METAL CUTTING TURNING TOOL

Abstract

A turning tool includes a coupling portion, which extends along a coupling axis, the coupling axis defining a longitudinal axis of the turning tool. The turning tool includes a first cutting element and a second cutting element, wherein the first cutting element has a first cutting edge. The second cutting element has a second nose cutting edge separating and connecting a second forward cutting edge and a second rearward cutting edge. The first cutting element includes a first top surface, and the second cutting element includes a second top surface. A first top surface and the second top surface face in the same or substantially the same direction.

Claims

1. A turning tool comprising: a coupling portion, wherein the coupling portion extends along a coupling axis, the coupling axis defining a longitudinal axis of the turning tool; and a first cutting element and a second cutting element, wherein the first cutting element includes a first cutting edge; wherein the second cutting element comprises includes a second nose cutting edge separating and connecting a second forward cutting edge and a second rearward cutting edge; wherein the first cutting element comprises includes a first top surface, wherein the second cutting element comprises includes a second top surface, and wherein the first top surface and the second top surface are facing in a same or substantially the same direction.

2. The turning tool according to claim 1, wherein the first cutting element includes a first forward cutting edge and a first rearward cutting edge, wherein the first cutting edge is in the form of a first nose cutting edge, and wherein the first nose cutting edge separates and connects the first forward cutting edge and the first rearward cutting edge.

3. The turning tool according to claim 2, wherein in a top view, a first bisector between the first forward cutting edge and the first rearward cutting edge forms an angle of 45-90 in relation to a second bisector between the second forward cutting edge and the second rearward cutting edge.

4. The turning tool according to claim 2, wherein in a top view, the first rearward cutting edge and the second rearward cutting edge forms an angle of 6-20 in relation to each other.

5. The turning tool according to claim 1, wherein a distance from the first forward cutting edge to the second forward cutting edge is shorter than a distance from the first forward cutting edge to the second rearward cutting edge.

6. The turning tool according to claim 2, wherein a first nose angle, defined as an angle between the first forward cutting edge and the first rearward cutting edge, is acute.

7. The turning tool according to claim 1, wherein a second nose angle defined as an angle between the second forward cutting edge and the second rearward cutting edge, is acute.

8. The turning tool according to claim 1, wherein the first nose cutting edge and the second nose cutting edge are longitudinally at equal or substantially equal distances.

9. The turning tool according to claim 1, wherein the first nose cutting edge and/or the second nose cutting edge is a longitudinally most distal part of the turning tool.

10. The turning tool according to claim 1, wherein the first cutting element is in the form of a first turning insert, wherein the second cutting element is in the form of a second turning insert, wherein the first turning insert includes the first nose cutting edge, wherein the second turning insert includes the second nose cutting edge, the second forward cutting edge and the second rearward cutting edge.

11. The turning tool according to claim 10, wherein the first turning insert includes a first top surface and an opposite first bottom surface, wherein a first mid-plane extends substantially mid-way between the first top surface and the first bottom surface, wherein the second turning insert comprises includes a second top surface and an opposite second bottom surface, wherein a second mid-plane extends substantially mid-way between the second top surface and the second bottom surface, and wherein the first mid-plane and the second mid-plane extends in parallel or substantially parallel planes.

12. The turning tool according to claim 10, wherein in a top view, the first turning insert and the second turning insert partially overlap.

13. The turning tool according to claim 1, wherein the turning tool includes a third cutting element.

14. The turning tool according to claim 1, wherein the coupling portion is square or rectangular in a cross section or includes a conical or substantially conical portion.

15. A turning method for a CNC-lathe, comprising the steps of: providing a metal work piece; providing a turning tool according to claim 1; rotating the metal work piece in one direction around a rotational axis thereof; turning in a first direction such that the first nose cutting edge is in cut moving the turning tool in a direction such that the first nose cutting edge is moved away from the metal work piece and such that the second nose cutting edge is moved towards the metal work piece; and moving the turning tool in a second direction such that the second forward cutting edge is active at a second entering angle () which is 5-45, wherein the second direction is in the opposite direction or substantially opposite direction to the first direction.

16. A computer program having instructions which when executed by a CNC-lathe, causes the CNC-lathe to perform the steps according to claim 15.

Description

DESCRIPTION OF THE DRAWINGS

[0096] The present invention will now be explained in more detail by a description of embodiments of the invention and by reference to the accompanying drawings.

[0097] FIG. 1 is a perspective view of a turning tool according to an embodiment.

[0098] FIG. 2 is a side view of the turning tool in FIG. 1.

[0099] FIG. 3 is a front view of the turning tool in FIG. 1.

[0100] FIG. 4 is a top view of the turning tool in FIG. 1.

[0101] FIG. 5 is a magnified view of section B in FIG. 4.

[0102] FIG. 6 is a top view of the turning tool in FIG. 1 and a metal work piece.

[0103] FIG. 7 is a side view of the turning tool in FIG. 1 and a metal work piece.

[0104] FIG. 8 is a top view of the turning tool in FIG. 1 and a metal work piece.

[0105] FIG. 9 is a schematic figure of moving a turning tool in a first direction.

[0106] FIG. 10 is a schematic figure of moving a turning tool in a second direction.

[0107] FIG. 11 is a schematic figure showing a first cutting element and a rotating metal work piece in a cross section.

[0108] All turning tools in the figures are drawn to scale.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0109] Reference is made to FIGS. 1-8 which show a turning tool 1 according to an embodiment. The turning tool 1 comprising a coupling portion 3. The coupling portion 3 extends along a coupling axis A2.

[0110] The coupling axis A2 defines a longitudinal axis of the turning tool 1. The coupling portion 3 comprises a conical or substantially conical portion. In the example, the substantially conical portion is according to what is in the industry is known as Coromant Capto.

[0111] The coupling portion may have other shapes, such a shape which is square shaped or rectangular shaped in a cross section, where said cross section is perpendicular to the coupling axis.

[0112] The turning tool 1 comprises 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 third cutting element 9 in the form of a third turning insert 9. The first turning insert 7 comprises a first cutting edge 5 in the form of a first nose cutting edge 5, a first forward cutting edge 12 and a first rearward cutting edge 14. The first nose cutting edge 5 separates and connects the first forward cutting edge 12 and the first rearward cutting edge 14. The first turning insert 7 comprises a first top surface 20 and an opposite first bottom surface. The second turning insert 8 comprises a second nose cutting edge 6, a second forward cutting edge 13 and a second rearward cutting edge 15. The second nose cutting edge 6 separating and connecting a second forward cutting edge 13 and a second rearward cutting edge 15. In other words, the second forward cutting edge 13 and a second rearward cutting edge 15 converge towards the second nose cutting edge 6. The second cutting element 8 comprises a second top surface 21 and an opposite second bottom surface.

[0113] A first mid-plane P1 extends mid-way or substantially mid-way between the first top surface 20 and the first bottom surface. The first mid-plane P1 is parallel to or substantially parallel to the first bottom surface. In a corresponding manner, the second turning insert 8 comprises a second top surface 21 and an opposite second bottom surface, wherein a second mid-plane P2 extends mid-way or substantially mid-way between the second top surface 21 and the second bottom surface. The third turning insert 9 is arranged in a corresponding manner, having a third mid-plane P3 mid-way between a top and a bottom surface thereof. Said top surfaces 20, 21 are suitable to function as rake surfaces. The first, second and third mid-planes P1, P2, P3 extends in parallel or substantially parallel planes. As seen in e.g. FIG. 2, the first top surface 20 and the second top surface 21 are facing in the same or substantially the same direction, which is upwards in FIG. 2.

[0114] As seen in FIG. 3, a distance from the coupling axis A2 to the sec- and nose cutting edge is greater than a distance from the coupling axis A2 to the first nose cutting edge 5. Said distances are measured horizontally in FIG. 3. In other words, said distance from a first plane comprising the coupling axis, wherein said first plane is perpendicular to the first mid-plane. Thus, said distances are from said first plane and to the first nose cutting edge 5 and to the second nose cutting edge 6. In a top view, as seen in FIG. 4 and in FIG. 5 is a magnified view of section B in FIG. 4, a first bisector between the first forward cutting edge 12 and the first rearward cutting edge 14 forms an angle of 45-90 in relation to a second bisector between the second forward cutting edge 13 and the second rearward cutting edge 15. It can also be seen that the first rearward cutting edge 14 and the second rearward cutting edge 15 forms an angle of 6-20 in relation to each other. Further, a distance from the first forward cutting edge 12 to the second forward cutting edge 13 is shorter than a distance from the first forward cutting edge 12 to the second rearward cutting edge 15. A first nose angle defined as an angle between the first forward cutting edge 12 and the first rearward cutting edge 14 is acute. A second nose angle defined as an angle between the second forward cutting edge 13 and the second rearward cutting edge 15 is acute. In e.g. FIG. 4 the first nose cutting edge 5 and the second nose cutting edge 6 are longitudinally at an equal or substantially equal distances. The first nose cutting edge 5 and/or the second nose cutting edge 6 is the longitudinally most distal part of the turning tool 1, where longitudinally is defined as along the coupling axis or along axii parallel to the coupling axis A2.

[0115] In FIG. 5 the first turning insert 7 and the second turning insert 8 partially overlap in a top view.

[0116] FIG. 6 show an example of a first step of a turning method for a CNC-lathe (not shown). A metal work piece 2 is rotating in one direction 50 around a rotational axis A1 thereof. The coupling portion 3 of the turning tool 1 is connected to the CNC-lathe (not shown), more specifically the coupling portion is connected to a machine interface. The coupling axis A2 is perpendicular to the rotational axis A1. The turning tool 1 is moved in a first direction 17 such that the first nose cutting edge 5 is in cut and such that the first forward cutting edge forms an acute entering angle. The first rearward cutting edge 14 forms an obtuse back clearance angle. The second and third turning inserts 8, 9 are spaced apart from the metal work piece 2. The second nose cutting edge is ahead of the first nose cutting edge 5 in the first direction 17. The first direction is parallel to the rotational axis A1.

[0117] After the first step, the turning tool 1 is moved in a direction 19 perpendicular to the coupling axis A2 and perpendicular to the rotational axis A1, as seen in FIG. 7. Said direction 19 is in the same direction or substantially the same direction as the first top surface 20 is facing. Said direction 19 is along the Y-axis of the CNC-lathe (not shown) to which the turning tool 1 is connected. Said direction 19 is not radially in relation to the rotational axis A1 but rather tan-gential in relation to the metal work piece 2. Said movement of the turning tool 1 is a linear movement, where the first nose cutting edge is moved further away from the metal work piece 2 and such that the second nose cutting edge 6 is moved closer to or towards the metal work piece 2. None of the first, second or third cutting inserts 7, 8, 9 are in cut.

[0118] FIG. 8 show a further step, which is after the step shown in FIG. 7.

[0119] The turning tool 1 moved in a second direction 18 such that the second forward cutting edge 13 is in cut at an acute second entering angle which is 5-45. A machined surface is formed by the second nose cutting edge 6. The second direction 18 is in the opposite direction or substantially opposite direction to the first direction 17. The second rearward cutting edge 15 forms an obtuse back clearance angle. The first nose cutting edge is ahead of the second nose cutting edge 6 in the second direction. The first and third turning inserts 7, 9 are spaced apart from the metal work piece 2. At least a portion of the machined surface resulting from the step shown in FIG. 6 is machined in the step shown in FIG. 8.

[0120] The metal work piece can have a different shape compared to what has been described above. The metal work piece may be in the form of a bar, a hollow bar or any other shape which has a rotational symmetry or substantially has a rotationally symmetry around a rotational axis thereof. The shape which can be machined can be of different configurations than what have been described above. For example, the shape can have not only one but two side walls, i.e. surfaces which is in a plane perpendicular to the rotational axis. In other words, the turning tool can be used to machine an external groove.

[0121] FIG. 9 is a schematic figure of moving a turning tool in a first direction 17 where the first cutting element 7 is in cut. The first direction 17 is a feed direction. The first forward cutting edge forms a first entering angle which is 5-45, and the first rearward cutting edge forms an obtuse back clearance angle of at least 91. The second cutting element 8 is spaced apart from the metal work piece 2. A machined surface 25 is formed by the first cutting element 7.

[0122] More specifically, the surface 25 is formed by the first nose cutting edge 5.

[0123] FIG. 10 is a schematic figure of moving a turning tool in a second direction 18 where the second cutting element 8 is in cut. The second direction is a feed direction. The second forward cutting edge is in cut at a second entering angle which is 5-45, and the second rearward cutting edge forms an obtuse back clearance angle . At least a portion of a surface 25 machined when moving the turning tool 1 in the first direction 17, seen in FIG. 9, is machined by means of the second cutting element 8 in FIG. 10.

[0124] FIG. 9 show a first machining step, is followed by a step showed in FIG. 10. In FIG. 10, the second cutting element 8 is on the same side of the rotational axis A1 as the first cutting element 7 in FIG. 9, and the first top surface is facing the same direction as the second top surface.

[0125] The metal work piece 2 in FIGS. 24 and 25 is clamped by clamping means 60 at one end. Said clamping means 60 are connected to and driven by a rotating or rotatable spindle (not shown), which are part of a CNC-lathe (not shown). Said clamping means may be in the form of e.g. a collet chuck, a 3-jaw chuck or a face driver. A distance from the clamping means 60 to the second nose cutting edge 6 is shorter than a distance from the clamping means 60 to the first cutting edge 5, where said distances are measured along lines parallel to the rotational axis A1. In FIGS. 24 and 25, the first direction 17 is away from the clamping means 60, and the second direction 18 is towards the clamping means. Alternatively (not shown), the first direction 17 is towards the clamping means 60, and the second direction 18 is away from the clamping means. The first and second directions 17, 18 are thus in opposite directions along the rotational axis A1. Opposite directions can thus be understood as towards or away from the clamping means or towards or away from one longitudinal end of the metal work piece 2. The first and second directions 17, 18 are thus not necessarily linear and parallel to the rotational axis A1.

[0126] FIG. 11 is a schematic figure showing a first cutting element 7 in the form of a first turning insert 7 and a rotating metal work piece 2 in a cross section. The first turning insert 7 comprises a first top surface 20 and a first bottom surface 22, both are horizontal or substantially horizontal. A first mid plane P1 is 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 to or substantially parallel to the first bottom surface 22. The metal work piece 2 rotates in one direction 50 around a rotational axis A1 thereof. The first top surface 20 is facing upwards in the figure. When the first turning insert 7 is in cut, the second turning insert (not shown) is spaced apart from the metal work piece 2.

[0127] FIG. 10 show how the second direction 18 is in a direction away from a corner of the metal work piece 2. In other words, the second direction 18 is in a direction away from a surface which is in a plane perpendicular to the rotational axis A1. Said corner, or a shoulder, is the intersection between a surface concentric with the rotational axis, and a second surface perpendicular to the rotational axis. Said corner is a 90 corner. Said corner is preferably completely formed by the second cutting element, where the turning tool is moved towards the rotational axis A1, immediately prior to moving the turning tool in the second direction 18.

[0128] The first and second turning inserts 7, 8 described in the embodiments above are preferably made from a wear resistant material, preferably cemented carbide. The first and second top surfaces 20, 21 preferably comprises chip forming means or chip breaking means (not shown). Preferably, a distance from at least a portion of said chip forming means or chip breaking means to the mid-plane of the respective turning insert is greater than a distance from the cutting edge bordering to the top surface to said mid-plane. In other words, the top surfaces 20, 21 of the first and second turning inserts comprises at least one protrusion, which in a side view is higher than or above the cutting edge. In such a way, the turning inserts are more suitable for turning.

[0129] The first and second turning inserts 7, 8 described in the embodiments above are preferably designed such that the first forward cutting edge 12 is sloping downwards, i.e. towards the first bottom surface 22, at increasing distance from the first nose cutting edge 5.

[0130] The second forward cutting edge 13 is preferably arranged in a corresponding manner. In such a way, the chip control is further improved.

[0131] The forward and rearward cutting edges are forward and rearward in the respective feed directions, not necessarily forward or rearward in relation to forward or rearward directions of the turning tool itself.