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), and the second cutting element (8) comprising a second top surface (21). wherein the first and second cutting elements (7, 8) intersect with an imaginary circle or cylinder (C1) having its central axis (A3) perpendicular to 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 second top surface (21) faces in a direction that is perpendicular or substantially perpendicular to the connecting axis (A2) and perpendicular or substantially perpendicular to the central axis (A3) of the imaginary circle or cylinder (C1).

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 blade, the second cutting element comprising a second nose cutting blade separating and connecting the second front cutting blade and the second rear cutting blade, the first cutting element comprising a first top surface, and the second cutting element comprising a second top surface.

[0003] In a further aspect, the present invention relates to a machining method for a CNC lathe. [Background technology]

[0004] 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.

[0005] 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.

[0006] 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.

[0007] The present inventors have discovered that there is a need for further improved turning tools. Summary of the Invention

[0008] 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.

[0009] At least one of the foregoing objects is achieved by a turning tool as defined initially, in which the first and second cutting elements intersect an imaginary circle or cylinder having a central axis perpendicular to the connecting axis, the first cutting element is inclined at an inclination angle relative to the second cutting element, said inclination angle being measured around the central axis of the imaginary circle, and the second top surface faces in a direction that is perpendicular or substantially perpendicular to the connecting axis and perpendicular or substantially perpendicular to the central axis of the imaginary circle or cylinder.

[0010] With such a turning tool, 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, such as through a short traverse in the X-axis of the CNC lathe, said X-axis being coincident with the linkage axis.

[0011] 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.

[0012] 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.

[0013] 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.

[0014] The coupling portion extends along a coupling axis or central axis, which defines the longitudinal axis of the turning tool.

[0015] 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.

[0016] The first top surface may have a diamond, triangle, square, circle, or polygon 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 or substantially 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 that the first top surface faces.

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

[0022] 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.

[0023] The second cutting element includes a second nose cutting edge separating and connecting the second leading cutting edge and the second trailing cutting edge.

[0024] 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.

[0025] 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 rotating in one direction about its axis of rotation. Said axis of rotation is parallel to the central axis of an imaginary circle or cylinder, as defined below.

[0026] Therefore, turning tools are suitable for machining complex shapes, where the metal workpiece is rotated in only one direction. Changing the rotation direction of the metal workpiece is time-consuming.

[0027] The first and second cutting elements intersect with or are arranged along an imaginary circle or cylinder having a central axis perpendicular to the connecting axis. Preferably, the cutting elements are arranged along the imaginary circle. Such a turning tool allows the turning tool to be made relatively slimmer, particularly narrower, where narrower is defined as the distance along the axis of rotation.

[0028] Preferably, the central axis intersects or substantially intersects the connecting axis. By substantially intersects, we mean less than 20 mm from the connecting axis. The first cutting element is inclined at an inclination angle relative to the second cutting element. Preferably, the inclination angle is 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 an imaginary circle or cylinder is located between the first cutting edge and the second nose cutting edge.

[0029] The distance from the connecting portion to the second cutting element is preferably greater than the distance from the connecting portion to the central axis of the imaginary circle or cylinder.

[0030] 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 second nose cutting edge is the portion of the second cutting element furthest from the connecting portion. In other words, the second nose cutting edge is the portion of the second cutting element most forward, or the longitudinally most forward portion of the second cutting element.

[0031] The first cutting edge is the portion of the first cutting element closest to the central axis.

[0032] 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.

[0033] 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.

[0034] The top surface of the first cutting element faces in a direction different from the direction in which the second top surface faces. If the first and second top surfaces are not flat, the direction in which the top surfaces face may be defined by an imaginary plane that intersects all corners of the respective top surfaces.

[0035] A plane parallel to the first central plane and comprising the first top surface intersects with a plane parallel to the second central plane and comprising the second top surface, and said intersection coincides with or is parallel to the central axis of an imaginary circle or cylinder, and if parallel, is at a distance of less than 20 mm, preferably less than 10 mm, from said central axis.

[0036] The first cutting element may be angled 180° or substantially 180° relative to the second cutting element, in which case the rake face associated with the first cutting edge and the rake face associated with the second cutting edge face in opposite or substantially opposite directions.

[0037] The second top surface faces perpendicular or substantially perpendicular, i.e., within 15°, to the connecting axis or an axis parallel to the connecting axis. 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, i.e., within 15°, to the connecting axis or an axis parallel to the connecting axis.

[0038] The second top surface faces in a direction perpendicular to or substantially perpendicular to the central axis of the imaginary circle or cylinder, i.e., within 15°.

[0039] A first tool reference plane according to ISO 3002-1:1982 associated with the first cutting element intersects a second tool reference plane according to ISO 3002-1:1982 associated with the second cutting element. The first and second tool reference planes may preferably lie in a common plane. In such a case, a first presumed direction of primary motion according to ISO 3002-1:1982 of the first cutting element is opposite to a second presumed direction of primary motion of the second cutting element. The connecting axis preferably extends in said common plane. Alternatively, the connecting axis extends in a plane parallel to said common plane, in which case the distance between said planes is 20 mm or less. Alternatively, i.e., when said tool reference planes do not extend in a common plane, the first and second tool reference planes may be at an angle to each other, in which case said angle is equal to the angle between a first inferred direction of primary motion of the first cutting element and a second inferred direction of primary motion of the second cutting element. Preferably, the first and second tool reference planes intersect along a line parallel to the axis of rotation of the metal workpiece to be machined.

[0040] No part of the turning tool is between the first cutting edge and the second nose cutting edge, or in other words, no part of the turning tool is along a straight line between the first cutting edge and the second nose cutting edge.

[0041] The first and second cutting elements are longitudinally spaced apart, the longitudinal direction being defined by a connecting axis.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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 less than 160°, more preferably between 30° and 80°. With such a turning tool, more complex shapes can be machined.

[0046] The first leading cutting edge is preferably positioned to form an acute first cutting edge 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 edge angle is preferably 3 to 45°, and more preferably 5 to 30°. Such a turning tool can reduce wear on the first leading cutting edge.

[0047] During the aforementioned movement of the turning tool, the first nose cutting edge and the first leading cutting edge are cutting, i.e., active.

[0048] According to one embodiment, the distance from the connecting shaft to the first nose cutting edge is less than the distance from the connecting shaft to the second nose cutting edge.

[0049] The above-mentioned distances are measured along parallel lines perpendicular to the connecting axis, and the difference in distance is preferably 1 to 30 mm, more preferably 5 to 15 mm.

[0050] Thus, the first cutting element and the second cutting element are positioned such that the second nose cutting edge is ahead of the first cutting edge in the first direction when the turning tool is moved in the first direction.

[0051] According to one embodiment, the turning tool comprises an intermediate portion having a concave portion that is curved about a central axis of an imaginary circle or cylinder, and the first and second cutting elements are connected at spaced apart portions along the concave portion.

[0052] The first and second cutting elements are directly connected to spaced apart portions along the recessed portion or indirectly connected, for example, by an exchangeable cutting tool head. The rotation axis is perpendicular to the connecting axis and intersects or substantially intersects the connecting axis, i.e., within 20 mm. The intermediate portion is between and connects the connecting portion and the cutting portion. The turning tool has a portion including a recessed portion, a C-shaped portion, a curved portion, or elements that together form a curved or bent recessed portion around the central axis of an imaginary circle or cylinder. In other words, the recessed portion is spaced a certain distance from the central axis of the imaginary circle or cylinder. The distance may be constant or variable. In any case, the distance is not smaller than the radius of the imaginary circle or cylinder.

[0053] According to one embodiment, the recessed portion comprises a first side surface, said first side surface extending in a plane that is perpendicular or substantially perpendicular to the central axis of an imaginary circle or cylinder, said plane being spaced apart from the connecting axis, the first and second cutting elements being connected to the first side surface, and the intermediate portion comprising an opening.

[0054] Such turning tools allow the turning tool to be relatively slimmer, and in particular narrower, where narrow is defined as the distance along the axis of rotation, and can be conveyed toward the metal workpiece in more ways, such as when the metal workpiece is connected to a tailstock at one end.

[0055] With respect to said plane, the first and second cutting elements are disposed on one side of said plane, and the connecting shaft is disposed on the opposite side of said plane.

[0056] The recess has two sides, a first side and an opposite second side, and the first and second cutting elements are connected to the same side.

[0057] The first side may be planar or substantially planar, or the first side may have a surface that deviates slightly from a plane.

[0058] The first and second cutting elements are connected to a protruding element that protrudes from the first side in a direction away from the connecting axis.

[0059] The intermediate portion comprises an opening, said opening being radial with respect to the central axis of the imaginary circle or cylinder, in other words, said opening being perpendicular to the central axis of the imaginary circle or cylinder, in other words, the intermediate portion is non-circumferential.

[0060] In other words, the first side does not completely surround or encircle the central axis. For example, the middle section may be C-shaped in side view rather than O-shaped.

[0061] 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.

[0062] Such turning tools allow for more complex shapes to be machined. 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 top view of the first cutting element is when the first rake face faces the viewer. The first nose angle is preferably 25 to 80°, more preferably 30 to 60°.

[0063] 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.

[0064] Such turning tools allow for more complex shapes to be machined. More feed directions, such as outward feed, are possible with such turning tools. The first nose angle is conventionally measured in a top view. The top view of the second cutting element is when the second rake face faces the viewer. The second nose angle is preferably 25 to 80°, more preferably 30 to 60°.

[0065] 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.

[0066] With such a turning tool, only the turning insert needs to be replaced after use. The top surface comprises a rake surface. The bottom surface comprises a seat or contact surface.

[0067] A first through hole for a first screw intersects the first top surface and the first bottom surface.

[0068] A second through hole for a second screw intersects the second top surface and the second bottom surface.

[0069] According to one embodiment, the first cutting element is positioned such that the first leading cutting edge forms an acute first cutting angle when the turning tool is moved in a first direction perpendicular to the connecting axis, and the second cutting element is positioned such that the second leading cutting edge forms an acute second cutting angle when the turning tool is moved in a second direction opposite the first direction.

[0070] Such a turning tool reduces wear. The first direction is the feed direction and is parallel to the rotation axis of the metal workpiece. The second direction is the feed direction and is parallel to the rotation axis and perpendicular to the connecting shaft. The first cutting angle is preferably 3 to 45°. The second front cutting edge is preferably 3 to 45°.

[0071] According to one embodiment, the first cutting element is positioned such that the first trailing cutting edge forms an obtuse first clearance angle when the turning tool is moved in a first direction.

[0072] With such a turning tool, the first cutting element can be used in more feed directions, for example outward. With such a turning tool, more complex shapes can be machined. The first clearance angle is preferably 91 to 135°, more preferably 93 to 120°. The sum of the leading edge angle, nose angle, and clearance angle is equal to 180°. This applies to both the first and second cutting elements.

[0073] According to one embodiment, the second cutting element is positioned such that the second trailing cutting edge forms an obtuse second clearance angle when the turning tool is moved in the second direction.

[0074] With such a turning tool, the second cutting element can be used in more feed directions, for example outward. The second clearance angle is preferably between 91° and 135°, more preferably between 93° and 120°.

[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 first cutting edge and the second nose cutting edge intersect or substantially intersect a plane containing the connecting axis.

[0078] With such a turning tool, indexing can be performed by linearly moving the turning tool along the connecting shaft. Such a turning tool can be used on most CNC lathes. "Substantially intersecting" means that the distance from the aforementioned plane is less than 2.0 mm. Preferably, the first and second top surfaces are in a common plane or are substantially in a common plane.

[0079] According to one embodiment, the turning tool is arranged such that a cylindrical metal workpiece can be positioned between the first and second cutting elements, with the longitudinal axis of the metal workpiece being located between said cutting elements.

[0080] The longitudinal axis, which is the rotation axis of the metal workpiece, is preferably perpendicular to the connecting shaft. The cylindrical metal workpiece preferably has a diameter of 16 to 500 mm, more preferably 20 to 200 mm. The diameter of the metal workpiece is smaller than the imaginary circle or cylinder. The longitudinal axis is parallel to the central axis of the imaginary circle or cylinder.

[0081] According to one embodiment, the link is square or rectangular in cross section or comprises a tapered portion or a conical or substantially conical portion.

[0082] With such a turning tool, mounting is easily achieved on most CNC lathes. The aforementioned cross-sections are in a plane perpendicular to the connection axis. The connection part preferably comprises a tapered or conical or substantially conical part and a polygonal hollow tapered joining part, preferably including a flange contact surface as per ISO 26623-1:2014, or a ring-shaped part, such as in the form of a hollow tapered part including a flange contact surface according to DIN 69893, ISO 12164-1 or ISO 12164-1F.

[0083] According to one embodiment, the first and second cutting elements are positioned on the same side with respect to a plane, said plane including the connecting axis; The aforementioned plane is parallel to a plane that intersects the first top surface at a right angle.

[0084] According to one embodiment, the distance from the connector to the first cutting element is greater than the distance from the connector to the second cutting element.

[0085] The aforementioned distances are longitudinal distances, and therefore, the aforementioned distances are measured along the connecting axis. The difference between the aforementioned distances is preferably at least 12 mm, more preferably at least 25 mm. With such a turning tool, a metal workpiece having a diameter of 12 mm can be placed between the aforementioned cutting elements with its rotation axis perpendicular to the connecting axis.

[0086] 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.

[0087] 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.

[0088] 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.

[0089] 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.

[0090] The method includes rotating the metal workpiece about its axis of rotation in one direction, which may be clockwise or counterclockwise.

[0091] The axis of rotation is parallel to the central axis of the imaginary circle or cylinder.

[0092] The method includes moving a turning tool in a first direction, i.e., turning in the first direction. The first direction is the 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, which is 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.

[0093] The first cutting element preferably comprises a first leading cutting edge and a first trailing cutting edge, wherein the first cutting edge is in the form of a first nose cutting edge separating and connecting 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.

[0094] 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.

[0095] The movement of the turning tool may preferably be a linear movement, i.e., the turning tool is moved linearly. The movement of the turning tool may preferably be in a direction perpendicular to the rotation axis. The movement of the turning tool may preferably be in a direction along the connecting axis. The movement may be an indexing movement, i.e., a movement having the purpose of changing from placing a first cutting element in an operative position to placing a second cutting element in an operative position.

[0096] The method includes a step of moving the turning tool in a second direction, i.e., turning in the second direction. The second direction is the feed 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 above step is included in a second pass, defined as between the start of cutting and the end of cutting. 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 cut such that the second leading cutting edge cuts at a second entering angle of 5 to 45°, more preferably 5 to 30°.

[0097] 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.

[0098] The second direction is preferably opposite or substantially opposite to the first direction.

[0099] When cutting in the first direction, the first front cutting edge preferably forms an acute first cutting angle. The first cutting angle is preferably 3 to 45°, more preferably 5 to 30°. The first rear cutting edge preferably forms an obtuse first clearance angle. The first clearance angle is preferably 91° to 135°, more preferably 93° to 120°.

[0100] When turning in the second direction, the second front cutting edge preferably cuts at an acute second cutting angle, preferably 5 to 45°. The second rear cutting edge preferably forms an obtuse second clearance angle. The second clearance angle is preferably 91 to 135°, more preferably 93 to 120°.

[0101] The aforementioned method preferably includes the step of moving the turning tool such that the first cutting blade is moved away from the metal workpiece and the second nose cutting blade is moved in a linear motion toward the metal workpiece.

[0102] The aforementioned movement is an indexing movement, in other words a movement in which the first cutting element is brought into a non-operative position and the second cutting element is brought into an operative position, i.e. a position in which the second element is suitable for cutting metal from a metal workpiece.

[0103] The aforementioned linear movement can be, for example, by moving the turning tool linearly along the connecting shaft. Preferably, 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 toward the metal workpiece does not involve rotation of the turning tool about the connecting shaft. Thereby, the indexing time can be reduced compared to rotational movement.

[0104] 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.

[0105] The aforementioned method preferably includes the step of turning or machining, during a second pass, at least a portion of the surface machined during the first pass.

[0106] The first and second nose cutting edges are preferably spaced apart a constant distance along the axis of rotation when cutting in the first direction and when cutting in the second direction.

[0107] The aforementioned method preferably includes the step of setting the connecting shaft perpendicular to the axis of rotation.

[0108] The aforementioned method preferably includes the step of setting the second nose cutting edge forward of the first cutting edge during the first pass, i.e., while the turning tool is moving in the first direction.

[0109] The method preferably includes the step of setting the first cutting edge ahead of the second nose cutting edge during the second pass, i.e., while moving the turning tool in the second direction, 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 first pass is preferably in the direction toward the corner. This means that the first pass is in the direction toward the corner or toward a future corner, preferably a corner that will be finished after the second pass. Thus, the first pass involves roughing out the corner, i.e., removing some, but not all, of the material to achieve the desired or predetermined shape. 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 bore. The first surface is preferably the exterior surface, i.e., the radially outer surface.

[0112] According to one aspect of the present invention, there is provided a computer program having instructions which, when executed by a CNC lathe, cause the CNC lathe to perform steps according to any of the preceding methods.

[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] 1 is a perspective view of a turning tool and a metal workpiece according to a first embodiment. FIG. [Figure 2] FIG. 2 is a side view of the turning tool and metal workpiece in FIG. 1. [Figure 3] 2 is a bottom schematic view of a portion of the turning tool and metal workpiece in FIG. 1. [Figure 4] 2 is a further bottom view of the turning tool and a portion of the metal workpiece in FIG. 1. FIG. [Figure 5] 2 is a further bottom view of the turning tool and a portion of the metal workpiece in FIG. 1. FIG. [Figure 6] 2 is a further bottom view of the turning tool and a portion of the metal workpiece in FIG. 1. FIG. [Figure 7] FIG. 10 is a side view of a turning tool according to a second embodiment. [Figure 8] FIG. 10 is a side view of a turning tool and a metal workpiece according to a third embodiment. [Figure 9] FIG. 1 is a schematic diagram of moving a turning tool in a first direction. [Figure 10] FIG. 10 is a schematic diagram of moving the turning tool in a second direction. [Figure 11] 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] 1 to 6, which show a turning tool 1 according to a first embodiment suitable for carrying out the method defined above. A metal workpiece 2 is connected to a spindle (not shown) of a CNC lathe (not shown) by means of clamping means (not shown). The turning tool 1 comprises a coupling part 3 extending along a coupling axis A2, which defines the longitudinal axis of the turning tool 1. The forward direction is away from the coupling part 3, i.e. the forward direction is substantially towards the left in FIG. 1. The rotation axis A1 of the metal workpiece 2 is arranged perpendicular to and intersects the coupling axis A2. The turning tool 1 comprises 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.

[0118] As can be seen in Figures 3-6, the first cutting element 7 includes a first cutting edge 5 in the form of a first nose cutting edge 5 that separates and connects a first leading cutting edge 12 and a first trailing cutting edge 14. The second turning insert 8 includes a second nose cutting edge 6 that separates and connects a second leading cutting edge 13 and a second trailing cutting edge 15.

[0119] As can be seen in FIG. 2, the first turning insert 7 includes a first top surface 20, and the second turning insert 8 includes a second top surface 21. In FIG. 2, the metal workpiece 2 rotates clockwise about its rotation axis A1. The first cutting edge and the second nose cutting edge intersect or substantially intersect a plane containing the connection axis A2 and the rotation axis A1. In FIG. 2, the first turning insert 7 is cutting, and the second turning insert 8 is located a short distance from the metal workpiece 2. The distance between the metal workpiece 2 and the inactive second turning insert 8 is preferably greater, as shown in FIGS. 3 and 4. FIG. 2 shows that the distance from the connection portion (3) to the first cutting element (7) is greater than the distance from the connection portion (3) to the second cutting element (8).

[0120] 1 and 2, the turning tool 1 comprises an intermediate portion 33 in the form of a recessed or curved portion connecting the first and second turning inserts 7, 8. The intermediate portion 33 comprises an opening 41. The opening 41, or void, or cavity, makes room for the metal workpiece to be machined. The recessed portion 33 is curved about an axis perpendicular to the connecting axis A2, and said axis intersects said opening 41, or void, or cavity. As can be seen, for example, in FIG. 2, the opening 41 opens radially with respect to the rotation axis A1. The turning tool 1 can be brought from above in FIG. 2 to the position shown in FIG. 2, at least if the diameter of the metal workpiece 2 is less than the distance between the first cutting insert 7 and the second turning insert 8. This is particularly advantageous when the metal workpiece 1 is long or clamped at both ends.

[0121] The intermediate portion 33 comprises a first side surface 40 and an opposite second side surface. Due to an opening 41, the first side surface 40 does not completely surround or encircle the rotation axis A1. The first side surface 40 extends in a plane perpendicular to the rotation axis A1. Said plane 40 is spaced apart from the connecting axis A2.

[0122] Projecting from the first side surface 40 are protrusions 30, 31 in the form of interchangeable cutting heads 30, 31 which are connected to the first side surface 40 by clamping means. Each cutting head 30, 31 comprises at least one insert seat. The first and second turning inserts 7, 8 are connected to the first side surface 40 by their respective cutting heads 30, 31.

[0123] In FIG. 2, the rotation axis A1 is perpendicular to and intersects the connecting axis A2. As can be seen in FIG. 2, the rotation axis A2 of the metal workpiece 2 is located between the first cutting insert 7 and the second turning insert 8. The coupling 3 has a tapered portion. The coupling 3 is a quick change coupling known in the industry as Coromant Capto®. In an alternative embodiment (not shown), the coupling 3 has a square cross section, and the connecting axis A2 is parallel to and 5 to 20 mm below the connecting axis A2 in FIG. 2.

[0124] When the first cutting insert 7 is viewed in a top view, for example as in FIG. 3, 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.

[0125] The second nose angle, defined as the angle between the second leading cutting edge 13 and the second trailing cutting edge 15 when the second turning insert is viewed in a top view or in a bottom view, for example as in FIG. 3, is an acute angle.

[0126] For example, as seen in FIG. 1 , a first through hole for a first screw (not shown) intersects the first top surface and the first bottom surface, and a second through hole for a second screw (not shown) intersects the second top surface and the first bottom surface.

[0127] 3 and 4 show a first machining step in which the turning tool 1 is moved in a first direction 17 perpendicular to the connecting axis A2. The first leading cutting edge 12 forms an acute first leading angle. The first trailing cutting edge 14 forms an obtuse first leading clearance angle. The first turning insert 7 is cutting. The second turning insert 8 is spaced from the metal workpiece 2. The second nose cutting edge 6 is forward of the first nose cutting edge 5 in the first direction 17.

[0128] 3 and 4, the first turning insert 7 finishes cutting and the turning tool 1 is moved in 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, as shown in FIG. 5. The first turning insert 7 is moved radially away from the rotation axis A1 of the metal workpiece 2.

[0129] The step shown in Figure 5 is followed by the step shown in Figure 6. Figure 6 shows moving the turning tool 1 in a second direction 18, which is opposite to the first direction 17 shown in Figures 4 and 5. The second turning insert 8 is cutting. The first turning insert 7 is not operating. In other words, the first turning insert is spaced apart from the metal workpiece 2. The second leading cutting edge 13 forms an acute second leading edge angle. The second trailing cutting edge 15 forms an obtuse second leading edge angle.

[0130] The metal workpiece 2 rotates in the same direction about its axis of rotation A1 in FIGS.

[0131] In Figures 4-6, the first and second turning inserts 7, 8 operate in the XZ plane of a CNC lathe (not shown). Thanks to the use of small entering angles, insert wear is reduced, but thanks to the separate insert it is still possible to machine corners with the other insert. The very quick change of inserts, as seen in Figure 5, is due to the short traverse in the X axis of the CNC lathe.

[0132] FIG. 7 shows a turning tool 1 according to a second embodiment. The only substantial difference between the turning tool 1 according to the first embodiment and the turning tool 1 according to the second embodiment is that the turning tool 1 according to the second embodiment includes a third turning insert 9. Indexing from the first turning insert 7 to the second turning insert 8 or from the second turning insert 8 to the first turning insert 7 is achieved by moving the turning tool 1 along the connecting axis A2, while indexing to the third turning insert 9 is achieved by moving the turning tool in a direction perpendicular to the connecting axis A2, more specifically, downward in FIG. 2 . As can be seen in FIG. 7 , the first turning insert 7, the second turning insert 8, and the third turning insert 9 intersect with an imaginary circle or cylinder C1 having its central axis A3 perpendicular to the connecting axis A2. The first turning insert 7 is inclined with respect to the second turning insert 8 by an inclination angle ω. The tilt angle ω is measured around the central axis A3 of the imaginary circle C1. The second top surface 21 faces in a direction that is perpendicular to the connecting axis A2 and perpendicular or substantially perpendicular to the central axis A3 of the imaginary circle or cylinder C1.

[0133] 8 shows a turning tool 1 and a metal workpiece 2 according to a third embodiment. The only substantial difference between the turning tool 1 according to the second embodiment and the turning tool 1 according to the third embodiment is that the turning tool 1 according to the third embodiment includes a fourth turning insert 10 and that the intermediate portion 33 completely surrounds the rotation axis A1. In other words, the intermediate portion does not include a radial opening.

[0134] 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.

[0135] FIG. 9 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.

[0136] 10 is a schematic illustration of a turning tool moving 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.

[0137] Figure 9 shows a first machining step which may be followed by the step shown in Figure 10. In Figure 10, the second cutting element 8 is on the opposite side of the rotation axis A1 from the first cutting element 7 in Figure 9, and the first top surface faces in the opposite direction from the second top surface.

[0138] 9 and 10, 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 FIGS. 9 and 10, 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.

[0139] The steps shown in Figures 9 and 10 may be performed using a turning tool according to the first, second, or third embodiment.

[0140] FIG. 11 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 in accordance with the first, second, or third turning tool 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 around 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. For example, in FIG. 11 , the distance from the connecting axis A2 to the first nose cutting edge 5 is shorter than the distance from the connecting axis A2 to the second nose cutting edge 6.

[0141] FIG. 10, as well as FIGS. 6 and 15, show 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 that is 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.

[0142] The first and second turning inserts 7, 8 described in the above embodiments 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 the 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 the 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.

[0143] The first and second turning inserts 7, 8 described in the above embodiments are preferably designed such that the first leading cutting edge 12 slopes downward, i.e., towards 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.

[0144] 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); A turning tool (1), wherein the second cutting element (8) comprises 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) perpendicular to the connecting axis (A2); the first cutting element (7) is inclined with respect to the 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 turning tool (1) is characterized in that the second top surface (21) faces in a direction perpendicular to the connecting axis (A2) and perpendicular to the central axis (A3) of the imaginary circle or cylinder (C1).

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. The distance from the connecting shaft (A2) to the first nose cutting edge (5) is shorter than the distance from the connecting shaft (A2) to the second nose cutting edge (6). A turning tool (1) according to claim 2.

4. The turning tool (1) comprises an intermediate part (33), The intermediate portion (33) comprises a concave portion (33), The concave portion (33) is curved around the central axis (A3) of the imaginary circle or cylinder (C1), the first and second cutting elements (7, 8) are connected to spaced apart portions along the recess (33); A turning tool (1) according to any one of claims 1 to 3.

5. The recess (33) has a first side (40); the first side surface (40) extends in a plane perpendicular to the central axis (A3) of the imaginary circle or cylinder (C1); The plane is spaced apart from the connecting axis (A2), the first and second cutting elements (7, 8) are connected to the first side surface (40); the intermediate portion comprises an opening (41); A turning tool (1) according to claim 4.

6. 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; A turning tool (1) according to claim 2.

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 a first top surface (20) and an opposite first bottom surface (22); the second turning insert (8) comprises a 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 the first front cutting edge (12) forms an acute first cutting angle (α) when the turning tool (1) is moved in a first direction (17) perpendicular to the connecting axis (A2); the second cutting element (8) is arranged such that the second leading cutting edge (13) forms an acute second cutting angle (β) when the turning tool (1) is moved in a second direction (18) opposite to the first direction (17); A turning tool (1) according to claim 2.

10. the first cutting element (7) is arranged such that the first rear cutting edge (14) forms an obtuse first clearance angle (γ) when the turning tool (1) is moved in a first direction (17); A turning tool (1) according to claim 2.

11. the second cutting element (8) is arranged such that the second rear cutting edge (15) forms an obtuse second clearance angle (δ) when the turning tool (1) is moved in a second direction (18); 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 (2) 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 first cutting edge (5) and the second nose cutting edge (6) intersect with a plane including the connecting axis (A2); A turning tool (1) according to any one of claims 1 to 12.

14. 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 (A2) 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 13.

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

16. the first and second cutting elements (7, 8) are positioned on the same side of a plane; the plane includes the connecting axis (A2), The plane is parallel to a plane that intersects the first top surface (20) at a right angle. A turning tool (1) according to any one of claims 1 to 15.

17. The distance from the connecting portion (3) to the first cutting element (7) is greater than the distance from the connecting portion (3) to the second cutting element (8). A turning tool (1) according to any one of claims 1 to 16.

18. 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 17; 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:

19. 20. A computer program having instructions that, when executed by a CNC lathe, cause the CNC lathe to perform the steps of claim 18.

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