Abstract
A turning tool includes a coupling portion extending along a coupling or longitudinal axis, a first cutting element having a first cutting edge, and a second cutting element having 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. The first and second cutting elements intersect an imaginary circle or cylinder having a center axis perpendicular to 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 second top surface faces in a direction, which is perpendicular to or substantially perpendicular to the coupling axis and perpendicular or substantially perpendicular to the center axis of the imaginary circle or cylinder.
Claims
1. A turning tool comprising: a coupling portion, wherein the coupling portion extends along a coupling axis, and wherein the coupling axis defines 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, and wherein the second cutting element 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 includes a first top surface, and 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 perpendicular to 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, wherein the second top surface is facing in a direction which is perpendicular to or substantially perpendicular to the coupling axis and perpendicular or substantially perpendicular to the center axis of the imaginary circle or cylinder.
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 the first forward cutting edge and the first rearward cutting edge.
3. The turning tool according to claim 2, wherein a distance from the coupling axis to the first nose cutting edge is shorter than a distance from the coupling axis to the second nose cutting edge.
4. The turning tool according to claim 1, further comprising an intermediate portion, wherein the intermediate portion includes a concave portion, wherein the concave portion is curved around the center axis of the imaginary circle or cylinder, and wherein the first and second cutting elements are connected to spaced apart portions along the concave portion.
5. The turning tool according to claim 4, wherein the concave portion includes a first side surface, wherein said first side surface extends in a plane which is perpendicular to or substantially perpendicular to the center axis of the imaginary circle or cylinder, wherein said plane is spaced apart from the coupling axis, wherein the first and second cutting elements are connected to the first side surface, and wherein the intermediate portion includes an opening.
6. The turning tool according to claim 1, 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 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 a first top surface and an opposite first bottom surface, wherein the second turning insert includes a 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 perpendicular to the coupling axis the first forward cutting edge forms an acute first entering angle, 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 acute second entering angle.
10. 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, the first rearward cutting edge forms an obtuse first back clearance angle.
11. The turning tool according to claim 10, wherein the second cutting element is arranged such that when moving the turning tool in a second direction, the second rearward cutting edge forms an obtuse second back clearance angle.
12. 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 are arranged 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.
13. The turning tool according to claim 1, wherein the first cutting edge and the second nose cutting edge intersect or substantially intersect a plane having 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 has a tapered or conical or substantially conical portion.
16. The turning tool according to claim 1, wherein the first and second cutting elements are positioned on the same side relative to a plane, where said plane includes the coupling axis, and where said plane is parallel to plane which intersects the first top surface at a right angle.
17. The turning tool according to claim 1, wherein a distance from the coupling portion to the first cutting element is greater than a distance from the coupling portion to the second cutting element.
18. 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.
19. A computer program having instructions, which when executed by a CNC-lathe, causes the CNC-lathe to perform the steps according to claim 18.
Description
DESCRIPTION OF THE DRAWINGS
[0111] 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.
[0112] FIG. 1 is a perspective view of a turning tool according to a first embodiment and a metal work piece.
[0113] FIG. 2 is a side view of the turning tool and metal work piece in FIG. 1.
[0114] FIG. 3 is a schematic bottom view of a part of the turning tool and metal work piece in FIG. 1.
[0115] FIG. 4 is a further bottom view of a part of the turning tool and metal work piece in FIG. 1.
[0116] FIG. 5 is a yet a bottom view of a part of the turning tool and metal work piece in FIG. 1.
[0117] FIG. 6 is a yet a bottom view of a part of the turning tool and metal work piece in FIG. 1.
[0118] FIG. 7 is a side view of a turning tool according to a second embodiment.
[0119] FIG. 8 is a side view of a turning tool according to a third embodiment and a metal work piece.
[0120] FIG. 9 is a schematic figure of moving a turning tool in a first direction.
[0121] FIG. 10 is a schematic figure of moving a turning tool in a second direction.
[0122] FIG. 11 is a schematic figure showing a first cutting element, a second cutting element and a rotating metal work piece in a cross section.
[0123] All turning tools in the figures are drawn to scale.
DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION
[0124] Reference is made to FIGS. 1-6 which show a turning tool 1 according to a first embodiment suitable for carrying out the above defined method. A metal work piece 2 is connected to a spindle (not shown) of a CNC-lathe (not shown) by clamping means (not shown). The turning tool 1 comprises a coupling portion 3 extending along a coupling axis A2. The coupling axis A2 defines a longitudinal axis of the turning tool 1. The forward direction is away from the coupling portion 3, i.e. the forward direction is substantially towards the left-hand side in FIG. 1. The rotational axis A1 of the metal work piece 2 is arranged perpendicular to and intersecting 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.
[0125] As seen in FIGS. 3-6, the first cutting element 7 comprises a first cutting edge 5 in the form of a first nose cutting edge 5, which separates and connects a first forward cutting edge 12 and the first rearward cutting edge 14. The second turning insert 8 comprises a second nose cutting edge 6 separating and connecting a second forward cutting edge 13 and a second rearward cutting edge 15.
[0126] As seen in FIG. 2, the first turning insert 7 comprises a first top surface 20 and the second turning insert 8 comprises a second top surface 21. In FIG. 2, the metal work piece 2 rotates clock-wise around a rotational axis A1 thereof. The first cutting edge and the second nose cutting edge intersect or substantially intersect a plane comprising the coupling axis A2 and the rotational axis A1. In FIG. 2, the first turning insert 7 is in cut and the second turning insert 8 is only a very small distance from the metal work piece 2. Preferably, the distance between the metal work piece 2 and the inactive second turning insert 8 is greater, such as shown in FIGS. 3 and 4. FIG. 2 shows that a distance from the coupling portion (3) to the first cutting element (7) is greater than a distance from the coupling portion (3) to the second cutting element (8).
[0127] In FIGS. 1 and 2, the turning tool 1 comprises an intermediate portion 33 in the form of a concave portion 33 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 a metal work piece to be machined. The concave portion 33 is curved around an axis perpendicular to the coupling axis A2, where said axis intersect said opening 41 or void or cavity. As can be seen in e.g. FIG. 2, the opening 41 opens radially in relation to the rotational axis A1. The turning tool 1 can be brought in the position as shown in FIG. 2 from above in FIG. 2, at least if the metal work piece 2 diameter is less than the distance between the first and second turning inserts 7, 8. This is an advantage especially if the metal work piece 1 is long or is clamped at both ends.
[0128] The intermediate portion 33 comprises a first side surface 40 and an opposite second side surface. Due to the opening 41, the first side surface 40 does not completely surround or enclose the rotational axis A1. The first side surface 40 is extends in a plane which is perpendicular to the rotational axis A1. Said plane 40 is spaced apart from the coupling axis A2.
[0129] Protruding from the first side surface 40 are protruding portions 30, 31 in the form of replaceable cutting heads 30, 31, which are connected to the first side surface 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 means of a respective cutting heads 30, 31.
[0130] In FIG. 2, the rotational axis A1 is perpendicular to and intersecting the coupling axis A2. As seen in FIG. 2, the rotational axis A2 of the metal work piece 2 is between the first and second turning insert 7, 8. The coupling portion 3 comprises a tapered portion. The coupling portion 3 is quick-change coupling which in the industry is known as Coromant Capto. In an alternative embodiment (not shown), the coupling portion 3 is square shaped in a cross section, and the coupling axis A2 is parallel to the coupling axis A2 in FIG. 2 and 5-20 mm below the coupling axis A2 in FIG. 2.
[0131] When the first turning insert 7 is seen in a top view, as in e.g. FIG. 3, a first nose angle defined as an angle between the first forward cutting edge 12 and the first rearward cutting edge 14 is acute.
[0132] When the second turning insert is seen in a top view, or in a bottom view as in e.g. FIG. 3, a second nose angle defined as an angle between the second forward cutting edge 13 and the second rearward cutting edge 15 is acute.
[0133] As seen in e.g. FIG. 1, a first through hole for a first screw (not shown) intersects the first top and first bottom surfaces, and a second through hole for a second screw (not shown) intersects the second top and first bottom surfaces.
[0134] FIGS. 3 and 4 show a first machining step where the turning tool 1 is moved in a first direction 17, perpendicular to the coupling axis A2. The first forward cutting edge 12 forms an acute first entering angle. The first rearward cutting edge 14 forms an obtuse first back clearance angle. The first turning insert 7 is in cut. The second turning insert 8 is spaced apart from the metal work piece 2. The second nose cutting edge 6 is in the first direction 17 ahead of the first nose cutting edge 5.
[0135] After the step shown in FIGS. 3 and 4, the first turning insert 7 goes out of cut, and the turning tool 1 is moved in a direction 19 such that the first 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, as shown in FIG. 5. The first turning insert 7 is moved radially away from the rotational axis A1 of the metal work piece 2.
[0136] After the step shown in FIG. 5 follows the step shown in FIG. 6. FIG. 6 shows moving the turning tool 1 in a second direction 18, where the second direction 18 is in the opposite direction to the first direction 17 shown in FIGS. 4 and 5. The second turning insert 8 is in cut. The first turning insert 7 is inactive. In other words, the first turning insert is spaced apart from the metal work piece 2. The second forward cutting edge 13 forms an acute second entering angle. The second rearward cutting edge 15 forms an obtuse second back clearance angle.
[0137] The metal work piece 2 rotates in the same direction around the rotational axis thereof A1 in FIGS. 3, 4 and 6.
[0138] In FIGS. 4-6, the first and second turning inserts 7, 8 work in the XZ-plane of the CNC-lathe (not shown). Thanks to utilizing small entering angles the insert wear is reduced, but thanks to another insert it is still possible to machine a corner with the other insert. The very quick change of insert as seen in FIG. 5 is due to a short traverse in the X-axis of the CNC-lathe.
[0139] 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 and second embodiments is that the turning tool 1 according to the second embodiment comprises a third turning insert 9. While indexing from the first turning insert 7 to the second turning insert 8 or vice versa is through a movement of the turning tool 1 along the coupling axis A2, indexing to the third turning insert 9 is through a movement of the turning tool in a direction perpendicular to the coupling axis A2, more specifically downwards in FIG. 2. As seen in FIG. 7, the first and second turning inserts 7, 8 as well as the third turning insert 9 intersect an imaginary circle or cylinder C1 having a center axis A3 thereof perpendicular to the coupling axis A2. The first turning insert 7 is inclined in relation to the second turning insert 8 by an inclination angle . The inclination angle is measured around the center axis A3 of the imaginary circle C1. The second top surface 21 is facing in a direction which is perpendicular to the coupling axis A2 and perpendicular or substantially perpendicular to the center axis A3 of the imaginary circle or cylinder C1.
[0140] FIG. 8 shows a turning tool 1 according to a third embodiment and a metal work piece 2. The only substantial difference between the turning tool 1 according to the second and third embodiments is that the turning tool 1 according to the third embodiment comprises a fourth turning insert 10 and that the intermediate portion 33 completely surrounds rotational axis A1. In other words, the intermediate portion does not comprise a radial opening.
[0141] The metal work piece can have a different shapes 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.
[0142] 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. More specifically, the surface 25 is formed by the first nose cutting edge 5.
[0143] 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 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.
[0144] FIG. 9 show a first machining step, which can be followed by a step showed in FIG. 10. In FIG. 10, the second cutting element 8 is on the opposite side of the rotational axis A1 as the first cutting element 7 in FIG. 9, and the first top surface is facing the opposite direction as the second top surface.
[0145] The metal work piece 2 in FIGS. 9 and 10 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. 9 and 10, 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.
[0146] The steps shown in FIGS. 9 and 10 can be performed using the turning tool according to the first, second or third embodiment.
[0147] FIG. 11 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 first, second or third turning tool embodiments. 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 mid-plane 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. In e.g. FIG. 11, a distance from the coupling axis A2 to the first nose cutting edge 5 is shorter than a distance from the coupling axis A2 to the second nose cutting edge 6.
[0148] FIG. 10, as well as FIG. 6 and FIG. 15, shows 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.
[0149] 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.
[0150] 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. The second forward cutting edge 13 is preferably arranged in a corresponding manner. In such a way, the chip control is further improved.
[0151] 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.
