Tangential Cutting Insert and Insert Holder
A tangential indexable cutting insert can be used for metal cutting processes in general and for radial and axial turning of a stepped square shoulder in particular. The cutting insert exhibits 180° rotational symmetry about three mutually perpendicular axes. The cutting insert has generally “S”-shaped cutting edges extending between raised and lowered corners. The cutting edges and side surfaces are concave in an end view of the cutting insert. The cutting insert enables radial and axial turning operations of a square shoulder with unlimited depth of cut.
1 . An indexable cutting insert comprising:
two identical opposing end surfaces having 180° rotational symmetry about a first axis passing therethrough,
a peripheral side surface extending between the two opposing end surfaces, and
a peripheral edge formed at the intersection of each end surface and the peripheral side surface, at least two sections of each peripheral edge constituting cutting edges;
the peripheral side surface comprising:
two identical opposing major side surfaces having 180° rotational symmetry about a second axis passing therethrough, the second axis being perpendicular to the first axis; and
two identical opposing minor side surfaces having 180° rotational symmetry about a third axis passing therethrough, the third axis being perpendicular to the first axis and the second axis;
a median plane being defined by the second axis and the third axis;
each end surface having four corners, two lowered corners and two raised corners, the lowered corners being closer to the median plane than the raised corners;
the four raised corners belonging to the two end surfaces being equidistant from the median plane; and
the four lowered corners belonging to the two end surfaces being equidistant from the median plane.
2 . The indexable cutting insert according to claim 1 , wherein, in an end view, the cutting insert is generally rectangular in shape.
3 . The indexable cutting insert according to claim 2 , wherein adjacent major and minor edges extend from a corner edge of a raised corner to a respective lowered corner.
4 . The indexable cutting insert according to claim 3 , wherein the cutting insert further comprises an insert through bore having a bore axis.
5 . The indexable cutting insert according to claim 1 , wherein the cutting insert has a first distance between the minor side surfaces that is greater than a second distance between the major side surfaces.
6 . The indexable cutting insert according to claim 5 , wherein each peripheral edge has at least one major edge comprising a major cutting edge which slopes from an associated raised corner towards a first lowered corner for a major cutting edge length, the major cutting edge length being greater than one half of the first distance between the minor side surfaces.
7 . The indexable cutting insert according to claim 6 , wherein a slope of the at least one major edge decreases adjacent the lowered corner.
8 . The indexable cutting insert according to claim 6 , wherein each peripheral edge has at least one minor edge, the at least one minor edge comprising a minor cutting edge which slopes from said associated raised corner towards a second lowered corner for a minor cutting edge length, the minor cutting edge length being approximately one half of the second distance between the major side surfaces.
9 . The indexable cutting insert according to claim 5 , wherein each peripheral edge has at least one minor edge, the at least one minor edge comprising a minor cutting edge which slopes from an associated raised corner towards a first lowered corner for a minor cutting edge length, the minor cutting edge length being approximately one half of the second distance between the major side surfaces.
10 . The indexable cutting insert according to claim 1 , wherein each minor side surface merges with an adjacent major side surface at a corner side surface, wherein each corner side surface extends between a raised corer of a first of the two opposing end surfaces and a lowered corner of a second of the two opposing end surfaces.
11 . The indexable cutting insert according to claim 10 , wherein, each cutting edge comprises a major edge, a minor edge and a corner edge, therebetween.
12 . The indexable cutting insert according to claim 11 , wherein each major edge, corner edge, and minor edge is formed at the intersection of adjacent major side surface, corner side surface, and minor side surface, respectively with an adjacent end surface.
13 . The indexable cutting insert according to claim 12 , wherein each raised corner forms a corner cutting edge and adjacent major and minor edges form major and minor cutting edges, respectively.
14 . The indexable cutting insert according to claim 13 , wherein the major cutting edge has a major cutting edge length that is greater than one half of a first distance between the minor side surfaces.
15 . The indexable cutting insert according to claim 14 , wherein the minor cutting edge has a minor cutting edge length that is approximately one half of a second distance between the major side surfaces.
16 . The indexable cutting insert according to claim 13 , wherein the minor cutting edge has a minor cutting edge length that is approximately one half of a distance between the major side surfaces.
17 . A cutting tool comprising:
the cutting insert according to claim 1;
an insert holder having an insert pocket in which cutting insert is securely retained.
18 . The cutting tool according to claim 17 , wherein:
the cutting insert has an insert through bore;
the insert pocket comprises a base surface provided with a threaded receiving bore;
a securing screw extends through the insert through bore and threadingly engages the threaded receiving bore of the base surface to secure the cutting insert to the insert pocket.