Ball end mill

A ball end mill comprising:

• an end mill body having an axis of rotation therethrough and having forward and rearward end portions;
• and
• first and second indexable cutter inserts each releasably attached to said forward end portion of said body, each insert comprising a plate having front and rear faces, said front face having at least one generally arcuate first marginal ridge with said first marginal ridge serving as a respective generally arcuate main cutting edge, said front face having at least one short second marginal ridge with said second marginal ridge serving as a respective short cutting edge, said main cutting edge having a leading end portion disposed at one end thereof and intersecting said short cutting edge in such a manner that an angle defined by said leading end portion and said short cutting edge is obtuse, said front face serving as a rake surface for said cutting edges and having a marginal surface portion disposed adjacent to said short cutting edge and said leading end portion, said marginal surface portion being convexly curved so as to slope toward said rear face toward said short cutting edge;
• the arrangement of said first insert with respect to said body being such that said leading end portion of said main cutting edge is disposed adjacent to said axis of said body, and that said short cutting edge of said first insert extends from said leading end portion beyond said axis of said body toward said rearward end portion of said body when viewed in a direction generally perpendicular to said front face, the arrangement of said second insert with respect to said body being such that said leading end portion is spaced radially outwardly of said body from said axis of said body.

A ball mill end comprising:

• an end mill body having an axis of rotation therethrough and having forward and rearward end portions;
• and
• an indexable first cutter insert releasably attached to said forward end portion of said body, said insert comprising a plate defined by a front face, a rear face and a plurality of pairs of first and second side faces disposed alternately and lying between said front face and said rear face, each of said first side faces cooperating with said front face to define a main cutting edge which is generally arcuately shaped when viewed in a direction perpendicular to said front face, each of said second side faces cooperating with said front face to define a secondary cutting edge, said secondary cutting edges being shorter than said main cutting edges, each of said main cutting edges having a leading end portion which intersects one of said secondary cutting edges at an obtuse angle and a trailing end portion which intersects the another of the secondary cutting edges, said front face serving as a rake surface for said main and secondary cutting edges and having a pair of marginal surface portions each disposed between the leading end portion of one of said main cutting edges and the trailing end portion of the other main cutting edge, said marginal surface portion being convexly curved so as to slope toward said rear face toward said secondary cutting edge;
• the arrangement of said first insert with respect to said body being such that said leading end portion of said main cutting edge is disposed adjacent to said axis of said body, and that said secondary cutting edge extends from said leading end portion beyond said axis of said body toward said rearward end portion of said body when viewed in a direction generally perpendicular to said front face so that said secondary cutting edge lies substantially opposite said axis from said main cutting edge.