TURNING TOOL CUTTING INSERT AND TURNING TOOL

Abstract

A turning tool cutting insert having an insert face with a rake face includes a primary land extending along a first cutting edge. The primary land includes a first primary land portion adjacent a linear edge portion, and a second primary land portion adjacent a central portion of the corner edge portion. The first primary land portion differs from the second primary land portion. A transitional primary land portion adjoins the first primary land portion and the second primary land portion, and forms a transition between the first primary land portion and the second primary land portion. The transitional primary land portion is arranged only adjacent an outer portion of the corner edge portion. Further, a turning tool including a turning tool cutting insert is disclosed.

Claims

1. A turning tool cutting insert comprising an insert body, including at least a first cutting edge, the first cutting edge extending along an intersection between a relief face and a rake face of the insert body, wherein the first cutting edge includes a convex corner edge portion and a straight linear edge portion, the corner edge portion adjoining the linear edge portion, and wherein the rake face includes a primary land extending along the first cutting edge, the primary land having a first primary land portion adjacent the linear edge portion and a second primary land portion adjacent a central portion of the corner edge portion, and wherein the first primary land portion differs from the second primary land portion, the primary land having a transitional primary land portion adjoining the first primary land portion and the second primary land portion and forming a transition between the first primary land portion and the second primary land portion, wherein the transitional primary land portion is arranged only adjacent an outer portion of the corner edge portion, the outer portion adjoining the central portion of the corner edge portion.

2. The turning tool cutting insert according to claim 1, wherein the first primary land portion extends over a first distance of the rake face, the first distance extending perpendicularly to the linear edge portion, and the second primary land portion over a second distance of the rake face, the second distance extending perpendicularly to tangents of the corner edge portion, and wherein the first distance is longer than the second distance.

3. The turning tool cutting insert according to claim 2, wherein the first distance is within a range of 50-500% longer than the second distance.

4. The turning tool cutting insert according to claim 1, wherein the second primary land portion has a rake angle larger than a rake angle of the first primary land portion.

5. The turning tool cutting insert according to claim 1, wherein the transitional primary land portion provides a gradual transition from the first primary land portion to the second primary land portion.

6. The turning tool cutting insert according to claim 5, wherein a width of the primary land measured perpendicularly to the first cutting edge in the transitional primary land portion decreases gradually from the first distance to the second distance.

7. The turning tool cutting insert according to claim 4, wherein a rake angle in the transitional primary land portion increases gradually from the rake angle in the first primary land portion (32) to the larger rake angle of the second primary land portion (34).

8. The turning tool cutting insert according to claim 1, wherein the first cutting edge includes a straight further linear edge portion adjoining the corner edge portion opposite to the linear edge portion, and wherein the first cutting edge is symmetrical about a bisector of the corner edge portion.

9. The turning tool cutting insert according to claim 8, wherein an 80 degree angle is formed between the linear edge portion and the further linear edge portion.

10. The turning tool cutting insert according to claim 1, wherein the insert body includes four cutting edges, each cutting edge being substantially similar to the first cutting edge, such that the turning tool cutting insert is four times indexable in a turning tool.

11. The turning tool cutting insert according to claim 1, wherein the second primary land portion has a constant width and a constant rake angle.

12. The turning tool cutting insert according to claim 4, wherein the rake angle of the first primary land portion is less than zero, and wherein the rake angle of the second primary land portion is greater than zero.

13. The turning tool cutting insert according to claim 1, wherein the first primary land portion, the second primary land portion and the transitional primary land portion are formed by powder pressing.

14. A turning tool comprising: a tool body, the tool body having a longitudinal axis extending in a direction from an attachment portion of the tool body towards a distal end portion of the tool body, wherein the tool body is provided with a recess arranged to receive a cutting insert at the distal end portion, the recess being shaped such that a cutting insert positioned in the recess points an engaging corner edge portion of a first cutting edge thereof in a direction sidewardly of the longitudinal axis; and a turning tool cutting insert arranged in the recess, the cutting insert including an insert body having at least a first cutting edge, the first cutting edge extending along an intersection between a relief face and a rake face of the insert body, wherein the first cutting edge includes a convex corner edge portion and a straight linear edge portion, the corner edge portion adjoining the linear edge portion, and wherein the rake face includes a primary land extending along the first cutting edge, the primary land having a first primary land portion adjacent the linear edge portion and a second primary land portion adjacent a central portion of the corner edge portion, and wherein the first primary land portion differs from the second primary land portion, the primary land having a transitional primary land portion adjoining the first primary land portion and the second primary land portion and forming a transition between the first primary land portion and the second primary land portion, wherein the transitional primary land portion is arranged only adjacent an outer portion of the corner edge portion, the outer portion adjoining the central portion of the corner edge portion.

15. A turning tool according to claim 14, wherein a bisector of the engaging corner edge portion of the first cutting edge extends sidewardly at an angle within a range of 43-47 degrees to the longitudinal axis.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Various aspects of the invention, including its particular features and advantages, will be readily understood from the example embodiments discussed in the following detailed description and the accompanying drawings, in which:

[0039] FIG. 1 illustrates a turning tool cutting insert according to embodiments,

[0040] FIG. 2 illustrates a partial top view of a first cutting edge of a turning tool cutting insert according to embodiments,

[0041] FIG. 3 illustrates a partial perspective view of a first cutting edge of a turning tool cutting insert according to embodiments,

[0042] FIG. 4 illustrates a partial top view of a first cutting edge of a turning tool cutting insert according to embodiments, and

[0043] FIG. 5 illustrates a turning tool according to embodiments.

DETAILED DESCRIPTION

[0044] Aspects of the present invention will now be described more fully. Like numbers refer to like elements throughout. Well-known functions or constructions will not necessarily be described in detail for brevity and/or clarity.

[0045] FIG. 1 illustrates a turning tool cutting insert 2 according to embodiments. The cutting insert 2 comprises an insert body 4. The insert body 4 is delimited by a top surface 6, an opposite bottom surface 8, and a side surface 10 extending between the top and bottom surfaces 6, 8. The cutting insert 2 is provided with a central hole 9 which extends through the insert body 4. The top and bottom surfaces 6, 8 are generally planar and are substantially parallel to each other and are provided with raised portions and ridge portions. The cutting insert 2 is indexable and the top surface 6 or the bottom surface 8 may face upwardly when the cutting insert 2 is mounted in a turning tool.

[0046] The insert body 4 comprises at least a first cutting edge 12 extending along an intersection between a relief face 14 and a rake face 16. The relief face 14 is provided at the side surface 10 of the insert body 4 and the corresponding rake face 16 is provided at the top surface 6.

[0047] The cutting insert body has a generally rhombus shape. A median plane can be defined as a plane in the middle between the top surface 6 and the bottom surface 8 that would transect the insert body into two halves, i.e. a top half and a bottom half. The rake face 16 is provided on one or both of the top and bottom surfaces.

[0048] The cutting insert 2 of these embodiments comprises four substantially identical cutting edges. In addition to the first cutting edge 12, there are provided a second cutting edge 18 at the top surface 6 opposite to the first cutting edge 12, and third and fourth cutting edges 20, 22 at the bottom surface 8. Accordingly, the cutting insert 2 is four times indexable in a turning tool.

[0049] The first cutting edge 12 comprises a convex corner edge portion 24 and a straight linear edge portion 26. The straight linear edge portion 26 is straight and linear at least as seen in a top view of the cutting insert, i.e. seen along a centre axis 46 of the central hole 9. The corner edge portion 24 adjoins the linear edge portion 26. A straight further linear edge portion 30 adjoins the corner edge portion 24 opposite to the linear edge portion 26. The first cutting edge 12 is symmetrical about a bisector 28 of the corner edge portion 24, the symmetry including the linear edge portion 26 and the further linear edge portion 30.

[0050] Also an intermediate corner portion 25 of the rhombus shaped insert body 4, and corresponding corner portions, may form part of cutting edges. That is, depending on a relevant turning tool either the corner edge portion 24 engages with a workpiece or the intermediate corner portion 25 engages with a workpiece.

[0051] With reference to FIGS. 2-4 below, various embodiments of the first cutting edge 12 and an adjacent primary land portion are discussed. The discussion applies mutatis mutandis to a cutting edge including the intermediate corner portion 25.

[0052] FIG. 2 illustrates a partial top view of the first cutting edge 12 of a turning tool cutting insert 2 according to embodiments. The rake face 16 comprises a primary land extending along the first cutting edge 12. The primary land comprises a first primary land portion 32 adjacent the linear edge portion 26, and a second primary land portion 34 adjacent a central portion 36 of the corner edge portion 24. The central portion 36 is the edge portion crossing the bisector 28 of the corner edge portion 24. The primary land further comprises a transitional primary land portion 38 adjoining the first primary land portion 32 and the second primary land portion 34, and forming a transition between the first primary land portion 32 and the second primary land portion 34. The transitional primary land portion 38 is arranged only adjacent an outer portion 40 of the corner edge portion 24, the outer portion 40 adjoining the central portion 36 of the corner edge portion 24. Put differently, the corner edge portion 24 of the first cutting edge 12 comprises the central portion 36 and the outer portion 40. The second primary land portion 34 extends along the central edge portion 36 and the transitional primary land portion 38 extends along the outer portion 40. The transitional primary land portion 38 does neither extend along the central portion 36 nor along linear edge portion 26.

[0053] The first primary land portion 32 differs from the second primary land portion 34. In these embodiments, the first primary land portion 32 extends over a first distance 42 of the rake face 16. The first distance 42 extends in a direction perpendicularly to the linear edge portion 26. The second primary land portion 34 extends over a second distance 44 of the rake face 16. The second distance 44 extends in a direction perpendicularly to tangents of the corner edge portion 24. The first distance 42 is longer than the second distance 44.

[0054] The first distance 42 is at least 50% longer than the second distance 44. In these embodiments the first distance 42 is approximately three times as long as the second distance 44. The transitional primary land portion 38 provides a gradual transition from the first primary land portion 32 to the second primary land portion 34. A width of the primary land measured perpendicularly to the first cutting edge 12 in the transitional primary land portion 38 decreases gradually from the first distance 42 to the second distance 44.

[0055] Mentioned purely as an example, the first distance 42 may be within the range of 0.1-0.5 mm and the second distance 44 may be within the range of 0.05-0.25 mm in a cutting insert having a linear edge portion 26 length of approximately 9-19 mm. In a cutting insert having a longer linear edge portion 26, the first distance may be up to 1 mm.

[0056] FIG. 3 illustrates a partial perspective view of the first cutting edge 12 of a turning tool cutting insert 2 according to embodiments. Again, the rake face 16 comprises a primary land extending along the first cutting edge 12. The primary land comprises a first primary land portion 32 adjacent the linear edge portion 26, and a second primary land portion 34 adjacent a central portion 36 of the corner edge portion 24. The primary land further comprises a transitional primary land portion 38 adjoining the first primary land portion 32 and the second primary land portion 34, and forming a transition between the first primary land portion 32 and the second primary land portion 34. The transitional primary land portion 38 is arranged only adjacent an outer portion 40 of the corner edge portion 24, the outer portion 40 adjoining the central portion 36 of the corner edge portion 24.

[0057] Again, the first primary land portion 32 differs from the second primary land portion 34. In these embodiments the second primary land portion 34 has a larger rake angle α2 than rake angle α1 of the first primary land portion 32. The transitional primary land portion 38 provides a gradual transition from the first primary land portion 32 to the second primary land portion 34. The rake angle in the transitional primary land portion 38 increases gradually from the rake angle α1 in the first primary land portion 32 to the larger rake angle α2 in the second primary land portion 34.

[0058] Mentioned purely as an example, the rake angle α1 in the first primary land portion 32 may be within a range of −15-15 degrees, which means that the wedge angle in the first primary land portion 32 may be within a range of 105-75 degrees. The wedge angle is the angle formed by the insert body, i.e. the angle between the relief face 14 and the primary land of the rake face 16. The rake angle α2 in the second primary land portion 34 may be within a range of 0-20 degrees which means that the wedge angle in the second primary land portion 34 may be within a range of 90-70 degrees. The rake angles α1 and α2 are nominal rake angles measured between a plane extending in parallel with a median plane of the rake face 16, and the first and second primary land portions 32, 34, respectively. The plane extending in parallel with a median plane of the rake face 16 extends perpendicularly to the centre axis 46 of the central hole 9, see FIG. 1.

[0059] In FIG. 3 the upper broken lines indicating the rake angles α1 and α2 extend in the above-mentioned plane extending in parallel with the median plane of the rake face 16. Accordingly, the rake angles α1 and α2 exemplified in FIG. 3 are positive rake angles with the first and second primary land portions 32, 34 extending below the plane extending in parallel with the median plane of the rake face 16. In a negative rake angle, which is encompassed by the exemplified range of the rake angle α1, the first primary land portion would extend above the plane extending in parallel with the median plane of the rake face 16. The term “increasing gradually” in the context of the rake angle in the transitional primary land portion 38 relates to positive rake angles in the first and second primary land portions 32, 34. Accordingly, in case the rake angle α1 in the first primary land portion is negative, the term “increasing gradually” is to be interpreted as reducing the rake angle until the rake angle becomes positive, at which point the positive rake angle may increase further. Put differently, the wedge angle in the transitional primary land portion 38 decreases gradually from the wedge angle in the first primary land portion 34 to the wedge angle of the second primary land portion 34.

[0060] In the embodiments of FIGS. 2 and 3 the convex corner edge portion 24 of the first cutting edge 12 has a standard ISO cutting insert nose radius e.g. within the range of 0.4-2.4 mm. The corner edge portion 24 extends over an angle of 80 degrees. In alternative embodiments the corner edge portion 24 may extend over an angle within a range of 60-90 degrees. Accordingly, the intermediate corner portion 25 indicated in FIG. 1 may extend over an angle within a range of 90-120 degrees. Mentioned purely as an example, the outer portion 40 of the corner edge portion 24 may extend over an angle γ within the range of 10-25 degrees, see FIG. 2. When the nose radius is small, such as e.g. 0.1-0.6 mm, the outer portion of the corner edge portion 24 may extend over a larger angle γ, e.g. 20-40 degrees. According to some embodiments the angle δ of the central portion 36 of the corner edge portion 24 may be larger than the two angles γ of the outer portions 40, 40′ together.

[0061] FIG. 4 illustrates a partial top view of the first cutting edge 12 of a turning tool cutting insert 2 according to embodiments. These embodiments resemble in much the embodiments of FIG. 2. The main differences is that the convex corner edge portion 24 in these embodiments is a multi-radius corner edge portion 24, as described e.g. in EP 759827. In these embodiments the corner edge portion 24 has three different radii R1, R2 and R3. The number of radii may be smaller or larger in alternative embodiments.

[0062] Again, the primary land comprises the first primary land portion 32 adjacent the linear edge portion 26, and the second primary land portion 34 adjacent the central portion 36 of the corner edge portion 24. The primary land further comprises a transitional primary land portion 38 adjoining the first primary land portion 32 and the second primary land portion 34, and forming a transition between the first primary land portion 32 and the second primary land portion 34. The first primary land portion 32 extends over a first distance 42 of the rake face 16. The first distance 42 extends in a direction perpendicularly to the linear edge portion 26. The second primary land portion 34 extends over a second distance 44 of the rake face 16. The second distance 44 extends in a direction perpendicularly to tangents of the corner edge portion 24. The first distance 42 is longer than the second distance 44.

[0063] In the embodiments of FIGS. 2 4 the first cutting edges 12 each may comprise a further linear cutting edge portion 30, as discussed in connection with FIG. 1. Accordingly, the primary land may also comprise a further transitional primary land portion 38′ adjoining a further first primary land portion 32′ and the second primary land portion 34 and forming a transition between the further first primary land portion 32′ and the second primary land portion 34.

[0064] In FIGS. 2-4 lines have been shown indicating both ends of the transitional primary land portion 38 for illustration purposes. In practice, the transition between each of the first and second primary land portions 32, 34 into the transitional primary land portion 38 may be less distinct.

[0065] FIG. 5 illustrates a turning tool 50 according to embodiments. The turning tool 50 comprises a tool body 52. The tool body 52 has a longitudinal axis 54 extending in a direction from an attachment portion 56 of the tool body 52 towards a distal end portion 58 of the tool body 52. The tool body 52 is provided with a recess 60 for receiving a cutting insert 2 at the distal end portion 58. The recess 60 is shaped such that the cutting insert 2 positioned in the recess 60 points an engaging corner edge portion 24 of a first cutting edge 12 thereof in a direction sidewardly of the longitudinal axis 54. That is, a bisector 28 of the corner edge portion 24 forms an angle β with the longitudinal axis 54. The angle β is within the range of >0-90 degrees. According to some embodiments the angle β may be within a range of 43-47 degrees to the longitudinal axis 54.

[0066] The cutting insert 2 arranged in the recess 60 is a turning tool cutting insert 2 according to aspects and/or embodiments discussed herein. A clamping mechanism 62 ensures that the cutting insert 2 is held securely in the recess 60. As an alternative to the illustrated clamping mechanism 62, the cutting insert 2 may be provided with a through hole 9 as disclosed in connection with the embodiments of FIG. 1, through which hole 9 a screw threaded into the tool body 52 may extend.

[0067] This invention should not be construed as limited to the embodiments set forth herein. A person skilled in the art will realize that different features of the embodiments disclosed herein may be combined to create embodiments other than those described herein, without departing from the scope of the present invention, as defined by the appended claims. The corner edge portion 24 may for instance comprise a further edge portion between the outer edge portion 40 and the linear edge portion 26. Accordingly, in some embodiments the first primary land portion 32 may extend along the further edge portion of the corner edge portion 24. Although the invention has been described with reference to example embodiments, many different alterations, modifications and the like will become apparent for those skilled in the art. The transitional primary land portion 38 may for instance provide a gradual transition both of the width of the primary land as well as the rake angle. Therefore, it is to be understood that the foregoing is illustrative of various example embodiments and that the invention is defined only by the appended claims.

[0068] As used herein, the term “comprising” or “comprises” is open-ended, and includes one or more stated features, elements, steps, components or functions but does not preclude the presence or addition of one or more other features, elements, steps, components, functions or groups thereof.