Indexable milling cutter

Claim 1

A cutting tool comprising an annular body with a central axis, a pair of end faces and an outer peripheral surface, a plurality of slots formed in the outer peripheral surface intersecting at least one end face of the body, each slot defining a generally longitudinally extending bottom wall surface and a pair of generally opposing side wall surfaces, an indexable cutting insert positioned in each slot and configured to define side surface faces, leading, trailing and bottom edges with the leading edge adjacent said at least one end face of the body, a wedge member positioned in the slot so as to bear against one side surface face of the cutting insert and one side wall surface of the slot securing the cutting insert therein, a backer plate positioned in the slots longitudinally behind each cutting insert, the backer plate also defining side surface faces, leading, trailing and bottom edges, the bottom edge of the backer plate being a narrow, non-linear surface extending from the leading edge to the trailing edge thereof, said non-linear surface including a point intermediate said leading and trailing edges which is lower than any other point on said bottom edge surface thereby permitting the backer plate to rock against the bottom wall into a position which provides accurate line contact between the leading edge of the backer plate and the trailing edge of the cutting insert, a wedge member positioned in the slot so as to bear against one side surface face of the cutting insert and one side wall surface of the slot.