Abstract
A turning tool includes a coupling portion, which extends along a coupling axis defining a longitudinal axis of the turning tool, and a first and a second cutting element. The first cutting element has a first cutting edge and the second cutting element has a second cutting edge, which separates and connects a second forward cutting edge and a second rearward cutting edge. The first cutting element has a first top surface and the second cutting element has a second top surface. The first and second cutting elements intersect an imaginary circle or cylinder having a center axis thereof parallel to or coinciding with the coupling axis. The first cutting element is inclined in relation to the second cutting element by an inclination angle, which is measured around the center axis of the imaginary circle. The first top surface faces in a direction which is perpendicular to the coupling axis.
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 includes a second nose cutting edge which separates and connects a second forward cutting edge and a second rearward cutting edge, wherein the first cutting element includes a first top surface, wherein the second cutting element includes a second top surface, wherein the first and second cutting elements intersect an imaginary circle or cylinder having a center axis thereof parallel to or coinciding with the coupling axis, wherein the first cutting element is inclined in relation to the second cutting element by an inclination angle, wherein said inclination angle () is measured around the center axis of the imaginary circle, and wherein the first top surface is facing in a direction which is perpendicular to or substantially perpendicular to the coupling axis.
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 a first nose cutting edge, and wherein the first nose cutting edge separates and connects a first forward cutting edge and a first rearward cutting edge.
3. The turning tool according to claim 2, wherein, measured along the coupling axis, the second nose cutting edge is forward of the first cutting edge.
4. 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.
5. The turning tool according to claim 1, wherein the turning tool includes a forward facing surface, wherein at least two elements protrude in the forward direction from the forward facing surface, wherein a first of said protruding elements includes the first cutting element, and wherein a second of said protruding elements includes the second cutting element.
6. The turning tool according to claim 5, wherein the at least two forwardly protruding elements are spaced apart from the coupling axis.
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 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 top surface and an opposite first bottom surface, wherein the second turning insert includes the second top surface and an opposite second bottom surface, wherein the first top surface includes the first rake surface, and wherein the second top surface includes the second rake surface.
9. The turning tool according to claim 1, wherein the first cutting element is arranged such that when moving the turning tool in a first direction parallel to the coupling axis the first forward cutting edge forms a first entering angle of 3-45, and wherein the second cutting element is arranged such that when moving the turning tool in a second direction, opposite to the first direction, the second forward cutting edge forms an second entering angle of 3-45.
10. The turning tool according to claim 1, wherein the first cutting element is arranged such that when turning in the first direction the first rearward cutting edge forms a first back clearance angle of 93-135.
11. The turning tool according to claim 10, wherein the second cutting element is arranged such that when turning in the second direction, the second rearward cutting edge forms a second back clearance angle of 93-135.
12. The turning tool according to claim 1, wherein the first cutting element and the second cutting element are arranged such that when turning in the first direction, the second nose cutting edge is ahead of the first cutting edge.
13. The turning tool according to claim 1, wherein the first cutting element and the second cutting element are arranged such that the first cutting element and the second cutting element can be used for turning a metal work piece rotatable in one direction around a rotational axis thereof, wherein said rotational axis is arranged perpendicular to and intersecting the coupling axis.
14. The turning tool according to claim 1, wherein the turning tool is arranged such that a cylindrical metal work piece can be arranged between the first cutting element and the second cutting element, wherein a longitudinal axis of the metal work piece is between said cutting elements.
15. 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.
16. 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; moving the turning tool in a first direction such that the first cutting edge is in cut; moving the turning tool in a direction such that the first 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 in cut 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.
17. A computer program having instructions, which when executed by a CNC-lathe, causes the CNC-lathe to perform the steps according to claim 16.
Description
DESCRIPTION OF THE DRAWINGS
[0113] 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.
[0114] FIG. 1 is a perspective view of a turning tool according to an embodiment.
[0115] FIG. 2 is a top view of the turning tool in FIG. 1.
[0116] FIG. 3 is a front view of the turning tool in FIG. 1.
[0117] FIG. 4 is a side view of the turning tool in FIG. 1.
[0118] FIG. 5 is a top view of the turning tool in FIG. 1 and a metal work piece.
[0119] FIG. 6 is a further top view of the turning tool in FIG. 1 and a metal work piece.
[0120] FIG. 7 is yet a top view of the turning tool in FIG. 1 and a metal work piece.
[0121] FIG. 8 is a schematic figure of moving a turning tool in a first direction.
[0122] FIG. 25 is a schematic figure of moving a turning tool in a second direction.
[0123] FIG. 9 is a further schematic figure of moving a turning tool in a second direction.
[0124] FIG. 10 is a schematic figure showing a first cutting element, a second cutting element and a rotating metal work piece in a cross section.
[0125] All turning tools in the figures are drawn to scale.
DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION
[0126] Reference is now to FIGS. 1-7 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, defining a longitudinal axis of the turning tool 1. The coupling portion defines the rear end of the turning tool 1. 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. As seen in e.g. FIG. 2 the first turning insert 7 comprises a first forward cutting edge 12, a first rearward cutting edge 14 and a first nose cutting edge 5. The first nose cutting edge 5 is the part of the first turning insert 7 which is closest to the coupling axis A2. 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. 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.
[0127] As seen in e.g. FIG. 2, measured along or parallel to the coupling axis A2, the second nose cutting edge 6 is forward of the first cutting edge 5. Forward is defined as away from the coupling portion 3, towards the first and second turning inserts 7, 8.
[0128] As seen in e.g. FIG. 3, 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 top surface 21 and an opposite second bottom surface. The first top surface 20 comprises a first rake surface, and the second top surface 21 comprises a second rake surface. As seen in FIG. 3 the first and second cutting inserts 7, 8 intersect an imaginary circle or cylinder C1 having a center axis A3 thereof which parallel to the coupling axis A2. The first turning insert 7 is inclined in relation to the second turning insert 8 by an inclination angle , where said inclination angle is measured around the center axis A3 of the imaginary circle C1. The first top surface 20 is facing in a direction which is perpendicular to or substantially perpendicular to the coupling axis.
[0129] As seen in e.g. FIG. 1, the turning tool 1 comprises a forward facing surface 42, i.e. a surface facing away from the coupling portion 3. Two elements 30, 31 in the form of replaceable cutting heads 30, 31 which protrude in the forward direction from the forward facing surface 42. The first cutting head 30 comprises the first turning insert 7, meaning that the first cutting head comprises an insert seat in which the first turning insert 7 is mounted. The second cutting head 31 comprises the second cutting element 8. The cutting heads 30, 31 are spaced apart from the coupling axis A2.
[0130] The coupling portion 3 defines the rear end of the turning tool 1 and is suitable for being inserted into a machine interface (not shown) which preferably comprise a cavity or a recess (not shown). The coupling portion 3 shown in e.g. FIG. 1 comprises a substantially conical or substantially tapered or tapered portion. The coupling portion is in the field of metal cutting tools known as Coromant Capto. Other types of coupling portions are possible, for example such known as square shank types. For example, if the coupling portion is of the square shank type, the cross section of the coupling portion, perpendicular to the coupling axis, is square shaped or rectangular shaped. Further, for such a turning tool, the coupling axis is parallel to and 5-20 mm below the coupling axis A2 in FIG. 4.
[0131] FIG. 5 shows a first machining step. A metal work piece 2 rotates in one direction around a rotational axis A1 thereof. The turning tool 1 is moved in a first direction 17 parallel to the coupling axis A2 and parallel to a rotational axis A1 of a metal work piece 2 thereof. The first direction 17 is a forward direction, i.e. in a direction away from the coupling portion 3 and in the direction which the forward facing surface 42 is facing. The top surface of the first turning insert 7 is facing the viewer in FIG. 5. A machined 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 arranged such that the first forward cutting edge 12 forms an acute first entering angle of 3-45. The first rearward cutting edge 14 forms an obtuse first back clearance angle of 93-135. The second turning insert 8 is spaced apart from the metal work piece 2. When moving the turning tool 1 in the first direction 17, the second nose cutting edge 6 is ahead of the first nose cutting edge 5. As seen in FIG. 5, the turning tool 1 is arranged such that the metal work piece 2, which is cylindrical, is arranged between the first turning insert 7 and the second turning insert 8, wherein the rotational axis A1 which is a longitudinal axis A1 of the metal work piece (2) is between said turning inserts 7, 8.
[0132] FIG. 6 shows a step after the step shown in FIG. 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 work piece 2 and such that the second nose cutting edge 6 is moved towards the metal work piece 2.
[0133] The turning tool 1 is moved in a direction 19 which is perpendicular to the coupling axis A2 and perpendicular to the rotational axis A1. Said movement is a linear movement.
[0134] FIG. 7 shows a step which is after the step shown in FIG. 6. The turning tool 18 is moved in a second direction 18. The second direction 18 is in the opposite direction to the first direction 17. The second forward cutting edge 13 forms an acute second entering angle of 3-45. The second rearward cutting edge 15 forms an obtuse second back clearance angle of 93-135. The first turning insert 7 is spaced apart from the metal work piece 2. The first nose cutting edge 5 is ahead 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, showed in FIG. 5, is machined by the second turning insert 8.
[0135] FIG. 8 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.
[0136] 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.
[0137] FIG. 8 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. More specifically, the surface 25 is formed by the first nose cutting edge 5.
[0138] FIG. 9 is a further schematic figure of moving a turning tool in a second direction 18 where the second cutting element 8 is in cut. 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 . The second bottom surface is facing the viewer.
[0139] FIG. 8 show a first machining step, which can be followed by a step showed in FIG. 9. In FIG. 9, the second cutting element 8 is on the opposite side of the rotational axis A1 as the first cutting element 7 in FIG. 8, and the first top surface is facing the opposite direction as the second top surface.
[0140] The metal work piece 2 in FIGS. 8-9 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. 24-26, 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. The first and second directions are thus not necessarily linear and parallel to the rotational axis.
[0141] FIG. 9 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.
[0142] FIG. 10 is a schematic figure showing 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 work piece in a cross section. The first and second turning inserts 7, 8 are arranged according to the above described embodiment. The first turning insert 7 comprises a first top surface 20 and a first bottom surface 22, both are horizontal or substantially horizontal. The second cutting insert 8 comprises second top surface 21 and a second bottom surface 23, 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 midplane P1 is parallel to or substantially parallel to the first 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 work piece 2 rotates in one direction 50 around a rotational axis A1 thereof. The first and second turning inserts 7, 8 are located on opposite sides of the rotational axis A1. The first top surface 20 is facing upwards in the figure, and the second top surface 21 is facing downwards in the figure. When the first turning insert 7 is in cut, the second turning insert 8 is spaced apart from the metal work piece 2.
[0143] The first and second turning inserts 7, 8 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.
[0144] The first and second turning inserts 7, 8 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. The second forward cutting edge 13 is preferably arranged in a corresponding manner. In such a way, the chip control is further improved.
[0145] 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.
