CEMENTED CARBIDE CUTTING INSERT FOR PARTING METAL WORKPIECES

Abstract

A two-cutting-edge parting insert including a first cutting portion, a second cutting portion and an elongated body portion connecting the first and second cutting portions. The elongated body portion has a body width (BW) measurable parallel to a lateral axis and a body length (BL) measurable parallel to an elongation axis. The body width is smaller than both cut widths of the cutting edges of the first and second body portions and fulfills the condition: 0.65 mmBW0.95 mm; and the body length fulfills the condition: 2 mmBL14 mm.

Claims

1. A two-cutting-edge parting insert comprising: a first cutting portion; a second cutting portion; an elongated body portion connecting the first and second cutting portions; a rake surface; a base surface located opposite the rake surface; and a peripheral surface connecting the rake and base surfaces; the peripheral surface comprising: a front sub-surface at the first cutting portion; a rear sub-surface located at the second cutting portion and located opposite the front sub-surface; a left sub-surface connecting the front and rear sub-surfaces and located at one side of the parting insert; and a right sub-surface connecting the front and rear sub-surfaces and located opposite the left sub-surface; the body portion is elongated along an elongation axis extending through the center of the body portion; the elongation axis (A.sub.E) defines a forward direction (D.sub.F) from the second cutting portion towards the first cutting portion and a rearward direction (D.sub.R) opposite to the forward direction; the parting insert having an insert length (IL) measured along the elongation axis (A.sub.E); the parting insert having a height (H) measured perpendicular to the elongation axis (A.sub.E); a first central axis (A.sub.C1) is defined as perpendicular to the elongation axis and extending through the center of the parting insert and through the base surface and rake surface, the first central axis (A.sub.C1) defining an upward direction (D.sub.U) from the base surface towards the rake surface and a downward direction (D.sub.D) opposite to the upward direction; a second central axis (A.sub.C2) is defined as perpendicular to both the elongation axis (A.sub.E) and the first central axis (A.sub.C1) and extending through the center of the parting insert, the second central axis (A.sub.C2) defining a first side direction (D.sub.S1) and a second side direction (D.sub.S2) opposite thereto; the first cutting portion comprising: a first sub-rake surface at the rake surface; a first front sub-relief surface at the front sub-surface; a first left sub-relief surface at the left sub-surface; a first right sub-relief surface at the right sub-surface; a first cutting edge formed at an intersection of the first front sub-rake surface and each of the first front sub-relief surface, first left sub-relief surface and first right sub-relief surface; the first cutting edge comprising: a first forwardmost cutting sub-edge extending along an intersection of the first sub-rake surface and the first front sub-relief surface; a first left side sub-edge extending along an intersection of the first sub-rake surface and the first left sub-relief surface; a first right side sub-edge extending along an intersection of the first sub-rake surface and the first right sub-relief surface; a first left corner formed at an intersection of the first forwardmost cutting sub-edge and the first left side sub-edge; and a first right corner formed at an intersection of the first forwardmost cutting sub-edge and the first right side sub-edge; the second cutting portion comprising: a second sub-rake surface at the rake surface; a second front sub-relief surface at the rear sub-surface; a second left sub-relief surface at the right sub-surface; a second right sub-relief surface at the left sub-surface; a second cutting edge formed at an intersection of the second front sub-rake surface and each of the second front sub-relief surface, second left sub-relief surface and second right sub-relief surface; the second cutting edge comprising: a second forwardmost cutting sub-edge extending along an intersection of the second sub-rake surface and the second front sub-relief surface; a second left side sub-edge extending along an intersection of the second sub-rake surface and the second left sub-relief surface; a second right side sub-edge extending along an intersection of the second sub-rake surface and the second right sub-relief surface; a second left corner formed at an intersection of the second forwardmost cutting sub-edge and the second left side sub-edge; and a second right corner formed at an intersection of the second forwardmost cutting sub-edge and the second right side sub-edge; a lateral axis (A.sub.L) extends through a forwardmost part of the first cutting edge, the lateral axis (A.sub.L) extending parallel to the second central axis (A.sub.C2) and defining a first side direction (D.sub.S1) and a second side direction (D.sub.S2) opposite first side direction (D.sub.S1); the first cutting edge has a first cut width (CW1) measurable parallel to the lateral axis and from the first left corner to the first right corner; the second cutting edge has a second cut width (CW2) measurable parallel to the lateral axis and from the second left corner to the second right corner; the elongated body portion has a body width (BW) measurable parallel to the lateral axis and a body length (BL) measurable parallel to the elongation axis; wherein: the body width (BW): is smaller than both the first cut width (CW1) and the second cut width (CW2); and fulfills the condition: 0.65 mmBW0.95 mm; and the body length (BL): fulfills the condition: 2 mmBL14 mm.

2. The parting insert according to claim 1, wherein the body width (BW) fulfills the condition: 0.75 mmBW.

3. The parting insert according to claim 1, wherein the body width (BW) fulfills the condition: BW0.85 mm.

4. The parting insert according to claim 1, wherein the body length (BL) fulfills the condition: 6 mmBL.

5. The parting insert according to claim 4, wherein the body length (BL) fulfills the condition: 8 mmBL.

6. The parting insert according to claim 1, wherein the body length (BL) fulfills the condition: BL12 mm.

7. The parting insert according to claim 6, wherein the body length (BL) fulfills the condition: BL11 mm.

8. The parting insert according to claim 1, wherein the first cut width (CW1) and the second cut width (CW2) fulfill the condition: 0.9 mmCW1, CW21.1 mm.

9. The parting insert according to claim 8, wherein the first cut width (CW1) and the second cut width (CW2) fulfill the condition: 0.96 mmCW1, CW21.04 mm.

10. The parting insert according to claim 1, wherein the parting insert has a first operative length (OL1), measurable parallel to the elongation axis (A.sub.E) from a forwardmost point of the first cutting edge until an intersection of the body portion and the second cutting portion, fulfilling the condition: 5 mmOL115 mm.

11. The parting insert according to claim 10, wherein the first operative length (OL1) fulfills the condition: 9 mmOL113.5 mm.

12. The parting insert according to claim 11, wherein the first operative length (OL1) fulfills the condition: 11 mmOL112.5 mm.

13. The parting insert according to claim 1, wherein the parting insert is devoid of ground surfaces.

14. The parting insert according to claim 1, wherein the parting insert is 180 rotationally symmetric about the first central axis.

15. The parting insert according to claim 1, wherein the height (H) of the body portion fulfills the condition 3.5 mmH4.5 mm.

16. The parting insert according to claim 15, wherein the height (H) of the body portion fulfills the condition: 4.0 mmH4.3 mm.

17. The parting insert according to claim 1, wherein each corner of each cutting edge has a radius (R) fulfilling the condition 0.8 mmR1.20 mm.

18. The parting insert according to claim 1, wherein each of the first and second cutting portions has a chip-former arrangement comprising a single depression.

19. The parting insert according to claim 1, wherein the first cutting portion further comprises a first cutting portion length (L.sub.C1), measurable parallel to the elongation axis A.sub.E and fulfilling the condition 1.25 mmL.sub.C11.5 mm.

20. The parting insert according to claim 1, wherein a first insert ratio (R1) is defined as the ratio of the depth of cut (DC) to the first cutting width (CW1) (R1=DC/CW1), and fulfills the condition: 6R116.

21. The parting insert according to claim 1, wherein a second insert ratio (R2) is defined as the ratio of the insert length (IL) to the insert height (H) (R2=IL/H), and fulfills the condition: 1R24.5.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0093] For a better understanding of the subject matter of the present invention, and to show how the same may be carried out in practice, reference will now be made to the accompanying drawings derived from a scale model, in which:

[0094] FIG. 1 is a perspective view of a parting insert according to the present invention;

[0095] FIG. 2 is a plan view of a rake surface of the insert in FIG. 1;

[0096] FIG. 3 is a plan view of a rake surface of another insert according to the present invention and only differing to the insert in FIG. 1 in that it is a left type insert;

[0097] FIG. 4 is a plan view of a rake surface of yet another insert according to the present invention and only differing to the inserts in FIGS. 1 and 3 in that it is a right type insert;

[0098] FIG. 5A is a front view of the insert in FIG. 1;

[0099] FIG. 5B is a plan view of the rake surface of the insert in FIG. 5A (and is an identical view to FIG. 2);

[0100] FIG. 5C is a right side view of the insert in FIG. 5A;

[0101] FIG. 5D is a bottom view of the insert in FIG. 5A; and

[0102] FIG. 5E is a rear view of the insert in FIG. 1.

DETAILED DESCRIPTION

[0103] FIGS. 1, 2 and 5A to 5E, illustrate an exemplary parting insert 100 according to the present invention, which will be described in additional detail below. FIGS. 3 and 4 also illustrate parting inserts according to the present invention but the differences to parting insert 100 have already been described above in sufficient detail.

[0104] The parting insert 100 comprises a first cutting portion 110, a second cutting portion 112 and an elongated body portion 114 connecting the first and second cutting portions.

[0105] An arrow designated 116 shows the area that a cutting portion (in this example the second cutting portion 112) transitions to become the elongated body portion 114 (hereinafter a transition region 116). While this is visible by the thinning of the cutting portion until it reaches the width of the elongated body portion, it should also be understood that a cutting portion is functionally connected to a cutting function (i.e. contact with a workpiece (not shown) and the chips which are machined therefrom), whereas a body portion is not configured to provide a cutting function.

[0106] The parting insert 100 further comprises a rake surface 118, a base surface 120 (also referred to as a lower surface; the base surface is devoid of cutting edges) and a peripheral surface 122.

[0107] Referring to FIG. 2, the body portion 114 is elongated along the elongation axis A.sub.E extending through the center thereof. The elongation axis A.sub.E defines a forward direction D.sub.F from the second cutting portion 112 towards the first cutting portion 110 and a rearward direction D.sub.R opposite thereto.

[0108] Referring to the remainder of the figures as well, a first central axis A.sub.C1 (vertical axis) is defined as perpendicular to the elongation axis A.sub.E and extending through the center of the parting insert 100 and through the base surface 120 and rake surface 118, and, as shown in FIG. 5C, defines an upward direction D.sub.U and a downward direction D.sub.D.

[0109] A second central axis A.sub.C2 is defined as perpendicular to both the elongation axis A.sub.E and the first central axis A.sub.C1 and extending through the center of the parting insert 100, the second central axis A.sub.C2 defining a first side direction D.sub.S1 a second side direction D.sub.S2 opposite thereto.

[0110] The parting insert 100 comprises an insert length IL, measurable parallel to the elongation axis A.sub.E.

[0111] For the sake of conciseness, some of the description below may be only made to one part of the parting insert 100, since it is rotationally symmetric about the first central axis A.sub.C1 it should be understood that such features also exist at the opposing end thereof.

[0112] The peripheral surface 122 comprises a front sub-surface 122A at the first cutting portion 110, a rear sub-surface 122B located at the second cutting portion 112, a left sub-surface 122C and a right sub-surface 122D.

[0113] The first cutting portion 110 comprises a first sub-rake surface 110A at the rake surface 118. The first sub-rake surface 110A comprises a chip-former arrangement 124 in the form of a single depression.

[0114] The first cutting portion 110 further comprises a first front sub-relief surface 110B at the front sub-surface 122A, a first left sub-relief surface 110C at the left sub-surface 122C; a first right sub-relief surface 110D at the right sub-surface 122D. Notably, the preferred sub-relief surfaces (which are inwardly slanted) exemplified do not extend until the base surface 120, however it is also feasible for them to extend to the base surface 120. As shown in the preferred embodiment the sub-relief surfaces extend less than a third of the height H of the parting insert 100.

[0115] The first cutting edge 102 is formed at an intersection of the first front sub-rake surface 110A and each of the first front sub-relief surface 110B, first left sub-relief surface 110C and first right sub-relief surface 110D.

[0116] The portions of the cutting edge 102 are described above with reference to FIG. 2.

[0117] The first cutting portion 110 further comprises a first cutting portion length L.sub.C1, measurable parallel to the elongation axis A.sub.E. Similarly, the second cutting portion 112 can comprise a second cutting portion length L.sub.C2.

[0118] Rearward of the cutting edge, in a plan view of the rake surface (22), similar to the front and lateral surfaces (24, 78, 80) of U.S. Pat. No. 11,278,968, at least a portion of the insert body directly adjacent to the rake surface is relieved from the cut width defined by the cutting edge (see FIG. 2C). Stated differently, said portion is thinner than the cut width (i.e. extends in an inward lateral direction on both sides), so the insert body does not contact the slit in the workpiece being formed by the cutting edge.

[0119] The first cutting edge 102 has a first cut width CW1 and the second cutting edge 104 has a second cut width CW2.

[0120] The elongated body portion 114 has a body width BW and a body length BL.

[0121] The insert length IL equals the body length BL plus the first and second cutting portion lengths L.sub.C1, L.sub.C2 (IL=BL+L.sub.C1, +L.sub.C2).

[0122] Since the parting insert 100 can only enter a slit until the width of the insert body becomes wider, (taking into account that body widths BW are designed to be as wide as possible even at the thinnest portion thereof to avoid unnecessary weakening of the structure) when the first cutting portion 100 is the operative cutting portion (i.e. the parting insert 100 is being moved, relatively, towards a workpiece in the forward direction D.sub.F, the depth of cut DC is effectively equal to a first operative length OL1, measurable from a forwardmost point of the first cutting edge 102 until a transition region 116 between the elongated body portion 114 and the second cutting portion 112.

[0123] The parting insert 100 will have an identical depth of cut DC after the insert is indexed for the second cutting portion 112, i.e. a second operative length OL2.

[0124] The insert can have a first insert ratio R1 defined as the ratio of the depth of cut to the first cutting width (R1=DC/CW1). Thus, for an insert having a depth of cut DC=12 mm and a first cutting width CW1=1 mm, the first insert ratio is 12. Preferably, the first insert ratio R1 for a cutting insert in accordance with the subject matter of the present application fulfills the condition: 6R116, more preferably 10R114, and most preferably 11R113.

[0125] The insert can have a second insert ratio R2 defined as the ratio of the insert's length IL to the insert's height H (R2=IL/H). Thus, for an insert having a length IL=14 mm and height H=4 mm, the second insert ratio is 3.5. Preferably, the second insert ratio R2 for a cutting insert in accordance with the subject matter of the present application fulfills the condition: 1R24.5, more preferably 2.5R23.8, and most preferably 3R23.6.