Cutting knife with multiple insert blades

A rotary cutting knife for use in cutting apparatus wherein the cutting knife is rotated in a predetermined direction about an axis of rotation, comprising:

• a) a circular periphery blade carrier of predetermined thickness, having a planar front face, a rear face, and a peripheral wall of which at least a major portion is cylindrical about the axis of rotation, the blade carrier including a plurality of cylindrical bores extending inwardly from the peripheral wall at sites spaced equally around the periphery and at a predetermined distance from the front face, each bore having a longitudinal axis and being so oriented that i) an extension of its longitudinal axis beyond the peripheral wall intersects the plane defined by the front face at a first angle of from 12 to 25 degrees, and ii) its peripheral terminus lags its radially inward portion in the direction of rotation at a lag angle of up to 33 degrees, the lag angle being measured in a plane parallel to the front face between an extension of the bore's longitudinal axis at a point spaced a predetermined distance from the peripheral wall and a radius passing through said point from the axis of rotation, said point being on the circumference of a blade circle;
• b) a plurality of generally cylindrical blade inserts received in the cylindrical bores, each insert having inner and outer ends and a longitudinal axis, the outer end of each insert including a planar blade face inclined to form said above-mentioned first angle with the insert's longitudinal axis, the line of intersection of the blade face with the cylindrical surface of the insert defining a cutting edge which is a segment of an ellipse;
• and
• c) means securing the inserts in the cylindrical bores in such positions that their radially outermost tips lie along the blade circle and their blade faces all lie in a cutting plane parallel to the carrier's front face and located between said front face and the peripheral termini of the bores.