Patent ID: 8082958

Claim:
A wood chipping knife comprising: a knife body having an inner side and an outer side, said body having a first edge, defined by an intersection of a first outer edge forming surface on the outer side of the knife and a first inner edge forming surface on the inner side of the knife; a second edge, defined by an intersection of a second outer edge forming surface on the outer side of the knife and a second inner edge forming surface on the inner side of the knife; a ridge on said inner side of the knife, said ridge projecting from said inner side and terminating in a crest; said ridge being positioned such that the crest of the ridge is parallel to the first and second edges; a concave surface portion on said inner side of the knife between the first inner edge forming surface and the crest of the ridge; and a flat planar surface portion on said inner side of the knife adjacent to the concave surface portion and located between the first inner edge forming surface and the concave surface, said first and second edges of the knife each being located on a reference plane which intersects the first and second edges; said flat planar surface portion forming a dihedral acute angle to and extending outward from, said reference plane; said concave surface tangentially joining said flat planar surface portion and curving outward therefrom away from the reference plane, and wherein the distance between any point on the concave surface portion on the inner side of the knife and the reference plane measured perpendicular to the reference plane and towards the inner side of the knife body is not less than a distance between any point on the flat planar surface and the reference plane, whereby the concave surface portion is exposed to wood chip flow during use to provide a chip guiding function during use.