HELICAL CUTTING INSERT WITH OFFSET CUTTING EDGES

摘要

A cutting insert (20) for use in a rotary milling tool (10) is provided. The cutting insert (20) includes an insert body including a bottom face (22), a top face (24) and a side face (26). A stepped cutting edge (20) is formed at the intersection of the top face (24) and the side face (26) for engaging a workpiece and removing a chip from it. The stepped cutting edge includes at least two offset edge portions (30a-c) which produce distinct, transversely- spaced chip segments during the cutting operation. The offset edge portions (30a-c) are connected by transition edge portions (30d-e) which are disposed at an obtuse angle with respect to the offset edge portions. The angle of th e transition edge portions tends to spread the individual chip segments apart during the machining operation to effect a thinning of the chip between the individual chip segments. The entire cutting edge is helically curved so tha t the cutting edge lies on the surface of a circumscribing cylinder defined by the rotation of the cutting edge about the axis of the milling cutter.