Cutting insert having a rearwardly offset cutting edge and cutting tool
A cutting insert includes opposing forward and rear surfaces and a peripheral surface extending therebetween. The peripheral surface includes opposing side surfaces and opposing upper and lower surfaces. The upper surface and the forward surface intersect to form a main cutting edge having an associated relief surface that extends therefrom in the forward surface. One of the side surfaces comprises an insert side abutment surface. The rear surface comprises an insert rear abutment surface. The lower surface comprises an insert lower abutment surface. The insert rear and insert lower abutment surfaces form an obtuse abutment angle with respect to each other. In a side view along a side axis, a relief surface line tangent to the relief surface intersects the insert lower abutment surface.
1. A cutting insert ( 22 ) having an insert longitudinal axis (A), the cutting insert ( 22 ) comprising:
opposing forward and rear surfaces ( 34 , 36 ) and a peripheral surface ( 28 ) extending therebetween, the peripheral surface ( 28 ) comprising opposing side surfaces ( 26 ) connecting opposing upper and lower surfaces ( 38 , 40 ); and
an insert through bore ( 30 ) passing through the side surfaces ( 26 ) along a side axis (S); wherein:
the forward and upper surfaces ( 34 , 38 ) intersect to form a main cutting edge ( 42 ) having an associated relief surface ( 44 ) that extends therefrom in the forward surface ( 34 );
one of the side surfaces ( 26 ) comprises an insert side abutment surface ( 60 );
the rear surface ( 36 ) comprises an insert rear abutment surface ( 50 );
the lower surface ( 40 ) comprises an insert lower abutment surface ( 52 ); and
the insert rear and lower abutment surfaces ( 50 , 52 ) form an obtuse abutment angle (α) with respect to each other; wherein
in a side view of the cutting insert ( 22 ) along the side axis (S), a relief surface line (L R ) tangent to the relief surface ( 44 ) intersects the insert lower abutment surface ( 52 ).
2. The cutting insert ( 22 ) according to claim 1 , wherein the obtuse abutment angle (α) is in the range 110°≦α≦125°.
3. The cutting insert ( 22 ) according to claim 1 , wherein the insert rear and lower abutment surfaces ( 50 , 52 ) are planar.
4. The cutting insert ( 22 ) according to claim 1 , wherein the insert side abutment surface ( 60 ) is planar.
5. The cutting insert ( 22 ) according to claim 1 , wherein:
the insert lower abutment surface ( 52 ) extends longitudinally in the direction of the insert longitudinal axis (A).
6. The cutting insert ( 22 ) according to claim 1 , wherein
in a side view of the cutting insert ( 22 ) along the side axis (S), a main cutting edge line (L CE ) oriented perpendicularly to the insert longitudinal axis (A) and passing through the main cutting edge ( 42 ) intersects the insert lower abutment surface ( 52 ).
7. The cutting insert ( 22 ) according to claim 1 , wherein:
in a side view of the cutting insert ( 22 ) along the side axis (S), the upper and lower surfaces ( 38 , 40 ) are substantially parallel and define a cutting insert height (H), measured perpendicular to the insert longitudinal axis (A).
8. The cutting insert ( 22 ) according to claim 7 , wherein:
the cutting insert ( 22 ) has a maximum cutting insert length (L), measured in a direction of the insert longitudinal axis (A); and
the maximum cutting insert length L is in the range H≦L≦2H.
9. The cutting insert ( 22 ) according to claim 7 , wherein
in a side view of the cutting insert ( 22 ) along the side axis (S), an imaginary circle (IC), having a radius (R) which is greater than the cutting insert height (H), and which is positioned such that its circumference (C) touches the main cutting edge ( 42 ) at a circumference point (E) having a circle tangent line (L T ) that is perpendicular to the insert longitudinal axis (A), does not intersect the forward surface ( 34 ).
10. The cutting insert ( 22 ) according to claim 1 , wherein
in a side view of the cutting insert ( 22 ) along the side axis (S), the forward surface ( 34 ) comprises a forward concave portion ( 54 ), a forward convex portion ( 56 ) and a forward straight portion ( 58 ) extending therebetween, the forward concave portion ( 54 ) being located adjacent the relief surface ( 44 ) and the forward convex portion ( 56 ) being located adjacent the lower surface ( 40 ).
11. The cutting insert ( 22 ) according to claim 10 , wherein
in a side view of the cutting insert ( 22 ) along the side axis (S), the relief surface line (L R ) intersects the forward straight portion ( 58 ) proximate the forward concave portion ( 54 ).
12. The cutting insert ( 22 ) according to claim 10 , wherein
in a side view of the cutting insert ( 22 ) along the side axis (S), the forward straight portion ( 58 ) forms an acute forward surface angle (β) with respect to the insert lower abutment surface ( 52 ).
13. The cutting insert ( 22 ) according to claim 12 , wherein the acute forward surface angle β is in the range 55°≦β≦70°.
14. The cutting insert ( 22 ) according to claim 1 , wherein the cutting insert ( 22 ) comprises two main cutting edges ( 42 , 42 ′).
15. The cutting insert ( 22 ) according to claim 14 , wherein the cutting insert ( 22 ) has 180° rotational symmetry about the side axis (S).
16. The cutting insert ( 22 ) according to claim 1 , wherein in a side view of the cutting insert ( 22 ) along the side axis (S):
the cutting insert ( 22 ) is generally parallelogram-shaped; and
the main cutting edge ( 42 ) is located at an insert cutting corner ( 66 ) of the cutting insert.
17. The cutting insert ( 22 ) according to claim 1 , wherein:
each side surface ( 26 ) comprises a side clearance surface ( 62 ) extending between the upper and lower surfaces ( 38 , 40 ) and extending from a side raised surface ( 64 ) towards the forward surface ( 34 ), the side clearance surface ( 62 ) being recessed relative to the side raised surface ( 64 ), in a front view of the cutting insert ( 22 ).
18. The cutting insert ( 22 ) according to claim 1 , wherein
in a side view of the cutting insert ( 22 ) along the side axis (S), a clearance surface boundary (B CS ) of the side clearance surface ( 62 ) adjacent the side raised surface ( 64 ), on each side surface ( 26 ), is convex in the direction of the side axis (S).
19. The cutting insert ( 22 ) according to claim 1 , wherein the cutting insert ( 22 ) is one selected from a group consisting of a grooving insert, a threading insert, a profiling insert and a parting insert.
20. The cutting insert ( 22 ) according to claim 1 , wherein the forward and upper surfaces ( 34 , 38 ) are devoid of any abutment surfaces.
21. A cutting tool ( 20 ) comprising, in combination:
an insert holder ( 24 ), having a holder longitudinal axis (B); and
a cutting insert, in accordance with claim 1 , removably attached to the insert holder ( 24 ).
22. The cutting tool ( 20 ) according to claim 21 , wherein:
the insert holder ( 24 ) comprises:
a holder forward end surface ( 72 ) and a holder peripheral surface ( 74 ) forming a circumferential boundary thereof; and
an insert pocket ( 76 ) recessed in the holder peripheral surface ( 74 ) and opening out to the holder forward end surface ( 72 ), the insert pocket ( 76 ) comprising:
a pocket side surface ( 78 ) and a pocket peripheral wall surface ( 80 ) oriented substantially perpendicularly thereto, the pocket side surface ( 78 ) comprising a pocket side abutment surface ( 82 ), and the pocket peripheral wall surface ( 80 ) comprising pocket rear and lower abutment surfaces ( 86 , 88 ); wherein in an assembled position of the cutting tool ( 20 ):
the pocket lower abutment surface ( 88 ) abuts the insert lower abutment surface ( 52 ), the pocket rear abutment surface ( 86 ) abuts the insert rear abutment surface ( 50 ) and the pocket side abutment surface ( 82 ) abuts the insert side abutment surface ( 60 ).
23. The cutting tool ( 20 ) according to claim 22 , wherein the pocket side surface ( 78 ) comprises a threaded pocket bore ( 84 ) and the fastening member ( 32 ) is a screw.
24. The cutting tool ( 20 ) according to claim 22 , wherein
in a side view of the cutting tool ( 20 ) along the side axis (S), the relief surface line (L R ) intersects the pocket lower abutment surface ( 88 ).
25. The cutting tool ( 20 ) according to claim 22 , wherein
in a side view of the cutting tool ( 20 ) along the side axis (S), a main cutting edge line (L CE ) oriented perpendicularly to the insert longitudinal axis (A) and passing through the main cutting edge ( 42 ) intersects the pocket lower abutment surface ( 88 ).
26. The cutting tool ( 20 ) according to claim 22 , wherein:
the insert longitudinal axis (A) and the holder longitudinal axis (B) extend in the same direction.
27. The cutting tool ( 20 ) according to claim 22 , wherein
each side surface ( 26 ) comprises a side clearance surface ( 62 ) extending between the upper and lower surfaces ( 38 , 40 ) and extending from a side raised surface ( 64 ) towards the forward surface ( 34 ), the side clearance surface ( 62 ) being recessed relative to the side raised surface ( 64 ), in a front view of the cutting insert ( 22 ); wherein
in a side view of the cutting tool ( 20 ) along the side axis (S), viewing the side surface ( 26 ) that comprises the insert side abutment surface ( 60 ), the holder forward end surface ( 72 ) does not overlap the side clearance surface ( 62 ).
28. The cutting tool ( 20 ) according to claim 22 , wherein
a cutting force (F) applied to the main cutting edge ( 42 ) when the cutting insert ( 22 ) engages a work piece is opposed by both the pocket rear and pocket lower abutment surfaces ( 86 , 88 ).
29. A cutting tool ( 20 ) comprising, in combination:
a cutting insert ( 22 ) having an insert longitudinal axis (A), the cutting insert ( 22 ) comprising:
opposing forward and rear surfaces ( 34 , 36 ) and a peripheral surface ( 28 ) extending therebetween, the peripheral surface ( 28 ) comprising opposing side surfaces ( 26 ) connecting opposing upper and lower surfaces ( 38 , 40 ); and
an insert through bore ( 30 ) passing through the side surfaces ( 26 ) along a side axis (S); wherein:
the forward and upper surfaces ( 34 , 38 ) intersect to form a main cutting edge ( 42 ) having an associated relief surface ( 44 ) that extends therefrom in the forward surface ( 34 );
one of the side surfaces ( 26 ) comprises an insert side abutment surface ( 60 );
the rear surface ( 36 ) comprises an insert rear abutment surface ( 50 );
the lower surface ( 40 ) comprises an insert lower abutment surface ( 52 ); and
the insert rear and lower abutment surfaces ( 50 , 52 ) form an obtuse abutment angle (α) with respect to each other; and
an insert holder ( 24 ), having a holder longitudinal axis (B), comprising:
a holder forward end surface ( 72 ) and a holder peripheral surface ( 74 ) forming a circumferential boundary thereof;
an insert pocket ( 76 ) recessed in the holder peripheral surface ( 74 ) and opening out to the holder forward end surface ( 72 ), the insert pocket ( 76 ) comprising:
a pocket side surface ( 78 ) and a pocket peripheral wall surface ( 80 ) oriented substantially perpendicularly thereto, the pocket side surface ( 78 ) comprising a pocket side abutment surface ( 82 ), and the pocket peripheral wall surface ( 80 ) comprising pocket rear and lower abutment surfaces ( 86 , 88 ); wherein in an assembled position of the cutting tool ( 20 ):
the cutting insert ( 22 ) is removably attached to the insert holder ( 24 ) by a fastening member ( 32 );
the pocket lower abutment surface ( 88 ) abuts the insert lower abutment surface ( 52 ), the pocket rear abutment surface ( 86 ) abuts the insert rear abutment surface ( 50 ) and the pocket side abutment surface ( 82 ) abuts the insert side abutment surface ( 60 );
a forwardmost abutment point (P F ) is defined between the insert lower abutment surface ( 52 ) and the pocket lower abutment surface ( 88 ) furthest from the rear surface ( 36 ); and
in a side view of the cutting tool ( 20 ) along the side axis (S), the main cutting edge ( 42 ) is offset in a direction towards the rear surface ( 36 ) relative to the forwardmost abutment point (P F ), as measured along the insert longitudinal axis (A).
30. An indexable cutting insert ( 22 ) having an insert longitudinal axis (A), the cutting insert ( 22 ) comprising:
opposing forward and rear surfaces ( 34 , 36 ) and a peripheral surface ( 28 ) extending therebetween, the peripheral surface ( 28 ) comprising opposing side surfaces ( 26 ) connecting opposing upper and lower surfaces ( 38 , 40 ); and
an insert through bore ( 30 ) passing through the side surfaces ( 26 ) along a side axis (S) around which the cutting insert has 180° rotational symmetry; wherein:
the forward and upper surfaces ( 34 , 38 ) intersect at a first insert cutting corner ( 66 ) to form a first main cutting edge ( 42 ) having an associated rake surface ( 48 ) in the upper surface ( 34 ) and an associated relief surface ( 44 ) in the forward surface ( 34 );
the rear and lower surfaces ( 36 , 40 ) intersect at a second insert cutting corner ( 66 ) to form a second main cutting edge ( 42 ′) having an associated rake surface ( 48 ) in the lower surface ( 36 ) and an associated relief surface ( 44 ) in the rear surface ( 34 );
the cutting insert has a generally parallelogram-shape in a view along the side axis (S); and
the generally parallelogram-shape includes a short diagonal (D 1 ) connecting the insert cutting corners ( 66 ) and a long diagonal (D 2 ) connecting insert non-cutting corners ( 65 ).