The present invention relates to a cutting insert for grooving operations. In particular the present cutting insert according to the invention is suitable for radial grooving, although it also can be used for various axial grooving operations, as well as for axial and radial longitudinal turning operations.
During such machining operations, chip breaking and chip formation are often of decisive importance for undisturbed production. Modern high productive machines put very high priority on good chip transport. Long uncontrollable chips can easily cause machine interruptions and cessation. Chip control must therefore be given large attention and governs, to a high degree, the tool design.
Cutting inserts intended for grooving operations and parting off are usually clamped in a holder, which is blade shaped in order to be useful in the slot being produced. The expression xe2x80x9cholder of blade typexe2x80x9d is also intended to comprise slot mills. Such cutting inserts are, for example, known from U.S. Pat. Nos. 4,778,311, 4,992,008, 5,135,336 and 5,423,639. At the same time there is nowadays a demand if possible to be able to obtain improved surface finish of the surfaces in the slots produced.
A first purpose of the invention is to produce a cutting insert, which is well suited to give an improved and stronger cutting edge.
It is another purpose of the invention to produce a cutting insert, which is well suited for repeated radial grooving.
It is a third purpose to produce a cutting insert, which enables a good axial stop to be achieved in combination with high feed.
It is a fourth purpose with the present invention to produce a cutting insert, which also can be used for longitudinal turning.
The present invention involves a cutting insert which comprises a longitudinally elongated body having an upper face, a lower face, two side faces, and an end face disposed at a longitudinal end of the body. An upper edge of the end face forms a main cutting edge. A portion of the end face extending downwardly from the main cutting edge defines a clearance surface. Two side edges extend from respective ends of the main cutting edge. The clearance surface is of non-planar configuration, having a curvature which varies from one end of the main cutting edge to the other end thereof. A curved corner cutting edge extends between an end of the main cutting edge and a secondary cutting edge defined by one of the side edges. The curved corner cutting edge includes a curved primary portion extending from the respective end of the main cutting edge and having a first radius, and a curved secondary portion extending from the primary portion and having a larger radius than the primary portion.