when turning in the first direction, and the first cutting element is inactive when turning in the second direction.

[0095] Preferably, the method includes the step of setting the connecting shaft parallel to the axis of rotation.

[0096] The second direction is preferably opposite or substantially opposite to the first direction.

[0097] Preferably, the method includes the further step of setting a first depth of cut for the first leading cutting edge when turning in a first direction, the first direction being parallel to the axis of rotation, preferably between 3° and 45°, more preferably between 5° and 30°.

[0098] When turning in the second direction, the second front cutting edge preferably cuts at a second cutting angle, which is preferably an acute angle of between 5° and 45°.

[0099] During the second pass, the second trailing cutting edge preferably forms an obtuse clearance angle, said clearance angle preferably being between 91° and 135°, more preferably between 93° and 120°.

[0100] During the first pass, the first trailing cutting edge preferably forms a clearance angle of at least 91°.

[0101] The step of moving the turning tool so that the first cutting blade is moved away from the metal workpiece and the second nose cutting blade is moved towards the metal workpiece is preferably a linear movement, said linear movement being preferably in a direction perpendicular to the connecting axis.

[0102] The step of moving the turning tool so that the first cutting blade is moved away from the metal workpiece and so that the second nose cutting blade is moved toward the metal workpiece preferably does not involve rotation of the turning tool about the connecting shaft, whereby indexing time can be reduced compared to rotational movement.

[0103] The turning tool preferably does not rotate about the connecting axis during the first pass, during the second pass, or between the first and second passes. The turning tool preferably does not rotate about any other axis, such as any axis parallel to the connecting axis, during the first and second passes, or between the first and second passes.

[0104] Preferably, the method includes turning, during a second pass, at least a portion of the surface machined or turned during the first pass.

[0105] Preferably, the method includes the further step of positioning said nose cutting blades so that the first and second nose cutting blades are spaced apart a constant distance along the axis of rotation during all steps of the method.

[0106] Preferably, the method comprises the further step of setting the connecting shaft parallel to the axis of rotation.

[0107] The method preferably includes the step of clamping a metal workpiece with a collet chuck, where the metal workpiece is a bar having a diameter of 50 mm or less.

[0108] The distance from the clamping means to the second nose cutting blade is preferably shorter than the distance from the clamping means to the first cutting blade.

[0109] The second nose cutting edge is preferably located ahead of the first cutting edge during the first pass, and the first cutting edge is preferably located ahead of the second nose cutting edge during the second pass, where ahead should be understood as ahead in the feed direction along the axis of rotation.

[0110] The second pass is preferably in a direction away from the corner. The corner or shoulder is defined as the intersection between a first surface concentric with the axis of rotation and a second surface perpendicular to the axis of rotation. The first surface may be the exterior surface or the interior surface, i.e., the surface inside the lumen. Preferably, the first surface is the exterior surface, i.e., the radially outer surface.

[0111] The second direction is preferably in a direction away from an exterior corner of the metal workpiece, said corner preferably being formed at least in part by the second cutting element, said corner or shoulder being defined as the intersection between a first surface concentric with the axis of rotation and a second surface perpendicular to the axis of rotation.

[0112] According to one embodiment, a computer program has instructions that, when executed by a CNC lathe, cause the CNC lathe to perform steps according to the above method.

[0113] The computer program or computer program product may be included in a CAM software product, i.e., software for computer-aided manufacturing. The computer program may be in the form of a computer-readable medium, such as a USB stick, a CD-ROM, or a data stream.

[0114] The invention will now be explained in more detail by a description of embodiments of the invention and by reference to the accompanying drawings. [Brief explanation of the drawings]

[0115] [Figure 1] FIG. 1 is a perspective view of a turning tool according to one embodiment. [Figure 2] FIG. 2 is a top view of the turning tool in FIG. [Figure 3] FIG. 2 is a front view of the turning tool in FIG. [Figure 4] FIG. 2 is a side view of the turning tool in FIG. [Figure 5] 2 is a top view of the turning tool and metal workpiece in FIG. 1; [Figure 6] 2 is a further top view of the turning tool and metal workpiece of FIG. 1. [Figure 7] 2 is a further top view of the turning tool and metal workpiece of FIG. 1. [Figure 8] FIG. 1 is a schematic diagram of moving a turning tool in a first direction. [Figure 25] FIG. 10 is a schematic diagram of moving the turning tool in a second direction. [Figure 9] FIG. 10 is a further schematic illustration of moving the turning tool in a second direction. [Figure 10] 1 is a schematic diagram showing a first cutting element, a second cutting element, and a rotating metal workpiece in cross section. DETAILED DESCRIPTION OF THE INVENTION

[0116] All turning tools in the figures are drawn to scale.

[0117] Reference is now made to Figures 1-7, which illustrate a turning tool 1 according to one embodiment. The turning tool 1 includes a connecting portion 3. The connecting portion 3 extends along a connecting axis A2, which defines a longitudinal axis of the turning tool 1. The connecting portion defines a rear end of the turning tool 1. The turning tool 1 includes a first cutting element 7 in the form of a first turning insert 7 and a second cutting element 8 in the form of a second turning insert 8. As can be seen, for example, in Figure 2, the first turning insert 7 includes a first leading cutting edge 12, a first trailing cutting edge 14, and a first nose cutting edge 5. The first nose cutting edge 5 is the portion of the first turning insert 7 closest to the connecting axis A2. The second turning insert 8 includes a second nose cutting edge 6, a second leading cutting edge 13, and a second trailing cutting edge 15. The first nose angle, defined as the angle between the first leading cutting edge 12 and the first trailing cutting edge 14, is an acute angle. The second nose angle, defined as the angle between the second leading cutting edge 13 and the second trailing cutting edge 15, is an acute angle.

[0118] For example, as seen in Figure 2, when measured along or parallel to the articulation axis A2, the second nose cutting edge 6 is located in front of the first cutting edge 5. Forward is defined as away from the articulation 3 towards the first and second turning inserts 7, 8.

[0119] For example, as seen in FIG. 3 , the first turning insert 7 includes a first top surface 20 and an opposite first bottom surface. The second turning insert 8 includes a second top surface 21 and an opposite second bottom surface. The first top surface 20 includes a first rake surface, and the second top surface 21 includes a second rake surface. As seen in FIG. 3 , the first and second cutting inserts 7, 8 intersect with an imaginary circle or cylinder C1 having a central axis A3 parallel to the connecting axis A2. The first turning insert 7 is inclined by an inclination angle ω with respect to the second turning insert 8, the inclination angle ω being measured around the central axis A3 of the imaginary circle C1. The first top surface 20 faces in a direction perpendicular or substantially perpendicular to the connecting axis.

[0120] 1, the turning tool 1 comprises a forward-facing surface 42, i.e., the surface facing away from the connecting part 3. Projecting forward from the forward-facing surface 42 are two elements 30, 31 in the form of interchangeable cutting heads 30, 31. The first cutting head 30 comprises a first turning insert 7, i.e., the first cutting head comprises an insert seat in which the first turning insert 7 is mounted. The second cutting head 31 comprises a second cutting element 8. The cutting heads 30, 31 are spaced apart from the connecting axis A2.

[0121] The connecting portion 3 defines the rear end of the turning tool 1 and is suitable for insertion into a machine interface (not shown), preferably having a cavity or recess (not shown). For example, the connecting portion 3 shown in FIG. 1 has a substantially conical portion or a substantially tapered or tapered portion. The connecting portion is known in the field of metal cutting tools as Coromant Capto®. Other types of connecting portions are possible, such as those known as square-shank types. For example, if the connecting portion is of the square-shank type, the cross section of the connecting portion perpendicular to the connecting axis is square or rectangular. Furthermore, for such turning tools, the connecting axis is parallel to the connecting axis A2 in FIG. 4 and is located 5 to 20 mm below the connecting axis A2.

[0122] FIG. 5 illustrates the first machining step. The metal workpiece 2 rotates in one direction around its rotation axis A1. The turning tool 1 is moved in a first direction 17 parallel to the connecting axis A2 and the rotation axis A1 of the metal workpiece 2. The first direction 17 is the forward direction, i.e., the direction away from the connecting portion 3 and the direction in which the forward-facing surface 42 faces. In FIG. 5, the top surface of the first turning insert 7 faces the viewer. The cutting surface is formed by the first nose cutting edge 5; in other words, the first nose cutting edge 5 is a surface-generating cutting edge. The first turning insert 7 is positioned so that the first leading cutting edge 12 forms an acute first cutting angle α of 3 to 45°. The first trailing cutting edge 14 forms an obtuse first clearance angle γ of 93 to 135°. The second turning insert 8 is spaced apart from the metal workpiece 2. When the turning tool 1 is moved in the first direction 17, the second nose cutting edge 6 is in front of the first nose cutting edge 5. As can be seen in FIG. 5 , the turning tool 1 is positioned such that the cylindrical metal workpiece 2 is positioned between the first turning insert 7 and the second turning insert 8, and the axis of rotation A1, which is the longitudinal axis A1 of the metal workpiece 2, is located between the turning inserts 7, 8.

[0123] Figure 6 shows a step subsequent to the step shown in Figure 5. The turning tool 1 is moved in a direction 19 such that the first nose cutting edge 5 is moved away from the metal workpiece 2 and the second nose cutting edge 6 is moved towards the metal workpiece 2. The turning tool 1 is moved in a direction 19 that is perpendicular to the connecting axis A2 and perpendicular to the rotation axis A1. The aforementioned movement is a linear movement.

[0124] FIG. 7 illustrates a subsequent step shown in FIG. 6. The turning tool 18 is moved in a second direction 18, which is opposite to the first direction 17. The second leading cutting edge 13 forms an acute second leading angle β of 3° to 45°. The second trailing cutting edge 15 forms an obtuse second leading clearance angle δ of 93° to 135°. The first turning insert 7 is spaced apart from the metal workpiece 2. The first nose cutting edge 5 is forward of the second nose cutting edge 6 in the second direction 18. At least a portion of the surface machined by the first turning insert 7 in the first step shown in FIG. 5 is machined by the second turning insert 8.

[0125] FIG. 8 shows an example of a first step of a turning method for a CNC lathe (not shown). A metal workpiece 2 rotates in one direction 50 around its rotation axis A1. The coupling 3 of the turning tool 1 is connected to the CNC lathe (not shown), and more specifically, the coupling is connected to a machine interface. The coupling axis A2 is perpendicular to the rotation axis A1. The turning tool 1 is moved in a first direction 17 so that the first nose cutting edge 5 cuts and the first leading cutting edge forms an acute leading edge angle. The first trailing cutting edge 14 forms an obtuse leading edge angle. The second and third turning inserts 8, 9 are spaced apart from the metal workpiece 2. The second nose cutting edge is located forward of the first nose cutting edge 5 in the first direction 17. The first direction is parallel to the rotation axis A1.

[0126] The metal workpiece may have various shapes compared to those described above. The metal workpiece may be in the form of a rod, a hollow bar, or any other shape that has rotational symmetry or substantially rotational symmetry around its axis of rotation. The shapes that can be machined may be configured differently from those described above. For example, the shape may have two sidewalls, i.e., two surfaces in a plane perpendicular to the axis of rotation, rather than just one sidewall. In other words, the turning tool may be used to machine an external groove.

[0127] FIG. 8 is a schematic diagram of a turning tool moving in a first direction 17, with a first cutting element 7 cutting. The first direction 17 is the feed direction. The first leading cutting edge forms a first entering angle α that is between 5 and 45°, and the first trailing cutting edge forms an obtuse clearance angle γ of at least 91°. A second cutting element 8 is spaced from the metal workpiece 2. A cutting finish surface 25 is formed by the first cutting element 7. More specifically, surface 25 is formed by the first nose cutting edge 5.

[0128] 9 is a further schematic illustration of moving the turning tool in a second direction 18, with the second cutting element 8 cutting. The second leading cutting edge is cutting at a second entering angle β that is between 5 and 45°, and the second trailing cutting edge forms an obtuse clearance angle δ. The second bottom surface faces the viewer.

[0129] Figure 8 shows a first machining step which may be followed by the step shown in Figure 9. In Figure 9, the second cutting element 8 is on the opposite side of the rotation axis A1 from the first cutting element 7 in Figure 8, and the first top surface faces in the opposite direction from the second top surface.

[0130] In Figures 8-9, the metal workpiece 2 is clamped at one end by a clamping means 60. The clamping means 60 is connected to and driven by a rotating or rotatable spindle (not shown) that is part of a CNC lathe (not shown). The clamping means may be in the form of a collet chuck, a three-jaw chuck, or a face driver. The distance from the clamping means 60 to the second nose cutting blade 6 is less than the distance from the clamping means 60 to the first cutting blade 5, and the distance is measured along a line parallel to the axis of rotation A1. In Figures 24-26, the first direction 17 is a direction away from the clamping means 60, and the second direction 18 is a direction toward the clamping means. Alternatively (not shown), the first direction 17 is a direction toward the clamping means 60, and the second direction 18 is a direction away from the clamping means. The first and second directions 17, 18 are therefore opposite directions along the axis of rotation A1. Opposite directions are therefore understood as being towards or away from the clamping means or towards or away from one longitudinal end of the metal workpiece. The first and second directions are therefore not necessarily linear and parallel to the axis of rotation.

[0131] FIG. 9 shows how the second direction 18 is directed away from the corner of the metal workpiece 2. In other words, the second direction 18 is directed away from a surface that is in a plane perpendicular to the rotation axis A1. The corner, or shoulder, is the intersection between a surface concentric with the rotation axis and a second surface that is perpendicular to the rotation axis. The corner is a 90° corner. Preferably, the corner is formed entirely by the second cutting element, in which case the turning tool is moved toward the rotation axis A1 immediately before moving the turning tool in the second direction 18.

[0132] FIG. 10 is a schematic cross-sectional view of a first cutting element 7 in the form of a first turning insert 7, a second cutting element 8 in the form of a second turning insert 8, and a rotating metal workpiece. The first and second turning inserts 7, 8 are arranged according to the above-described embodiment. The first turning insert 7 has a first top surface 20 and a first bottom surface 22, both of which are horizontal or substantially horizontal. The second cutting insert 8 has a second top surface 21 and a second bottom surface 23, both of which are horizontal or substantially horizontal. A first mid-plane P1 is located mid-way or substantially mid-way between the first top surface 20 and the first bottom surface 22. The first mid-plane P1 is parallel or substantially parallel to the second bottom surface 22. The second mid-plane P2 is arranged in a corresponding manner. The first and second mid-planes P1, P2 are arranged in parallel planes. The metal workpiece 2 rotates in one direction 50 about its rotation axis A1. The first and second turning inserts 7, 8 are positioned on opposite sides of the rotation axis A1. The first top surface 20 faces upward in the figure, and the second top surface 21 faces downward in the figure. When the first turning insert 7 is cutting, the second turning insert 8 is spaced apart from the metal workpiece 2.

[0133] The first and second turning inserts 7, 8 are preferably made of a wear-resistant material, preferably a cemented carbide. The first and second top surfaces 20, 21 are preferably provided with chip-forming or chip-breaking means (not shown). The distance from at least a portion of said chip-forming or chip-breaking means to the central plane of the respective turning insert is preferably greater than the distance from the cutting edge bordering the top surface to said central plane. In other words, the top surfaces 20, 21 of the first and second turning inserts are provided with at least one protrusion that is higher than or located above the cutting edge in side view. In this way, the turning inserts are more suitable for turning.

[0134] The first and second turning inserts 7, 8 are preferably designed so that the first leading cutting edge 12 slopes downward, i.e., toward the first bottom surface 22, with increasing distance from the first nose cutting edge 5. The second leading cutting edge 13 is preferably arranged in a corresponding manner. In this way, chip control is further improved.

[0135] The leading and trailing cutting edges are forward and trailing in the respective feed direction, and not necessarily forward or trailing relative to the leading or trailing direction of the turning tool itself.

Claims

1. A turning tool (1) comprising a connecting part (3), The connecting portion (3) extends along a connecting axis (A2), The connecting shaft (A2) defines the longitudinal axis of the turning tool (1), The turning tool (1) comprises a first cutting element (7) and a second cutting element (8), said first cutting element (7) comprising a first cutting edge (5); the second cutting element (8) comprises a second nose cutting edge (6) separating and connecting a second leading cutting edge (13) and a second trailing cutting edge (15); the first cutting element (7) comprises a first top surface (20); the second cutting element (8) comprises a second top surface (21); In the turning tool (1), The first and second cutting elements (7, 8) intersect with an imaginary circle or cylinder (C1) having its central axis (A3) parallel to or coinciding with the connecting axis (A2); said first cutting element (7) is inclined with respect to said second cutting element (8) by an inclination angle (ω); The tilt angle (ω) is measured around the central axis (A3) of the imaginary circle (C1), The first top surface (20) faces in a direction perpendicular to the connecting axis (A2), The first cutting element (7) is arranged such that a first front cutting edge (12) forms a first cutting angle (α) of 3 to 45° when the turning tool (1) is moved in a first direction (17) parallel to the connecting axis (A2); The turning tool (1), characterized in that the second cutting element (8) is arranged such that the second front cutting edge (13) forms a second cutting angle (β) of 3° to 45° when the turning tool (1) is moved in a second direction (18) opposite to the first direction (17).

2. said first cutting element (7) comprising a first forward cutting edge (12) and a first rearward cutting edge (14); the first cutting edge (5) is a first nose cutting edge (5); The first nose cutting edge (5) separates and connects the first leading cutting edge (12) and the first trailing cutting edge (14); A turning tool (1) according to claim 1.

3. When measured along the connecting axis (A2), the second nose cutting edge (6) is located in front of the first cutting edge (5); A turning tool (1) according to claim 2.

4. a first nose angle defined as the angle between the first leading cutting edge (12) and the first trailing cutting edge (14) is an acute angle; Turning tool (1) according to claim 2 or 3.

5. The turning tool (1) has a forward-facing surface (42), At least two elements (30, 31) project forward from said forward-facing surface (42); a first one (30) of the protruding elements comprises said first cutting element (7); a second one of said protruding elements (31) comprising said second cutting element (8); A turning tool (1) according to any one of claims 1 to 4.

6. the at least two forwardly projecting elements (30, 31) are spaced apart from the connecting axis (A2); A turning tool (1) according to claim 5.

7. a second nose angle defined as the angle between the second leading cutting edge (13) and the second trailing cutting edge (15) is an acute angle; A turning tool (1) according to any one of claims 1 to 6.

8. said first cutting element (7) being in the form of a first turning insert (7); said second cutting element (8) being in the form of a second turning insert (8); the first turning insert (7) comprises the first top surface (20) and an opposite first bottom surface (22); the second turning insert (8) comprises the second top surface (21) and an opposite second bottom surface (23); the first top surface (20) comprises a first rake surface; the second top surface (21) comprises a second rake surface; A turning tool (1) according to any one of claims 1 to 7.

9. the first cutting element (7) is arranged such that when turning in the first direction (17), the first rear cutting edge (14) forms a first clearance angle (γ) of 93° to 135°; A turning tool (1) according to any one of claims 1 to 8.

10. the second cutting element (8) is arranged such that when turning in the second direction (18), the second rear cutting edge (15) forms a second clearance angle (δ) of 93° to 135°; A turning tool (1) according to any one of claims 1 to 9.

11. the first cutting element (7) and the second cutting element (8) are arranged such that the second nose cutting edge (6) is located in front of the first cutting edge (5) when turning in the first direction (17); A turning tool (1) according to any one of claims 1 to 10.

12. The first cutting element (7) and the second cutting element (8) are arranged so as to be usable for turning a metal workpiece (2) which is rotatable in one direction about its rotation axis (A1), the rotation axis (A1) being arranged perpendicular to and intersecting the connecting axis (A2); A turning tool (1) according to any one of claims 1 to 11.

13. The turning tool (1) is arranged so that a cylindrical metal workpiece (2) can be placed between the first cutting element (7) and the second cutting element (8), and the longitudinal axis (A1) of the metal workpiece (2) is located between the cutting elements (7, 8). A turning tool (1) according to any one of claims 1 to 12.

14. the connecting part (3) has a square or rectangular cross section or comprises a conical part, A turning tool (1) according to any one of claims 1 to 13.

15. 1. A turning method for a CNC lathe, comprising: providing a metal workpiece (2); Providing a turning tool (1) according to any one of claims 1 to 14; Rotating the metal workpiece (2) in one direction (30) around its rotation axis (A1); moving the turning tool (1) in a first direction (17) so that the first cutting edge (5) cuts; moving the turning tool (1) in a direction (19) such that the first cutting edge (5) is moved away from the metal workpiece (2) and the second nose cutting edge (6) is moved towards the metal workpiece (2); moving the turning tool (1) in a second direction (18) so that the second leading cutting edge (13) cuts at a second entering angle (β) of 5 to 45°; the second direction (18) being opposite to the first direction (17); A turning method comprising:

16. 16. A computer program having instructions that, when executed by a CNC lathe, cause the CNC lathe to perform the steps of claim 15.

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