Patent ID: 6193446
Filing Date: 2001-02-27
Classification: B23C,Y10T

Abstract:
In a cutting insert for chip forming machining, which comprises a basically polygonal body including a top face, a planar bottom face, two side surfaces extending between the top face and the bottom face and intersecting the top face to form two main cutting edges, and two end faces extending between the top face and the bottom face, a first portion of each end face intersecting the top face to form a first end edge, a second portion of each end face intersecting the top face to form a second end edge, each first end edge defining a secondary cutting edge and being offset outwardly relative to the respective second end edge, wherein each secondary cutting edge is disposed on a protruding cutting corner wherein each main and secondary cutting edge has a chamfer, wherein each of said peripheral side surfaces has a width increasing towards the respective cutting corner such that the cutting corner becomes situated on a raised portion of the insert body, the top face including sloping surfaces extending inwards from said chamfers of said main and secondary cutting edges and at least one upper chip surface arranged inside each of said sloping surfaces while extending towards a center of the insert so as to provide chip curling zones therebetween, the improvement wherein:a) each of the peripheral side surfaces is inclined at an acute angle from the top face wherein upper portions of the peripheral surfaces define clearance surfaces, each clearance surface and a lower portion of the respective peripheral side surface having a generally helical contour along their entire length,b) each of the sloping surfaces forming a primary chip breaking surface next to the respective main cutting edge and extending generally helically along its entire length and having a constant width along the entire main cutting edge, andc) each of the primary chip breaking surfaces extending inwards to an upwardly inclined surface defining a secondary chip breaking surface such that a V-shaped chip-curling cavity is formed therebetween.